宁南地区区域蒸发（散）量的遥感研究

【作者】 郭建茂；

【导师】 郑有飞； 王连喜；

【作者基本信息】 南京气象学院 ， 气象学， 2004， 硕士

【摘要】 区域蒸发散的计算是一个非常复杂的问题。利用遥感资料求取NDVI，依据NDVI和地理信息资料，将地表分成6类：水体、裸地区、草地—裸地区(有草覆盖但未完全覆盖)、草地完全覆盖区、树林区、灌木丛区。将水体单独处理，由参考作物蒸散乘以比例系数直接计算得出水体蒸发；建立了4种单一类型下垫面(裸地区、草地完全覆盖区、乔木林区、灌丛区)蒸散计算模型；对混合下垫面(草地—裸地区)区域蒸发(散)计算方法使用裸土和草地完全覆盖蒸发(散)计算模型，然后结合植被覆盖度给出。将下垫面分类，不同的类型使用不同的方法，是可行的和合理的，可使计算更符合实际情况。 在没有实测的日蒸发(散)资料的情况下，本研究采用被公认和广泛使用的国际粮农组织推广使用的彭曼—蒙蒂斯方法计算日蒸发(散)量，以此作为对照进行结果检验。 估算区域蒸发(散)量的过程中，得到许多有意义的量：地表特征参数(植被指数NDVI、地表反射率、地表温度)；地表辐射平衡各量(地表短波吸收辐射、地表长波辐射、大气逆辐射、地表净辐射)；地表热量平衡各量(土壤热通量、显热通量、潜热通量)。并得出其各量的分布图和直方图，分类别讨论了其分布特征，使得对宁夏南部区域地表特征、地表辐射和热量平衡区域分布有一个直观、综合的了解和认识。 分析各量的分布图和直方图，可以清楚地发现：各量的分布呈现明显的地带性。大面积的森林和灌丛(如六盘山一带)、茂密的草地(如月亮山)、河流边缘及附近有灌溉的地域(分布有草地和农田)、水体以及裸地区，这些区域各量的分布特征与其周围地域明显不同。研究分析还发现，植被的覆盖对下垫面的水热性状影响很大。更多还原

【Abstract】 It is a very complicated problem to estimate evapotranspiration (ET) over a large area natural surface. Based on the information of satellite remote sensing and geography, the natural surface is divided into 6 categories: water, bare soil, dense grass, partly grass covered, forest, bosk. The evapration of water area is calculated by ET0 multiplied by Kc; and then the evapotranspiration estimation models for other categories (singular underling surface) are presented; based on bare soil and dense grass models the evapotranspiration estimation models for partly grass covered surface is presented combined with vegetation fraction data. It is feasible and logical each categories using singular way and mean, the result of regional evapotranspiration over South Ningxia is given.Cause have no test evapotranspiration (ET) data, in this paper, using the result that calculated by FAO-PM equation as comparison, the remote sensing result is analyzed and verified.Some variables regional distribution over South Ningxia is given out in the course of evapotranspiration estimation: the regional distribution of surface characteristic parameters (normalzed difference vegetation index, surface albedo, surface temperature), radiation balance components ( surface absorbed shortwave radiation, surface longwave radiation, atmospheric counter radiation, net radiation ) , surface heat and balance components ( soil heat flux, sensible heat flux, latent heat flux ) . And then each distribution figs and straight-bar figs of every parameters and components are given out. Characters of each distribution are discussed by each types. This given a clear and general knowledge about South Ningxia.Analying each distribution figs and straight-bar figs of every parameters and components,it is obvious: each distribution showed clearly terrain character. Large area forest and bosk (in Liupan mountain ), dense grass (moon mountain), river and irrigative area, water, bare soil, each distribution characaters is differened from others. The case is showed that vegetation covered influence surface moist-heat character.更多还原