Showing papers in "Polar Geography in 2000"
TL;DR: The Circumpolar Active Layer Monitoring (CALM) program, designed to observe the response of the active layer and near surface permafrost to climate change, currently incorporates more than 100 sites involving 15 investigating countries in both hemispheres.
Abstract: The Circumpolar Active Layer Monitoring (CALM) program, designed to observe the response of the active layer and near‐surface permafrost to climate change, currently incorporates more than 100 sites involving 15 investigating countries in both hemispheres. In general, the active layer responds consistently to forcing by air temperature on an interannual basis. The relatively few long‐term data sets available from northern high‐latitude sites demonstrate substantial interannual and interdecadal fluctuations. Increased thaw penetration, thaw subsidence, and development of thermokarst are observed at some sites, indicating degradation of warmer permafrost. During the mid‐ to late‐1990s, sites in Alaska and northwestern Canada experienced maximum thaw depth in 1998 and a minimum in 2000; these values are consistent with the warmest and coolest summers. The CALM network is part of the World Meteorological Organization's (WMO) Global Terrestrial Network for Permafrost (GTN‐P). GTN‐P observations consis...
531 citations
TL;DR: In this article, the authors used the International Permafrost Association (IPA) map of permafrost and ground ice conditions to determine the area occupied by the permafure region (up to 22.79 × 106 km2, or 23.9% of the exposed land area of the Northern Hemisphere).
Abstract: The authors, based on the International Permafrost Association (IPA) Circumarctic Map of Permafrost and Ground Ice Conditions, determine the area occupied by the permafrost region (up to 22.79 × 106 km2, or 23.9% of the exposed land area of the Northern Hemisphere). They argue, however, that permafrost may not be present everywhere within this permafrost region. They present estimates that indicate that the actual area underlain by permafrost is smaller (ranging approximately from 12.21 to 16.98 × 106 km2, or from 12.8% to 17.8% of the exposed land area). They also estimate the volume of ground ice, as varying approximately from 10.80 to 35.46 × 103 km3 (about 2.7 to 8.8 cm sea‐level equivalent).
244 citations
TL;DR: In this paper, the authors used hydrological and meteorological observations at Lake Tuborg, Ellesmere Island, Nunavut, Canada in 1995 to investigate contemporary water and sediment transport processes.
Abstract: Hydrological and meteorological observations at Lake Tuborg, Ellesmere Island, Nunavut, Canada in 1995 are used to investigate contemporary water and sediment transport processes. Here we describe a new environmental data set for the High Arctic, where such data are scarce. The studied watershed (∼460 km2) ranges in elevation between 63 and ∼1900 m asl and is 88% covered by a lobe of the Agassiz Ice Cap. Streamflow and sediment transport were strongly associated with snowmelt runoff, whereas the direct influence of summer precipitation events was negligible. Snowmelt was primarily controlled by synoptic‐scale climatic processes. Two high‐magnitude pulses of meltwater and slush contributed a significant portion of the measured suspended sediment load to Lake Tuborg. Such events may be associated each year with snowmelt along the Agassiz Ice Cap margin. Additional years of data collection are needed to define the annual and inter‐annual variability of the sediment delivery system, particularly with...
16 citations
TL;DR: In this article, the authors found that the 18 GHz vertically polarized channel is the best predictor of accumulation rate and used a linear regression to these multi-year average values reproduces the corresponding measured accumulation rates to within about ±5%.
Abstract: Numerical modeling based on radiative transfer theory and observations of grain growth with depth have indicated that passive microwave brightness temperatures over the polar ice sheets should be a function of accumulation rate. Using accumulation‐rate time series from nine shallow cores in the dry‐snow facies in central Greenland, we find that multi‐year averages of mean annual SMMR brightness temperatures and accumulation rates are highly correlated. The 18 GHz vertically polarized channel is found to be the best predictor of accumulation rate. If the 18V brightness temperatures and the measured annual accumulation rates are averaged over 1979–1986, a linear regression to these multi‐year average values reproduces the corresponding measured accumulation rates to within about ±5%. This regression also was used to compute annual accumulation rates at the nine core sites from the corresponding average annual SMMR brightness temperature. Measured and predicted annual accumulation rates agree to wit...
15 citations
TL;DR: In this article, the authors summarize the results of two field campaigns conducted during the 1980s by scientists at The Ohio State University's Byrd Polar Research Center to measure absolute surface velocities and to obtain 20-30 year average accumulation rates from shallow firn cores.
Abstract: This report is the first of two papers summarizing the glaciologal 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. Velocities were determined using the U.S. Navy Navigational Satellite System, otherwise known as the TRANSIT system. To obtain accurate positions for survey stations on the ice sheet, the short‐arc method was used, in which satellite tracking stations at two stationary coastal stations wer...
11 citations
TL;DR: Despite what is often claimed, the French mathematician Jean Baptiste Joseph Fourier was not the first to compare the Earth's atmosphere with a greenhouse or a hothouse as mentioned in this paper.
