ERA5L precipitation reanalysis datasets were provided by the European Centre for Medium-Range Weather Forecasts（ECMWF） Fifth Generation Land Surface Reanalysis （ERA5L）. An investigation of the applicability of ERA5L precipitation reanalysis datasets produced for Sichuan， Chongqing， Guizhou， Yunnan and Xizang in Southwest China has been conducted.Statistical metrics， including Pearson correlation coefficients （CCs）， mean relative deviations （MREs）， root mean square errors （RMSEs）， probability of detections （PODs）， false alarm rates （FARs）， and critical success indices （CSIs）， were employed to assess the features and accuracy of ERA5L precipitation data using 441 national ground stations of the China Meteorological Administration between 2018 and 2020.The characteristics and deviations of ERA5L precipitation data were analysed in aspects of different regions， stations， altitudes， and timescales （monthly and seasonal） in our assessment phase.The following insights were revealed： （1） ERA5L better represents precipitation changes in the southwestern region； however， it tends to show higher precipitation levels than the in-situ observations， especially in Xizang.（2） In the Sichuan Basin， high correlation has been found between ERA5L precipitation data and in-situ observations， with a small error.The areas of Xizang， Yunnan， Guizhou and Western Sichuan are characterized by complex terrains and mountainous regions.The ERA5L data here has a relatively higher error.（3） The ERA5L exhibits a clear monthly variation in error， with a decline in overall precipitation leading to higher MRE， lower POD， and increased FAR from July to February.The MRE decreases， the POD increases， and the FAR rate decreases as precipitation increases from February to July.The quality of ERA5L varies between provinces and seasons.There is excellent precipitation quality in Chongqing during spring and autumn， and in Guizhou and Sichuan during summer and winter.（4） ERA5L precipitation is overestimated compared to in-situ observations in light rain magnitude， but underestimated in moderate and above-moderate rain.The underestimate becomes more severe as the rain intensity increases.As a whole， ERA5L has the potential for various applications in Southwest China.The hierarchy of ERA5L precipitation quality from high to low occurs in the following order： low altitude， medium altitude， and high altitude.In the context of five provinces， the order of applicability from high to low is as follows： Chongqing， Guizhou， Sichuan， Yunnan， and Xizang.

The quantitative analysis of ground-based observations of atmospheric aerosols is a basic way to understand the optical properties of aerosols and the characteristics of atmospheric pollution， which can provide a certain basis for exploring the direction of pollution control.In recent years， there are few studies on the analysis of aerosol optical properties in different regions of Gansu Province using ground-based observations.In order to understand the atmospheric aerosol optical characteristics of different land surfaces in Gansu Province， we obtained the aerosol optical depth （AOD） of four stations in Gansu Province through ASTPwin software based on CE-318 solar photometer observations from April 2018 to September 2020 and calculated the Angstrom wavelength index α.The distribution and variation characteristics of AOD and α in different regions of Gansu Province in different seasons and the relationship between aerosol optical depth and wavelength index were analyzed.The results show that： （1） the changes of AOD in each wavelength band tend to be consistent in all stations during the observation period， and the AOD value decreases with increasing wavelength.The AOD values of Lanzhou and Gaolan Mountain were the highest in winter， followed by spring and autumn， and the lowest in summer.The winter and spring AOD values of Lanzhou exceeded the annual average by 14.98% and 4.68%， respectively， and the winter AOD value of Gaolan Mountain exceeded the annual average by 3.88%.Dunhuang and Minqin both had the highest AOD values in spring， which were 24.49% and 26.30% higher than their respective annual averages.The seasonal distribution of AOD in Dunhuang was： spring > summer > winter > autumn， while Minqin showed a trend of gradually smaller values from spring to winter.（2） The dominant particles in Lanzhou and Gaolan Mountain are coarse modal in spring and summer， while fine particles dominate in autumn and winter.Dunhuang and Minqin atmospheric aerosols are dominated by coarse modal particles all year round.In the winter of 2019， the AOD value of Lanzhou was 68.0% higher than that of Gaolan Mountain； Dunhuang and Minqin had more serious sand and dust aerosol pollution in spring 2019， and the AOD value of Dunhuang exceeded that of Minqin by 42.42%.（3） The frequency distribution of AOD and α at all sites showed a single-peaked curve， with variability in the range of high-frequency distribution of AOD in different seasons， but they were all below 1.0.The distribution of high-frequency range of α was more complex， with the range of α distribution less than 1.0 in spring in Lanzhou， spring and summer in Gaolan Mountain， four seasons in Dunhuang， and spring， summer and autumn in Minqin， while α in summer， autumn and winter in Lanzhou， autumn and winter in Gaolan Mountain， and winter in Minqin was mainly distributed at 1.1 or above.（4） The relationship between AOD and α differs in different seasons， which shows that the size of the dominant particles of aerosol differs in different seasons when the atmosphere is seriously or locally polluted.In spring when the atmosphere is in local or serious pollution and in summer when the atmosphere is in local pollution， the aerosols at the four stations are mainly large particle size， with the contribution of sand and dust aerosols being larger.In summer when the atmosphere is in serious pollution， Gaolan Mountain aerosol is mainly fine mode particles， Lanzhou， Dunhuang and Minqin aerosol is still controlled by coarse mode， but the proportion of pollution caused by small particle size in Lanzhou is higher than the remaining two stations， of which more than 85% belongs to urban industrial - aerosol pollution.In autumn， when the atmosphere is in serious pollution， Lanzhou and Gaolan Mountain are both dominated by fine modal particles， of which urban industrial-aerosols account for a significant increase， while Dunhuang and Minqin are still dominated by coarse modal particles， of which dust aerosols account for a large proportion.In winter， Lanzhou is still dominated by fine modal particles， while the other three stations are dominated by coarse modal particles.In winter， Dunhuang and Minqin are dominated by coarse and fine modal particles， while Gaolan Mountain is dominated by fine modal particles when the atmosphere is locally polluted.The analysis shows that， in general， aerosol pollution in the northern part of Gansu is dominated by sand and dust aerosols， while aerosol pollution in the southern part of Gansu shows alternating coarse-mode and fine-mode particles， which provides some references for the next study of aerosol properties and atmospheric pollution characteristics in different regions of Gansu by combining satellite remote sensing data.

Squall lines often produce extremely disastrous gales and play a crucial role in the safety of hytropower stations.This article explores a squall line event over the lower reaches of Jinsha River on June 4， 2016， which brought 13-level wind at the canyon of Baihetan Hytropower Station.This research detect the formation mechanism of this squall line from environmental conditions and medium-scale meteorology.The following conclusions are obtained： （1） Before the squall line arrived， the ground pressure dropped steadily by 9 hPa because of the low pressure， and the temperature of the canyon rises up above 14 ℃.As the squall line arrived， the pressure rises sharply with thunderstorm high pressure， and the temperature dropped more than 10 ℃.At the same time， the relative humidity reached as higher as 70%， accompanied by short-term precipitation.After the squall line left， the aforementioned meteorological elements restored to their original values.（2） Analysis on the synoptic scale circulation， we finds that Baihetan hytropower station located in the south of southwest vortex， which induced a wind convergence background at the low level.Meanwhile， the station lied in right side of the jet stream inlet at upper level， and strong vertical motion formed by the wind shear.As a result， the squall line to come into being.Furthermore， in the troposphere before the squall line， the atmospheric circulation displayed a dry-cold advection in the middle-upper level superimposed over a warm-wet advection and higher ground temperature in the lower levels， increasing the temperature lapse rate.t As a result， the strong static instability and convection accumulated， and the conditions were favorable for the squall line to live a long time.The analyses from vertical wind speed showed that the subsidence movement made the momentum spread down， and promoted the uplift in the front side of line， and a positive feedback effect developed， promoting a stable mechanism for the strong storm.（3） Radar of Zhaotong detection indicates that echo cell that greater than 30 dBZ aggregated costly into a band and embed with the strong echo cores of greater than 50 dBZ， as a cylindrical convective cloud of higher than 10 km.On the radical velocity field， the meso-scale convergence line coinciding with the banded strong echo， as well as MARC （Mid-Altitude Radial Convergence） characteristics of the mid-altitude radial convergence， were the trigger mechanism for the squall line.As the cloud structure of the storm， strong upward movement in front of the squall line leaded to the dome.As the squall line arrived， the echo core dropped rapidly， and the extreme gale of downburst formed， resulted the new convective monomers come in being along the canyon.

