We provide a data set that illustrates how the amount of water that is stored in the subsurface as groundwater varies in time over the continents of the Earth. A main source of the data are observations with satellites that weigh the changing amount of water by its mass attraction effect. The data allow for assessing how groundwater as the most important freshwater resource for mankind and ecosystems is affected by climate variability, climate change and withdrawal by human activities.

This study presents a method to make the spatial resolution of global Water Storage Compartments (WSCs) compatible with terrestrial water storage (TWS) data from Gravity Recovery And Climate Experiment (GRACE) missions. The method compares the spatial structure of the WSCs and TWS by considering the correlation between neighboring grid cells. An isotropic Gaussian filter with an optimal filter width of 250 km is found to be the most suitable, ensuring compatibility for consistent comparison with GRACE data in hydrological applications.

As seawater is moved about by the different types of ocean flow, the pressure at the ocean bottom changes with time and location. We show that such bottom pressure variations are represented reasonably well by high-resolution climate models and that in some regions, like the Arctic Ocean, the intensity of the pressure fluctuations will likely increase under global warming. These insights are useful for the design of future satellite missions that will track mass variations in the Earth system.

The study assesses the Global Precipitation Climatology Centre (GPCC) and Global Precipitation Climatology Project (GPCP) precipitation products by estimating hydrological drought recovery time (DRT) using satellite gravimetry data, Jet Propulsion Laboratory mass concentration solution (JPL mascon), and Global Gravity-based Groundwater Project (G3P) terrestrial water storage (TWS) products. The findings reveal that DRTs from GPCC and GPCP are comparable, and JPL mascon shows longer DRT, while G3P demonstrates greater consistency. These results contribute to a deeper understanding of precipitation and water storage dynamics and are essential for meteorological and hydrological research.

Vertical mixing is an important process, for example, for tropical sea surface temperature, but cannot be resolved by ocean models. Comparisons of mixing schemes and settings have usually been done with a single model, sometimes yielding conflicting results. We systematically compare two widely used schemes with different parameter settings in two different ocean models and show that most effects from mixing scheme parameter changes are model-dependent.

GRACE and GRACE-FO are unique observing systems to quantify mass changes at the Earth’s surface from space. Time series of these mass changes are of high value for various applications, e.g., in hydrology, glaciology, and oceanography. GravIS (Gravity Information Service) provides easy access to user-friendly, regularly updated mass anomaly products. The portal visualizes and describes these data, aiming to highlight their significance for understanding changes in the climate system.

Flows in the ocean are driven either by atmospheric forces or by small-scale internal disturbances that are inherently chaotic. We use computer simulation results to show that these chaotic oceanic disturbances can attain spatial scales large enough to alter the motion of Earth's pole of rotation. Given their size and unpredictable nature, the chaotic signals are a source of uncertainty when interpreting observed year-to-year polar motion changes in terms of other processes in the Earth system.

The satellites GRACE and GRACE-FO observe continental terrestrial water storage (TWS) changes. With over 20 years of data, we can look into long-term variations in the East Africa Rift region. We focus on analysing the interannual TWS variations compared to meteorological data and observations of the water storage compartments. We found strong influences of natural precipitation variability and human actions over Lake Victoria's water level.

Current climate models typically do not include full representation of ice sheets. As the climate warms and the ice sheets melt, they add freshwater to the ocean. This freshwater can influence climate change, for example by causing more sea ice to form. In this paper we propose a set of experiments to test the influence of this missing meltwater from Antarctica using multiple different climate models.

How is the ocean affected by continued Greenland Ice Sheet mass loss? We show in a systematic set of model experiments that atmospheric feedback needs to be accounted for as the large-scale ocean circulation is more than twice as sensitive to the meltwater otherwise. Coastal winds, boundary currents, and ocean eddies play a key role in redistributing the meltwater. Eddy paramterization helps the coarse simulation to perform better in the Labrador Sea but not in the North Atlantic Current region.

Observations of the eastern subpolar North Atlantic in the 2010s show exceptional freshening and cooling of the upper ocean, peaking in 2016 with the lowest salinities recorded for 120 years. Using results from a high-resolution ocean model, supported by observations, we propose that the leading cause is reduced surface cooling over the preceding decade in the Labrador Sea, leading to increased outflow of less dense water and so to freshening and cooling of the eastern subpolar North Atlantic.

The Atlantic Meridional Overturning Circulation (AMOC) quantifies the impact of the ocean on climate and climate change. Here we show that a high-resolution ocean model is able to realistically simulate ocean currents. While the mean representation of the AMOC depends on choices made for the model and on the atmospheric forcing, the temporal variability is quite robust. Comparing the ocean model with ocean observations, we able to identify that the AMOC has declined over the past two decades.