Extraction Of Flat Sea Surface Brightness Temperature Information In The Western And Central Pacific Ocean Based On L-Band SMAP Satellite

Compared with optical remote sensing,microwave remote sensing has the advantages all-weather,day and monitoring a wide range of hydrologic and Marine environmental dynamic elements,which is one of the effective means of satellite remote sensing monitoring sea surface brightness temperature,including the L-band?1.4 to 1.427 GHz?is protected by international treaty,used for radio astronomy research,cloud influence can be neglected for the band,and microwave observations are recognized international monitoring sea surface brightness temperature preferred band.Sea surface brightness temperature is a key factor in the study of microwave remote sensing forward radiation transmission model,and obtaining true and effective brightness temperature is the basis of inversion of other ocean surface physical and geometric parameters.In the disseration,takes the central and western Pacific Ocean as the research object,and simulates the difference in the widely used seawater dielectric constant models of KS?Klein-Swift?,MW?Meissner-Wentz?,and Bl?Blanch-Auasca?,then analyzes correction between wind speed and brightness tempeature gain in the four seasons of spring,summer,autumn,and winter,2018,and extraction and error analysis of seasonal flat sea surface brightness temperature imformation in the central and western Pacific Ocean.Therefore,this study has certain scientific significance and application prospect for the inversion of ocean surface salinity and other marine environmental factors.The disseration first through the use of K-S?M-W?Bl three kinds of polarized brightness temperature simulation for water dielectric constant model,and then comparative analysis of three kinds of model of the real part and imaginary part of differences in values change with the electromagnetic wave incident angle,and the use of dielectric constant model simulation with three kinds of brightness temperature,calm sea surface analysis in salinity is 30?40 psu and the cases of different incident angle,polarization brightness temperature on salinity sensitivity of differences,so as to choose the most suitable model,then based on the satellite L2C SMAP sea surface brightness temperature and 10 m sea surface wind speed data,analysis on the correlation between wind speed and brightness temperature gain,then using least square method according to the different wind speed range build L-band brightness temperature gain model of rough sea surface temperature and take into the brightness white crown consideration,the influence of the last input Argo buoy data set temperature and salt,flat sea surface through the calculation of water dielectric constant model brightness temperature,and model correction of the calm sea surface brightness temperature calibrate comparative analysis,further the applicability of the quantitative evaluation of the model in the region.The results show:?1?In 0?4 GHz,low K-S dielectric constant model real value relative to the other two models,and K-S values of the model into the youngest of the three,the imaginary part of the change of the three models are basically the same,in the L-band?1.4 to 1.427 GHz?,K-S greater attenuation model,and the M-W model and attenuation values Bl model is basically consistent,on the whole,three models of dielectric constant real component with the increase of frequency,real value decreases,imaginary part rapidly in low frequency band is decreased,then increased,finally tended to be stable.?2?The electromagnetic wave incident angle,the greater the horizontal polarization brightness temperature is lower,and the vertical polarization brightness temperature is increased with the increase of incident angle,considering the differences of the three models from multiple angles and applicability,integrated a number of factors,and considering the high frequency case,M-W model is chosen as the calm sea brightness temperature model is most appropriate.?3?The wind speed and gain present positive correlation relationship between brightness temperature,the higher the wind speed,gain more brightness temperature,and under the same wind speed,the horizontal polarization brightness temperature gain relative to the vertical polarization brightness temperature gain is on the high side.In wind speed within the range of 0?3 m·s^-1,horizontal polarization brightness temperature sensitivity is higher than vertical polarization mode,0.25 K/m·s^-1,in the range of 3?12 m·s^-1 of the former is higher than the latter,0.02 K/m·s^-1 in more than 12 m·s^-1 wind speed range,higher than the former wind velocity range of 0.01 K/m·s^-1,namely with the increase of wind speed,wind speed of V,H polarized brightness is more close to the influence of temperature,on the whole,horizontal polarization brightness temperature sensitivity to gain brightness temperature is higher than that of vertical polarization mode;?4?Brightness temperature model of error analysis,the research area is in the western and central Pcaific Ocean near the land surface brightness temperature deviation is large,but in the open ocean brightness temperature polarization error can control within 0.2 K,in quantitative evaluation,between the regression analysis of model brightness temperature and reference brightness temperature for spring?October?,summer?January?,autumn?April?and winter?July?in 2018,the coefficient of determination was above 0.5,RMSE can be controlled within 0.2 K,so you can determine the model is suitable for the area.