Abstract: Despite what is often claimed, the French mathematician Jean Baptiste Joseph Fourier was not the first to compare the Earth's atmosphere with a greenhouse or hothouse. That comparison was made more than a century earlier by Edme Mariotte in 1681. Neither did Fourier provide a correct analytical description of the heat balance of the Earth surface and its atmosphere. It appears that the first scientist to do so was the French physicist Claude Pouillet in 1838.
7 citations
TL;DR: The results of many years of Russian-French-American studies of an ice core from a borehole in central Antarctica to a depth of 3310 m are presented in this paper.
Abstract: The results of many years of Russian‐French‐American studies of an ice core from a borehole in central Antarctica to a depth of 3310 m are presented. The data encompass four climatic cycles over the course of 420,000 years. The similarity and differences of each of the studied glacial epochs and interglacials are demonstrated with respect to a number of parameters: isotopic temperature, insolation conditions, airborne particulates, and greenhouse gases.
4 citations
TL;DR: In this paper, the first results of pollen analysis of the mammoth-enclosed deposits and 14C dating of remnants of mammoth (bone, tooth, and skin fragments) were presented.
Abstract: A multidisciplinary team of researchers describe the discovery, in July 1997, of the skull of a mammoth with two very well preserved tusks. The discovery was made by natives on the steep bank of the Great (Bol'shaya) Balakhnya River, northeastern Taimyr, Russia. During a preliminary excavation at this site, about a quarter of the skeleton was discovered, as well as a fragment of skin (1 × 1 m) with hair, and several kilograms of wool. This note describes the first results of pollen analysis of the mammoth‐enclosed deposits and 14C dating of remnants of mammoth (bone, tooth, and skin fragments).
4 citations
TL;DR: A geologist with extensive experience in the study of northern Alaska's petroleum resources provides an overview of the first comprehensive reassessment of the petroleum potential of section 1002 of the Arctic National Wildlife Refuge since the original study of 1987 as discussed by the authors.
Abstract: A geologist with extensive experience in the study of northern Alaska's petroleum resources provides an overview of the first comprehensive reassessment of the petroleum potential of section 1002 of the Arctic National Wildlife Refuge since the original study of 1987. The paper surveys the region's geology, and provides a description of the methods employed and assessment results. The current resource is compared with that estimated in the original study, and is considerably larger, given the availability of new geologic and geophysical data, improved seismic processing and interpretation capabilities, and changes in the economics of North Slope oil development.
2 citations
TL;DR: Torrey et al. as mentioned in this paper presented the results of a survey of contamination levels in bottom sediments from the Pechenega Bay, Barents Sea, are presented.
Abstract: The results of a 1977 survey of contamination levels in bottom sediments from the Pechenega Bay, Barents Sea, are presented. Aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons (11 PCB congeners, DDT with metabolites, HCB, alpha‐HCH, lindane), and trace elements were analyzed in samples from five sites. Levels of trace elements and of polycyclic aromatic hydrocarbons (PAH) were found to be low. High levels of PCB and some pesticides found in the bottom sediments indicate anthropogenic contamination sources. Translated by Edward Torrey, Alexandria, VA from: Izvestiya Rossiyskoy Akademii Nauk, seriya geograficheskaya 2000, No. 1, pp. 79–87.
TL;DR: In this article, the authors reported the results of regression analysis performed on the yearly averaged ice extents for the two time periods 1979-1990 and 1990-1999, and revealed two important findings: (1) for the Arctic as a whole, the decade of the 1990s witnessed a deceleration of the trend toward lesser ice Extents; and (2) the sign of trend reversed from the 1979−1990 period to the 1990−1999 period in seven of the nine regions into which the Arctic ice cover is divided for analysis.
Abstract: Decreases in Arctic sea ice extents since late 1978, found through analysis of satellite data, have been widely reported and have added to concerns regarding global warming. This paper reports the results of regression analysis performed on the yearly averaged ice extents for the two time periods 1979–1990 and 1990–1999, and reveals two important findings: (1) for the Arctic as a whole, the decade of the 1990s witnessed a deceleration of the trend toward lesser ice extents; and (2) the sign of the trend reversed from the 1979–1990 period to the 1990–1999 period in seven of the nine regions into which the Arctic ice cover is divided for analysis. The paper explores the possible connection between the spatial patterns of the sea ice trends and their reversals and the North Atlantic Oscillation (NAO), which reached a peak in its annual index in 1990.
TL;DR: In this paper, the authors examine the post-Soviet evolution of decision-making authority between the regions of Northwest Russia (Arkhangelsk Oblast, Republic of Karelia, Murmansk oblast, and Nenets Autonomous Okrug) and the Russian Federation government in Moscow, with particular attention to the arena of natural resource use and management.
Abstract: Two Norwegian researchers examine the post‐Soviet evolution of decision‐making authority between the regions of Northwest Russia (Arkhangelsk Oblast, Republic of Karelia, Murmansk Oblast, and Nenets Autonomous Okrug) and the Russian Federation government in Moscow, with particular attention to the arena of natural resource use and management. The authors document an ongoing struggle for authority (including the right to allocate quotas for the fish catch) between fisheries management departments of the regional administrations and the State Committee on Fisheries (and its quasi‐subsidiary basinwide management body Sevryba). The analysis highlights the unstable power balance in management of this important northern resource.