Observed soil moisture and precipitation as well as GLDAS and CMFD reanalysis data are used to analyze the spatial and temporal distribution and variation trend in the Loess Plateau region.Regression analysis， Granger causality test and singular value decomposition （SVD） are used to study the relationship between soil moisture and precipitation， and to analyze the temporal scale and spatial range of the influence of initial soil moisture on subsequent precipitation.The results show that the explained variance of the regression analysis of soil moisture and subsequent 1~2 months precipitation on the Loess Plateau is relatively high， with larger values in the summer and fall seasons （July， August， September， and October）.That the correlation between soil moisture and the subsequent 21 days of precipitation in different regions of the Loess Plateau （zones I， II， and III） is more frequent and concentrated than that in the whole region.This indicates that soil moisture on the Loess Plateau is heterogeneous so that a larger lagged precipitation time scale is just suitable for analysis at larger spatial scales.The Granger causality test shows that the initial soil moisture in the fall （October and November） across the Loess Plateau has a significant effect on the precipitation in the following 1 or 2 months， and the soil moisture in August also has a significant effect on the precipitation in October in Area III， which is consistent with the results of the regression analysis.The result of the SVD decomposition shows that from 1979 to 2014， when soils in the central， northern， and eastern parts of the Loess Plateau are wetter in July， the precipitation in the western and northern margins of the plateau is accordingly more in August.A wetter soil in the eastern part of the plateau in September means more precipitation in the western part of the plateau， as well as some parts of the northern and southern parts of the plateau， in October.The significant correlation between soil moisture and precipitation has fewer overlapping regions， suggesting spatial and temporal asymmetry in the influence of soil moisture on precipitation on the Loess Plateau.

The Qinghai-Xizang Plateau Vortex is a mesoscale low-pressure vortex system generated within the boundary layer of the Qinghai-Xizang plateau in summer， which not only has an important influence on the weather patterns and precipitation dynamics across the plateau， but also profoundly impacts the surrounding regions.In this study， the database of the plateau vortex obtained from an objective analysis method， along with ERA5-land reanalysis data， was utilized to conduct a comprehensive statistical and analytical investigation of the vortex's activity from 1950 to 2021.Various analytical methods， including correlation analysis， regression analysis， Bayesian time series analysis algorithm， and probability statistics were used.Furthermore， the intensity and path of the plateau vortex during the years 1950 and 2021 were specifically examined to identify the areas most sensitive to its activity during this time span.Results reveal a noteworthy increasing trend （at a 95% confidence level） in both the annual number and duration of the plateau vortex， with climate tendency rates of 0.16·a^-1 and 1.25 h·a^-1， respectively.However， the growing trend for the total number and duration of the plateau vortex during the active period （May to August） is not statistically significant.The sensitive areas that affect the activity of the plateau vortex are located on the north side of the northern Qinghai-Xizang Plateau and near the Hoh Xil Mountains， corresponding to the main mountains in the central and western Qinghai-Xizang Plateau.Furthermore， the study investigates the relationship between land surface parameters and the vortex's characteristics， showing positive correlations between latent heat， surface longwave radiation， and surface soil moisture （0~7 cm） with the number and duration of the plateau vortex.Conversely， sensible heat exhibits a negative correlation， it is further found that the plateau vortex is relatively consistent with precipitation when the time scale of the study is inter-annual， while on the daily scale， the sensible heat is positively correlated with the number， duration， and intensity of the plateau vortex mainly in the sensitive areas and to the east of the sensitive areas， with the most significant correlation being in the months of May and June.In conclusion， the results derived from this study provide a solid theoretical foundation for further exploration of the land-atmosphere interaction mechanism in the identified sensitive area.Moreover， these findings lay a critical foundation for enhancing numerical simulations and data assimilation studies of the Qinghai-Xizang Plateau Vortex.

Wind farm wakes have a significant impact on momentum and turbulence fluxes within the atmospheric boundary layer， thereby influencing the local climate and environment.Mesoscale numerical models incorporating wind farm parameterizations are powerful tools for studying the climate and environmental impacts of wind farms.In this study， the wind speed and turbulence kinetic energy profiles of the Fitch wind farm parameterization scheme in the WRF mesoscale model are evaluated in the turbine and wake regions using high-resolution Large Eddy Simulations （LES） as “true values” and a method based on the relation derived from classical momentum theory is proposed to correct the grid-inflow wind speed.The method takes into account the blocking effect caused by the grid equivalent thrust and the corrected wind speed is closer to the free-stream wind speed.Results show that the difference between the grid-inflow wind speed from the original Fitch parameterization scheme and the LES is significant and sensitive to the model horizontal resolution.The Fitch-new parameterization with corrected grid-inflow wind speed reduces the relative error in absolute value between grid-inflow and free-stream wind speed to less than 1% across different horizontal resolutions （1000 m， 500 m， and 250 m）.The spatially averaged thrust and output power are consistent with LES results.The Fitch-new parameterization improves the simulated wind speed deficit in the wake zone of wind turbine， especially in the grid with turbine under high resolution.Although the simulated increase in turbulent kinetic energy and its vertical distribution in the wake zone is improved compared to the original Fitch scheme， there are certain issues that require further investigation.

Based on station data and high-resolution reanalysis data， this study conducted a diagnostic analysis of the persistent heat wave that occurred in the arid region of northwest China during the summer of 2022 and quantified the contributing factors.The results showed a total of 2092 occurrences of high temperatures， primarily concentrated in the northern part of northwest China.Furthermore， the high temperatures exceeded historical extreme values recorded in the past 40 years at 108 stations and persisted for over 10 days at 98 stations， both of which are historically rare occurrences.The studied heatwave has a wide impact and long duration.During the prolonged period of high temperatures， the South Asian high-pressure center is positioned further north than usual and exhibits stronger intensity.In the early stages of the event， it is influenced by the warm ridge in the mid to upper levels， which gradually shifts eastward during the transition period.The continental high-pressure system gradually extends eastward and connects with the western Pacific subtropical high-pressure system （referred to as the "Western Pacific Subtropical High"） which extends both eastward and westward.This connection affects most of the northwestern regions.Within the northwestern region， there is strong water vapor divergence， making it difficult for precipitation to form.At the same time， there is an abnormal strengthening of the descending airflow， leading to warming in the upper atmosphere， which favors the development and maintenance of hot weather conditions.Whether it is in the early or later stages of the process， the temperature advection term contributes minimally to the warming process， while the vertical transport term and non-adiabatic heating term are key factors that influence extreme heat weather.From the perspective of influencing factors， the early stage of the process is mainly influenced by dynamic factors， while in the later stage， thermodynamic contributions dominate after the formation of a stable heat do stable heat dome.

