陇中黄土高原LAS在非均匀下垫面的观测优势及其在区域陆面模式验证中的初步应用

Superiority of LAS in observation on heterogeneous surface and its preliminary application for the validation of land surface models in Longzhong Loess Plateau

目前通用的通量观测技术涡动相关仪(EC)在区域陆面模式验证中存在能量不闭合和空间代表性有限的问题,寻求改进EC观测热通量的新技术是提高陆面模式验证效果的关键环节,大孔径闪烁仪(LAS)的出现有效改善了这一现状。基于黄土高原定西站2010年1月和6月的同步综合观测资料以及目前比较有代表性的陆面过程模式CLM的模拟数据,分析研究了LAS对EC观测地表能量不平衡问题的改进以及LAS对EC在区域陆面模式验证中的提高,结果表明:LAS可有效解决EC观测存在的地表能量不平衡问题,提高EC的地表能量闭合度,在非均匀下垫面LAS观测优势突出;利用LAS观测的感热通量进行区域陆面模式的验证,能够很大程度地避免EC能量不闭合和空间尺度不匹配在验证中造成的偏差,LAS观测更适合于大尺度模拟的验证,验证效果更好。

The commonly used surface fluxes observed by Eddy Covariance system （EC） have the problems of energy unclosure and limited representative areas. The improvement of surface heat fluxes measurement is a critical for the validation of land surface models. The development of Large Aperture Scintillometer （LAS） effectively improved this situation. On the basis of observations from January to June 2010 and CLM modeled flux data of the same period, an analysis was made on the improvements of EC observed surface unclosure and validation of CLM by LAS. Results showed that： LAS efficiently improved the surface unclosure observed by EC, especially over heterogeneous surface; LAS could avoid the bias caused by the energy unclosure of EC and mismatch between spatial scales of CLM and EC when applied to validate the sensible heat flux modeled by CLM. Our study shows that LAS is more appropriate for the model validation in large scales, better performance compared to EC.