# Passive Microwave Imagers, Their Applications, and Benefits: A Review
## 1 Introduction
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**PMWI 1** & **Satellite** & **Launch Date** & \begin{tabular}{c} **Central Frequency** \\ **(GHz)** \\ \end{tabular} & \begin{tabular}{c} **Number of** \\ **Channels** \\ \end{tabular} & \
\begin{tabular}{c} **Swath Width** \\ **(km)** \\ \end{tabular} &
\begin{tabular}{c} **FOV 2** \\ **(km)** \\ \end{tabular} \\ \hline ESMR 3 & Nimbus-5, 6 & 1972 & 19.35H 4 & 1 & 1270–3100 & 25–160 \\ \hline SMMR 5 & Nimbus-7, SeaSat-1 & 1978 & 6.6 (V 6, H)–37 (V, H) & 10 & 780 & 17–160 \\ \hline SSM/17 & DMSP 8 & 1987 & 19.35 (V, H)–85 (V, H) & 7 & 1400 & 11–68 \\ \hline TMI 9 & TRMM 10 & 1998 & 10.65 (V, H)–85.5 (V, H) & 9 & 760 & 5–63 \\ \hline MSMR 11 & OceanSat-1 & 1999 & 6.6 (V, H)–21.0 (V, H) & 8 & 1360 & 22–105 \\ \hline AMSR 12 & ADEOS 13-2 & 2002–2003 & 6.925 (V, H)–89 (V, H) & 16 & 1600 & 3.1–70 \\ \hline AMSR-E 14 & Aqua & 2002–2011 & 6.925 (V, H)–89 (V, H) & 12 & 1450 & 40–75 \\ \hline WindSat & Coriolis & 2003 & 6.9 (V, H)–36.6 (V, H \(\pm\) 45, L, R 15) & 22 & 1025 & 8–71 \\ \hline SSMIS 16 & DMSP & 2004 & 19.35 (V, H)–183.31 \(\pm\) 1 (H) & 24 & 1700 & 13.1–70.1 \\ \hline MWRI 17-1 & FY 18-3(A, B, C, D) & 2008–2010 & 10.65 (V, H)–150 (V, H) & 12 & 1400 & 7.5-85 \\ \hline MIRAS 19 & SMOS 20 & 2009 & 1.413 (V, H) & 2 & 1000 & 35–50 \\ \hline MADRAS 21 & Megha-Tropiques & 2011 & 18.7 (V, H)–157 (V, H) & 9 & 1700 & 6–60 \\ \hline MWRI 22 & HY 23-2(A, B, E) & 2011, 2018, and \(\geq\)2024 & 6.6 (V, H)–37 (V, H) & 9 & 1600 & 15-120 \\ \hline AMSR 24 & GCOM-W1 25 & 2012 & 6.925 (V, H)–89.0 B (V, H) & 16 & 1450 & 3–62 \\ \hline GM 26 & GPM-CO 27 & 2014 & 10.65 (V, H)–183.31 \(\pm\) 3 (V) & 13 & 850 & 4.4-32 \\ \hline MWRI-2 & FY-3(F, H) & 2023 and \(\geq\)2025 & 10.65 (V, H)–118.7503 \(\pm\) 1.2 (V) & 22 & 1400 & 6–45 \\ \hline MWRI-RM 28 & FY-3(G, I) & 2023 and \(\geq\)2026 & 10.65 (V, H)–183.31 \(\pm\) 7.0 (V) & 26 & 800 & 4–35 \\ \hline COWVR 29 & ISS COWVR 30 & 2022–2024 & 18.7 (V, H, P 31, M2, L 33, R)–33.9 & 18 & 890 & 11–31 \\ \hline AMSR3 & GOSAT-GW 34 & \(\geq\)2025 & 6.925 (V, H)–183.31 \(\pm\) 3 (V) & 21 & 1450 & 4–58 \\ \hline MWI 35 & WSF 36-M1, M2 & 2024, 2028 & 10.85 (V, H, 3 rd, 4 th)–89 (V, H) & 18 & 1450 & 10–50 \\ \hline MWI & Metop-SG 37-(B1, B2, B3) & \(\geq\)2026, \(\geq\)2033, \(\geq\)2040 & 18.7 (V, H)–183.31 \(\pm\) 2 (V) & 26 & 1700 & 10–50 \\ \hline ICI 38 & Metop-SG-(B1, B2, B3) & \(\geq\)2026, \(\geq\)2033, \(\geq\)2040 & 183.31 \(\pm\) 7.0 (V)–664 \(\pm\) 4.2 (V, H) & 13 & 1700 & 16 \\ \hline CIMR 39 & CIMR A & \(\geq\)2029 and \(\geq\)2031 & 1.41, 6.9, 10.65, 18.7, 36.5 (V, H, P, & 30 & 1900 & 3–64 \\ \hline  & CIMR B & \(\geq\)2029 and \(\geq\)2031 & 1.41, 6.9, 10.65, 18.7, 36.5 (V, H, P, & 30 & 1900 & 3–64 \\ \hline  & & & & & & \\ \end{tabular} \({}^{1}\) Passive Microwave Imagers, \({}^{2}\) Field of View, \({}^{3}\) Electrically Scanning Microwave Radiometer, \({}^{4}\) Horizontal, \({}^{5}\) Scanning Multichannel Microwave Radiometer, \({}^{6}\) Vertical, \({}^{7}\) Special Sensor Microwave/Imager, \({}^{8}\) Defense Meteorological Satellite Program, \({}^{9}\) Tropical Rainfall Measuring Mission Microwave Imager, \({}^{10}\) Tropical Rainfall Measuring Mission Microwave Naming Radiometer, \({}^{12}\) Advanced Microwave Scanning Radiometer, \({}^{13}\) Advanced Microwave Scanning Radiometer–Earth Observing, \({}^{15}\) Right-hand Circular Polarization, \({}^{16}\) Special Sensor Microwave Imager/Sounder, \({}^{17}\) Microwave Radiation Imager Radiometer, \({}^{18}\) Feng-Yun, \({}^{19}\) Microwave Imaging Radiometer with Aperture Synthesis, \({}^{3}\) Soil Moisture and Ocean Salinity, \({}^{22}\) MicroWave Imaging Radiometer with Advanced Sounder, \({}^{22}\) Microwave Radiation Imager, \({}^{23}\) Hai Yang, \({}^{24}\) Advanced Microwave Scanning Radiometer, \({}^{25}\) Global Change Observation Mission—Water 1, \({}^{26}\) Global Precipitation Measurement Microwave Imager, \({}^{27}\) Global Precipitation Measurement-Core Observatory, \({}^{28}\) Radiometer, \({}^{29}\) Compact Ocean Wind Vector Radiometer, \({}^{30}\) International Space Station Compact Ocean Wind Vector, \({}^{31}\) Polarization, \({}^{32}\) Multipolarization, \({}^{33}\) Linear Polarization, \({}^{34}\) Greenhouse Gases Observing Satellite—Global Water, \({}^{35}\) Microwave Imaging Radiometer, \({}^{36}\) Wind and Sea-Focused Microwave Radiometer, \({}^{37}\) Meteorological Operational Satellite—Second Generation, \({}^{38}\) Imaging Microwave Radiometer, \({}^{39}\) Copernicus Imaging Microwave Radiometer. \\ \end{tabular} \({}^{38}\) Meteorological Operational Satellite—Second Generation, \({}^{38}\) Imaging Microwave Radiometer, \({}^{39}\) Copernicus Imaging Microwave Radiometer.  
\end{table}