Brightness Temperature’s Sensitivity Analysis For" Clear Region"Amvs Derivation From Geo Satellite Infrared Imagery

The current techniques for atmospheric motion vector derivation from satellite images are mainly concentrated on cloud motion which uses cloud in IR imagery as tracer and water vapor motion which uses water vapor in water vapor imagery as tracer. The main theory is to search the matching tracer module from two or three continuous satellite images with half or one hour time interval and calculate the displacement of module to represent the atmospheric wind vector on corresponding altitude. If a region can not be identified as cloud-covered, the cloud-tracing technique would fail to obtain atmospheric motion vectors in this "clear" region with IR imagery.This paper is focused on retrieving atmospheric motion information in "clear regions" from geostationary satellite IR images to provide more wind materials with better spatial continuity for meteorological application. This work mainly includes the following four aspects:1、We analysis the attenuation characteristics of radiation and the refractive index difference characteristics of some different kind of aerosol particles in IR window spectrum region on the basis of atmosphere’s selective absorption characteristics of radiation. On this basis, we point out the atmosphere’s attenuation characteristics of radiation provide possibility for derive atmospheric motion vectors in clear region with IR imageries.2、On the basis of radiation transfer theory in IR window, we apply MODTRAN radiation transfer model to make sensitivity analysis on brightness temperature in thermal IR window channels with respect to water vapor and aerosol contents in the observation pixel, which might be used as tracers for deriving atmospheric motion wind vectors in clear atmosphere regions under middle latitude summer and winter atmosphere condition, by combination of atmospheric parameters and satellite-borne radiometer sensitivity performance. Additionly, we calculate the threshold value of tracer content change which could cause the difference of satellite-borne IR radiometer observation brightness temperature be greater than the different sensitivity of temperature (0.2-0.5K) in FY-2E borne radiometer IR channels. 3、We also carry out the feasibility analysis to ensure the existence of the tracer signals under certain conditions in real atmosphere by combination of the sensitivity results and data that includes FY-2E Atmospheric Total Precipitation Water products and Terra MODIS MOD04_L2Atmospheric Aerosol products. In addition, we calculate the monthly average percent of effective modules in total clear modules with FY-2E Atmospheric Total Precipitation Water products data in the region of (15°N～50°N,70°E～140°E) of2010and with Terra MODIS MOD04_L2Atmospheric Aerosol products data during the day time of03:00～04:00(UTC) of2009. The cases study and statistical analysis results reveal the estimated value to meet the required conditions for deriving atmospheric motion vectors in clear regions from IR imageries.4、We take a case analysis on retrieving atmospheric motion information in "clear" regions from satellite IR images with "split window" difference method and the calculate result shows a good consistency with the NCEP atmospheric wind on850hPa height.