20 December, 2002

Mass Balance

Date: 12/20/02

Latitude: 85° 00’ 01.57” S

Longitude: 104° 59’ 42.57” W

Time of Observations: 8:00 PM local time

Temperature: -25 C / -13 F

Wind speed: 5 knots

Wind Chill: -33 C/ -27 F

Wind direction: Northerly

Meters of ice collected: 318m

By Vandy Blue Spikes

Greeting from Antarctica. I am excited to finally be typing up my first daily log. I’ll start by saying that is was a glorious day on the ice sheet. It was quite cold (-13F), but that’s to be expected. The best thing about today was the lack of wind and the abundance of sunshine. We couldn’t have asked for a better day to work in this usually hostile environment. The worst thing about today was the fact that we still can’t see many mountains. The Ohio Range is barely peaking over the western horizon, but despite the fact that the rest of the Transantarctic Mountains are only about 40 miles away, they still cannot be seen. This minor let down will surely be overcome on the next leg of the traverse.

Throughout this season many of the parcticipating ITASE scientists have had the opportunity to explain their individual projects to those of you who follow this daily log. I’d like to take this opportunity to tell you about one of the projects that Gordon Hamilton, Steven Arcone, and I are working on. The project involves ground calibration and validation of the Geoscience Laser Altimetry System (GLAS) on board NASA’s Ice, Cloud, and land Elevation Satellite (ICESat), which was supposed to be launched today from Vandenberg Air Force Base in Southern California. We have yet to receive confirmation of a successful launch, but hopefully we will get the good news tomorrow. As with most scientific satellites, the details of how the laser altimetry system works could make your head spin, but the important thing to understand is that the satellite will measure elevations all over Earth’s surface. However, the orbit of the satellite makes it ideal for studying Earth’s Polar Regions. Scientists plan to use the system to track elevation changes over ice sheets in order to determine whether they are getting larger or smaller with time.

As many of you know, the Antarctic Ice Sheet plays an important role in Earth’s climate system and water budget. The ice sheet influences and responds to changes in climate, and sea level is modulated in part by the storage and release of water from the ice sheet. The Antarctic contribution to global sea level rise is determined by calculating the mass balance of the ice sheet. The term ‘mass balance’ refers to the difference between the amount of new snow accumulation versus the amount of ice that is lost to melting, sublimation, calving of icebergs, etc. An important goal of both US ITASE and the ICESat mission is to understand the mass balance of the Antarctic Ice Sheet and thus determine its contribution to rising sea level.

To help NASA determine whether or not their new system is producing reliable results; we used snowmobile-mounted GPS units to map two regions along this year’s traverse. The first site was established during our lengthy delay at Byrd Surface Camp. The second was just completed today at Site 3. The ground-based mapping technique is highly accurate, so if NASA’s elevation measurements agree with ours, the satellite mission can be considered a success. If the satellite measurements do not agree, NASA will make the necessary adjustments to correct their instrument.

It should be noted that after six hours of surveying I was pretty cold and had taken all the abuse I could from our rough-riding snowmobile. Lucky for me, Jim Laatsch was kind enough to finish the last two hours of the survey for me. I believe this was Jim’s first experience navigating a snowmobile across the Antarctic plateau with nothing more than a hand-held GPS unit. He didn’t get lost, so I’d say he did a great job.

Well, that about does it for this daily log. I hope you all got something out of it. Please stay tuned for more daily updates from US ITASE.