## Appendix A
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Instrument** & **Classification** & **Wavelength** & **Average Size** [**nm**] & **Average Size** [**km**] & **Spatial Resolution** & **Swath** [km] & **Mass Power** & **Data** [**W]** & **Data** [**Mpps]** & **Orbit** **Attitude** [**Mpps]** \\ \hline  & Fourier Transform & & & & & & & & & \\ IASI \({}^{b}\) & spectrometer b & [3.62–15.5] 8641 & 1.1 & 25, 1–30 & 2052 & **236** & **210** & 1.5 & 827 \\ (MeOp) [25] & Radiometer/ter & spectral sampling & & & & & & & \\  & Hyperspectral resolution & & & & & & & & \\ \hline AIRS \({}^{d}\) (Aqua) [25] & Infrared sounder/ & [0.4–15.4] & & & & & & & & \\  & Hyperspectral resolution & spectral channel \textgreater{}2300 & 0.219 & 13.5, 1 & 1650 & 177 & **220** & 1.27 & 705 \\ \hline Crls \({}^{d}\) (JPSS) [25] & Infrared Sounder/ & [3.92–15.8] 1345 & & & & & & & \\  & Hyperspectral resolution & spectral channels & & & & & & \\ \hline HIRS/ d\({}^{d}\) (MeOp, NOAA) & Infrared sounder/ & [0.69–14.95] & & & & & & & \\  & Multispectral resolution & 20 spectral channels & & & & & & \\ \hline EON-IR \({}^{d}\) & Infrared Sounder/ & [4.08–5.13] & & & & & & & \\ CIRA [25] 6.21 & Hyperspectral resolution & 625 channels & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Survey of optical sounders instruments: multispectral and hyperspectral. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Instrument/Mission** & **Frequency** & **Antenna Size** & \begin{tabular}{c} **Spatial** \\ **[GHz]** \\ \end{tabular} & \begin{tabular}{c} **Mass** \\ **[km]** \\ \end{tabular} & \begin{tabular}{c} **Power** \\ **[kg]** \\ \end{tabular} & \
\begin{tabular}{c} **Data Rate** \\ **[W]** \\ \end{tabular} &
\begin{tabular}{c} **Orbit Altitude** \\ **[km]** \\ \end{tabular} \\ \hline Altika/SARAL [25] & 23.8, 36.5, 35.75 & 1 & 10 & 40 & 85 & 43 & 800 \\ \hline SWIM/CRSAT [25] & 13.58 & 0.9 & - & 120 & 50 & 519 \\ \hline Altimeter/SWOT [24] & 5.3, 13.58 & 1.2 & 25 & 70 & 78 & 22.5 & 891 \\ \hline Karin*/SWOT [24] & 35.75 & \(5\times 0.25\) & \(\begin{array}{c}0.05\,^{a}\\ 1\,^{b}\end{array}\) & & & & & & \\ \hline RA-2/Envisat [24, 25] & 3.2, 13.6 & 1.5 & 20 & 110 & 161 & 100 & 774 \\ \hline SSALT/TOPEX-Poseidon [24, 25] & 13.65 & 1.5 & 25 & 24 & 49 & - & 1336 \\ \hline \hline \end{tabular}  
* The background color in the table indicates the type of platform suitable for the instrument according to the power and mass requirements: light gray: micro-platform; gray: mini-platform. \({}^{a}\) Interferometry; \({}^{a}\) Spatial resolution over land; \({}^{b}\) Spatial resolution over ocean.  
\end{table} 
Table 10: Survey of Radar Altimeter instruments. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Instrument/Mission** & **Frequency** & **Antenna Size** & \begin{tabular}{c} **Spatial** \\ **[GHz]** \\ \end{tabular} & \begin{tabular}{c} **Mass** \\ **[m]** \\ \end{tabular} & \begin{tabular}{c} **Power** \\ **[km]** \\ \end{tabular} & \
\begin{tabular}{c} **Data Rate** \\ **[kg]** \\ \end{tabular} &
\begin{tabular}{c} **Orbit Altitude** \\ **[km]** \\ \end{tabular} \\ \hline SIRAL/Cryosat-2 [24, 25] & 13.56 & 1.2 & \(\begin{array}{c}15\\ 0.25\,^{a}\end{array}\) & 70 & 149 & 24,000 & 717 \\ \hline SRAL/Sentinel-3 [24, 25] & 5.3, 13.58 & 1.2 & \(\begin{array}{c}0.03\,^{a}\\ 0.3\,^{a}\end{array}\) & & & & & & \\ \hline Poseidon-4/ Sentinel-6 [24] & 5.3, 13.58 & - & \(\begin{array}{c}20\\ 0.3\,^{a}\end{array}\) & & & & & & \\ \hline \hline \end{tabular}  
* The background color in the table indicates the type of platform suitable for the instrument according to the power and mass requirements: light gray: micro-platform; gray: mini-platform. \({}^{a}\) Along track resolution (SAR mode).  
\end{table} 
Table 2: Survey of Radar Altimeter instruments with SAR processing.