Paper reviewing the impact of the NCAR GPS dropwindsonde on tropical cyclone research and operations since its introduction in 1996 published in The Bulletin of the American Meteorological Society

The Global Positioning System dropwindsonde has provided thousands of high-resolution soundings of wind velocity, temperature, moisture, and humidity in and around tropical cyclones (TCs) since 1997. These data have revolutionized the understanding of TC structure, improved forecasts, and validated observations from remote-sensing platforms like satellites. About 400 peer-reviewed studies on TCs using these data have been published to date. This paper reviews the history of dropwindsonde observations, changes to dropwindsonde technology since it was first used in TCs in 1982, and how the data have improved forecasting and changed our understanding of TCs.

(left) View of a standard dropwindsonde, and (right) inside view of all sensors showing location of additional infra-red sensor that can measure sea-surface temperature.

Conclusions:

1. The GPS dropwindsonde has revolutionized observations of tropical cyclones, especially when it comes to:
   a. Real-time and post-storm estimates of the maximum surface wind speed.
   b. Validation of newer observing systems, especially those that measure quantities remotely from aircraft and satellites.
   c. Improvements to forecasts of maximum surface wind speed, track, and structure from computer models, and the design of flight tracks to optimally observe to improve these forecasts.
   d. Observing and understanding tropical cyclone structure, especially as it relates to intensity change. This includes observations in the hard-to-observe region close to the ocean surface, and in the interaction between tropical cyclones and vertical wind shear.
   e. Improvements to how computer models forecast interactions between the tropical cyclone and the warm ocean below that provides its fuel.
2. The future holds promise for new innovations in dropwindsonde technology, including:
   a. A new, smaller dropwindsonde to replace the current larger one was deployed in tropical cyclones during the 2023 hurricane season.
   b. Communications upgrades from aircraft to ground will soon allow for more data from each instrument to be transmitted the ground for use by specialists and computer models.
   c. Innovations to the over-arching technology will allow for the use of new, but similar observing systems like uncrewed aerial systems that can take measurements for many hours, and swarms of dropwindsonde-like instruments that can observe tropical cyclone structure at the same time.

You can read the paper at https://doi.org/10.1175/BAMS-D-22-0119.1. For more information, contact aoml.communications@noaa.gov. Jun Zhang acknowledges support from NOAA Grants NA21OAR4590370, NA22OAR4590118, and NA22OAR4590178, NSF Grant AGS2211308, and ONR Grant N00014-20-1-2071. Jonathan Zawislak acknowledges support from NASA Grant 80NSSC19K0012 under the Weather and Atmospheric Dynamics program and TCRI ONR BAA N00014-19-S-B001. Kathryn Sellwood acknowledges funding from TCRI ONR BAA N00014-19-S-B001.