News & Events

Greenland rivers gauge ice sheet processes

Monday, November 18, 2013, 12:00PM - 1:00PM

Speaker

Irina Overeem

Location:

ARC room 620

The Greenland ice sheet exhibits dramatic melt trends that are likely to continue with rapid warming in the Arctic region. Models and measurements from satellites indicate that since the early 1990s, Greenland ice sheet mass loss has nearly doubled. However, storage of meltwater along its pathway to rivers and the global ocean is difficult to quantify.

We use MODIS remote-sensing reflectance data as a proxy of river discharge. Focus is on three West-Greenlandic rivers over the summers of 2000-2012. For validation, we surveyed and instrumented these rivers and fjords between 2010-2012. We found that both river braidplain inundation and fjord suspended sediment concentration (SSC) can be reasonably observed with MODIS from space.

The proxies indicate that annual summer river inundation may not have significantly changed over the last decade. Also, the RACMO2 surface melt model predicts a considerably higher water flux than our reconstructions, especially for the largest on-ice catchment. Both these results provide circumstantial evidence for a large component of englacial water storage.

Regionally aggregated data shows higher volumes of modeled runoff are associated with higher melt-season plume SSC values, but this relationship does not hold for individual rivers. Sediment plumes show large variability and no evident upward trend over the last decade, but zones of high sediment concentration did expand, with potential consequences for biological productivity.

Audience

Free and open to the public