Potential for Remote Sensing of Precipitation using the Dynamic Microwave Radiometer on the NASA INCUS Mission based on the Heritage of TEMPEST Scientific Results

The INvestigation of Convective UpdraftS (INCUS) is a NASA Earth Venture mission (EVM-3) that will provide the first global systematic investigation into convective mass flux, the vertical transport of air and water, and its evolution within deep tropical convection.  The overarching goal of the INCUS mission is to understand why, when and where tropical convective storms form, and why only some storms produce extreme weather.  INCUS is led by PI Susan van den Heever of Colorado State University (CSU), in collaboration with NASA/Jet Propulsion Laboratory (JPL), Blue Canyon Technologies, and Tendeg Systems.  INCUS consists of a series of three small satellites flying in formation, each carrying a Ka-band radar based on RainCube and one cross-track scanning radiometer based on TEMPEST. A novel time-differencing approach among the three satellites flown in close succession (30, and 90, and 120 seconds apart) will provide the first estimates of convective mass flux across the tropics.

The success of the INCUS EVM-3 proposal to NASA relied on the prior success of two pathfinder CubeSat missions: RainCube, the first weather radar on a CubeSat, led by NASA/JPL, and the Temporal Experiment for Storms and Tropical Systems – Demonstration (TEMPEST-D) mission, led by CSU, producing the first global (up to 58 degrees latitude) observations from a multi-frequency microwave radiometer on a CubeSat, operating for nearly three years in LEO.

TEMPEST-D, a NASA Earth Venture Technology mission, produced global atmospheric science data, a well-calibrated, highly stable radiometer over three years of operations. TEMPEST-D brightness temperatures were validated using scientific and operational microwave sensors, including GPM/GMI and four MHS sensors, operating at similar frequencies to TEMPEST-D channels at 87, 164, 174, 178 and 181 GHz. Using the double-difference approach, TEMPEST-D performance was shown to be comparable to or better than much larger scientific and operational sensors, in calibration accuracy, precision, stability and instrument noise, during its nearly 3-year mission.

A duplicate TEMPEST sensor produced alongside TEMPEST-D was integrated with the Compact Ocean Wind Vector Radiometer (COWVR) from NASA/JPL and launched by the U.S. Space Force to demonstrate low-cost space technologies to improve global weather forecasting. COWVR/TEMPEST were launched on the STP-H8 mission on December 21, 2021, and have performed coordinated observations of Earth’s oceans and atmosphere from the ISS since January 7, 2022.  Retrievals of water vapor profiles, clouds, and precipitation from COWVR/TEMPEST-H8 are being performed in collaboration between JPL and CSU.

Previous studies have validated the accuracy and precision of TEMPEST-D brightness temperatures using clear-sky oceanic observations.  Recent advances extended the validation of TEMPEST-D and TEMPEST-H8 brightness temperature observations over tropical cyclones using GPM/GMI brightness temperatures and GPM/DPR vertical cumulative reflectivity. 

Prior studies demonstrated accurate quantitative precipitation estimation using machine learning over CONUS.  Recent advances expanded this capability to a global basis using GPM/GMI and AMSR-2 datasets for training and validation and IMERG rain rates for cross comparison.  The heritage of TEMPEST-D and TEMPEST-H8 will be used to demonstrate the potential for remote sensing of precipitation from the Dynamic Microwave Radiometer on the INCUS mission.