Evaluation Of Remotely Sensed Debris Surface Temperature(DST)and Study On Thermal Infrared Radiative Transfer Processes

The scarcity of water resources is one of the main factors restricting the economic and social development of inland areas in northwest China.Mountain glaciers and snow are considered as massive solid reservoirs,sensitive indicators of climate change and ideal storage media of the past climate change events.Therefore,it is of great significance to study the melting of snow and ice for water resource management and also global climate change studies.Different from the traditional research methods that confined to a single glacier,remote sensing technology provides a new,more effective way for the study of glaciers in large areas.In the moraine covered areas,glacier ablation is closely related to the overlying debris surface temperature(DST).In order to estimate the melting of ice under moraine from remotely sensed data,this dissertation made a thorough study on the accuracy of remotely sensed DST and it's applicability on glacier melting estimation as well as the processes of thermal infrared radiative transfer from moraine surface to the top of atmosphere,the main efforts mainly include:(1)Select the Koxkar glacier as an experimental glacier,the near surface meteorological characteristics,melting features of the Tuomuer type glaciers as well as its influence on river runoff and water resources in Xinxiang were investigated and summarized;(2)Evaluated the accuracies of the MODIS C6 land surface temperature products over moraine surface,and correct the bias of the remotely sensed MODIS surface temperature products and ground observations.Further,analyzed the feasibility of applying remotely sensed DST in the application of glacier ablation estimation;(3)The error sources of surface temperature retrieved from space-based data over moraine surface were investigated.With mathematical derivation and masses of the numerical experiment,it was proved that the error caused by replacing the spectral radiation transfer equation with the band radiative transfer equation could be ignored.At the same time,the simplification of Planck function in Becker theory is improved through the systematic research of thermal radiation transfer process.The main achievements and innovations of this dissertation include:(1)A comprehensive and systematic investigation of the accuracy of the remotely sensed DST indicates that the MODIS C6 products underestimate by 2.0? 5.2K during ablation seasons.Therefore,it is not recommended to use the remotely sensed DST to estimate glacier ablation.(2)It is proved that the inversion error of DST caused by replacing band radiative transfer equation with the corresponding spectral radiative transfer equation could be ignored.(3)In the course of investigating the retrieval error sources of the remotely sensed DST,it is found that the precision of Planck function simplification in Becker-Li's local split window was rude and then improvements were made.The accuracy of retrieval of DST from space-based data could be improved in a theoretical perspective by the improvements the new Planck function simplification equation.