Using daily 700 hPa geopotential height charts from October 2013 to October 2022， Southwest Vortex （SWV） annual data， European Centre for Medium-Range Weather Forecasts （ECMWF） ERA5 reanalysis data， and precipitation data from stations in Shaanxi Province， a statistical and diagnostic analysis was conducted on individual cases of heavy rain induced by the Southwest Vortex in southern Shaanxi.The results reveal the following insights： （1） Over the course of 10 years， there were a total of 119 days with heavy rain， among which 38 days were associated with heavy rain caused by the Southwest Vortex， accounting for about one-third （32%） of the total heavy rain days.These events were mostly observed from May to September， with the highest frequency in June.Statistically， the precipitation tended to start at night and end during the day.（2） The Southwest Vortex influencing southern Shaanxi originates primarily from the basin vortex， and typically， its movement eastward by 12 to 24 hours can lead to heavy rain in the region.The heavy rain area associated with the Southwest Vortex is mainly located in the northeast quadrant of the 700 hPa vortex center， to the south of the shear line， in the area with a large gradient of potential pseudo-equivalent potential temperature， at the intersection of the 500 hPa westerly trough and the outer southwest flow of the subtropical high， corresponding to the region of strong divergence at the 200 hPa level.（3） The study of the vertical structure of the Southwest Vortex indicates that the strong convergence center at 700 hPa is located to the east of the positive vorticity center.This region corresponds well with the heavy rainfall area.Strong divergence under high-altitude jet streams leads to air quality adjustment， lower-level convergence， and frontal genesis.（4） There are three moisture transport channels： one comes from the warm sea surface of the western Bay of Bengal， the second originates from the warm sea surface in the eastern Bay of Bengal， and the third derives from the South China Sea.During heavy rain periods， the cyclonic-like vorticity， divergence， moisture flux divergence generated by the terrain in the Qinba Mountain region combined with the systematic vorticity， divergence， and moisture flux divergence， enhancing the lower-level convergence.This is also an important factor contributing to the formation of heavy rain induced by the Southwest Vortex in southern Shaanxi.

Heavy rainfall and high air temperature are the main factors inducing glacial debris flows.In-depth understanding of the variation of disaster-pregnant meteorological conditions of glacial debris flows in small watersheds can provide basis and basic data for early warning and disaster prevention of glacial debris flows.Based on the China Meteorological Forcing Dataset （CMFD） （1979 -2018）， the inter-annual and intra-annual variation characteristics of rainfall， air temperature， and extreme climate index in Kada valley are analyzed using several methods， including Sen's slope， Mann-Kendall trend and mutation test， Sliding t-test， Morlet wavelet transform， coefficient of variation （CV）， and precipitation concentration index （PCI）.The results show that： （1） Both the average annual air temperature and the warm days showed a significant rising trend at rates of 0.05 ℃·a^-1 and 1.46 d·a^-1， respectively， but the inter-annual variance of the warm days was very high.Both the average annual air temperature and the warm days exhibited quasi-periods of 32 a and mid to short-term scale periods.（2） The air temperature in spring， summer， autumn and winter increased significantly at rates of 0.044 ℃·a^-1， 0.039 ℃·a^-1， 0.049 ℃·a^-1 and 0.06 ℃·a^-1， respectively.The air temperature increased significantly in all months， with March and November showing significant inter-annual fluctuations.（3） The decreasing trend of annual rainfall was not significant.Although no significant trend in extreme rainfall days was observed， it fluctuated considerably from year to year， with a sudden change occurring in 1988.Both annual rainfall and extreme rainfall days exhibited multiscale periods of 16~22 a， 8~10 a， 4~6 a， 2~5 a and 2~3 a.（4） The intra-annual distribution of rainfall is generally more balanced.The overall changing pattern of seasonal and monthly rainfall was not significant， except for a noticeable decline in rainfall during June and July， at rates of 1.44 mm·a^-1 and 1.15 mm·a^-1， respectively.In general， the climate in the Kada valley is transitioning from hot and humid to dry and hot.Additionally， it is in the rainy period of multiscale periodic strong amplitude centers superposition of 2~3 a and 4~6 a， as well as the high air temperature period of 8~11 a.At the same time， the warm days， extreme rainfall days， and monthly rainfall have moderate or greater variation， increasing the likelihood of extreme drought and flood events.The combination of extreme hydrothermal conditions raises the risk of glacial debris flow outbreak in the Kada valley.

Reliable precipitation information is particularly important for understanding the water balance and water cycle processes in the Qinghai-Xizang Plateau.As a new generation of satellite precipitation data， IMERG （Integrated Multi-satellitE Retrievals for Global Precipitation Measurement） represents an advanced iteration in satellite precipitation data， characterized by expanded coverage and heightened spatiotemporal resolution.However， due to the complex terrain in the Qinghai-Xizang Plateau， IMERG still has great uncertainty in the plateau region.In view of this， this study performs bias correction of IMERG daily precipitation data based on the Quantile Delta Mapping （QDM） method.The transfer function is established seasonally using CMFD （China Meteorological Forcing Dataset） precipitation and IMERG daily precipitation data during 2001 -2010 to correct IMERG daily precipitation during 2011 -2014.The results show that： （1） The QDM method can effectively correct the frequency， value， and spatial distribution of IMERG precipitation products， and the corrections are more effective for extreme precipitation and large negative deviation regions.The probability distribution of corrected IMERG daily precipitation is closer to that of the observations， and the precipitation deviation is more in line with the normal distribution.Monthly precipitation and the spatial distribution characteristics of annual and seasonal precipitation are improved.（2） The root mean square error of the corrected daily precipitation is reduced from 1.49 mm·d^-1 to 1.26 mm·d^-1 with an improvement by 15.44%.The critical success index CSI， probability of detection POD， false alarm rate FAR， precision rate， and F_score of the corrected daily precipitation in different precipitation intensities are improved， and the Bias score of tiny and torrential precipitation is enhanced.（3） After correction， the extreme precipitation is significantly improved， and the mean values of the simple daily intensity index （SDII） and percentile-based threshold indices （R95p and R99p） are closer to the observed values.The spatial distribution of extreme precipitation is effectively displayed， and the bias of extreme precipitation is reduced from over 30% to within 5%.The root mean square error of SDII， R95p， and R99p is reduced from 1.59， 6.54， and 14.89 mm·d^-1 to 0.65， 3.01， and 8.99 mm·d^-1 with the accuracy improved by 59.12%， 53.98%， and 39.62%， respectively.This study verifies the applicability of the Quantile Delta Mapping method in the Tibetan Plateau， which is beneficial for obtaining more accurate precipitation data for meteorological and hydrological studies in the region.

Many new-generation Doppler weather radars in China are located in mountainous areas with complex topography， and the problem of low elevation angle terrain occlusion is prominent.When estimating precipitation by radar in the occluded area， observations with higher elevation angles need to be used， and due to the micro-physical changes and horizontal motion of precipitation particles during their descent， the reflectivity factor at high locations of the same site is often very different from that near the surface， which will increase the estimation error when used directly for estimating surface precipitation.In this paper， we propose a method for the vertical revision of reflectivity factor.First， we establish the vertical reflectivity factor profiles （VPR） of different precipitation types in the unobstructed observation area， and then revise the observations above the height to be revised to the target height by determining the height threshold to be revised and the near-surface target height based on the vertical variation characteristics of the profiles.The comparison test results show that： the revised target reflectivity factor data are less different from the actual observed data values， and the consistency is improved； moreover， the data at low VPR are more accurate by considering the occlusion factor； since the VPR of different precipitation types are significantly different， the differentiation of precipitation types can avoid mis-correction.The proposed revision method is not only applicable to the beam blocking area， but also generally applicable to the revision of the observed data at high beam height at long distances.

