Microwave Emissivity of Typical Vegetated Land Types Based on AMSR2

To investigate the microwave radiation characteristics of different vegetation types, “pure pixels” 12 typical vegetated land types were selected and corresponding emissivity was retrieved under clear sky based on L1C AMSR2 observed brightness temperatures (TBs). According to values for spectral features in summer from 10.65 89 GHz analyzed first. Then, temporal variations at 10.65, 18.7, 36.5 H-polarized (hereinafter 10H, 18H 36H) are shown period January 2018 September 2020. Finally, responses 10H surface skin temperature (SKT), normalized differential index (NDVI), soil moisture content (SMC) quantitatively evaluated using a step-by-step analysis method. The general results as follows: (H-pol) increases with frequency biomass, while polarization differences decrease biomass. V-pol biomass those H-pol emissivity, there negative correlations unusually high low-frequency grasslands open shrublands (OS). variation amplitude seems be negatively correlated evergreen broadleaf forests show little variation. In general, seasonal changes consistent NDVI most types. Nevertheless, some cases, change is obviously ahead or behind that NDVI, revealing may sensitive elements do not sync. addition, frequencies also amplitudes turning points. Generally, response SKT weak, regardless whether positive negative. relatively large can attributed other indirect causes. plays role low-biomass drier environments medium- high-biomass SMC complex factor have effect emissivity.