Showing papers in "Polar Geography in 2001"

Terrain analysis and data modeling for alpine glacier mapping

Abstract: We investigate the utility of object‐oriented data modeling and analysis of the topography for alpine glacier mapping at Nanga Parbat, in northern Pakistan. Results indicate that first‐ and second‐order morphometric parameters can be used to study glacier features and delineate debris‐covered glaciers. Object‐oriented data modeling using a two‐level hierarchy was found to be successful for delineating the Raikot Glacier, although a three‐level hierarchy is required for more detailed glacier mapping. These findings are of special importance to the Global Land Ice Measurements from Space (GLIMS) project, which will use satellite imagery to assess and map the Earth's glaciers. Furthermore, hierarchical modeling of the topography may serve to provide a foundation upon which scientists may learn more about the polygenetic nature of topographic evolution.

Mountain glaciers at the end of the twentieth century: Global analysis in relation to climate and water cycle

Abstract: This work presents historical data on glacier mass balance. Until now, these data have been scattered throughout many publications, limiting their utility in the geosciences. The main objective of this contribution is to summarize data available in the digital data base of Dyurgerov (2002), and to discuss in some detail their quality and limitations. This paper is intended for glaciologists, climatologists, hydrologists, and other specialists interested in high-mountain and polar environments. Other potential users include those interested in the state of modern glaciers, their change on a global scale, or in changes occurring in any particular region.

Soils of the Barrow region, Alaska 1

Abstract: Soils have been studied near Barrow, Alaska for nearly 50 years. Since 1995 we have described, sampled, and characterized 26 pedons in the Barrow region, primarily within the Barrow Experimental Observatory, as part of a legacy soils database. The soils occur on land cover types that range from dry to wet acidic tundra. Cryoturba‐tion is the dominant process that affects most of the soils, but other processes include paludization, gleization, melanization, base‐cation leaching, and anthrosolization. In general, the soils have high levels of total organic carbon, total N, and silt. The cation‐exchange capacity is high but is dominated by exchangeable acidity. Twelve soil subgroups were recognized in the region, of which four were classified as Turbels, four as Orthels, and four as Histels. There is considerable spatial variability in the soils due to the presence of low‐, flat‐, and high‐centered frost polygons. The thaw‐lake cycle is of special importance in the Barrow region.

The Mcmurdo Dry Valleys Long‐Term Ecological Rsearch Program: New understanding of the biogeochemistry of the Dry Valley Lakes: A review 1

Abstract: The McMurdo Dry Valleys Long‐Term Ecological Research (MCM‐LTER) site represents the highest‐latitude location of the 24 LTER sites supported by the U.S. National Science Foundation. Although the perennial ice‐covered lakes in the dry valleys have been investigated since IGY, detailed, ecosystem‐based studies have been conducted on these lakes since 1993 by LTER investigators. A review of recent findings on the biogeochemistry and food‐ chain dynamics of these lakes is summarized within. The lakes are much more complicated and more dynamic than previously thought. The importance of collecting long‐term data is imperative if an understanding of how these sensitive systems respond to climate change is to be gained.

Onset of rapid calving and retreat of Glaciar San Quintin, Hielo Patagónico Norte, southern chile 1

Abstract: This note records the recent rapid retreat of the terminus of Glaciar San Quintin, which drains the western edge of the Hielo Patagonico Norte (HPN) in southern Chile. In 1993, the glacier terminus was advancing strongly into vegetated ground, while from 1996 to May 2000 the glacier underwent a transition between advance and retreat. A satellite image taken in 2000 showed that the ice front was undergoing substantial retreat and calving into proglacial lakes. Our research suggests that the glacier had lost an average of 1.89 km2 a−1 in ice surface between 1996 and 2000. The total surface loss is 7.55 km2, by far the largest retreat documented for the glaciers of the HPN since 1945.

Response of the large‐scale, Southern Hemisphere extratropical atmospheric circulation to extremes of Antarctic sea‐ice concentration in a general circulation model

Abstract: The study uses a general circulation model (GCM) to simulate the Southern Hemisphere atmospheric response to observed extremes in sea‐ice concentration. Two multi‐year simulations were completed for minimum and maximum sea‐ice climatologies and the results compared. The comparisons show that the Southern Hemisphere atmosphere is sensitive to sea‐ice extremes and the signs of this sensitivity extend to middle and lower latitudes. The sea‐ice extremes force patterns of variability that resemble the leading mode of circulation. Zonal wave one is reduced and zonal wave 3 is almost completely dampened in the minimum sea‐ice simulation. These responses in the zonal waves are attributed to changing variability in the atmosphere over the mid‐latitude Pacific and the Bellingshausen, Amundsen, and Weddell Seas.

Accumulation rates in South and Central Greenland

Abstract: This is the second of two papers summarizing the glaciological observations made on the southern and central parts of the Greenland Ice Sheet during two field campaigns conducted during the 1980s by scientists at The Ohio State University's Byrd Polar Research Center. Three large clusters of survey stations, as well as a strain grid leading to the Dye‐3 borehole, were deployed and surveyed in 1980, and resurveyed the next summer (1981). In 1987 and 1989, similar surveys were conducted in the Summit region as part of the GISP2 site selection. The primary objectives of these field campaigns were to measure absolute surface velocities and to obtain 20–30 year average accumulation rates from shallow firn cores. At a number of the survey sites, shallow cores were retrieved to determine accumulation rates and firn temperatures were measured in some of the boreholes. Each core was sampled for density and gross beta‐radioactivity. The latter reveals specific stratigraphic horizons associated with nuclear...

Spatial and temporal temperature change in the arctic basin since 1994: Assessment of localized short‐term data sets

Abstract: The daily averaged temperatures from 1994 to the year 2000 for the high Arctic stations of Alert, Resolute, Eureka, and Thule Air Base are investigated to assess both regional temperature variability and temperature trends. For this localized region of the Arctic Basin, data are analyzed on both an annual and seasonal basis to reconcile the observed differences in temperature between the stations, to assess the magnitude of air temperature change for the individual stations and for the region, and to examine the seasonal patterns of temperature variability. Results from such detailed regional analyses can be placed in context with the recognized temperature trends for the Arctic as a whole.