This paper describes the characteristics of the Special Sensor Microwave/Imager (SSM/I) onboard the Defense Meteorological Satellite Program (DMSP),analyzes absorbing,re-emitting and scattering effects of the atmosphe...This paper describes the characteristics of the Special Sensor Microwave/Imager (SSM/I) onboard the Defense Meteorological Satellite Program (DMSP),analyzes absorbing,re-emitting and scattering effects of the atmospheric particles (especially cloud particles and rain drops).The inner physical cause of typhoon's representative form on microwave images is revealed.An index of particle size is then induced as such:Symmetrically inverse channel 85H's (85H is an abbreviation for channel 85.5 GHz in horizontal polarization,see Table 1 in the text.) absorption segment and put it into the extension of the scattering segment.The precipitation index was formed as the average of three elements:normalized 19H,normalized 37H,and inversed normalized 85H.It is approved that the image of particle size index overcomes some shortcomings of the single raw channel,such as:37H is not sensitive to large rain drops,85H is not sensitive to mid-size rain drops and can reveal typhoon's spiral structure more clearly.展开更多
A collocated SSM/I and radiosonde measurement data set provided by the NASDA(Japan) was used to retrieve the total precipitable water(PW)over oceans.The retrieval results obtained with several regression algorithms we...A collocated SSM/I and radiosonde measurement data set provided by the NASDA(Japan) was used to retrieve the total precipitable water(PW)over oceans.The retrieval results obtained with several regression algorithms were compared against the radiosonde measurements.It is shown that:(a)the routinely operational algorithm of Alishouse et al.(1990)yields significant underestimation in high PW regime and overestimation in low PW regime;(b)a cubic correction by Colton and Poe(1994)is not sufficient and globally improves slightly the retrieval results;and (c)the regression algorithm with the form of brightness temperature(T_b)function In (280-T_b) gives a little largely scattered retrievals in whole PW range but without considerable over-and underestimates in low and high PW regimes.To improve the estimation of the oceanic precipitable water from the SSM/I measurements,a composite algorithm with different forms of T_b function in low.medium and high PW regimes is proposed and tested.展开更多
文摘This paper describes the characteristics of the Special Sensor Microwave/Imager (SSM/I) onboard the Defense Meteorological Satellite Program (DMSP),analyzes absorbing,re-emitting and scattering effects of the atmospheric particles (especially cloud particles and rain drops).The inner physical cause of typhoon's representative form on microwave images is revealed.An index of particle size is then induced as such:Symmetrically inverse channel 85H's (85H is an abbreviation for channel 85.5 GHz in horizontal polarization,see Table 1 in the text.) absorption segment and put it into the extension of the scattering segment.The precipitation index was formed as the average of three elements:normalized 19H,normalized 37H,and inversed normalized 85H.It is approved that the image of particle size index overcomes some shortcomings of the single raw channel,such as:37H is not sensitive to large rain drops,85H is not sensitive to mid-size rain drops and can reveal typhoon's spiral structure more clearly.
基金This work was supported by NASDA(Japan)under Contract No.A2-RA-A-0017by Committee of Science and Technology of China for a microwave remote sensing project.
文摘A collocated SSM/I and radiosonde measurement data set provided by the NASDA(Japan) was used to retrieve the total precipitable water(PW)over oceans.The retrieval results obtained with several regression algorithms were compared against the radiosonde measurements.It is shown that:(a)the routinely operational algorithm of Alishouse et al.(1990)yields significant underestimation in high PW regime and overestimation in low PW regime;(b)a cubic correction by Colton and Poe(1994)is not sufficient and globally improves slightly the retrieval results;and (c)the regression algorithm with the form of brightness temperature(T_b)function In (280-T_b) gives a little largely scattered retrievals in whole PW range but without considerable over-and underestimates in low and high PW regimes.To improve the estimation of the oceanic precipitable water from the SSM/I measurements,a composite algorithm with different forms of T_b function in low.medium and high PW regimes is proposed and tested.
