Preparing for Advanced Hurricane Analysis with High-Resolution Satellite Soundings from the NASA TROPICS Mission
by Erika Duran, PhD, UAH/NASA SPoRT
In 2017, three destructive hurricanes underwent rapid intensification: Harvey, Irma, and Maria. The following year, Hurricane Michael experienced two periods of rapid intensification, the second of which continued through landfall, making it one of only four Category 5 hurricanes to make landfall in the United States. Rapid intensification is defined as an increase in tropical cyclone (e.g., hurricane, typhoon) wind speeds of 35 mph or more in a 24-hour period. These storms are particularly dangerous and pose a significant threat to society.
Hurricane Michael’s location in the Western Caribbean and Gulf of Mexico provided the opportunity for multiple aircraft reconnaissance missions: nine flights from the U.S. Air Force, and six flights by NOAA Aircraft Operations Center (AOC). Measurements from these flights combined with data from satellites were used to monitor Michael’s intensification, and to give timely warnings prior to landfall. However, most tropical cyclones are not observed by aircraft, particularly those that occur far from land masses. The current constellation of passive microwave remote-sensing observing platforms is limited by the temporal frequency of overpasses (~ once every 3 hours), which is insufficient to fully observe rapid intensification. Such measurements are crucial for increasing our knowledge of tropical cyclone intensity change, and for providing accurate warnings of storms that threaten both coastal and inland communities. The NASA Short-term Prediction Research and Transition (SPoRT) Center has a history of providing these satellite-observations to the National Hurricane Center to assess storm structure and intensity, and the imagery is regularly used in operations and mentioned in public text products.
In 2021, we anticipate the launch of the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) satellite designed to measure atmospheric conditions in tropical cyclones. TROPICS will provide weather observations of three-dimensional temperature, humidity, cloud ice, and precipitation horizontal structure over the tropical latitudes with a less than 60-minute revisit time and with unprecedented horizontal and temporal resolution. TROPICS is a constellation of smallsats in low-earth orbit equipped with a 12-channel passive microwave radiometer measuring frequencies from 91 to 205 GHz, which are used mainly for measurement of atmospheric temperature and moisture profiles. These high-temporal frequency measurements will improve the observation of dynamic processes such as rapid intensification, as well as mesoscale time scales that are often challenging to observe.
As an Early Adopter, SPoRT is currently assessing the capabilities and applications of the upcoming TROPICS mission by using synthetic TROPICS data. In addition, SPoRT plans to collaborate with operational partners to design new products and explore the utility of TROPICS in the operational environment. TROPICS proxy data are designed to simulate the format and accuracy of the future mission, providing an opportunity to evaluate the potential applications of the mission prior to launch. These proxy data are derived from a high-resolution numerical simulation of a tropical cyclone in the North Atlantic Ocean, capturing a full life cycle. The figure shows an example of TROPICS proxy data estimated at 205 GHz. This channel is sensitive to the distribution of ice in the atmosphere, and can distinguish the ice within deep convective clouds (dark blue colors) and drier air wrapping around the storm (orange to yellow colors). These data, which are available to the scientific community, can help to accelerate our ability to use real TROPICS data once the instrumentation is calibrated in orbit.
For more information on the TROPICS mission, applications, and the Early Adopter program, visit www.nsstc.uah.edu/tropics/overview.html.
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