区域蒸散发遥感估算研究与实现

发布时间：2018-04-15 23:04

本文选题：蒸散发 + 遥感　；参考：《兰州交通大学》2014年硕士论文

【摘要】：地球上的任何地方都存在着蒸散发现象。地表通过吸收太阳辐射获取能量，而能量的消耗则主要通过水分蒸散发的方式进行。大气中的水分以雨、雪、雾、霜、冰雹等气体、液体或固体的方式转移到地表，而地表水体水面蒸发、土壤蒸发和植被蒸腾则将70%的降水蒸散发到大气中。在水分交换的过程中，能量也随着水分的交换而传输，实际上地表和大气之间的水分交换是一个物质和能量同时参与的过程。在这一过程中，蒸散发成为地表和大气之间水分平衡和能量平衡不可或缺的组成部分。受时间变化以及地形、气候、植被空间分布不均等因素影响，蒸散发具有很强的时间变异性和空间变异性。传统方法如波文比法、空气动力学方法、涡旋相关法等都基于点源来计算蒸散量，计算结果适用于点或周围很小范围，并不能向区域扩展，在空间尺度上的区域蒸散发研究中难以实现。遥感技术可提供长时间序列大范围地表信息，能够对地物特征信息进行整体上的描述，在时间和空间上连续，可以将观测结果向区域扩展，打破了传统方法的局限性，从而使区域蒸散发估算更为方便，应用更为广泛。准确的估算地表蒸散发对于我们研究人类活动和气候变化对生态系统的影响有十分重要的意义。本文以SEBAL模型为基础，采用Landsat5TM影像结合DEM数据和气象数据，选取甘肃省庆阳市正宁县为研究区进行区域蒸散发遥感估算研究。研究中使用ArcGIS和ENVI软件，对遥感影像、DEM数据做镶嵌、裁剪、矢栅转换等处理并得到了蒸散发估算所需要的很多中间数据。在TM影像预处理方面，主要研究了遥感影像辐射校正的原理并实现了辐射定标和FLAASH大气校正。对DEM数据进行了栅格和矢量的转换，生成的点要素参与了基于DEM的气象数据反距离权重法插值，从而预测出研究区的气象数据，弥补了研究区缺少气象数据的不足。对SEBAL模型估算蒸散发的过程进行了仔细深入的研究，并成功反演了地表参数和能量通量。最终估算出了研究区日蒸散量，并对结果进行了验证及分析。通过研究发现，，利用遥感技术来估算区域蒸散发能够比较方便地获取研究数据，采用SEBAL模型计算过程清晰。同时，由于所获数据具有瞬时性，反演地表参数和能量通量采用较多简化的经验公式，使得最终的结果往往误差较大。因此，还需要进一步的研究，以期得到更好的估算区域蒸散发的方法，从而为人类更深刻地认识自己所处的生态环境做贡献。
[Abstract]:There is evapotranspiration anywhere on the earth.The surface absorbs solar radiation to obtain energy, and the energy consumption is mainly carried out by water evapotranspiration.Water in the atmosphere is transferred to the surface of the earth in the form of rain, snow, fog, frost, hail and other gases, liquids or solids, while surface water evaporation, soil evaporation and vegetation transpiration send 70% of the precipitation evapotranspiration into the atmosphere.In the process of water exchange, energy is also transferred with the exchange of water. In fact, the water exchange between the earth's surface and the atmosphere is a process in which both substance and energy are involved.In this process, evapotranspiration becomes an integral part of water balance and energy balance between the surface and atmosphere.The evapotranspiration has strong temporal variability and spatial variability due to the influence of time variation, topography, climate and spatial distribution of vegetation.The traditional methods, such as Boven ratio method, aerodynamics method and vortex correlation method, are all based on point sources to calculate evapotranspiration. The results are applicable to a very small range of points or around, and can not be extended to the region.It is difficult to study the regional evapotranspiration on spatial scale.Remote sensing technology can provide a large range of surface information in a long time series, can describe the feature information of ground objects as a whole, be continuous in time and space, can extend the observation results to the region, and break the limitation of traditional methods.Thus, the estimation of regional evapotranspiration is more convenient and widely used.Accurate estimation of surface evapotranspiration is of great significance for us to study the impacts of human activities and climate change on ecosystems.In this paper, based on SEBAL model and Landsat5TM image combined with DEM data and meteorological data, the remote sensing estimation of regional evapotranspiration was studied in Zhengning County, Qingyang City, Gansu Province.In this study, ArcGIS and ENVI software are used to deal with Dem data of remote sensing images, such as mosaic, clipping, vector gate conversion, and so on, and many intermediate data for estimation of evapotranspiration are obtained.In the aspect of TM image preprocessing, the principle of remote sensing image radiation correction is studied and the radiometric calibration and FLAASH atmospheric correction are realized.The transformation of grid and vector for DEM data is carried out, and the generated point elements participate in the inverse distance weight interpolation of meteorological data based on DEM, which can predict the meteorological data in the study area and make up for the lack of meteorological data in the study area.The process of estimating evapotranspiration by SEBAL model is studied in detail and the surface parameters and energy flux are retrieved successfully.Finally, the daily evapotranspiration was estimated, and the results were verified and analyzed.It is found that using remote sensing technology to estimate regional evapotranspiration can obtain the research data conveniently and the calculation process using SEBAL model is clear.At the same time, due to the instantaneous nature of the obtained data, many simplified empirical formulas are used for inversion of surface parameters and energy fluxes, which results in large errors in the final results.Therefore, further research is needed in order to obtain a better method for estimating regional evapotranspiration, thus contributing to a deeper understanding of the ecological environment in which human beings live.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP79

【参考文献】