Dr. Su Xiaoli, from The Ohio State University of USA, gave us a splendid presentation titled “Inter-annual Ice Mass Variations over Greenland and Antarctica Combining GRACE Gravimetry and Envisat Altimetry” on invitation at SHAO, 26 February, 2016. Dozens of researchers attended the presentation and made effective communications as well.

　　Inter-annual mass variations of continental ice sheets driven by the variability in accumulation have an important impact on the mass balance of continental ice sheets, and evaluating the fidelity of global or regional atmospheric models. The GRACE twin-satellites provide observations of ice sheet mass change at spatial scales longer than 350 km since 2002. Continuous near-polar observing satellite radar altimeter data became available since the 1990s, and have more than an order of magnitude (~50 km) better in spatial resolutions than GRACE. However, radar altimetry measures elevation or volume changes and has no knowledge of the snow/ice column density to accurately estimate ice-sheet mass balance. Here the presentation investigates the inter-annual variations using GRACE and Envisat data from 2003 through 2009 over Greenland ice sheet (GrIS) and Antarctic ice sheet (AIS). High correlation is found on the order of 0.6 over most of the GrIS and AIS. By combining GRACE and Envisat data—GRACE data provide mass change, while Envisat data provide volume change, the presentation estimates the nominal density of snow/ice associated with measured inter-annual mass and elevation changes—with the objective of estimating higher resolution mass change using altimeter data at the inter-annual scale.

　　After that, the attendees (researchers and students), according to their own research area, questioned the presenter on aspects they are interested in, exchanged views.