## 2 Clouds Properties from Infrared and Microwave Satellite Observations
### Infrared Observations Only  
Passive IR observations are mainly sensitive to atmospheric humidity, temperature, liquid/ice clouds, and trace gases. Approaches to deriving cloud properties from infrared observations were among the first methods developed in the satellite meteorology initial years [34; 35; 36], while aspects of cloud microphysics, such as cloud optical thickness and particle size [37; 38; 39], were developed later. Inferring very good values for cloud optical thickness and the effective radius is the aim of the statistical technique developed by [40], a new discrete ordinates radiative transfer method, and asymptotic terms for thick layers reflection function were developed. A non-absorbing visible wavelength (0.75 \(\upmu\)m) and two absorbing wavelengths (2.16 and 3.7 \(\upmu\)m) are used for the effective radius and optical thickness of stratiform cloud retrievals. To reduce ambiguity in deriving the effective radius for optically thin clouds, the two absorbing near-infrared wavelengths are used. However, for optically thin clouds, the retrievals become uncertain. Following [41], the optical thickness and the effective radius uncertainty (5%) are analyzed as a function of errors in the measured reflection function, as well as in the phase function surface albedo. Finally, their method's performance using Advanced \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{3}{*}{**Authors**} & \multirow{3}{*}{**Year**} & \multicolumn{3}{c}{**Satellite**} & \multirow{3}{*}{**Main Features**} & \multirow{3}{*}{**Uncertainty or Accuracy of the Method (When Declared/Applicable)**} \\ \cline{3-4}  & & & & **Channel Frequency** & & **Main Features** \\  & & & & **[GHz]** & & **Declared/Applicable** \\ \hline \multirow{3}{*}{[PERSON] et al. [16]} & \multirow{3}{*}{2003} & \multirow{3}{*}{AMSU} & \multirow{3}{*}{23.8, 31.4} & Evolution of [13] & \\  & & & & G by using SST & \\  & & & & and SW from & \\  & & & & NWP models & \\ \multirow{3}{*}{[PERSON] et al. [17]} & \multirow{3}{*}{2005} & \multirow{3}{*}{AMSU} & \multirow{3}{*}{-} & MSPPS & \\  & & & 50–60, 89, 150, & 10-Var retrieval & \\  & & & 183 & algorithm & \\ \multirow{3}{*}{[PERSON] [18]} & \multirow{3}{*}{2006} & \multirow{3}{*}{AIRS,} & \multirow{3}{*}{-} & CLWC profiles & \\  & & & AMSU, HSB & & \\ \multirow{3}{*}{[PERSON] et al. [20]} & \multirow{3}{*}{2009} & \multirow{3}{*}{MMW} & \multirow{3}{*}{89–229} & CLWC, CIWC & \\  & & & 2010 & scanning & profiles & \\ \multirow{3}{*}{[PERSON] and [PERSON] [21]} & \multirow{3}{*}{2010} & radiometers & & & \\  & & & & & \\ \multirow{3}{*}{[PERSON] et al. [23]} & \multirow{3}{*}{2010} & SSM/I, & \multirow{3}{*}{-} & TPW, CLWP & \multirow{3}{*}{RSME\({}_{\text{VW}}=1.34\) kg/m\({}^{2}\)} \\  & & & AMSR-E & & \\ \multirow{3}{*}{[PERSON] and Weng [25]} & \multirow{3}{*}{2012} & SSMI/S & \multirow{3}{*}{-} & CIWP, D\({}_{\text{e}}\) & - \\  & & & & NOAA MIRS & \\ \multirow{3}{*}{[PERSON] et al. [26]} & \multirow{3}{*}{2013} & \multirow{3}{*}{ATMS} & \multirow{3}{*}{-} & algorithm & 13\%\(<\) SD\({}_{\%}\)\(<\) 24\% \\  & & & & outputs & \\ \multirow{3}{*}{[PERSON] et al. [27]} & \multirow{3}{*}{2017} & \multirow{3}{*}{FY-3D} & \multirow{3}{*}{52.8, 118.75 \(\pm\) 2.5} & TPW, CLWP & \multirow{3}{*}{RMSE\({}_{\text{TPW}}=3.19\) kg/m\({}^{2}\)} \\  & & & ATMS & & CLWP & SD\({}_{\text{CLWP}}=0.2\) mm \\ \multirow{3}{*}{[PERSON] et al. [30]} & \multirow{3}{*}{2018} & ISMAR, & \multirow{3}{*}{-} & SIWP, LWP, IWV & \multirow{3}{*}{MFE\({}_{\text{IWV,low}}=2\) kg/m\({}^{2}\)} \\  & & & MARSS & & \\ \multirow{3}{*}{[PERSON] et al. [31]} & \multirow{3}{*}{2018} & \multirow{3}{*}{TROPICS} & \multirow{3}{*}{90, 118.75, 183,} & WV profiles, LP, & \\  & & & & 205 & IP & - \\ \multirow{3}{*}{[PERSON] et al. [32]} & \multirow{3}{*}{2018} & TEMPEST- & \multirow{3}{*}{89–183} & WV profiles, & \\  & & D & & CLWP, CIWP & - \\ \multirow{3}{*}{[PERSON] et al. [28]} & \multirow{3}{*}{2021} & FY-3D & \multirow{3}{*}{52.8, 118.75 \(\pm\) 2.5} & TPW, CLWP & - \\ \hline \hline \end{tabular}
\end{table}