| Dust storm is a typical disaster weather which outbreaks in arid and semi-arid areas globally.The dust aerosol generated from dust storm dominates the aerosol loading in the troposphereand make very comprehensive impacts on the global environment,weather,climate and ecology.Satellite remote sensing has showed the great priority on dust monitoring and has become indispensable way for dust aerosol study.And the remote sensing of thermal infrared,especially the hyperspectral infrared method,has become a rising concern in dust aerosol study in rencent years.For severe dust storm,it can be used to develop the dust aerosol optical depth retriveal algorithm when the visible and near-infrared signals saturated.In this paper,the thermal infrared spectral characteristics of dust aererol are analysed in details,using the CrIS hyperspectral infrared satallite data.And the visible-infrared and thermal infrared radiance of dust aerosol observed by satellite have been discussed by the RTTOV v11.3radiative transfer model.Main works are summarized as follow:(1)The CrIS hyperspectral infrared satallite data has been used to show infrared spectral characteristics under different atmospheric conditions.As the results show,different states of weather have totally different spectral characteristics in the infrared bands.The atmosphere window about 800 to 1000 cm-~1 is a sensitive area for dust aerosol,and the dust brightness temperature curves show a distinctly negative slope.Then,we use a threshold score method to recognize the dust area employing Cr IS data.Moreover,the results show that CrIS hyperspectral data have some advantages in the study of dust aerosol.(2)The visible-infrared and thermal infrared radiance of dust aerosol observed by satellite have been simulated by the RTTOV v11.3 radiative transfer model.Futhermore,the accuracy of simulation results and the validation of the RTTOV v11.3 radiative transfer model by the other remote sensing data are discussed.On the basis of the previous tasks,through sensitivity analysis of dust aerosol properties to the top of the atmosphere brightness temperature and the influence of brightness temperature caused by the changes of atmospheric and surface parameter as well as the characteristic parameters of dust itself,the variation of CrIS spectrum signature of dust aerosol is deeply discussed.In the sensitivity study of dust aerosol properties,both the optical depth of dust and the dust layer height have great influence on the atmosphere brightness temperature,substantially sensitive to in the thermal infrared band.Assuming that the dust layer height remains unchanged,with the increase of dust optical depth,the values of brightness temperature in the 800-1000cm~-11 interval all decrease,while the attenuation degrees enlarge.In addition,the larger the optical depth is,the more obvious the negative slope of dust brightness temperature is.The study also finds that when remaining the optical depth constant and changing the height of dust layer only,the higher the dust layer is,the more obvious the negative slope characteristic of dust is.With the increase of the height of the dust layer,the value of the brightness temperature gradually reduces.It indicates that the brightness temperature of the top of atmosphere is very sensitive to the change of dust layer height.(3)At last,the Jacobian function is used to analyse the brightness temperature variation at different heights,and we also find that the sensitivity of dust optical depth in different dust layers and spectral ranges is different.And then the effects of land surface temperature on brightness temperature of dust layer is also studied.Finally,the channel selection issue has been discussed for the thermal infrared hyperspectral remote sensing. |
PDF Full Text Request