HJ-1B Data Based Land Surface Temperayure Retrival Anspatiotemporal Analysis In Nanjing,China

Land Surface Temperature(Land Surface Temperature,LST)is a key parameter of global climate change,dominate factor of surface energy exchange and various circulation processes on the earth,LST is closely related to people's life.With the rapidly accelerating of global urbanization,environmental issues have become more prominent.The study of LST has become an important part of exploring urban heat island.LST of Nanjing was retrievaled using Radioactive Transfer Equation(RTE)method,Qin Zhi-hao mono-window algorithm(Qins')method,generalized single-channel algorithm(JM&S)method,based on the data of HJ-1B/IRS thermal infrared,supported by the remote sensing technology and software of ENVI,ArcGIS.Seasonal variations and inter-annual variations of LST were analyzed,using the LST images of 2010 summer and four seasons of 2013.On this basis,the influences of land utilization and vegetation index on LST were analyzed.The main conclusions are as follows:1 LST tendency of Nanjing can be well reflected through the three methods.RET method has the highest precision with a D-value of about 2.1K compared with MODIS,Qins' method has a slight poor precision with a D-value of about 3.87K,while JM&S method which has an obvious poor precision with a D-value of about 5.96K.2 As a whole,the surface temperature of Nanjing city decreased from center to suburbans gradually.The area of the high-temperature and high-temperature in City proper occupied over 60%;the temperature grade was similar in Luhe,Pukou and Gaochun District,all of which were dominated by the low temperature and middle temperature.While Jiangning and Lishui District,which are close to City proper District,their temperature grade are mostly focused on middle temperature and higher-temperature.The earth's surface temperature and the percentage of forest land have the largest correlation,next is PD,then flowed by PerBuild,AREA,LPI.The vegetation index,Pv and NDVI,were closely related to LST.The correlation between Pv and LST was stronger(R2=0.64)than NDVI(R2=0.51).Compared with NDVI,Pv could better predict surface temperature which was effected by the surface vegetation cover.3 Compared with 2010,the high-temperature area and higher-temperature area in City proper significantly increased in 2013,while the low-temperature and middle-temperature region reduced;In Jiangning District,the low-temperature area and lower-temperature area has decreased,while the high-temperature area and higher-temperature area has increased;Change rules in Pukou were similar to Jiangning District.The area of low-temperature and lower-temperature has decreased,and the area of high temperature and higher-temperature has increased.The LST of the whole study area transformed from the middle to the poles:difference of temperature level has increased,and Urban heat island effect has been more significant.Generally speaking,as the change of time,during 2010-2013,the natural landscape in research area of Nanjing reduced,however,the artificial landscape increased.As the unceasing expansion of city,the thermal island scope would increase unceasingly.The change of the land using condition would have very tremendous influence to the surface temperature spatial distribution.Among them,the land used for urban construction was the main reason for the formation of heat island,while the water and forest land had quite good temperature decrease function.When relations of vegetation index and surface temperature,they found that LST had almost opposite with NDVI and Pv in the spatial distribution(except water).From the seasonal change characteristic,people could find that heat island effect was obvious in Spring and Summer of Nanjing,especially in Summer.But effects of heat island were not obvious in other two seasons.Along with season change,different vegetation cover had different influence to land surface temperature.LST had displayed contrary tendency with NDVI and Pv in Spring,Summer,and Autumn.The temperature of the region that had higher degree vegetation cover was relatively low,while,the value of LST,NDVI and Pv were generally low in Winter.