INSAT-3DR Sounder

INSAT-3DR Sounder is the mission's 19-channel geostationary atmospheric sounder, separate from the six-channel INSAT-3DR Imager ^[1][2]. It uses 18 infrared sounding channels plus one visible channel for cloud and Earth context, supporting temperature and humidity vertical profiles, atmospheric stability indices, water-vapour content, and total column ozone ^[1][3]. The channel groups cover VIS 0.67-0.72 um, SWIR/MWIR 3.74-4.58 um, and MIR/LWIR 6.51-14.71 um; the same sounder class can place the rounded longwave limit near 14.85 um, without changing the 18-IR-plus-VIS configuration ^[1][3]. Ground sampling is 10 km, with full-frame sounding every 3 hours; the 6000 km by 6000 km sounding area is listed at 160 minutes ^[1]. This makes the instrument relevant for geostationary profile and stability products where vertical thermal and moisture information is more important than high-resolution scene imaging ^[1].