Gravity surveying is challenging in Antarctica because of its hostile environment and inaccessibility. Nevertheless, many ground‐based, airborne, and shipborne gravity campaigns have been completed by the geophysical and geodetic communities since the 1980s. We present the first modern Antarctic‐wide gravity data compilation derived from 13 million data points covering an area of 10 million km2, which corresponds to 73% coverage of the continent. The remove‐compute‐restore technique was applied for gridding, which facilitated leveling of the different gravity data sets with respect to an Earth gravity model derived from satellite data alone. The resulting free‐air and Bouguer gravity anomaly grids of 10 km resolution are publicly available. These grids will enable new high‐resolution combined Earth gravity models to be derived and represent a major step forward toward solving the geodetic polar data gap problem. They provide a new tool to investigate continental‐scale lithospheric structure and geological evolution of Antarctica.

SUMMARY Based on the Ice, Cloud and Land Elevation Satellite (ICESat) laser altimetry data, the hydrostatic equilibrium (HE) condition for the subglacial Lake Vostok, East Antarctica, is evaluated. A digital elevation model (DEM) of the ice surface is derived by a regional crossover adjustment. The analysis of the DEM and its comparison with GPS derived ice‐surface elevations and an ice‐surface DEM based on radar altimetry data reveal an overall accuracy of better than ± 0.7  m for the lake area. The DEM is combined with an ice‐thickness model and a regional geoid model to determine the deviation of the local ice‐surface height from HE. For large parts of the lake, the ice sheet fulfils the HE. Our results reveal a strong positive deviation of about 10  m along the lake shoreline. In addition, positive deviations are found in the northern part of the lake which coincide with ice rumples detected by radio‐echo sounding. In the southern part of the lake, we find a linear negative deviation (−4.0  m) which coincides with the convoy route from Vostok station to Mirny base. In addition to the DEM, relative biases for the ICESat laser operational periods are determined in the regional crossover adjustment.

Sea surface topography observations are deduced from an airborne reflectometry experiment. A GNSS (Global Navigation Satellite System) receiver dedicated for reflectometry was set up aboard the German HALO (High Altitude Long Range) research aircraft. Flights were conducted over the Mediterranean Sea about 3500 m above sea level. A signal path model divided into large‐ and small‐scale contributions is used for phase altimetry. The results depict geoid undulations and resolve anomalies of the sea surface topography. For the whole experiment 65 tracks over the Mediterranean Sea are retrieved and compared with a topography model. Tracks differ between right‐handed and left‐handed circular polarization. The difference, however, is not significant for this study. Precision and spatial resolution decrease disproportionately at low elevations. Eight tracks with centimeter precision are obtained between 11° and 33° of elevation. At higher elevation angles the number of tracks is significantly reduced due to surface roughness. In future such retrievals could contribute to ocean eddy detection.

The question whether Antarctica's largest lake, subglacial Lake Vostok, exchanges water is of interdisciplinary relevance but has been undecided so far. We present the potential pathway, outlet location, and threshold height of subglacial water discharge from this lake based on a quantitative evaluation of the fluid potential. If water left Lake Vostok, it would flow toward Ross Ice Shelf. Discharge would occur first to the east of the southern tip of the lake. At this location the bedrock threshold is 91 ± 23 m higher than the hydrostatic equipotential level of Lake Vostok. It is concluded that Lake Vostok is not likely to reach this level within climatic timescales and that no discharge of liquid water is to be expected. We show that in absence of the ice sheet the Lake Vostok depression would harbor a lake significantly deeper and larger than the present aquifer.