Modelling of passive microwave signatures of supercooled clouds over the polar ocean

Radiative fluxes at the Earth's surface are very sensitive to small changes of liquid water path (LWP) if clouds with LWP <; 0.05 kg/m² are present. Supercooled liquid water (SLW) was detected and measured using ground-based microwave radiometers, aircraft instruments, and various satellite remote sensing techniques. Theoretical calculations were used to examine the EOS Aqua Advanced Microwave Scanning Radiometer (AMSR-E) and AMSU brightness temperatures T_Bs over the polar ocean for non-precipitating clouds with warm and supercooled water droplets. The AMSR-E and AMSU simulated data has been analyzed to determine the frequency and cloud temperature dependences of sensitivity of T_Bs to LWP change for several permittivity models. The sensitivity changes with the decrease of t_cl and with the increase of frequency. T_Bs difference between models also depends on t_cl and frequency. The values, spectral and polarization features of these differences are significant and can be used to improve description of supercooled water permittivity and decrease LWP retrieval errors of supercooled clouds.