山地地表水热通量遥感反演的地形影响及建模研究

Land surface water and heat fluxes are the land surface key variables and play important roles in climate change, hydrological and ecological processes. However, due to the impacts from topographic relief, remote sensing based land surface water and heat fluxes estimation over mountainous areas has become an important and difficult problem. It is highly affected by the complexity in land surface water and heat fluxes field observation and the uncertainties in key land surface parameter estimations. Consequently, it greatly limits the application of remote sensing method in this field. Focusing on the scientific problems during the estimation related to the terrain effects and validation, this project aims to develop a new model for land surface water and heat fluxes estimation over mountainous areas by using high resolution remote sensing data combined with gradient observations and analyzing the spatial and temporal variation of surface water and heat fluxes in mountainous region. The Gongga alpine ecosystem, a typical mountainous region, is selected as the study area. Field observations and numeric simulations are jointly used to conduct systematical study about the effects of topographic factors on the estimation processes. Combining with the field measurements, the sources of the estimation uncertainty, the performance of current popularly used models, and the responding mechanism of the estimation result on surface conditions are addressed to help to decrease the errors in final estimation and propose suitable revisions to the terrain effect correction and model parameterization to develop a new model in mountainous region. In generally, the successful implement of this project will enrich the land surface water and heat fluxes estimation methods, and provide useful method to accelerate the research of ecology, climate and hydrology over mountainous areas.

在山地特殊的气候环境和地形条件下，山地地表水热交换过程呈现极大的复杂性及地形相关性，导致山地地表水热通量遥感反演面临诸多问题与挑战，并成为当前山地遥感应用一个亟待突破的研究方向。针对反演过程中地形因素的综合作用与影响，本项目采用地面观测与数值模拟相结合、机制分析与反演建模相匹配的研究思路，基于现有理论方法，选择贡嘎山典型山地环境为研究区，基于多地形梯度水热通量地面观测开展山地地表水热通量遥感反演理论与方法研究，分析地形因素对地表水热交换过程的影响机制，评估当前通用模型在山地环境的适用性，并结合参数敏感性分析方法阐明地表水热通量遥感反演的不确定性特征及传递机制。本项目面向山地环境，特色显著，同时系统性地分析山地地形影响机制，分别针对模型机理和参数地形效应提出改进方案，具有较好的创新性。项目成功实施将进一步丰富山地定量遥感理论与方法，满足山地生态系统动态监测过程中对山地水热过程认识的实际需求。

在山地特殊的气候环境和地形条件下，山地地表水热交换过程呈现极大的复杂性及地形相关性，导致山地地表水热通量遥感反演面临诸多问题与挑战，并成为当前山地遥感应用一个亟待突破的研究方向。针对反演过程中地形因素的综合作用与影响，本项目采用地面观测与数值模拟相结合、机制分析与反演建模相匹配的研究思路，基于现有理论方法，选择贡嘎山典型山地环境为研究区，基于多地形梯度水热通量地面观测开展山地地表水热通量遥感反演理论与方法研究，分析地形因素对地表水热交换过程的影响机制，评估当前通用模型在山地环境的适用性，并结合参数敏感性分析方法阐明地表水热通量遥感反演的不确定性特征及传递机制。根据研究内容，项目在山地地表水热通量反演关键参量——地表温度、地表入射短波辐射、地表土壤水分等方面开展了地形效应分析及改正工作，获得了时空无缝且表征山地异质性分布的估算结果，并构建了山地地表水热通量遥感反演模型，为山地地表水热通量估算与反演提供了重要基础。项目共发表学术论文18篇，其中SCI论文15篇，获批软件著作权和发明专利3项，培养硕士研究生4人，撰写了年度总结报告和项目总报告，全面完成了预定的研究目标和研究内容。本项目所取得的的研究成果将对山地地表水热通量高精度反演的理论与实践起到积极的促进作用。