Impact of Windborne Observation Assimilation on Prediction of a TPV Merger and Arctic Cyclogenesis Case Study from THINICE

This study investigates the observation impact of, and optimal assimilation parameters for, assimilating in situ observations from Windborne balloons during an Arctic cyclone case study from the THINICE2022 field campaign. Windborne balloons present an opportunity to improve Arctic cyclone predictions by expanding the coverage of in situ observations over Arctic regions, given their long flight time of up to a week or more and altitude control that allows targeting of specific features to observe. In order to realize such improvements, and guide the targeting of future Windborne flights, diverse case studies are needed to evaluate the impacts of assimilating Windborne observations of specific meteorological features and the sensitivity of such impacts to data assimilation parameters such as covariance localization and observation error.

The case selected for this study includes a tropopause polar vortex (TPV) that was directly sampled by a Windborne balloon before interacting with another long-lived TPV. The interaction of the two TPVs affected multiple subsequent episodes of Arctic cyclogenesis. An initial set of experiments shows that assimilating the windborne observations on this case does improve forecasts of the interaction of the two TPVs while reducing the RMSE of the MSLP forecast up to ~1 day lead time. Additional quantitative diagnostics, and additional experiments on the horizontal localization and observation error parameters, are ongoing and will also be presented.