“Exploring the Earth’s Time-Variable Gravity Field using Satellite Observations” – Pro ISSI Talk with Adrian Jäggi

A new era in satellite gravimetry was initiated with the launch of dedicated gravity missions such as CHAMP (2000–2010), GRACE (2002–2017), GOCE (2009–2013), and the still on-going GRACE Follow-On (GRACE-FO) mission that was launched in 2018. Whereas CHAMP and GOCE significantly improved our knowledge of the Earth’s static gravity field, GRACE and GRACE-FO were/are mainly devoted to measure its tiny variations in time by providing monthly snapshots of the Earth’s gravity field.

Time-variable gravity as derived from ultra-precise GRACE/GRACE-FO inter-satellite ranging is the only observable to provide integrative measures of total water storage variations on a global scale, i.e., the sum of groundwater, soil moisture, snow, ice, and surface water bodies. As such it is of great interest for large user communities in hydrology, climate modeling, ice observation, geodetic, geophysical, oceanographic, atmospheric, and environmental sciences.

Moreover, it is paramount for separating the variations of individual compartments that are not well accessible by combining the total water storage variations with other remote sensing data. In this talk an overview of the underlying principles of the challenging GRACE/GRACE-FO data analysis will be given and selected key scientific results will be highlighted. A special focus will be on the relevance of European and international initiatives, and in particular also on the important role of ISSI in this context, to further exploit and promote this unique observable to continuously monitor the on-going changes in our Earth system.

This talk was organised by the Association Pro ISSI and was recorded on March 24, 2021.