"21·7" severe torrential rain occurred in Middle-North of Henan Province from 18 to 22 July 2021， which has been studied by many scholars.Affected by the northward movement of the weather systems in “21·7” torrential rain， a regional heavy rainstorm occurred subsequently in the middle section of Taihang Mountains from 20 to 22 July.Based on 0.25°×0.25° hourly ERA5 reanalysis data and multi-source high-resolution observation data from 2508 ground dense automatic weather stations， Doppler radar， wind profile radar， L-band radiosonde， ground-based GPS water vapor and so on， the characteristics and synoptic analysis of the heavy rain in the middle section of Taihang Mountains from 20 to 22 July 2021 were analyzed.The results show that： （1） The main weather systems were subtropical high， upper-tropospheric low vortex， shear line， low-level jet， moreover the long-distance water vapor transport of double typhoon of "In-Fa" and "Cempaka" was favorable to the heavy rain.The main synoptic background was stable atmospheric circulation and long-term maintenance of low-level easterly wind.（2） The locations of surface convergence line， surface dew point temperature front area， the strong echo area with reflectivity factor greater than 30 dBz， and short-term heavy precipitation zone of hourly precipitation greater than 10 mm were nearly consistent and stably maintained at the eastern foot of Taihang Mountains with less movement and long duration.During heavy precipitation phases， the easterly component of low-level winds increased， and the maximum height of east wind decreased.Farther， the maximum easterly component was 8 to 11 m·s^-1， the maximum height of east wind was 510 m.The maximum height of low-level easterly jet was 510 m to 2310 m， the maximum low-level jet index was 33.1×10^-3 s^-1； The maximum vertical wind shear of 0~1 km and 0~3 km were 11.9 m·s^-1 and 16.9 m·s^-1 respectively.The easterly wind and Taihang Mountains made a horizontal convergence on windward slope， also the obvious terrain effect induced the increase of precipitation.（3） The deep wet layer extended from the ground to 400 hPa.During the precipitation process， the condensation height was close to the surface.The convective effective potential energy in the early stage of precipitation was 1925.5 J·kg^-1.In the stage of heavy precipitation， when the GPS water vapor was higher than 50 mm， the start time of high water vapor was 5~6 hours ahead of the precipitation.The large value of water vapor flux of the middle and lower layers in the western mountainous area lasted for more than 10 hours， and the water vapor convergence was significantly higher than that in the East.Heavy precipitation presented as a band shape in front of Taihang Mountains.（4） The centroid of radar echo was low， and the strong echo area with reflectivity factor greater than 30 dBz lasted for 20 hours， the characteristics of train effect and warm-cloud precipitation were obvious in the western mountainous area.

The hinterland of the Qinghai-Xizang （Tibet） Plateau is affected by two major circulation systems， Westerly Wind and Indian Ocean monsoon.The average altitude of the region is high， and the terrain is complex and changeable.It is extremely complicated that the temperature and precipitation conditions in this region as a comparison to other areas of the Qinghai-Xizang （Tibet） Plateau.In order to accurately obtain the temporal and spatial changes of temperature and precipitation in this region and predict future temperature and precipitation changes， based on the CN05.1 observation dataset， the ability of CMIP6 data to simulate temperature and precipitation in the hinterland of the Qinghai-Xizang （Tibet） Plateau was evaluated.CMIP6 was corrected using Spatial Disaggregation and Equidistant Cumulative Distribution Functions Method Temperature and precipitation conditions of 5 climate models and 7 scenarios in 2015-2100 were estimated.The results show that： （1） In the historical period （from 1961 to 2014）， the temperature and precipitation observation values of CMIP6 data have little deviation from the simulation values， and have strong space-time correlation.（2） In the future （from 2021 to 2100）， the annual average temperature and precipitation will show an overall upward trend.The percentage of temperature anomaly and precipitation anomaly in 2021-2100 of SSP3-7.0 and SSP5-8.5 scenarios increased significantly.The high value of temperatures anomaly is concentrated in the Qaidam Basin， and the high value of precipitation anomaly is located at the source of the Lancang River in the southeast.（3） In the future， the temperature will continue to increase in the four seasons， the precipitation will also show an overall trend of rise in four seasons.However， the degree of precipitation increase is distinct in different seasons and different scenarios.In the four seasons， the temperature increase of SSP5-8.5 scenario is the largest.The temperature of SSP5-8.5 scenario increases fastest in autumn； The precipitation of SSP3-7.0 scenario increases fastest in summer and winter， while that of SSP5-8.5 scenario increases fastest in spring and autumn.（4） Except for the SSP1-1.9 scenario， the temperature of each scenario from the recent period to the end of the period shows strong temporal and spatial similarity.Against to the historical period， the spatial distribution of temperature in spring and winter showed a consistently rising tendency is similar， and that in summer and autumn is similar.The precipitation increase is the largest in summer and the smallest in winter.Compared with the historical period， the spatial distribution of precipitation anomaly percentage shows a strong seasonality and regional feature.The high value area is mainly distributed in the southeast of the study area.

The Qinghai-Xizang （Tibetan） Plateau is known as the Asian water tower.The change of its water resources has an important impact on the weather and climate in the lower reaches.Precipitation is a key role in the water cycle.Therefore， it is of great significance to accurately simulate plateau precipitation for water resources security in China.In recent years， some studies have found that the convection-permitting model （the cumulus parameterization scheme could be turned off when grid scale is less than 4 km） could improve the precipitation simulation over the Qinghai-Xizang （Tibetan） Plateau.However， the previous studies only selected 1~3 cumulus parameterization schemes for comparison.It is still unknown whether convection-permitting model is superior to any cumulus parameterization scheme.In this paper， the ability of nine cumulus parameterization schemes in WRF and convection-permitting model （CPM） in simulating the precipitation over the Qinghai-Xizang （Tibetan） Plateau in the summer of 2009 was evaluated.The results showed that the simulations overestimate the summer precipitation over Qinghai-Xizang （Tibetan） Plateau in 2009， and the error was about 0.4~2 mm·d^-1.The over simulation of CAPE and latent heat flux in Qinghai-Xizang （Tibetan） Plateau may be one of the reasons for the overestimations.Among all simulations， the G3 cumulus parameterization scheme has the best simulation of the mean precipitation the mean precipitation and the dinural cycles precipitation and it can can better capture the precipitation intensity， spatial distribution， precipitation area and diurnal cycles of the mean precipitation.CPM showed overall the second best precipitation simulation following G3 cumulus parameterization scheme， which can not effectively improve the simulation of diurnal cycles of precipitation， but can improve the simulation of precipitation frequency.In different plateau ecological regions， all simulations cannot reasonably simulate the precipitation in the desert area and the southern foot of the Himalaya， but compared with the cumulus parameterization schemes， CPM can greatly reduce the error in the desert area.In other regions， CPM and Tiedtke cumulus parameterization scheme performed well.Considering the mean precipitation and precipitation frequency， the CPM， Tiedtke and G3 cumulus parameterization scheme have the minimum simulation error for precipitation in different regions and intensity.Therefore， we recommend to adopt G3 or Tiedtke cumulus parameterization schemes in simulating summer precipitation over the Qinghai-Xizang （Tibetan） Plateau， and when the computational resources are allowed， the high-resolution CPM can be considered to improve the precipitation frequency simulations.

Based on the MODIS MCD19A2 aerosol dataset， the temporal and spatial distribution characteristics of the atmospheric aerosol optical thickness （AOD） and the influence of meteorological factors in the Qaidam Basin from 2001 to 2021 were investigated by using linear trend， Spearman correlation analysis， and ?ngstr?m exponential interpolation， and the results show that： （1） On the interannual scale， the AOD in the Qaidam Basin fluctuates upward， with an annual increase of 3.74% and an annual mean value of 0.110±0.002； on the seasonal scale， AOD has obvious seasonal changes， and its value from high to low is spring， summer， autumn and winter， respectively.AOD in spring and summer fluctuates， while AOD in autumn and winter has no obvious change.on the monthly scale， the AOD is in the shape of a single peak， and the peak value is in April.（2） In space， the high value area of AOD is located in the hinterland of Qaidam Basin， showing the distribution characteristics of high in the middle and low around， and the low value area is located in the high altitude areas such as Kunlun Mountain Range and Qilian Mountain Range and the area with high vegetation cover.（3） Meteorological factors have a certain influence on AOD， among which wind speed， temperature， relative humidity， cloudiness and precipitation are positively correlated with AOD， and wind speed and temperature have the greatest influence on AOD.

