Nationwide aerosol optical thickness retrieval application using grid computing platform

Aerosol optical thickness retrieval (AOT) from remotely sensed data over land is still a difficult task because the solar light reflected by the Earth-atmospheric system mainly comes from the ground surface. A novel aerosol remote sensing model SYNTAM by exploiting the synergy of TERRA and AQUA MODIS data could be used to accomplish part of the task of aerosol retrieval over land, especially over higher reflective surface. This paper addressed the issue how the SYNTAM method is applied to the national wide MODIS data for retrieval of aerosol optical thickness over China. The retrieval process is time consuming and the EMS (enhanced memory systems) memory required is very high. To solve the problem, we adapted the SYTAM model to the Grid computing environment. First retrieval process is laid out. The process is decomposed into small steps in pipeline. Decomposing strategy does not consider the difference computability among the computing elements. A coordinator is in charge of load balance. And then the detailed data query, data pre-processing, job monitoring and post-processing are discussed. We have developed one middleware by which the retrieval algorithm can be parallel processed. Preliminary experiment of aerosol retrieval of nationwide range was conducted. The experimental results indicated the computational process had been accelerated in an effective way. Using Grid computing platform, wide range and real-time aerosol information can be retrieved.