Operation of a radar altimeter over the Greenland ice sheet

a thesis

Publisher: National Aeronautics and Space Administration, Publisher: National Technical Information Service, distributor in [Washington, DC, Springfield, Va

Written in English
Published: Downloads: 135
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  • Radio altimeters.,
  • Pulse compression.,
  • Greenland.,
  • Microwaves.,
  • Transmitter receivers.,
  • Arctic regions.,
  • Altimetry.

Edition Notes

ASIRAS radar altimeter was flown along the Expedition Glaciologique au Groenland (EGIG) line (Fischer et al., ) over the GrIS operating in High Altitude Mode (HAM). We present a km transect, along the EGIG line, on the western slope of the dry snow region of the ice sheet ranging in elevation from m to m. The system is. THE MODEL OF RADAR-ALTIMETER RETURN FROM ICE SHEETS In general, the radar echo returned from an ice sheet consists of both surface- and volume-scattered components. Ridley and Partington () have developed a model of the return, based on certain simplifying assumptions concerning the nature of the ice-sheet surface. This model is reviewed. The SEASAT-I radar altimeter data set acquired over both the Antarctic and Greenland continental ice sheets is analyzed to obtain corrected ranges to the ice surface. The radar altimeter functional response over the continental ice sheets is considerably more complex than over the oceans.   Greenland Campaign Takes Flight to Measure Ice Sheet Earlier this month, a NASA instrument nestled in the belly of a small plane flew over Greenland's ice sheet and the Arctic Ocean's icy waters. Flying above creviced glaciers, chunks of ice floating in melt ponds, and the slushy edges of the ice sheets, the instrument used a rapidly firing.

Radar data are tagged with GPS‐derived location information and are collected in conjunction with laser altimeter measurements. We have reduced all data collected since and derived ice thickness along all flight lines flown in support of Program for Regional Climate Assessment (PARCA) investigations and the North Greenland Ice Core by:   In addition, we carried a backpack with the GPS unit and a battery – they became pretty heavy after an hour of pulling the radar. Ludo and I set up the rule of not doing more than 2 hours of survey at a time, which corresponded to about 5 km total. Once on the ice sheet, as soon as the helicopter took off, we turned on the radar.   The light yellow over the central region of the ice sheet indicates a slight thickening due to snow. This accumulation, along with the weight of the ice sheet, pushes ice toward the coast.   Ice-Penetrating Radar Reveals Age of Greenland Ice Sheet Layers. First comprehensive analysis of deep radar data gives insight into the dynamics and history of the Greenland Ice Sheet.

  Figure shows the basic operation of such a pulse-limited radar altimeter. The short radar pulse expands as a spherical shell. As the shell intersects a flat surface, the area of the surface producing simultaneous backscattered power at the antenna has . The surface melt season on Greenland lasted up to 30 days longer than average in , and it affected 31 percent of the ice sheet surface. Ice mass loss from Greenland in was about gigatons—enough ice to raise global sea level by just over 1 millimeter. Atlas of Antarctica: Topographic Maps from Geostatistical Analysis of Satellite Radar Altimeter Data Professor Dr. Ute Christina Herzfeld (auth.) Although it is generally understood that the Antarctic Ice Sheet plays a critical role in the changing global system, to date there is a general lack of readily available information on the subject. ESA’s CryoSat-2 satellite, to test the possibility of sea ice classification based on radar altimeter waveforms on an Arctic wide scale. We define six parameters to account for the difference in the shape of the radar waveforms obtained over First- and Multi-Year-Ice and find significant differences for several of these by: 1.

Operation of a radar altimeter over the Greenland ice sheet Download PDF EPUB FB2


Conventional radar altimetry struggles with mapping the margins of the Greenland Ice Sheet due to the steep slopes characterizing this area. As a consequence and to avoid extrapolation in the merged SEC grid, we exclude all grid cells which are located on slopes exceeding ∘, if the SEC is based on conventional radar altimetry (ERS-1, ERS-2 and Envisat).Cited by: Get this from a library.

Operation of a radar altimeter over the Greenland ice sheet: a thesis. [Matthew D Grund; United States. National Aeronautics and Space Administration.]. There, Operation IceBridge has been observing the underside of the ice-sheet using an advanced radar, as well as closely monitoring an area of Pine Island Glacier known as the ice tongue that, were it to melt, would allow a large portion of the glacier to slide into the Amundsen Sea.

li et al.: radar measurements of ice thickness over antarctic and greenland ice sheets required to detect distant targets and compresses the received signal into a short-pulse to obtain fine.

Free 2-day shipping. Buy Operation of a Radar Altimeter Over the Greenland Ice Sheet at nd: Matthew D Grund. Since the late s, NASA has been monitoring changes in the Greenland Ice Sheet.

Recent analysis of seven years of surface elevation readings from NASA's ICESat satellite and four years of laser and and ice-penetrating radar data from NASA's airborne mission Operation IceBridge shows us how the surface elevation of the ice sheet has changed.

proven D2P radar altimeter ca n offer unprecedented mea surement accuracy over continen tal ice sheets and better precision from a smaller instrument over the op en ocean.

