Recent Elevation and Volume Changes of Russian Arctic Ice Caps as Measured by Envisat Radar Altimeter 2

Ice caps are one of the key indicators of changing climate because they are distributed across a wide geographical area that has been exposed to large temperature changes. Understanding the manner in which ice caps have responded to climate change is a matter of considerable importance, and is the key motivation for our study. The EnviSAT Radar Altimeter 2 (RA-2) and it's predecessor the ERS Radar Altimeter have been used to map the elevation change of certain land ice bodies. Because the coarse footprint of RA and RA-2 are optimized for studying large and flat terrain, it is not surprising that most of the previous work concentrates on the Greenland and Antarctic ice sheets. RA-2, however, has provided a global dataset of elevation measurements since 2002, and has an improved capacity to track rugged surfaces. Therefore the RA-2 can be used to map elevation changes of ice caps - ice bodies smaller than ice sheets but larger than mountain glaciers. We use the data recorded by the RA-2 to assess elevation changes of ice caps on Russian Arctic islands during 2002-2008. We show that the mean surface elevation of ice caps on Severniya Zemliya has not changed during this time. RA-2 measured elevation change rate of 3 +- 3 cm/a during our study period. The mean surface elevation of ice caps on Franz Josef Land and Novaya Zemliya has lowered slightly (RA-2 measured elevation change rates of -5 +- 3 cm/a and -18 +- 3 cm respectively). In addition to overall elevation change rates wepresent the RA-2 measured elevation time series for all three island groups. All three time series show similar overall pattern: maximum elevation measured during early winter 2003 and minimum elevation during spring or summer 2005. Magnitude of measured variability in surface elevation is largest on Novaya Zemliya (3.5 m peak-to-peak) when compared to Severniya Zemliya and Franz Josef Land (1.1 m and 1.3 m peak-to-peak respectively). We also presenelevation change rate maps of the studied ice caps to assess the spatial variation of elevation change rates. This work has been undertaken as part of the ESA GlobGlacier project (21088/07/I-EC): http://globglacier.ch/