Spaceborne geodetic sensors and observations of the Earth rotation have established themselves as valuable tools for hydrological, oceanographic, and cryospheric applications. For example, satellite altimetry serves now as virtual lake and river gauges, and surface water extent quantification with satellite imagery data allows for the high-resolution monitoring of the geometry of flooded regions. The satellite mission GRACE provides a fundamentally new remote sensing tool for a wide spectrum of Earth science applications by measuring changes in the Earth's gravitational field and thereby mass changes in both oceanic and terrestrial storages. Various Global Navigation Satellite Systems (GNSS) that are currently operating provide a wealth of information on several components of the water cycle, including GPS-based atmospheric sounding for tropospheric water vapour content assessment; GNSS-network deformations reflecting loading effects from hydrological, cryospheric and atmospheric mass changes; and GNSS-reflectometry aiming at the measurement of both changes in water-level heights and local soil moisture.

Furthermore, observations of the Earth’s rotation (i.e. the determination of the Earth Orientation Parameters: EOP) have been steadily improving in terms of accuracy and time resolution. The temporal variation of these parameters are closely linked to moving masses in the Earth system, and its monitoring and forecasting serve a vital role in spacecraft navigation and orbit determination of the above missions.

In addition to signals at weekly to interannual time-scales that are well resolved from repeated space observations, high-frequency variability and episodic events are potentially observable with space geodesy and may be visible in measured time series of the Earth’s rotation. Extreme precipitation events cause rapid changes in soil moisture, root zone storage and surface waters, which may affect the time-varying gravity field. Furthermore, temperature and moisture variability in the troposphere cause dispersion of, for example, GPS and radar signals.

This session welcomes multidisciplinary contributions that demonstrate new uses of spaceborne geodetic sensors and understanding of EOP time series for hydro-/geodesy/meteorology, oceanography, and cryospheric applications, as well as reports about state-of-the-art approaches to observe or model high-frequency variability of
geophysical origin. In addition, the session includes contributions of the IAG/IAU working group ‘Theory of Earth Rotation and Validation’ We encourage contributions which target a multidisciplinary audience interested in space geodesy and Earth rotation.