大孔径闪烁仪在黑河流域的应用分析研究

大孔径闪烁仪(LAS)是近年来发展较快的一种新型通量测量仪器,用以观测较大尺度上的感热通量变化.”黑河流域遥感-地面观测同步试验”项目在黑河上、中游地区不同下垫面貌一新建立了多个地面站,除常规气象参数、各辐射分量、土壤温湿梯度和热流以及涡动相关（EC）通量外,还在黑河上游阿柔冻融站及中游临泽草地站架设有大孔径闪烁仪.依据有关观测,着重分析大孔径闪烁仪所测感热通量的日、季变化特征.阿柔站所用数据时间段为2008年3月至2009年12月,临泽草地站为2008年5～8月.在与涡动相关通量数据进行对比分析中,除依据解析模式计算分析EC及LAS的源区差异及有关影响外,对不同大气稳定度下大孔径闪烁仪观测资料的质量控制、感热通量的计算方法等做了仔细分析,以提高LAS通量结果的总体质量.长期观测资料分析表明,大孔径闪烁仪与涡动相关仪的感热通量及其时间变化有较好的对应关系.部分时段的较明显差异,主要由二者源区所含下垫面类型的不同引起.多数情况下,LAS所测感热通量比EC的有关结果偏大,可能因为LAS的源区一般远比EC的大,大孔径闪烁仪所测通量有天然的面积平均效果.

A Study of Applications of Large Aperture Scintillometer in the Heihe River Basin

As a new flux measuring instrument, Large Aperture Scintillometer (LAS), which can measure sensible heat flux in large scales, has developed rapidly in recent years. A great number of ground stations were established over different surfaces in the upper and middle reaches of Heihe river basin, supported by the project “Watershed Airborne Telemetry Experimental Research (WATER)”. In addition to conventional meteorological parameters, radiation components, soil temperature/soil moisture, soil heat flux and Eddy Covariance system (EC), large aperture scintillometers were erected in the Arou freeze/thawing observation station (upper reaches) and Linze grassland station (middle reaches). This paper focused on the analysis of the diurnal and seasonal variations of sensible heat flux measured by LAS, and used the observation data from March, 2008 to December, 2009 at Arou station and from May to August, 2008 at Linze grassland station. In order to improve the overall quality of LAS measurements, analyzing carefully not only the difference of EC and LAS source area (based on analytical models) and the relevant influences, but also the quality control of LAS measurement data under different atmosphere stabilities and the calculation methods of sensible heat flux by the relative analysis with EC data were analyzed carefully. Long-term data analysis showed that: There were good correlations in sensible heat flux and its time variation between LAS and EC measurements. There were also significant differences in part time, which was caused mainly by the different underlying surfaces in their source areas. In most cases, the LAS measurements were on average larger than the EC′s. The reason seems that EC has a smaller source area than LAS, whose measurement has the effect of a natural area averaged fluxes.