INSAT-3DS Sounder

INSAT-3DS Sounder is the mission's geostationary atmospheric sounder, not the six-channel INSAT-3DS Imager ^[1][2]. It provides 18 infrared channels and one visible channel for cloud and Earth context, supporting temperature and humidity profiles, atmospheric stability indices, water-vapour content, and total column ozone ^[1][3]. Spectral coverage runs from about 0.695 um in the visible channel to 14.710 um in the longwave infrared channels; rounded wavelength and sensitivity values across the broader INSAT Sounder family do not change the 3DS-specific 18-IR-plus-VIS configuration ^[1][3][4]. Ground sampling is 10 km, full-frame sounding cadence is 3 hours, and the 6000 km by 6000 km sounding area is listed at 160 minutes; the 3DS sounder uses 13-bit measurements ^[1]. On 2024-03-07 the 3DS meteorological payloads began imaging and sounding with nominal parameters, giving the sounder an operational basis for geostationary profile retrieval workflows ^[2].