As a climate-sensitive region， precipitation over the Qinghai-Xizang （Tibetan） Plateau significantly impacts the water cycle and the climate of East Asia.Therefore， it is important to study its changes.Precipitation is an important variable in the global hydrological cycle and one of the major climate systems affected by climate change.To investigate the ability of the global climate models to simulate precipitation over the Qinghai-Xizang （Tibetan） Plateau and examine possible changes in future precipitation under the new model and scenarios， this paper uses the latest monthly precipitation data from the 31 climate models of the Coupled Model Intercomparison Project 6 （CMIP6） and the CN05.1 precipitation observation data set provided by the National Climate Center to evaluate the ability of the CMIP6 model to simulate precipitation over the Qinghai-Xizang （Tibetan） Plateau.Furthermore， better models are selected to project the future precipitation of the Qinghai-Xizang （Tibetan） Plateau under different Shared Socioeconomic Pathway （SSP） scenarios.The results show that the model distribution of observed precipitation over the Qinghai-Xizang （Tibetan） Plateau from 1995 to 2014 is characterized by a decrease from southeast to northwest and a summer precipitation concentration.Most of the models can simulate the precipitation distribution and seasonal trend， but almost all of them overestimate the precipitation phenomenon， and the average precipitation of multiple modes is 102% higher than that observed.In general， the latest model of CMIP6 has a poor ability to simulate precipitation over the Qinghai-Xizang （Tibetan） Plateau， and the average relative deviation index of the model from the observation is 102%， indicating that most of the models are not satisfactory， and EC-Earth3-Veg-LR， MPI-ESM1-2-LR， EC-Earth3-Veg， and MRI-ESM2-0 are selected as the better modes after quantitative analysis of all the models， which can roughly reflect the precipitation characteristics of the Qinghai-Xizang （Tibetan） Plateau.Climate models show the slowest increase of precipitation over the Qinghai-Xizang （Tibetan） Plateau under the SSP1-2.6 scenario and the fastest increase under SSP5-8.5.From SSP1-2.6 in the small radiative forcing scenario to SSP5-8.5 in the large scenario， the recent （from 2021 to 2040） precipitation increase on the plateau is difficult to find a large difference in each scenario， but there is a significant increase in the mid （from 2041 to 2060） and late （from 2081 to 2100） scenarios， indicating that carbon emission intensity has a small impact in the short term and a large impact in the long term.The future increase in precipitation mainly occurs in the area south of the Nianqing Tanggula Mountains， from a seasonal point of view， the summer increase is the largest， followed by spring and autumn， the smallest increase is in winter， so we should pay attention to the future summer and spring precipitation changes over the Qinghai-Xizang （Tibetan） Plateau and take coping measures.

In this paper， a new numerical scheme was proposed to solve the advection equation in a multi-moment nonhydrostatic dynamical core.To guarantee the shape-preserving property， the limiting operations are devised for a hybrid discretization framework adopted by the multi-moment dynamical core， consisting of the multi-moment finite-volume and the conservative finite-difference schemes for the horizontal and vertical discretizations respectively.In the horizontal direction， a nonoscillaory scheme is accomplished by adjusting the slope of the multi-moment reconstruction polynomial at the cell center with the application of a WENO （weighted essentially non-oscillatory） algorithm.The resulting multi-moment scheme can achieve the fourth-order accuracy in the convergence test.In the vertical direction， a TVD （total variation diminishing） slope limiter is applied in the finite-difference discretization to remove the non-physical oscillations around the discontinuities.To accomplish the time marching in the proposed advection model， a second-order paired explicit Runge-Kutta scheme is adopted， which is expected to be an efficient and practical method for the advection solvers in the atmospheric models with very high spatial resolutions.The explicit time marching， without the dimension splitting， is useful to avoid the divergence errors in the advection transport calculations.Two Runge-Kutta schemes， requiring different times of conducting the spatial discretization within a time step， are combined， and used for the time marching in the different directions.The finite-difference discretization is called for six times within a time step in order to increase the maximum available CFL （Courant-Friedrichs-Lewy） number in the vertical direction， while the horizontal multi-moment spatial discretization is conducted for two times as the regular second-order schemes.As a result， the difference between the maximum time steps determined by the horizontal and vertical discretizations， due to the very large aspect ratio of the computational cells in atmospheric modeling， can be diminished.The non-negativity property of the proposed advection scheme is assured by devising a new flux-correction algorithm.It improves the existing positivity-preserving algorithm through further considering the mass flowing into the computational cell in an iterative procedure during the flux-correction operations.The proposed flux-correction algorithm can approach the necessary and sufficient condition for assuring the non-negative solutions and is more accurate for the advection calculations with CFL numbers larger than one.The widely used two-dimensional benchmark tests were checked in this study and the numerical results verified the performance the proposed advection scheme， which has the practical potential to build an accurate and efficient advection equation solver for the scalable high-resolution nonhydrostatic atmospheric models.

Most of the regional heavy rain processes in the monsoon region of China are related to the low-level jet.However， in arid and semi-arid regions， the low-level jet stream is not necessarily associated with every rainstorm process.Based on the daily precipitation data from May to September from 1971 to 2020， hourly precipitation data from 2011 to 2020， and the radiosonde data from Ruoqiang Station twice a day， the observational characteristics of heavy rain with and without easterly low-level jet in southern Xinjiang in recent 40 years were analyzed by statistical methods.The results show that the number of rainstorm days accompanied by easterly low-level jet is slightly less than that without easterly low-level jet in southern Xinjiang in recent 40 years.Both of them showed an increasing trend in the past 40 years， but the increasing trend of the number of rainstorm days accompanied by the easterly low-level jet was more significant.In the past 40 years， the proportion of rainstorm days accompanied by easterly low-level jet to the total rainstorm days in southern Xinjiang showed an increasing trend， while the proportion of rainstorm days without easterly low-level jet showed a decreasing trend.In the warm season of southern Xinjiang， the number of rainstorm days accompanied by easterly low-level jet was the highest in May， while the number of rainstorm days without easterly low-level jet was the highest in July， and both of them were the least in September.From the 1970s to the 1990s， the heavy rain in the warm season in southern Xinjiang was mainly accompanied by the easterly low-level jet， and from the 2000s to the present， the heavy rain was mainly accompanied by the easterly low-level jet.The number of rainstorm days is relatively higher in the western part of southern Xinjiang， and the rainstorm is mainly accompanied by easterly low level jet stream.The proportion of short-time heavy precipitation events in the rainstorm without the easterly low-level jet in the warm season in southern Xinjiang is significantly higher than that in the rainstorm with the easterly low-level jet.The rainstorm accompanied by the easterly low-level jet is dominated by night rain， while the rainstorm without the easterly low-level jet is dominated by day rain.In the warm season of southern Xinjiang， the periods of maximum precipitation and maximum occurrence of the rainstorm with the easterly low-level jet mainly occurred around midnight， while the periods of maximum precipitation of the rainstorm without the easterly low-level jet mainly occurred from late afternoon to late afternoon.The maximum cumulative frequency of the rainstorm without the easterly low-level jet is similar to that of the rainstorm with the easterly low-level jet occurred around midnight.The maximum intensity of both types of torrential rain occurs from mid-afternoon to late afternoon.The peak value of rainstorm precipitation with easterly low-level jet in the warm season in southern Xinjiang was mainly caused by the frequency of precipitation in the early night， while the sub-peak value of rainstorm precipitation around evening was mainly caused by the intensity of precipitation.The diurnal variation characteristics of rainstorm precipitation without easterly low-level jet in the warm season in southern Xinjiang are similar to its precipitation intensity， and the difference between it and its precipitation frequency is great.There is a great difference between the rainstorm with easterly low level jet and the rainstorm without easterly low level jet in the warm season of southern Xinjiang.At present， the research on the formation mechanism of rainstorm in southern Xinjiang with the coordination of easterly low level jet from Tarim is relatively mature， while the formation mechanism of rainstorm without the coordination of easterly low level jet from Tarim is still unclear.

