Southern Hemisphere wind forecasting campaign

Accurately forecasting lower stratospheric winds in the Southern Hemisphere is essential for tracking and predicting the evolution of an aerosol plume from a field experiment and advancing stratospheric science more broadly. The Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) campaign demonstrated remarkable success in predicting the location of a plume of water from overshoot convection (thunderstorms powerful enough to reach the stratosphere) over North America (Bowman et al., 2026). North America is one of the most data-rich and well-observed regions on Earth. Southern Hemisphere forecasting capabilities, by contrast, lag considerably behind Northern Hemisphere capabilities, creating barriers to a range of scientific activities—from tracking volcanic aerosol impacts on regional climate to understanding how stratospheric circulation patterns respond to natural and human-caused perturbations.

A targeted balloon campaign offers an opportunity to characterize current forecasting skill in the Southern Hemisphere lower stratosphere and quantify how much it can be improved through additional in situ observations. This effort will yield data and analysis valuable to the broader atmospheric science community and support improved operational weather forecasting across a data-sparse region. Additionally, because stratospheric plumes from natural or deliberate aerosol emissions evolve over timescales of weeks, improved forecasting would provide the foundational capability necessary to track such phenomena if future experiments or events require plume-following observations. By testing and refining forecasting capabilities before such applications are needed, this work reduces scientific uncertainty about the feasibility and design of future observational campaigns.

The campaign will deploy approximately 100 lightweight, long-lived high-altitude balloons equipped with meteorological and global positioning sensors to ~15–16 km altitude over the Southern Hemisphere south of 45°S during summer (January or February). This campaign will be supplemented by balloons capable of taking vertical soundings, measurements that profile the atmosphere from top to bottom as a balloon ascends. A forecasting system will predict how these balloons move through the stratosphere in real time using wind data from existing models combined with observations from the balloon measurements themselves.

After the campaign concludes, researchers will conduct detailed analysis to understand how much forecasting skill was achieved and what drove that performance. By systematically comparing predictions made with and without the balloon observations, the analysis will quantify the following:

1. How accurately summertime Southern Hemisphere lower stratospheric winds can be forecast 1–5 days out
2. Whether wind forecasts that perform well at higher altitudes (~20 km) remain reliable at lower stratospheric levels
3. How much improvement in forecasting capability is added by the balloon observations compared to model predictions alone
4. Whether vertical soundings provide meaningful additional value beyond the free-floating balloon data alone.