GRACE/GRACE-FO radio occultations for weather forecast and climate research

Abstract

The major objective of the GRACE Follow On (GFO) mission with its two satellites GF1 and GF2 is to obtain precise global and high-resolution models for both the static and the time variable components of the Earth's gravity field. Additional goal is the continuation of the GPS radio occultation (RO) measurements from the predecessor GRACE, successfully performed between 2006 and 2017.Starting with the CHAMP mission, the GFZ has been continuously processing radio occultation data since 2001 and has been providing it operationally in near real time to weather services since 2006. GFZ RO data, as GRACE and GFO also contribute to the global RO data base for climate research.Following the successful RO missions CHAMP (2001–2008) and GRACE (2006–2017), the GFZ is currently still processing RO data from TerraSAR-X (since 2008), Tandem-X (since 2011), and the two GRACE-FO satellites (since 2020), with TerraSAR-X representing the longest continuous RO data set to date. The complete RO data set has been reprocessed since 2026.In this presentation, we discuss climatologies and temperature trends in the upper troposphere and lower stratosphere (5-40 km) and tropopause parameters derived from the GFZ data set (2002-2025) and compare the results with UCAR and ERA5 data. The importance of smaller RO missions for weather and climate research is emphasized.