Characteristics of Flux Footprint over Typical Underlying Surface of Qinghai-Xizang Plateau

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  • 1. School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China
    2. CAS Center for Excellence in Comparative Planetology,Hefei 230026,Anhui,China
    3. Jiangsu Collaborative Innovation Center for Climate Change,Nanjing 210023,Jiangsu,China
    4. Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China
    5. College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China
    6. College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000,Gansu,China
    7. Qomolangma Atmospheric and Environmental Observation and Research Station,Tingri 858200,Xizang,China
    8. Kathmandu Center for Research and Education,CAS-TU,Beijing 100101,China
    9. China -Pakistan Joint Research Center on Earth Sciences,Islamabad 45320

Online published: 2024-07-03

Abstract

The heterogeneity of the underlying surface affects the accuracy and representativeness of the land-atmosphere flux observation.The study on the flux footprint distribution of complex underlying surface over Qinghai-Xizang Plateau (QXP) is of great significance to the observation and simulation of land-atmosphere interaction and its influence on weather and climate.Flux footprint analysis plays a pivotal role in investigating the spatial representativeness of flux observation information.The Flux Footprint Prediction (FFP) model represents a proficient methodology for computing the flux footprint.Based on the observation data from multiple research stations, including the Qomolangma Atmospheric and Environmental Observation and Research Station, the Ngari Desert Observation and Research Station, the Nam Co Monitoring and Research Station for Multisphere Interactions, the Muztagh Ata Westerly Observation and Research Station, the Southeast Tibet Observation and Research Station for the Alpine Environment in 2013, the FFP model was utilized to investigate the sensitivity of model parameters concerning flux footprint distribution.Additionally, the spatiotemporal characteristics and specific influencing factors of flux footprint distribution at different stations were discussed, thereby providing valuable insights for the erection of future observing stations.The results reveal that the primary determinants of flux footprint are measurement height, wind speed and wind direction.Characterized by an underlying surface of evergreen coniferous forest, flux footprint at Linzhi station exhibits greater sensitivity to measurement height and planetary boundary layer depth compared to the other stations.In the QXP, the spatial extent of the flux footprint derived from the ultrasonic anemometer measurements ranges from approximately 250 m to 500 m.Among the five stations, Qomo station exhibited the lowest frequency of stable stratification times during daytime, representing 15.69% of the daytime data points, whereas Ali station had the lowest occurrence of unstable stratification times during nighttime, comprising for 13.32% of the nighttime data points.At these five stations on the TP, the nocturnal flux footprints demonstrate greater width and extent compared to their daytime counterparts.In summer, due to the influence of monsoon, the axis of flux footprint tends to be more consistent.Lake-land breeze at Nam Co station is the main factor affecting flux footprint, whereas glacier wind at Qomo station is the dominant factor.Linzhi station possesses the smallest footprint due to the smallest mean wind speed, thus demonstrating the highest level of representativeness among these five stations.Lowering the height of observation instruments at Qomo and Nam Co stations could potentially enhance the representativeness of in situ measurements.

Cite this article

Zixin WANG, Lei ZHONG, Yaoming MA, Yunfei FU . Characteristics of Flux Footprint over Typical Underlying Surface of Qinghai-Xizang Plateau[J]. Plateau Meteorology, 2023 , 42(5) : 1160 -1171 . DOI: 10.7522/j.issn.1000-0534.2022.00107

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