Advances in Water Vapor Profile Retrievals By Merged TEMPEST-D and GOES-16 ABI Soundings

The Temporal Experiment for Storms and Tropical Systems – Demonstration (TEMPEST–D) mission is designed to demonstrate the performance of the small CubeSat. During the three-year mission from 2018 to 2021, TEMPEST-D in the Low Earth Orbit provides well-calibrated microwave measurements at 87, 164, 174, 178, and 181 GHz with nadir spatial resolution of 14 km at 164 to 181 GHz and of 28 km at 87 GHz. The size of the TEMPEST-D, including the flight system and the instrument, is 10 cm x 20 cm x 34 cm with a weight of 11.2 kg and is much lighter than the similar operational Microwave Humidity Sounders (MHS; 63 kg) on board NOAA-18/19 and MetOp-A/B/C satellites. The first Geostationary Operational Environmental Satellites – R (GOES–R) series satellite, GOES-16, was launched on November 19, 2016, and carries multiple instruments, including the Advanced Baseline Imager (ABI). The ABI instrument measures 16 spectral bands from visible to infrared with spatial resolution from 0.5 km in visible to 2 km in infrared and observes the entire disk of the Earth every 5 to 15 minutes, depending on the operational modes. With the high spatial and temporal resolution of ABI measurements, TEMPEST-D and GOES-16 ABI observations can be effortlessly matched according to space and time. Compared with TEMPEST-D water vapor soundings, adding three ABI IR-sounding channels increases the vertical resolution of water vapor retrievals. Based on the simulations, the root mean squared errors (RMSEs) of retrieved water vapor decrease from 1.137 (1.009) g/kg using only TEMPEST to 0.990 (0.947) g/kg using jointed TEMPEST and ABI sensors under clear (cloudy) conditions. Retrieved water vapor profiles are validated by comparing radiosonde measurements from the Integrated Global Radiosonde Archive (IGRA), and the merged TEMPEST and ABI retrievals decrease water vapor RMSEs from 1.161 (1.477) g/kg using only TEMPEST to 1.047 (1.424) g/kg in clear (cloudy) skies.