Greenland - Release Level 05 (RL-05) (Go to RL-04)
Below are updated results continued from our recent paper Harig and Simons [2012]. As of the last update January 2013, these results use the Release level 5 UTCSR (http://www.csr.utexas.edu/grace/) data solutions from January 2003 up to and including January 2013.

The past few years have seen unprecedented melting in Greenland measured by a variety of indicators (see the 2011 Arctic Report Card: Greenland for a good scientific summary). For GRACE mass measurements this means that recent years have increased the trend estimated since 2003. The RL-05 data do not include months from 2002 that appear in the RL-04 data. As a result, Greenland estimates will be somewhat larger than estimates using RL-04 data since the months from 2002 were all below the average melting trend.

The latest trend estimate increased from our paper to -241 Gigatons per year by (1) using more months from September 2011 to January 2013 and (2) the absence of 2002 data. The trend estimate is an average for the middle of the time period. So the slope of the time around 2007 is about -241 Gt/yr. 2003 was actually melting less than this, while 2012 was melting much more than this. The estimate just for 2012 is that Greenland lost 412 Gt of ice mass (see Fig 3).
Total Trend
Figure 1: Total mass change trend for Greenland. The solid black line is the raw GRACE monthly solution. Here we use a bandwidth of 60 spherical harmonic degrees and a 0.5 degree buffer region. The solid blue line is the best-fitting exponential trend. For more technical details please see the Methods/Code webpage. CLICK HERE for a high resolution version of the published figure from Harig and Simons [2012]
In the updated total map below, we see that the overall pattern of mass change over the last 10 years is similar to what we estimated in 2011. You can see in Figure 3 that the mass change for 2011 follow the general pattern for the previous years, so we would not expect big changes in the 10 year cumulative pattern. Note the increased scale bar in this figure compared to the previous published figure shows the increase in magnitudes for both melt on the coasts and changes in the high elevation interior.
Total Map
Figure 2: Geographical pattern of the cumulative mass change over Greenland for the period between 1/2003 and 1/2012. The integral value "Int" for the entire epoch is shown in Gigatons. The zero cm water contour shown in black. For more technical details please see the Methods/Code webpage. CLICK HERE for a high resolution version of the published figure from Harig and Simons [2012]
Below are the mass loss maps for each year, updated through 2011. We can see that 2011 was a record year for ice melt in Greenland. Nearly all coastal areas experienced mass loss and at much higher rates of loss (deeper reds) than previous years. In addition, the middle of Greenland shows increased mass accumulation, with magnitudes over 15 cm/yr of water equivalent.
Yearly Maps
Figure 3: Yearly-resolved maps of mass change over Greenland from 2003 to 2011. For every year we show the difference of the signal estimated between January of that year and January of the next. The integral values of the mass change per year are shown as "Int", expressed in Gigatons. The zero cm/yr water contours are shown in black. For more technical details please see the Methods/Code webpage. CLICK HERE for a high resolution version of the published figure from Harig and Simons [2012]
References (see also About/Publications)
Harig, C. and F. J. Simons. Mapping Greeenland's mass loss in space and time. Proc. Natl. Acad. Sc., 109(49), 19934-19937. doi:10.1073/pnas.1206785109, 2012.