Using FNL （Final Reanalysis Data）， ERA5 （ECMWF Reanalysis V5） reanalysis data， and GPM （Global Precipitation Measurement） global half-hourly precipitation data， a strong precipitation event in the southwestern plateau of China was selected to study the forecasting ability of two initial perturbation methods， Breeding Growth Mode （BGM） and Local Breeding Growth Mode （LBGM）， in convective-scale ensemble forecasting of complex terrain rainfall.The MODE （Method for Object-Based Diagnostic Evaluation） method based on object diagnostics was used to evaluate the model's ability to predict the location， structure， and intensity of precipitation objects， and compared with scoring methods such as Threat Score （TS） to comprehensively assess the model's forecasting performance.The results show that： （1） The ensemble forecast systems BGM-EPS and LBGM-EPS， generated using BGM and LBGM methods to produce initial perturbations， have better ensemble mean forecast scores for precipitation of all magnitude levels at 24 hours compared to the control forecast， and LBGM-EPS has a higher TS score for heavy rainfall compared to BGM-EPS， this indicates that the LBGM method has a certain improvement effect on ensemble forecasts for heavy precipitation.However， the underlying mechanisms behind the different initial perturbation methods are worthy of further investigation； （2） Overall， the WRF model can capture precipitation objects well， especially for rainfall forecasts in complex terrain of the plateau mountains， with a better overall similarity in precipitation targets for LBGM-EPS compared to BGM-EPS， highlighting the advantage of LBGM method in representing convective-scale ensemble forecasting of intense convection.The initial perturbation total energy of BGM and LBGM shows a developing trend with forecast time.In the same forecast time， LBGM has a larger perturbation total energy than BGM， which better represents the growth of forecast error.This can partially explain why the LBGM method outperforms the BGM method in terms of precipitation object matching in the MODE evaluation； （3） Compared with traditional TS scoring and other verification methods， the MODE method can better reflect the spatial position information of precipitation forecasts， and under the same convolution radius and precipitation threshold， the ensemble mean forecast based on LBGM method performs better in identifying precipitation objects.By flexibly setting the convolution radius and determining the precipitation threshold， the WRF model can capture precipitation objects in complex terrain areas during heavy precipitation events.However， the matching degree of precipitation targets in high-altitude areas is lower than that in low-lying areas.The LBGM-EPS method outperforms the BGM-EPS method in terms of the shape of precipitation objects and the matching of precipitation areas， resulting in better identification of precipitation objects.The quality of precipitation object matching using the MODE method is related to parameter settings such as precipitation threshold and convolution radius， rather than the complex terrain background related to terrain gradients.

As the main mechanism of extratropical cyclogenesis， moist baroclinic instability plays a central role in the study of cyclone thermodynamics， which can be further divided into four categories： dry baroclinic instability， moist instability， diabatic Rossby wave and Type C cyclogenesis （tropopause intrusion）.The '7·20' heavy rainstorm was caused by the eastward movement of a Yellow River cyclone into North China after its rapid formation on July 18， 2016.Compared with the mature stage of the cyclone， the mechanism of the initial stage is still unclear.This article uses ERA5 reanalysis data and WRF model to study the moist baroclinic instability of the cyclogenesis event numerically.The results show that mid-lower troposphere presented diabatic Rossby wave pattern， that is， the eastward movement of the system was mainly driven by the cycle of vertical motion and diabatic effect.The vertical motion on which the wave relied was more provided by vorticity advection.The PV sink and the ageostrophic wind in the upper layer delayed the eastward movement of the tropopause intrusion PV， maintaining the phase difference between upper and lower layers.Finally， a PV column formed throughout the troposphere in front of dry intrusion.Using piecewise PV inversion， several sensitivity runs are designed to remove unbalanced circulation， tropopause dry intrusion PV and lower-level diabatic-produced PV from the initial field， respectively.Combined with the analysis of generalized omega equation， it shows that the baroclinic wave in this process must be coupled with the diabatic process with the help of sufficient water vapor to develop strongly.The cyclogenesis was suppressed when the latent heat was turned off.Dry baroclinic instability cannot explain this process.The removal of initial unbalanced field did not affect the baroclinic instability but will delay development of the system.Limited by humidity and mesoscale circulation structure， the active area of lower-level unbalanced flow was controlled by dry baroclinic dynamics.In this case， the gradient of {\theta }_{bottom} was too small to organize eastward diabatic Rossby wave by relying only on the initial lower-level PV.Nor can strong lower-level diabatic heating generate as in Type C cyclogenesis by tropopause intrusion.For this Yellow River cyclogenesis case， it is required the initial lower-level PV anomaly to be strong enough to counteract the suppression of the cooling subsidence in front of dry intrusion； on the other hand， it is also required that the dry intrusion， in an appropriate initial phase difference with the lower system， strengthened the ascending motion east of the low-level PV in form of vorticity advection through vertical penetration， so as to promote the eastward momentum of diabatic Rossby wave to enter north China with more saturated environment.None of dry baroclinic instability， diabatic Rossby wave and Type C cyclogenesis could independently explain this cyclogenesis event， which was an initial optimal perturbation growth under the combined effect of diabatic Rossby wave and tropopause dry intrusion.

Using the precipitable atmospheric water vapor （PWV） data of 17 ground-based GPS remote sensing stations， hourly and daily precipitation data of 14 meteorological stations in Tarim Basin and its surrounding areas from July 2018 to June 2022， this study analyzed the PWV distribution characteristics and its relationship with precipitation in the western （region A） and the eastern （region B） part of Tarim basin.The results show that： （1） The average annual PWV is largest in the northern and southwestern plain areas of the basin， and the average annual PWV is inversely proportional to the altitude at stations with over 1300 m， while that concentrated on 10~12 mm at stations with altitude below 1300 m.The average PWV value in summer is twice than that in spring and autumn at all GPS stations.（2） The monthly distribution of PWV in region A and region B presents a unimodal type， with the peaks occurred in August and in July， respectively.On the rain-day and no-rain day in region A， the both peak value of PWV occurred at 23:00 （Beijing Time， after the same）， While， the peak value of PWV occurred at 11:00 on rain-day and 17:00 on no-rain day in region B， respectively.（3） The peak of ΔPWV （PWV minus monhly mean PWV） at most stations occurred at 0~1 h before precipitation start time in region A， and within 1 h before and after precipitation in region B.In spring， the variation of PWV before the precipitation in region B is more severe than that in region A.In summer， there are more weather processes with σPWV （PWV divide monthly mean PWV） reached 1~1.8 times at 1 h and 5~6 h before the beginning of precipitation in region A and region B.In autumn and winter， The peak of σPWV are concentrated in 1.4~2.0 times and 1.6~2.4 times in region B， respectively.（4） At the end of precipitation in stations with altitude below 1400 m， the PWV value was concentrated in 10~20 mm during May to June and in 15~25 mm during July to August.In stations with altitude over 1400 m， the PWV value is increasing from 15~25 mm to 25~35 mm from May to August at the end of precipitation.

