Evaluation of the ATMS-MIRS and NUCAPS Retrievals in the Vicinity of the Tropical Cyclones

The Suomi National Polar-Orbiting Partnership satellite (S-NPP), launched in October 2011, is part of the Joint Polar Satellite System (JPSS), the next generation polar-orbiting operational environmental satellite system. S-NPP carries five instruments, including the Advanced Technology Microwave Sounder (ATMS) and the Cross-track Infrared Sounder (CrIS). ATMS is a successor to the Advanced Microwave Sounding Unit (AMSU) which has a wider swath and a higher resolution (26 km at nadir for ATMS and 52 km at nadir for AMSU). CrIS represents a considerable enhancement over the High Resolution Infrared Radiation Sounder (HIRS), NOAA's legacy infrared sounder. Together ATMS and CrIS provide data with improved quality, higher spatial and spectral resolution, and greater spatial coverage in the tropics when compared to their predecessors. ATMS temperature and moisture retrievals are routinely estimated using the new operational Microwave Integrated Retrieval System (MIRS), a physical 1-D retrieval system that simultaneously solves for vertical profiles of moisture and temperature.  The NOAA Unique CrIS ATMS Processing System (NUCAPS) combines ATMS and CrIS data to take advantage of the strengths of both instruments, specifically, the higher vertical resolution of the infrared spectrum of CrIS, and the all-weather sensing ability of the ATMS microwave sounders. The improvements provided by ATMS-MIRS and NUCAPS make it possible to obtain useful temperature and moisture profiles in many problematic (heavy rain, and convection) scenes. While the overall quality of the ATMS-MIRS and NUCAPS soundings have been evaluated globally, no validation has been done in the challenging tropical cyclone (TC) environment.

The ATMS-MIRS retrievals within 1000 km of the TC center have been collected and compared to dropsondes available from aircraft reconnaissance in the Atlantic and East Pacific during the 2012 - 2015 Hurricane Seasons and to the vertical profiles produced by the Global Forecast System (GFS).  Using this database, error and bias statistics were calculated, and a bias correction based on radial distance from the TC center was derived. In addition, an algorithm was developed for combining bias-corrected ATMS and GFS data to obtain more realistic thermodynamic fields in the TC environment, including a more realistic representation of the inflow boundary layer and warm core. The results of the above analysis will be presented as well as the comparison of separate algorithms developed for Atlantic and East Pacific. In addition, the results of applying a similar procedure to preliminary NUCAPS data will be discussed.  The corrected soundings will be used to develop a moisture flux application that allows for the detection of dry air intrusions.  This additional moisture flux information could be used by forecasters in a standalone manner or be incorporated into  statistical methods used to forecast intensity change such as the Rapid Intensification Index (RII), the statistical-dynamical tool for forecasting RI events used at the National Hurricane Center.  

Disclaimer: The views, opinions, and findings contained in this article are those of the authors and should not be construed as an official National Oceanic and Atmospheric Administration (NOAA) or U.S. Government position, policy, or decision.