 |
| Radar preparations during the 2010 BELISSIMA expedition in Antarctica |
It comprises 6 partners of several Belgian and foreign institutions, i.e. Université Libre de Bruxelles (ULB), Royal Observatory of Belgium (ROB), University of Luxembourg (UL), Norwegian Polar Institute (NPI), and Aberystwyth University (AU).
The IceCon project aims at a better understanding of the past and present ice volumes and extension of the Antarctic ice sheet in Dronning Maud Land (DML) through a new series of measurements and observations in conjunction with ice sheet system modelling.
Knowledge of past ice volumes are important, since the ice sheet is still reacting to what happened in the past, especially since the Last Glacial Maximum (LGM), roughly 18,000 years ago, when the Antarctic ice sheet was significantly bigger. Our main hypothesis is that the Last Glacial Maximum (LGM) ice sheet volume in DML was smaller than that predicted by large scale ice sheet models. This study will provide local data for fine tuning and modifying large-scale ice sheet models.
IceCon’s main hypothesis is that the LGM ice sheet volume in Dronning Maud Land was not as big as previously predicted by large-scale ice sheet models, although it advances further towards the coast. Less grounded ice during the LGM implies less ice loss during deglaciation (the process of mass loss between LGM and now), making it difficult to associate a historical event – “meltwater pulse 1A” to the Antarctic ice sheet. Meltwater pulse 1A was rise of around 20m in sea levels that took place during a 500-year period, some 14,200 years ago.
The freshwater source for this pulse remains controversial, but understanding its source is important to understand its effects on oceanography and climate, and because it provides a potential analogue for rapid ice sheet deglaciation now, and in the future. Some researchers place the pulse in the Northern Hemisphere, while others advocate that this important ice loss stemmed from the Antarctic ice sheet. Understanding the past changes in ice sheet volume in Dronning Maud Land will definitely improve our understanding of future changes of the ice sheet in this area.
Acorrect understanding of past ice volumes is also important for GIA (Glacial Isostatic Adjustment) corrections, hence interpretation of the present-day mass change of ice sheets through analysis of GRACE data.
So what has GRACE to do with it and why should this be important?
The Greenland and Antarctic ice sheets are losing mass at an accelerating pace. Some studies suggest these ice sheets are overtaking ice loss from Earth's mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted. However, these estimates are based on GRACE satellite data, which essentially measures changes in the gravity field at the surface of the Earth. Several corrections need to be applied to the data in order to filter out the signal that is due to changes in ice mass. One of these factors is to determine the isostatic uplift, which is currently done using a series of GIA models. However, such models need constraints on the present-day uplift rates. While these rates are generally well known for Greenland, in Antarctica useful direct measurements are mostly lacking for the East Antarctic ice sheet, since there is not much ice-free area. Other constraints may come from paleo evidence elucidating how thick the ice cover was during the Last Glacial Maximum, for instance.
Details on the 2012 Expedition to Antarctica
During the 2012-2013 BELARE season, the IceCon team will install two geodetic GPS systems that will run all-year long. This puts serious constraints on power, so they will rely on batteries powered by solar panels and wind turbines. One of the geodetic GPS systems will be set up on Seal, a small nunatak in the vicinity of Romnoesfjellet. The purpose of the GPS systems is to monitor, over a four-year period, vertical changes of the lithosphere in response to the unloading of the ice due to post-glacial rebound. This will give IceCon insight into the volume of ice present in this sector of Antarctica’s Dronning Maud Land during the Last Glacial Maximum. This information is essential for constraining models of Glacial Isostatic Adjustment (GIA), which form the basis of the interpretation of the GRACE satellite signal. One GPS system will also be deployed on Derwael ice rise. Understanding the dynamics of this ice rise will help understanding the deglaciation history as well. Ice rises are climate dipsticks that may tell us a lot on how the ice sheet behaved over the last thousands of years. By means of ice radar profiling and ice core drilling it is hoped to tie the ice dynamics of this area to the rest of the ice sheet.
Posted with Blogsy
No comments:
Post a Comment