科尔沁沙地典型区蒸散发估算及其对下垫面和气象因子的响应

发布时间：2018-07-07 10:46

  本文选题：科尔沁沙地 + 蒸散发　； 参考：《内蒙古农业大学》2017年硕士论文

【摘要】：本文以科尔沁沙地典型区为研究对象,运用Landsat遥感影像和气象数据,基于METRIC模型对2013年-2016年生长季5月-9月的地表特征参数(地表温度Ts、土壤热通量G、反照率Albedo、叶面积指数LAI、植被指数NDVI)及蒸散发(ET)进行估算,利用试验站点的涡度相关系统实测数据对反演结果进行验证,在此基础上分析了地表参数、ET的时空变化,并分析地表参数和气象因子对ET的响应关系。通过研究得到如下的主要结论:1.地表特征参数和ET估算值与涡度实测值的拟合结果均为良好,其中日ET的拟合系数为0.815,均方根误差为1.084mm。通过对METRIC模型输入数据的敏感性分析可知,草甸和农田区ET对地表参数的敏感程度排序为:TsAlbedoLAINDVI;沙丘区ET对地表参数的敏感程度排序为:AlbedoTsNDVILAI,而且对NDVI和Ts的敏感程度小于草甸和农田。2.研究区下垫面地表特征参数和ET的时空分布情况为:各年地表参数和ET在年内基本呈现相同的分布趋势,一般7-8月ET和各地表参数达到了峰值;空间分布表现为草甸和农田的LAI、NDVI和Rn比沙丘地区的大,相反沙丘地区的Albedo和Ts比草甸和农田大,最终导致草甸和农田的ET比沙丘地大。三年生长季平均ET草甸、农田集中在308mm-592mm;沙丘主要集中在400mm以下。2016年生长季沙丘总ET较大,这是由于2016年的平均气温较高,且降雨较多。3.草甸和沙丘的各年的净辐射、风速、空气温度对ET的影响均呈极显著正相关关系,而与相对湿度均呈负相关关系。气象因子对ET贡献率的大小排序为:净辐射风速空气温度土壤温度相对湿度。当净辐射≤179.19W/m2时,ET主要受空气温度和相对湿度的影响,当空气温度在22.99℃时,ET主要受风速和土壤温度的制约。ET与Ts、G、Albedo等地表参数呈极显著负相关关系,而与LAI和NDVI呈极显著正相关关系。草甸和沙丘的地表特征参数对ET贡献率大小排序为:NDVIAlbedoLAITsG.
[Abstract]:This paper takes the typical area of Horqin Sandy Land as the research object, using Landsat remote sensing image and meteorological data. Based on METRIC model, the surface characteristic parameters (surface temperature T _ s, soil heat flux G, albedo Albedo, leaf area index Lai, vegetation index NDVI) and evapotranspiration (et) of the growth season from 2013 to 2016 were estimated. The inversion results are verified by the measured data of vorticity correlation system of the test station. Based on this, the temporal and spatial variation of surface parameters and the response of surface parameters and meteorological factors to et are analyzed. The main conclusions are as follows: 1. The fitting results of the surface characteristic parameters and the estimated values of et and the measured vorticity values are all good. The fitting coefficient of daily et is 0.815, and the root mean square error is 1.084 mm. According to the sensitivity analysis of METRIC model, the sensitivity of et to surface parameters in meadow and farmland is in the order of: TsAlbedo LAINDVI, and in sand dunes et is in the order of: Albedo TsNDVILAII, and the sensitivity to NDVI and ts is less than that of meadow and farmland. The temporal and spatial distribution of surface characteristic parameters and et on the underlying surface of the studied area are as follows: the distribution trend of surface parameters and et in each year is basically the same, and the peak value of et and surface parameters is reached in July-August; The spatial distribution of LAIN NDVI and rn in meadow and farmland is larger than that in sand dune area, on the contrary, the Albedo and ts in sand dune area are larger than that in meadow and farmland, which leads to the et of meadow and farmland being larger than that of sand dune area. The average et meadow in three years growing season, the farmland is 308mm-592mm, the sand dune is mainly below 400mm. The total et of sand dune is larger in 2016 growth season, which is due to the higher average temperature in 2016 and the more rainfall. 3. The net radiation, wind speed and air temperature of meadow and sand dunes were positively correlated with et and negatively correlated with relative humidity. The order of contribution of meteorological factors to et is net radiation wind speed, air temperature, soil temperature and relative humidity. When net radiation 鈮，

本文编号：2104727