1. Impact of WindBorne Observation Assimilation on Prediction of a TPV Merger Case From THINICE.
- Author
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Johnson, Aaron, Wang, Xuguang, Hutchinson, Todd, and Creus‐Costa, Joan
- Subjects
STANDARD deviations ,POLAR vortex ,WEATHER balloons ,CYCLONE tracking ,CYCLONE forecasting ,CYCLONES - Abstract
The impact of assimilating in situ temperature, moisture and wind observations from a WindBorne Systems balloon, with long duration and adjustable ballast, is evaluated using a case study from the 2022 THINICE field campaign. A case is selected wherein the WindBorne balloon directly sampled a jet streak associated with a tropopause polar vortex (TPV). The observed TPV merged with another TPV at the same time as a downstream Arctic cyclone (AC) redeveloped eastward. The case is used to better understand the role of the observed TPV in the evolution of the downstream AC. The assimilation of the WindBorne observations improves the forecast track and amplitude of the TPV during the ∼1 day forecast period that the TPV can be tracked as a distinct feature. The root mean square error of temperature at 350 hPa is improved by the WindBorne assimilation throughout the 2.5 day forecast period. The surface cyclone track forecast is improved by the WindBorne assimilation during the period of eastward redevelopment of the surface cyclone, and the sea level pressure RMSE in the surrounding region is reduced during the first ∼1.5 days of forecast lead time. Results demonstrate the capability of the long‐duration controllable WindBorne balloons to improve the analysis of the TPV associated with the jet streak, leading to improved forecast of both tropopause‐level and surface pressure features. Additionally, the importance of observing the upstream TPV amplitude for improving forecasts of the process of TPV merging and its impact on the evolution and longevity of the mature AC is confirmed. Plain Language Summary: During a recent field campaign, WindBorne Systems deployed novel weather balloons that remain in the atmosphere for weeks at a time, adjusting their altitude to follow winds towards features of interest. These balloons provide an opportunity to study the impact of the merging of two upper‐level disturbances on the performance of an Arctic cyclone (AC) forecast. WindBorne observations of one of the two merged disturbances allowed for an improved forecast of the eastward redevelopment of the AC. These experiments confirm the importance of observing such features for AC prediction and the importance of the merging process in the maintenance and evolution of long‐lived Arctic cyclones. Key Points: WindBorne balloons can improve in situ sampling of small scale features critical for Arctic predictabilityTropopause polar vortex (TPV)‐related jet streak is important for predictability of subsequent TPV merging and Arctic cyclone (AC) redevelopmentMerging of TPVs without associated surface cyclone should be included in conceptual models of AC longevity [ABSTRACT FROM AUTHOR]
- Published
- 2024
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