Near-Real Time Surface-Based CAPE from Merged Hyperspectral IR Satellite Sounder and Surface Meteorological Station Data

Near-real time satellite-derived temperature and moisture soundings provide information about the changing atmospheric vertical thermodynamic structure occurring between the time gaps of successive routine National Weather Service (NWS) radiosonde launches. In particular, polar-orbiting satellite soundings become critical to the computation of stability indices over the central United States in the midafternoon, when there is no operational NWS radiosonde launch. Accurate measurements of surface temperature and dewpoint temperature are key in the calculation of severe weather indices, including surface-based convective available potential energy (SBCAPE). This paper shows that infrared-based satellite soundings often suffer from a cold and dry bias when estimating the surface parcel in severe weather conditions, which can lead to an underestimate of SBCAPE. To address this deficiency, this paper merges National Oceanic and Atmospheric Administration (NOAA) Center for Environmental Prediction (NCEP) Meteorological Assimilation Data Ingest System (MADIS) surface observation data coincident with soundings derived from the NOAA-Unique Combined Atmospheric Processing System (NUCAPS) to create an improved satellite-derived SBCAPE calculation. Biases of up to 4000 J/Kg in SBCAPE derived from NUCAPS-only soundings are corrected through the replacement of NUCAPS surface data with coincident MADIS surface observations. To address the need for reduced data latency, a near-real time merged satellite and surface observation product is demonstrated using NUCAPS products from the Community Satellite Processing Package (CSPP) applied to Direct Broadcast data received at multiple sites around CONUS, including University of Wisconsin (UW) with visualization using UW Space Science and Engineering Center’s RealEarth™ web map server.