Wind Diversity Trends in the Lower Stratosphere Analyzed From Radiosondes Launched in the Western Hemisphere

Abstract

High altitude balloons (HABs) with altitude control capability can leverage varying wind patterns at different altitudes to perform station-keeping maneuvers and other complex trajectories. At minimum, effective station-keeping of HABs requires opposing winds at two different altitudes. Wind diversity trends in the lower stratosphere are highly dependent on geographic area, altitude range, and time of year. To investigate historical wind diversity trends, we analyzed over 1.25 million radiosonde sounding launches from the Western Hemisphere between 2012 and 2023. Radiosondes provide higher vertical resolution than standard reanalysis forecasts, which often underestimate wind diversity due to smoothing during the global assimilation process. Overall, our analysis reveals that higher opposing winds probabilities tend to follow the summer months for each hemisphere, respectively, with the exception being the tropics, which typically have strong opposing wind probabilities year round. Similarly, the summer months also tend to have a higher probability of calm (“light-and-variable”) winds, although in a smaller latitudinal and altitude bands than opposing winds. Transition months, typically in the spring and fall, have the highest variation in opposing wind probabilities from decadal means, while the summer and winter months have more predictable regional trends. These wind diversity trends can assist with developing trajectories and mission planning for high altitude platforms.