那曲地区两种空间尺度感热通量的对比分析  

Comparison Analysis of Sensible Heat Fluxes at Two Spatial Scales in Naqu Area

作　　者：孙根厚[1,2] 胡泽勇[1,3] 王介民[1] 刘火霖 谢志鹏[1,2] 蔺筠[1,2] 黄芳芳[1,2] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所寒旱区陆面过程与气候变化重点实验室,兰州730000 [2]中国科学院大学,北京100049 [3]中国科学院青藏高原地球科学卓越创新中心,北京100101

出　　处：《高原气象》2016年第2期285-296,共12页Plateau Meteorology

基　　金：国家自然科学基金项目(91537101;91337212;41175068);国家重点基础研究发展计划(2012CB026101);公益性行业(气象)科研专项(GYHY201406001)

摘　　要：利用中国科学院那曲高寒气候环境研究观测站那曲/BJ观测点2010年涡动相关仪(EC)和大孔径闪烁仪(LAS)数据,MODIS的地表温度(LST)和归一化植被指数(NDVI)产品,结合印痕方法分析了由EC和LAS数据计算得到的感热通量的差异及造成这种差异的可能原因,研究了两种空间尺度下地表温度和土壤含水量对感热通量的影响。结果表明:干季和雨季时,EC与LAS的感热通量(H_EC和H_LAS)总体而言具有较好的一致性,其差异的主要原因是风向造成印痕差异;7月的感热通量与净辐射、风向的时间序列分析表明,云遮蔽导致的净辐射空间分布不均匀是造成H_EC和H_LAS差异的另一个重要原因;EC和LAS的印痕加权LST平均值与两者感热通量的统计分析表明,印痕内加权LST越高,感热通量越大;对雨季时的EC和LAS印痕内加权NDVI平均值表明,印痕加权NDVI越大,感热通量与净辐射之比越小;EC和LAS两种通量结果分析表明,空间尺度对藏北地区半小时尺度和月尺度感热通量结果都有较大影响。In this study,the comparison analysis on the differences in sensible heat fluxes calculated with eddy covariance（EC）data and large aperture scintillometer（LAS）data of Naqu Station for Plateau Climate and Environment,Chinese Academy of Sciences and the analysis on the possible reasons for such differences are made based on the automatic weather data and the land surface temperature（LST）and normalized differences vegetation index（NDVI）of MODIS. The results show that sensible heat fluxes calculated with LAS data（H_LAS）agree reasonably well with those with EC data（H_EC）both in rain season and dry season. One reason for the differences between H_EC and H_LAS is the differences in their footprints which are caused by wind directions.A detailed analysis of the H_EC and H_LAS changing with net radiation and wind directions in July,2010 indicates the spatial variability in net radiation in EC and LAS footprint which is created by cloud covers contributes greatly to the differences in the sensible heat fluxes at EC and LAS spatial scales. A statistical relationship between footprint- weighted averages of LST in EC and LAS footprints and their sensible fluxes reveals that high LST leads to large sensible fluxes. A statistical relationship between footprint-weighted averages of NDVI in EC and LAS footprints and the ration of H_EC and H_LAS to net radiations in rain season supported the analysis that the high NDVI leads to the small ratio of sensible heat fluxes to net radiations. The half-hour and monthly-averaged daily variations of sensible heat fluxes at EC and LAS spatial scales demonstrate that surface fluxes in Naqu are influenced by spatial scales,which should be kept in mind when surface fluxes were used to validate fluxes retrieving from remote sensing or from numerical models.

关 键 词：那曲地区 感热通量 空间尺度 EC和LAS 印痕分析 

分 类 号：P404[天文地球—大气科学及气象学]