Based on the knowledge that the main sources of summer water vapor on the Qinghai-Xizang （Tibet） Plateau are the Arabian Sea， the Bay of Bengal， and the South China Sea， a simulation study of the effects of different water vapor sources on the eastern-type and western-type precipitation on the Qinghai-Xizang （Tibet） Plateau in summer was carried out.Numerical simulations of water vapor content reduction at different water vapor source locations were conducted using conventional observations， NCEP/NCAR global reanalysis data， and the mesoscale numerical model WRF for two intense precipitation processes on the Qinghai-Xizang （Tibet） Plateau from June 28 to July 2， 2016 （eastern type） and from July 19 to 23， 2018 （western type）， by separately integrating the Arabian Sea， Bay of Bengal， and South China Sea By comparing three sets of sensitivity experiment and control experiment， the relative humidity at the Arabian Sea， the Bay of Bengal and the South China Sea was reduced by 70%， 60%， 50%， 40% and 30% from the ground to 100hPa respectively， and the effects of the reduction of water vapor content at different water vapor sources on summer precipitation on the plateau were explored in depth from the perspectives of circulation field， water vapor transport and precipitation changes， and the following main conclusions were obtained： （1） The reduction of water vapor content at three water vapor sources has an effect on The reduction of water vapor over the Bay of Bengal significantly reduced the summer precipitation of the Qinghai-Xizang （Tibet） Plateau by about 10% in 2016 （eastern type） and 2018 （western type） compared with the controlled experiment， while the reduction of water vapor over the South China Sea had minimal effects on the two summer precipitation processes of the Qinghai-Xizang （Tibet） Plateau.Reducing the water vapor over the Arabian Sea plays a catalytic role in the precipitation of the western type of the plateau， increasing the precipitation by about 10% relative to the controlled test； and inhibiting the precipitation of the eastern type of the plateau， making the precipitation decrease by about 5% relative to the controlled test.（2） Changing the water vapor conditions over the Bay of Bengal source has the most obvious effect on the precipitation on the Qinghai-Xizang （Tibet） Plateau.The possible reason is that reducing the water vapor conditions over the Bay of Bengal makes the low value system on the southern side of the plateau weaken， and the southerly wind on the plateau weakens， resulting in weaker water vapor transport， resulting in less precipitation on the plateau.（3） The difference of water vapor revenue and expenditure in the plateau region was not obvious in the control experiment and three sensitivity experiment at the beginning of the simulation， but with the increase of simulation time （after about 48 h）， there were obvious differences in water vapor revenue and expenditure in the Qinghai-Xizang （Tibet） Plateau， and there was an obvious correlation between water vapor revenue and expenditure and daily precipitation.

Limitations of complex topography and lack of basic meteorological and hydrological information make the hydrological early warning and forecasting technology in small-scale mountainous watersheds weak.Using high-resolution radar observations to drive distributed hydrological models is one of the effective ways to improve the flood forecasting capabilities in small mountainous watersheds.Focusing on the Erhe river basin located in central Chongqing as the study area， a study of WRF-Hydro model flash flood simulation based on radar-estimated rainfall data is carried out to evaluate the hydrological application effect of radar-estimated rainfall and the applicability of WRF-Hydro model in small mountainous watersheds.The typical storm flood process in the watershed was selected， and the WRF-Hydro model was driven by the estimated rainfall data from S-band Doppler weather radar， and further compared with the XAJ model to analyze the simulation effects.The results show that： （1） the WRF-Hydro model driven by radar-estimated rainfall data provides a better simulation of the flood process， flood flow and peak-to-peak time in the Second River Basin， with the Nash efficiency coefficient above 0.65， the Kling-Gupta efficiency coefficient above 0.50 and the correlation coefficient above 0.85.（2） Comparing the WRF-Hydro model with the XAJ model， the simulation effectiveness of the WRF-Hydro model is superior to that of the XAJ model in the Erhe River basin， with a difference of 0.03 in the Nash coefficient and 0.04 in the correlation coefficient， further indicating the superior flood simulation performance of the WRF-Hydro model in small mountainous basins.Overall， the WRF-Hydro model based on radar-estimated rainfall data exhibited satisfactory flood simulation performance in the Erhe basin， and can be further applied in similar small-scale mountainous basins.

The Qinghai-Xizang Plateau has complex terrain and climate， which is a great challenge to the airdrop parachute landing and aviation safety.This research focuses on Qinghai-Xizang Plateau wind field simulation in boundary layer based on numerical calculation method.Firstly， the study built a WRF-LES system and scaled down to 40 m horizontal resolution based on the large eddy simulation （LES） scheme of WRF （Weather Research and Forecasting） model， and undertook the application study of large eddy simulation on the Qinghai-Xizang Plateau.Based on a strong wind case over the Qinghai-Xizang Plateau， the impacts of LES scheme and terrain elevation data on wind field simulation were evaluated through sensitivity tests.Then， the parameters in the standard sub-grid turbulent stress models of LES scheme were analyzed， and the optimal schemes for wind field simulation on the Qinghai-Xizang Plateau was obtained.Finally， a batch test was conducted to verify the applicability of the optimal schemes to the Qinghai-Xizang Plateau wind field simulation.The test results show that the WRF-LES system with a resolution of 40 m can simulate more precise and accurate wind field information， and the MAE （Mean Absolute Error） of simulated wind speed is reduced by 1.4 m·s^-1 and the RMSE （Root Mean Square Error） is reduced by 1.81 m·s^-1 compared with the ACM2 scheme； The high-precision ASTER terrain data can also improve the effect of wind field simulation， and the error is approximately deduced by 0.2 m·s^-1； The LES scheme that use 1.5-order turbulent flow energy scheme and set parameter coefficient 0.1 has the best simulation result， and the MAE is 1.56 m·s^-1 and RMSE is 2.06 m·s^-1； The batch test verifies that the large eddy simulation scheme is fit for the wind simulation on the Qinghai-Xizang Plateau， and the wind field simulation results in the 40 m resolution is significantly better than in the mesoscale resolution.The result shows that WRF-LES system can provide accurate wind field information for the parachute landing on the plateau.

On September 11， 2020， severe convective weather occurred in the southern part of Liaodong Peninsula， and wet downbursts appeared.The maximum surface wind gust at Dalian Jinzhou Desheng station reached 21.7 m·s^-1.By using conventional observation data， Dalian Doppler radar data， ERA5 data and high-resolution mesoscale simulation data， the circulation background， convective environment and echo characteristics of this wet downburst was analyzed.The results show as follow： （1）the major synoptic system is shear line made up of southwest and southeast winds located to the east of upper-level cold vortex transformed by north-moving tropical cyclone.The mechanisms of convective initiation are surface convergence line and low-level jet.Coupling upper-level divergence enhances initial connection development.The convection system moved westward and landed on the frontal zone between the ground cold pool and the east warm air， and the convergence lifting effect increased， promoting higher organization and more severe of the convection system.（2）The highly warm and moist surrounding air and the instability are favorable conditions for convection.Before convection occurred， the sounding shows dry air overlapping moist air and "V" pattern.The lifting condensation level decreases distinctly.During the wet downburst， radar radial velocity shows mid-altitude radial convergence（MARC）， low-level divergence.Before and after the gale， high and low elevations all exhibits more than 45 dBZ reflectivity notch.The high reflectivity notch at high elevation appears prior to that at low elevation.Monitoring the changes of the high elevation reflectivity contributes to the early warning of wet downburst.

