Seasonal and Interannual Changes in Surface Elevation of the Greenland Ice Sheet from Satellite Radar Altimetry PDF Download

Author: Diana M. Segura
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 212

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Author: H. Jay Zwally
Publisher: BiblioGov
ISBN: 9781289289072
Category :
Languages : en
Pages : 32

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Book Description
Observed seasonal and interannual variations in the surface elevation over the summit of the Greenland ice sheet are modeled using a new temperature-dependent formulation of firn-densification and observed accumulation variations. The observed elevation variations are derived from ERS (European Remote Sensing)-1 and ERS-2 radar altimeter data for the period between April 1992 and April 1999. A multivariate linear/sine function is fitted to an elevation time series constructed from elevation differences measured by radar altimetry at orbital crossovers. The amplitude of the seasonal elevation cycle is 0.25 m peak-to-peak, with a maximum in winter and a minimum in summer. Inter-annually, the elevation decreases to a minimum in 1995, followed by an increase to 1999, with an overall average increase of 4.2 cm a(exp -1) for 1992 to 1999. Our densification formulation uses an initial field-density profile, the AWS (automatic weather station) surface temperature record, and a temperature-dependent constitutive relation for the densification that is based on laboratory measurements of crystal growth rates. The rate constant and the activation energy commonly used in the Arrhenius-type constitutive relation for firn densification are also temperature dependent, giving a stronger temperature and seasonal amplitudes about 10 times greater than previous densification formulations. Summer temperatures are most important, because of the strong non-linear dependence on temperature. Much of firn densification and consequent surface lowering occurs within about three months of the summer season, followed by a surface build-up from snow accumulation until spring. Modeled interannual changes of the surface elevation, using the AWS measurements of surface temperature and accumulation and results of atmospheric modeling of precipitation variations, are in good agreement with the altimeter observations.

Author: Gang Feng
Publisher:
ISBN:
Category : Altitudes
Languages : en
Pages : 124

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Author: Craig S. Lingle
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

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Mean changes in the surface elevation near the west margin of the Greenland ice sheet are measured using Seasat altimetry and altimetry from the Geosat Exact Repeat Mission (ERM). The Seasat data extend from early July through early October 1978. The ERM data extend from winter 1986-87 through fall 1988. Both seasonal and multi-year changes are measured using altimetry referenced to GEM T2 orbits. The possible effects of orbit error are minimized by adjusting the orbits into a common ocean surface. Seasonal mean changes in the surface height are recognizable during the Geosat ERM. The multi-year measurements indicate the surface was lower by 0.4 +/- 0.4 m on average in late summer 1987 than in late summer 1978. The surface was lower by 0.2 +/- 0.5 m on average in late summer 1988 than in late summer 1978. As a control case, the computations are also carried out using altimetry referenced to orbits not adjusted into a common ocean surface.

Author: Lee-Lueng Fu
Publisher: Elsevier
ISBN: 0080516580
Category : Science
Languages : en
Pages : 509

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The new level of precision and global coverage provided by satellite altimetry is rapidly advancing studies of ocean circulation. It allows for new insights into marine geodesy, ice sheet movements, plate tectonics, and for the first time provides high-resolution bathymetry for previously unmapped regions of our watery planet and crucial information on the large-scale ocean features on intra-season to interannual time scales. Satellite Altimetry and Earth Sciences has integrated the expertise of the leading international researchers to demonstrate the techniques, missions, and accuracy of satellite altimetry, including altimeter measurements, orbit determination, and ocean circulation models.Satellite altimetry is helping to advance studies of ocean circulation, tides, sea level, surface waves and allowing new insights into marine geodesy. Satellite Altimetry and Earth Sciences provides high resolution bathymetry for previously unmapped regions of our watery planet.Satellite Altimetry and Earth Sciences is for a very broad spectrum of academics, graduate students, and researchers in geophysics, oceanography, and the space and earth sciences. International agencies that fund satellite-based research will also appreciate the handy reference on the applications of satellite altimetry.

Author:
Publisher:
ISBN:
Category : Greenland
Languages : en
Pages : 116

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This document describes the process of production of maps of the surface of the Greenland ice sheet from data from remote sensing by a Seasat satellite, and defines ice flow directions, together with maps of the Jakobshavn Glacier drainage and the ice divide near Crete Station.

Author: Tammy I. Stein
Publisher: Institute of Electrical & Electronics Engineers(IEEE)
ISBN:
Category : Science
Languages : en
Pages : 828

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Book Description
The theme of IGARSS'99, Remote Sensing of the System Earth - A Challenge for the 21st Century, reflects the expectation that earth observation based on satellite remote sensing can significantly contribute to the future study of our environment and the changes it is undergoing, whether from natural causes or human activities. The wide range of topics suggested for presentation is not only an indication of the interdisciplinary nature of this complex task, it also implies an essential need for integrated approaches in remote sensing in order to meet the challenge of modeling and understanding a system as complex as our environment.

Author: Gotthilf Hempel
Publisher: Springer Science & Business Media
ISBN: 3642787118
Category : Science
Languages : en
Pages : 299

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Book Description
Public awareness of the importance of Antarctic research, particularly in relation to global problems, has increased. The book spans a broad spectrum of Antarctic science from the "ozone hole" to microbiology to the sea ice. The main focus is on the role of Antarctica and the Southern Ocean in the world climate system, e.g. the formation of sea ice and its relevance to ocean circulation, the biological pump in relation to CO2 release. The past climate history is revealed by the analysis of ice cores and sediments. Studies of plate tectonics and fossil records reach further back in earth history. Key words in the biological chapters are krill and the rich Antarctic benthos. Finally, the potential conflict between conservationists, researchers and tourists is discussed.

Author:
Publisher:
ISBN:
Category : Earth sciences
Languages : en
Pages : 720

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Author: Shihua Sun
Publisher:
ISBN:
Category : Barometric hypsometry
Languages : en
Pages : 126

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Book Description
In this project, GFO satellite altimeter data are added to extend the time period of ice sheet elevation change measurements to present day. Consequently, datasets spanning the period from 1978 through 2002, provide more accurate estimates of the long-term elevation change for the southern Greenland ice sheet. We produced elevation change results that had greater spatial coverage and were more accurate than previous results. The abrupt transition from positive to negative elevation change at the ice divide south of 67° N is present for all time periods observed. The strong thickening near Dye 2 was reduced to only +10 cm/yr. In addition, the strong thinning at Dye 3 was reduced to -10 cm/yr. This is consistent with previous results that indicated that decadal fluctuations in accumulation were responsible for the strong thinning and thickening in the previous UMC research results. The 15-yr Geosat x GFO results have significantly extended the coverage in SE Greenland and strongly indicate widespread thinning on the order of -10 cm/yr.