NPP Retrieval Based On HJ-1 And Spatial Distribution Study

Net primary production is base of matter and energy in ecosystem,that directly reflects plant community production in the natural and that is very important in carbon cycling and storage in the world.It is possible to retrieval NPP using china's satellite after HJ-1 satellite launch successfully.Based on the relationship between HJ-1/CCD spatial resolution and map scale, this paper uses it to resurvey land use coverage map of Beijing of 2000, and determines six feature type.After that, using the weighted average method,this paper calculates the maximum light use efficiency of the six feature . At last, this paper establish the modified CASA model that is suitable HJ-1/CCD and Bejing region.Based on the modified CASA model, using HJ-1/CCD image data, combined with meteorological data, this paper retrives solar radiation,vegatation photosynthetic active radiation, MVC-NDVI, light use efficiency .Using these parameters, the paper retrives NPP of Beijing in 2009. Estimates and measured value do regression analysis,the correlation coefficient closer to 1, this shows that the modified CASA model is reasonable and reliable.Based on the modified CASA model, estimation value of NPP shows that: different feature have different value, woodland is largest.Form Match to August are mainly accumlated time, the accumulation is seventy percent.NPP spatial distribution trend is from north to south, from west to east, by the vegetation distribution.Based on the modified CASA model, NPP retrieval system is established by IDL as algorith language and C# embedded ArcEngine as interactive interface language.This retrieval system achieves a fully automated production.In summary, the modified CASA model is fit for Beijing and NPP retrieval system is improved the operational capacity of NPP retrival.