Clouds play an important role in the Earth-atmosphere system.To deeply analyze the cloud characteristics in the Loess Plateau region （LP）， the macro and micro physical characteristics of clouds were analyzed by using the CloudSat-CALIPSO data from 2007 to 2016 in four regions of the Loess Plateau， namely， semi-humid， semi-arid， arid， and cold arid.The findings indicate that： （1） In the LP， the annual average frequency of clouds exceeds 55%， with the highest frequency in spring and summer， and relatively lower in autumn and winter.The frequency of clouds in semi-humid region is higher than that in other regions.However， the months with the highest frequency of cloud occurrence in the other three regions are earlier than those in the semi-humid region.（2） The frequency of single-layer clouds is the highest in all regions， accounting for over 60% of the total cloud amount， with double-layer clouds being the main type among multi-layer clouds， accounting for about 25% of the total cloud amount.The seasonal variation of cloud height in each region shows that it is greater in spring and summer than in autumn and winter， and that it is greater in semi-humid region than in other regions in all seasons.The seasonal variation of cloud geometric thickness is not significant in all regions， which is between 1 km and 4 km， with mainly thin clouds， and 78.13% of the cloud geometric thickness is less than 2 km.（3） The annual average value of cloud liquid water content in all regions reaches more than 220.5 mg·m^-3， about 6.5 times of the annual average ice water content.It is mainly distributed in the altitude below 8.5 km， and the liquid water content gradually increases as the altitude decreases， in which the cloud liquid water content in the semi-humid region is larger than that in other regions.The ice water content in each region is small throughout the year， mainly distributed in the altitude layer below 16.5 km.（4） The values of the effective radius of liquid droplets in each region are mainly concentrated in the range of 12~16 μm， with a maximum of about 24 μm in the spring in the semi-arid region； the maximum value of the effective radius of ice particles occurs in the summer in the semi-humid region.The values of droplet number concentration in all regions were concentrated at 60~80 cm³， which were smaller than the mean value of ice particle number concentration， with peaks occurring in the summer in all regions， and the peak of ice particle number concentration occurring in the spring in the semi-humid and semi-arid regions.The results of this study can help to understand the cloud characteristics of the Loess Plateau and provide a reference basis for the simulation of cloud characteristics in the Loess Plateau by regional climate models.

To prepare for the heavy rainfall resulting from future climate change in the upper reaches of the Yangtze River， this paper analyzed daily precipitation data from 687 meteorological stations in the region between 1990 and 2014， as well as simulation results from 24 global climate models （GCMs） provided by the Coupled Model Intercomparison Project Phase 6 （CMIP6）.The spatio-temporal characteristics and uncertainties of the mean annual rainstorm volume， rainstorm days and rainstorm intensity in the upper reaches of the Yangtze River during 2021 -2099 under different Shared Socioeconomic Pathways （SSPs） scenarios are studied.The results show： （1） Compared to the reference period of 1995 -2014， the mean annual volume， days and intensity of rainstorm in the upper reaches of the Yangtze River are projected to increase and strengthen during the whole projection period of 2021 -2099 and the end of the 21st century （2080 -2099） under the SSP1-2.6， SSP2-4.5， and SSP5-8.5 scenarios.The largest increase is observed under the SSP5-8.5 scenario.The predicted direction is consistent and the certainty of the projection among models increases with higher emissions.The distribution of rainstorm volume， days and intensity during 2021 -2099 is similar under SSP1-2.6 and SSP2-4.5 scenarios， but differs from that of the SSP5-8.5 scenario.By the end of the 21st century， the distribution of volume and days of rainstorm is similar under the three scenarios.However， the distribution of rainstorm intensity under the SSP5-8.5 scenario differs from that under the SSP1-2.6 and SSP2-4.5 scenarios.（2） Relative to the reference period， the rainstorm volume in the upper reaches of the Yangtze River increases by 3.5 mm·（10a）^-1， 5.4 mm·（10a）^-1 and 14.7 mm·（10a）^-1 under SSP1-2.6， SSP2-4.5， SSP5-8.5， respectively.The rainstorm days increases by 0.045 d·（10a）^-1， 0.07 d·（10a）^-1 and 0.18 d·（10a）^-1 under the three scenarios， respectively.The rainstorm intensity increases by 0.37 mm·d^-1·（10a）^-1， 0.78 mm·d^-1·（10a）^-1 and 1.94 mm·d^-1·（10a）^-1 under the three scenarios， respectively.All of the trends pass the 99% confidence test and the same-sign rate test.The period with a high level of prediction certainty is expected to occur in the late 21st century under the SSP5-8.5 scenario.（3） The analysis of the three scenarios indicates an increasing trend in the volume， days and intensity of rainstorm throughout the whole prediction period.The region of southeast Tibet has experienced the highest growth rate in terms of volume and days of rainstorms.The region with the largest increasing trend of rainstorm intensity under the SSP1-2.6 scenario is in northern Sichuan， while under the SSP2-4.5 and SSP5-8.5 scenarios， it is in northern Yunnan.（4） During the early 21st century（2021 -2040）， there is no significant change in the volume， days or intensity of rainstorm in the upper reaches of the Yangtze River， as compared to the reference period， under the three scenarios.While during the middle（2041 -2060）and the end of the 21st century， the volume， days and intensity of rainstorm increase significantly under the SSP2-4.5 and SSP5-8.5 scenarios.This effect is particularly pronounced during the end period of the 21st century under the SSP5-8.5 scenario， as well as the consistency of predicted direction among modes is the highest.

Drought is one of the most widespread and harmful natural disasters in the world.The standardized precipitation Index （SPI） is one of the most widely used meteorological drought indexes in the drought monitoring operation and research.At present， China has built a large number of high-density regional automatic weather stations， which can not be used to calculate the SPI due to the lack of long history sequence data.How to use these short-term data to carry out refined drought monitoring and assessment is the focus of attention.Based on the daily precipitation data of 2032 national meteorological stations from 1960 to 2020 and 1009 regional stations in Yunnan Province from 2010 to 2020， 31 national stations are selected as the method test stations.The SPI（Iab） is constructed by the Gamma distribution parameter interpolation method to fit the regional stations， compared with the commonly neighbor station substitution method and multiple linear regression method， and cross-test and error analysis were carried out.By comparing the correlation coefficient， root mean square error and average absolute error between the fitting value and the true value， it can be concluded that the fitting value Iab is significantly better than the fitting results of the other two methods except in the areas with sparse stations in Northwest China.In different seasons and different time scales， the SPI （Iab） obtained by parameter interpolation is the best.In Mid-Eastern China， the average error of Iab decreases from 0.02 to 0.30 compared with the other two methods.The maximum error change of fitting value Iab and true value Iz in Beijing and Kunming over the years is 0.16， less than half the drought grade 0.25.The correlation coefficient of Iab and the true value （Iz） is above 0.999， passed the significance test of 0.001.The monitoring results of the drought process of the regional stations using this method show that the drought index SPI calculated by the high-density regional stations is closer to the actual drought disaster than the SPI obtained by the interpolation of the national stations.In general， the gamma distribution parameter interpolation method can be used to calculate the drought index SPI from the precipitation data of high-precision short series regional stations， so as to realize the precise monitoring， prediction and evaluation services of meteorological drought.

Gansu-Yellow River basin is a natural-social-economic complex ecosystem intertwined with ecological and development issues.Soil conservation service （SCS） is an important safeguard for preventing soil erosion and promoting high-quality development in this region.Combining with the Revised Universal Soil Loss Equation（RULSE）， we obtained the annual SCS dataset for Gansu-Yellow River basin from the Standardized Vegetation Difference Vegetation Index， Land Cover Type product MCD12Q1， precipitation data， Digital Elevation Model data and the Harmonized World Soil Database version 1.1.The times span for this SCS dataset ranges from 2001 to 2015， with spatial coverage between 33°6′29″N -40°0′6″N and 97°23′38″E -108°42′38″E.This study offers a scientific basis for developing measures to improve SCS， and provides important data support for assessing ecological security and constructing ecological security pattern.The URL for obtaining the entity dataset is http： //www.ncdc.ac.cn/portal/metadata/a918f7ed-5988-44ea-80ad-ee14acab89aa.