The Study Of The Land Surface Temperature Retrieval Based On Grid Computing Technology

Land surface temperature is a key parameter of surface physical process and plays an important significance to the energy balance in the world, which affects the energy exchange between land surface and atmosphere. It has widely been applied to meteorology, geology, hydrology and zoology, especially the study on water content of soil, monitoring of forest fire.Atmospheric correction is an important part to retrieve land surface temperature. Based on the knowledge of atmospheric radiative transfer, the modeling scheme is ensured, and the Moderate spectral resolution atmospheric Transmittance algorithm and computer model is selected to model the atmosphere. The band respond functions of Terra/Aqua MODIS are taken into account to simulate the effects of view angle, solar zenith and water column of atmosphere on retrieval of land surface temperature. These simulation shows that the atmospheric transmission is decreasing with the viewing angle from 0 degree to 65 degree, and the changes to two satellites are the same. While change of the radiant temperature is about 5K from 0 degree to 65 degree, and it is flat before 30 degree than after 30 degree. The water column changes from 10% to 100%, and the transmission and radiant temperature are linearly decreasing with the water column. The change of solar zenith affects differently the surface-reflected solar beam term and surface-reflected solar irradiance. With the solar zenith angle increases, the solar beam at the surface level decreases, but the downward solar diffuse irradiance may increase in some situations.With higher spectral resolution and time resolution, MODIS data are fitted to measure the wide range of land surface temperature and its changes. The algorithm on retrieval of land surface temperature is based on day/night algorithm, which is suggested by Wan and Li. Land surface temperature is retrieved by MODIS data on Terra satellite during day and night. Now, the MODIS is not only being carried on the Terra, but being carried on the Aqua. The feasibility of retrieval of land surface temperature with MODIS data on Terra and Aqua satellites at the same time is our object in the study. From the simulation of MODIS data onboard Terra and Aqua satellites, the radiance changes are the same with the change of viewing angle, solar zenith angle and atmospheric profile. Therefore, the idea on retrieval of land surface temperature by MODIS data onboard Terra and Aqua satellites is feasible.To validate the retrieval algorithm by MODIS data onboard Terra and Aqua satellites, the retrieval process of the day/night algorithm is investigated during this study. Terra-MODIS data at 11:50 on 16 August 2004, Aqua-MODIS data at 14:10 on 17 August 2004 and at 03:50 on 18 August 2004 are selected to retrieve LST. At the same time, the field data of Qinghai Lake in the Qinghai province are measured. The retrieved result of Terra-MODIS data at 11:50 on 16 August 2004 and Aqua-MODIS data at 14:10 on 17 August 2004 has a difference of 0.35K to the field data, the retrieved result of Terra-MODIS data at 11:50 on 16 August 2004 and Aqua-MODIS data at 03:50 on 18 August 2004 has a difference of 1.6K to the field data.The powerful computing resource was required which the urgent requirement of disposal information and Plentiful Data . Retrieval of LST is a better example. when test aree extend all of the country ,the computing capability in single computer fall short of demand. So we introduce the Grid Computing conception the current status inside and outside the developmental trend. At the same time, compare the advantage & disadvantage with interrelated technology.On researching the Grid technology, we decide using the OGSA (Open Grid Services Architecture) to build Grid platform on the linux system of complete opening code—ubuntu. on the base of it ,building up the local area network on three node with install all kinds of network confer. when all are ready ,install the Globus(a Gird module) on it .And to sign the Grid certificate for each other.Finally,install the other soft and confer which necessary,set up the database in Grid environment.Every thing is ready .now we would put our al soul in to the study of retrieval of LST based on Grid Computing technology. it include four step as follows:1 Atmospheric correction based GridMODTRAN, Atmospheric correction module which we used,was A complicated mathematics model developed by Fortran. by Cactus,we can seting this model on Grid platform without more modification.2 Emmissivity of landsurface database and the parameter table of retrieval based GridIn the Grid environment,building up the database by PostgreSQL. according to longitude latitude the sensor wave band etc. build up the landsurface emmissivity database and the countrywide parameter talbe of retrieval .compile the whole shoot function relatively use JAVA. prepared for the next work.3 The Gridservice of retrieval of LST based on webservice technologyOn the Grid platform, using webservice technology, we attempt to implement the simple maths addition model. Later,replacing the model by math model of retrieval of LST, and debugging the problem in this process. Accomplish the gridservice on the retrieval of LST.4 Distribute the computing resource by MPICH-G2MPI (Message Passing Interface) can become a new edition which was suit the Grid computing environmental by MPICH-G2 groupware, Using the MPICH-G2 can resolve the task transfer among the Grid node.with this help we compile the Gridservice program. Lastly, design a graphics interface linkthe command for operate easily.