Preparing for a future satellite mission to measure wind and improve climate forecasts

Abstract

Stratospheric Inferred Winds (SIW) is a future satellite mission, which has been selected by the Swedish Space Agency to become the next Swedish research satellite, to be launched in 2024. It will consist of a sub-millimetre radiometer instrument, optimised for wind measurements in the middle atmosphere, and orbiting the Earth aboard a micro satellite platform. The goal of this master thesis was to carry out a preliminary study to assess the potential of the mission to contribute to a better understanding of the middle atmospheric dynamical events, and thus to improve weather and climate forecasts. The analysis of zonal mean zonal wind from two five year-long reanalysis data sets, namely ERA5 and MERRA-2, is described and compared to SIW estimated performances. The areas of major disagreement are investigated in details. It appears that the models have important difficulties to accurately reproduce the dynamical phenomena in the regions out of geostrophic balance due to wave forcing processes. The results show that a significant contribution can be provided by the SIW mission particularly at low latitudes, where the effects related to the Semi-Annual Oscillation can be studied, and at high latitudes during winter-time, where the effects of Sudden Stratospheric Warming events can be investigated. In those regions, at mesospheric altitudes, SIW estimated precision is most of the time significantly lower than the observed differences.