COSMIC-2 Radio Occultation Temperature and Water Vapor Soundings in Hurricane Ian (2022)

Radio occultation (RO) observations can be used with another dataset such as a numerical model analysis or forecast as a first guess to produce accurate atmospheric soundings of temperature and water vapor in all-weather conditions. In this research project we compared skew-T plots of temperature and dew points from the COSMIC-2 RO mission with dropsondes and the ERA5 model during Hurricane Ian (2022). COSMIC-2 consists of 6 satellites in low Earth orbit that produce 5,000-6,000 vertical profiles of refractivity per day over the tropics. The data is processed by the COSMIC Data Analysis and Archive Center to produce near real-time profiles of temperature and water vapor using a one-dimensional variational analysis (wetPf2, which stands for second-generation wet profiles).

Hurricane Ian made landfall over Cuba on September 27, 2022, and Florida on September 28, 2022, as a category 4 hurricane, producing widespread damage in both places. Using COSMIC-2 wetPf2 profiles from September 27 to September 29 of 2022, we extracted the relative humidity to calculate the dew point and plotted temperature and dew point profiles on skew-T charts using MetPy. We selected the nearest RO profiles to Ian’s center (less than 300 km) and compared these profiles to independent ERA5 and dropsonde profiles. Despite the very different types of soundings, the differences in temperature and dew point among the three were generally less than 3°C. We conclude that RO soundings can be a useful addition to near-real time weather analyses and forecasts, even under extreme environments such as hurricanes.