Mass changes of the Greenland and Antarctic Ice Sheet from GRACE and GRACE-FO: products, validation and interpretation
Authors: Groh Andreas , Horwath Martin , Barletta Valentina R. , Sandberg Sørensen Louise , Forsberg René , Shepherd Andrew 
Published: October 2020

&lt;p align=&quot;justify&quot;&gt;&lt;span lang=&quot;en-US&quot;&gt;Gravimetr&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;ic&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; Mass Balance (GMB) product&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;s&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; for the &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;ice sheets in Greenland (GIS) and&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; Antarctic&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;a &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;(AIS) &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;were &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;derived within the ESA Climate Change Initiative continuation project&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;s GIS_cci+ and &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; AIS_cci+, &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;respectively. We made use of the entire series of time variable gravity fields acquired by &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; GRACE and its successor GRACE-FO (Follow-On), &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;spanning&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; almost 19 years between 2002 and 2020&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;. Our products are based on the monthly solution se&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;ries &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;CSR RL06, which was chosen based on a quality assessment conducted for a wide range of available solutions. &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;The GMB&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; product comprises (a) time series of monthly mass changes for the &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;whole&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; ice sheet and for individual drainage basins, and (b) gridded mass changes covering the entire ice sheet. &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;For GIS we compare two variants of GMB products derived by means of differing methods, i.e. from a regional integration approach based on tailored sensitivity kernels applied by TU Dresden and from a point mass inversion approach utilised by DTU Space. &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;All products are freely available through the project websites and an interactive data portal hosted at TU Dresden (data1.geo.tu-dresden.de).&lt;/span&gt;&lt;/p&gt;
&lt;p align=&quot;justify&quot;&gt;&lt;span lang=&quot;en-US&quot;&gt;The GMB products allow us to study temporal variations in the ice sheets&amp;#8217; mass balance &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;from the basin integrated time series. Changes in the spatial &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;mass balance &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;patterns &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;are&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; quantified by means of the gridded products. &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;Independent&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; data sets are used to validate our products. To validate the &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;full&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; mass change signal of the AIS, comprising both changes in ice dynamics and surface mass balance (SMB), we make use of an &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;Antarctic&lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt; mass change time series from a multi-mission satellite altimetry analysis. &lt;/span&gt;&lt;span lang=&quot;en-US&quot;&gt;For both ice sheets, changes in cumulated SMB variations predicted by a regional atmospheric climate model (i.e. RACMO2.3p2) are compared to the GMB basin products. This intercomparison is limited to temporal components not related to changes in ice dynamics (e.g. seasonal variations). Both independent data sets bridge the gap between GRACE and GRACE-FO, providing valuable information to ensure a seamless continuation of the GRACE time series by GRACE-FO.&lt;/span&gt;&lt;/p&gt;