HR: 1340h
AN: C43C-0239    [Abstracts]
TI: NPEO North Pole Web Cams observe Arctic Summertime
AU: * Untersteiner, N
EM: n-u@runbox.com
AF: University of Alaska Fairbanks, Chapman Chair College of Natural Science and Mathematics P.O. Box 755940, Fairbanks,, AK 99775 United States
AU: Overland, J E
EM: james.e.overland@noaa.gov
AF: NOAA/Pacific Marine Environmental Laboratory, 7600 Sand Point Wy NE, Seattle, WA 98115 United States
AU: Soreide, N N
EM: nancy.n.soreide@noaa.gov
AF: NOAA/Pacific Marine Environmental Laboratory, 7600 Sand Point Wy NE, Seattle, WA 98115 United States
AB: In 2002, 2003, and 2004, North Pole Environmental Observatory (NPEO) automatic instrumented stations were deployed on an ice floe near the North Pole and started recording and telemetering data in April/May. The field teams also installed Web Cameras to show the installations and some scenery. These "web cams" collect and transmit images throughout the entire summer, from the beginning of snow melt to freeze-up in autumn and the onset of darkness. To appreciate the value of these data and images we should bear in mind that the proverbial "inaccessibility of the frozen Arctic Ocean" due to cold and darkness applies to the mild summer even more than to the cold and dark winter. The onset of melting usually occurs in early June, when the temperature reaches 0øC and the surface layer turns into a constant-temperature ice bath. In 2002, the temperature record shows an abrupt warming to about 0øC, on 24 May, suggesting an early arrival of the melt season. The warming event coincides with about a week of low short-wave (250 Wm-2) and high long-wave (300 Wm-2) down-welling radiation, which are typical of low overcast conditions. The web cam pictures of that period confirm the overcast. Both radiation and temperature values remained in the normal range for the rest of the summer, and freeze-up occurred as usual in the last week of August. Based on the early warming event in May, one may have expected an early onset of surface melting. Contrary to that expectation, the web cams show that it was not until late July 2002 when the snow cover took on a soggy appearance and isolated melt ponds appeared on the surface. For the rest of the summer, the web cam pictures show only insignificant melt pond coverage until the deposition of new snow in late August. The pictures clearly show that snow from the preceding winter survived the entire summer, and we must assume that there was no, or very little, ice ablation at the surface. In light of recent news about global warming and polar amplification, the all-summer snow cover of 2002 is clearly unexpected. Like the summer of 2002, the subsequent summer of 2003 also shows a somewhat belated (end of June) appearance of melt ponds but, by the first week of July, pond coverage was wide spread. Unexpectedly, toward the end of July, pond coverage decreased markedly while radiation and air temperatures were still at their normal summer values. A possible explanation is that the ice had become sufficiently porous for the melt water ponds to drain by percolation. However, in mid-August the melt ponds re-appeared putting in question the hypothetical pond drainage by percolation. The preceding samples illustrate the extraordinary value of the web cam pictures. The recently recorded data from automatic buoys and web cams represent a large, and very inexpensively obtained, increment of information about summer conditions in the central Arctic. The web cams have yielded interesting and sometimes puzzling information about summertime conditions. All data, whether they pertain to the atmosphere or the ocean or the ice, are valuable in their own right, and every additional year of observations during the summer represents a large addition to the existing data base.
UR: http://www.arctic.noaa.gov/gallery_np.html
DE: 9315 Arctic region
DE: 5462 Polar regions
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting