Mass Change in Ice Sheet Basins and Hydrological Catchments from GRACE: A Comparison of Level-1b Analysis Techniques
Andrews, Stuart¹; Moore, Philip¹; King, Matt^2
1Newcastle University, UNITED KINGDOM; ²Newcastle University/University of Tasmania, AUSTRALIA

Since the launch of GRACE in 2002 surface mass changes in ice sheet drainage basins and hydrological catchments have been estimated using a number of different approaches. These different estimation methodologies which include precise orbit determinations utilizing the K-band inter-satellite range-rate data and GPS tracking data in a conventional spherical harmonic estimation procedure, the mascon approach using the K-band data and reduced orbital dynamics and short-arc techniques are frequently produced by different groups and obtained using different codes and algorithms. Although these approaches are well document there are only a limited number of studies which compare the different approaches within the same software base and none that we are aware of that simulates a known signal and tests the ability of the various approaches to recover the input. In this study we address this by examining the accuracy of GRACE analyses based on the conventional spherical harmonic and the mascon approaches in a consistent analysis at spatial scales appropriate to hydrological/ice drainage basins. The overall aim is to assess the ability of each technique to resolve basin-level mass changes at a variety of spatial scales while gaining a better understanding of the errors and limitations associated with each technique. The different techniques will firstly be applied to a known signal using simulation, allowing analysis to be undertaken using perfect data, before applying the techniques to real GRACE Level-1B data and generating basin-level times series of surface mass change. We will present results from our work to date focussing on the recovery of a simulated mass signal, for both the mascon and conventional spherical harmonic approaches.