The response of the subglacial Lake Vostok, Antarctica, to tidal and atmospheric pressure forcing

Abstract

S U M M A R YLake Vostok is the largest subglacial lake in Antarctica. We show that as a result of its size tidal and atmospheric pressure forcings are large enough to induce vertical displacements of the ice surface above the lake. These effects have been modelled assuming equilibrium tides and an inverse barometer response based on mass conservation. Differences in the tidal potential on the area of the lake result in height changes with amplitudes of a few millimetres for the largest diurnal and semidiurnal tides with maximum values at the southern end of the lake. Air pressure differences above the lake cause a differential inverse barometer effect (IBE) with resulting height changes of up to 40 mm on timescales from days to weeks. Both effects could be verified by differential Global Positioning System (GPS) observations in the southern part of the lake during the 2001/2002 and 2002/2003 summer seasons. The measured amplitudes and phases of the main constituents correspond to the respective values of the differential equilibrium tides. ERS-1& 2 tandem interferograms of 1996 were used to analyse the spatial pattern of the surface displacement. For the southern part of the lake, these measurements reveal a bulge with a wide flexure zone of varying amplitude but a similar geometry. A quasi-simultaneous pair of interferograms from the northern and the southern part of the lake respectively, demonstrates surface height changes of opposite sign in both areas. Therefore, it can be concluded that the associated water redistribution as a result of tides and changing atmospheric pressure forms an additional component of the overall water circulation in the lake.

Observational evidence on the stability of the hydro‐glaciological regime of subglacial Lake Vostok

“…With the present study we extend our understanding based on own previous investigations on Lake Vostok [ Wendt et al , 2005; Masolov et al , 2006; Wendt et al , 2006; Roemer et al , 2007]. Here we present new results obtained from joint geodetic‐geophysical field measurements in the area of Vostok station taken in January 2007.…”

Geodetic observations of ice flow velocities over the southern part of subglacial Lake Vostok, Antarctica, and their glaciological implications

“…Due to the satellite constellation of GPS, vertical velocities are usually less precise than the horizontal ones. Another factor complicating the estimation of a mean vertical velocity of sites on the lake surface is a higher variability of the vertical position due to the response of the lake to tidal and atmospheric forcings (Wendt et al 2005). These effects can cause up to ±20 mm elevation changes within days and weeks.…”

“…Network and observation schedule (Fig. 2) were designed for the precise determination of the horizontal ice flow in this area and for investigating height changes of the surface above Lake Vostok as a response to tidal and atmospheric pressure forcing (Wendt et al 2005). During the first season, seven GPS sites (VOST, EAST, CNTR, VC10, VC20, G100 and G200) were installed over the southern part of subglacial Lake Vostok and the adjacent eastern area (Table 1).…”

Precise analysis of ICESat altimetry data and assessment of the hydrostatic equilibrium for subglacial Lake Vostok, East Antarctica

“…Both processes produce ice‐surface height variations in space and time with in the order of 1 cm. The synthetic aperture radar (SAR) interferograms (Wendt et al 2005, figs 8 and 9) showing the vertical displacement of the floating ice relative to the grounded ice sheet provided also insights into the location of the lake shore, islands and peninsulas, which partly were later confirmed by RES (Popov et al 2006). Combined geodetic, geophysical and glaciological in situ measurements were used by Richter et al (2008) to investigate the elevation change of the ice surface between 2001/2002 and 2006/2007 as well as the local ice‐mass balance in the area of Vostok station.…”

“…This data set is complemented by airborne geophysical data (Studinger et al 2003). Wendt et al (2005) provided the observational evidence on small elevation variations of the ice‐sheet surface in the lake area induced by tides and air pressure forcing. Both processes produce ice‐surface height variations in space and time with in the order of 1 cm.…”