Erika Duran (UAH/SPoRT) led the development of a publication related to the use of NASA/NOAA Earth Observing System hyperspectral infrared satellite sounding retrievals to study the tropical cyclone diurnal cycle (TCDC). Read the paper at https://doi.org/10.1175/MWR-D-20-0415.1.
The study bridges capabilities and expertise of two focus areas within the NASA Short-term Prediction Research and Transition (SPoRT) Center (remote sensing led by Emily Berndt and tropical meteorology led by Patrick Duran). E. Duran, Berndt, and Duran focused on the use of hyperspectral infrared satellite sounding retrievals to evaluate the diurnal variations of temperature, moisture, and stability within three hurricanes: Dorian (2019), Florence (2018), and Irma (2017). While previous studies have focused on documenting the TCDC using optical satellite imagery, radiosondes, dropsondes launched during reconnaissance flights, and numerical models, very few have taken advantage of the temporal and spatial resolution afforded by satellite sounding retrievals. The temporal, horizontal, and vertical resolution that satellite soundings provide an opportunity to assess key thermodynamic characteristics that result from the diurnal variation of radiation which can impact TC development, structure, and intensity.
The analysis of three hurricanes showed a marked diurnal signal that extended through the deep layer of the troposphere. Also, statistically significant differences were observed in temperature, moisture, and lapse rate profiles, indicating a moistening and destabilization of the mid to upper troposphere that is more pronounced in the TC inner core at night. The observations supported a favorable environment for the formation of deep convection caused by the diurnal differences in radiative heating tendencies. When separating results by intensity, storms category 3 and above demonstrate a clear diurnal signal. Identification of a clear diurnal signal indicates hyperspectral infrared satellite soundings are valuable for detecting the TCDC for use with traditional datasets. In the study, both the combined infrared and microwave and microwave-only satellite sounding retrievals captured the TCDC. Therefore the future microwave-only NASA TROPICS (Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats) mission with a rapid observational refresh rate could be used for this research extending capabilities beyond NASA’s current Earth Observing Satellites. Additionally, ongoing partnerships with SPoRT stakeholders (e.g., NOAA Hurricane Research Division and National Hurricane Center) and translation of this research to tools and capabilities will increase the societal benefit of NASA observations to support decision making related to hurricane reconnaissance, forecasting, and warning.
Vertical profiles of (a,b) temperature (K) anomalies and (c,d) water vapor mixing ratio anomalies (g/kg) for MW–only NUCAPS retrievals. Profiles are composite averages from 200–300 km in radius and from (a,c) 00-04 LT and (b,d) 12–16 LT. NUCAPS satellite soundings from S–NPP and NOAA–20 overpasses are shown for Hurricane Dorian (purple line), Hurricane Irma (cyan line), and Hurricane Florence (green line).