Recent land ice mass flux observations from GRACE mascon solutions and their connection to surface elevation change and melt data

Mass changes of the Earth's ice sheets and glacier systems are of considerable importance because of their sensitivity to climate change and their contribution to rising sea level. Recent changes in the cryosphere highlight the importance of methods for directly observing the complex spatial and temporal variation of land ice mass flux. Since its launch in March of 2002, the NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission has been acquiring ultra-precise inter-satellite K-band range and range-rate (KBRR) measurements enabling a direct mapping of static and time-variable gravity. These data provide new opportunities to observe and understand ice mass changes at unprecedented temporal and spatial resolutions. In order to improve upon the ice mass change observations derived from GRACE, we have employed unique data analysis approaches to obtain lumped harmonic local mass concentration solutions (mascon solutions) from GRACE inter-satellite range-rate measurements. We have computed multi-year time series of surface mass flux for Greenland and Antarctica coastal and interior ice sheet sub-drainage systems as well as the Alaskan glacier systems. These mascon solutions provide important observations of the seasonal and inter-annual evolution of the Earth's land ice. Additionally, these solutions facilitate a detailed comparison to surface elevation change observations from spaceborne and airborne laser altimetry as well as surface melt observations. We present our latest mascon solutions of the Greenland and Antarctica ice sheets as well as the Alaska mountain glaciers. We compare these mass flux solutions to ICESat and airborne laser altimeter observations of surface elevation change as well as surface melt observations derived from MODIS data. The combination of GRACE high-resolution mass flux observations together with the surface elevation change and surface melt observations is beginning to reveal a detailed understanding of the Earth's high latitude land ice evolution.