The D2P. Merging and Analysis of Elevation Time Series Over Greenland Ice Sheet From Satellite Radar Altimetry Kirill S.

Khvorostovsky Abstract—Spatial–temporal variability and changes of Green-land ice sheet elevation from to are analyzed from merged ERS. A radar altimeter (RA), radio altimeter (RALT), electronic altimeter, or reflection altimeter measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft.

This type of altimeter provides the distance between the antenna and the ground directly below it, in contrast to a. The Cryospheric Sciences Branch of the Hydrospheric and Biospheric Sciences Laboratory of NASA/GSFC under the direction of Dr. Jay Zwally with contractor support from SGT,inc.

has processed satellite radar ice altimetry over the continental ice sheets and surrounding sea ice to calculate surface elevations. Data from SeaSat, GeoSat, GFO, ERS-1, ERS-2, ENVISAT and CryoSat-2.

mcasurements over the Greenland Ice sheet and surrounding sea ice are documented in this first volume of a series.

The corrections derived and applied to the Seasat radar altimeter data ovcr ice are described in detail, including the editing and retracking algorithm to correct for height Satellite Radar Altimetry Over Ice Seasat.

Ice sheets Recently, ERS Radar Altimeter measurements (4 million ice-mode cross-over points) have been applied to show that the average elevation of the Antarctic Ice Sheet interior (63% of the grounded ice sheet) fell by ± cm/year from to Moreover, when the variability of snowfall observed in Antarctic ice cores is accounted.

A three-dimensional view of the age and structure of the Greenland Ice Sheet. Scientists using ice-penetrating radar data collected by NASA’s Operation IceBridge and earlier airborne campaigns have built the first-ever comprehensive map of layers deep inside the Greenland Ice Sheet. The suite includes a scanning lasar to measure the ice surface, a radar trained at the upper crust of the ice sheet, about to yards, another radar to.

Altitude results from both experiments are presented along with comparisons to the laser altimeter and calibration passes over the Sondrestroem runway in Greenland.

Although it is too early to make a conclusion about the growth or decay of the ice sheet, these results show that the instrument is capable of measuring small-scale surface changes.

For nearly a century, scientists have been studying the form and flow of the Greenland Ice Sheet. They have measured the change in the elevation of the surface over time using satellites.

They have drilled ice cores in the field to reveal a record of what the past climate was like. They have flown aircraft over the surface of the ice sheet laden with instruments to gleen information about the. Radar altimetry on high latitude polar zones started in with the launch of the ERS-1 mission by the European Space Agency, the first mission using specialized instruments on board for the studying of poles, for which an inclined orbit of ° enabled us to fly over almost all of Greenland in the Northern Hemisphere, and more than 75% of Cited by: 1.

A cm bias that exists bewteen the ERS-1 and ERS-2 altimeter ranges. Overview: The European Space Agency's (ESA) ERS-2 Radar Altimeter Satellite was launched in April of in an orbit that extended coverage over the ice sheets to +/- degrees.

In April. The Ice sheets of Greenland and Antarctica are losing mass at a rapid rate and there has been significant decrease in sea ice volume over the last few years.

CryoSat-II with optimized radar altimeter for ice-sheet and sea ice surface elevation measurements is launched. Analysis of airborne radar altimetry measurements of the Greenland ice sheet. Ellen Jeanne Ferraro, University of Massachusetts Amherst. Abstract. This dissertation presents an analysis of airborne altimetry measurements taken over the Greenland ice sheet with the GHz Advanced Application Flight Experiment (AAFE) pulse compression radar by: 4.

In this study, we extend the analysis of radar altimeter data from the two European Remote-sensing Satellites (ERS-1 and -2) to % of the Greenland ice sheet, % of the Antarctic ice sheet and % of the Antarctic ice shelves.

In Greenland, we use results of Airborne Topographic Mapper Journal of Glaciology, Vol. 51, No. A km resloution digital elevation model (DEM) of the Greenland ice sheet has been produced from the full days of the geodetic phase of ERS During this period the altimeter was operating in ice-mode over land surfaces providing improved tracking around the margins of the ice sheet.

The results showed thickening in East Antarctica on the order of cm per year, but thinning across a substantial part of West Antarctica. Data were unavailable for much of the Antarctic Peninsula, subject to recent ice sheet thinning due to regional climate warming, again because of limitations in current radar altimeter performance.

to − ± 23 m over Greenland and to ± 26 m over Antarctica. Index Terms—Altimetry, ice, laser measurements, radar altime-try, remote sensing.

INTRODUCTION S ATELLITE altimetry over the continental ice sheets has proven to be a valuable tool in studying decadal ice sheet mass balance changes by yielding measurements of elevationFile Size: KB.

term surface elevation time series of Greenland Ice Sheet is important for study its current state, inter- and intra-annual mass balance changes.

Measurements of radar altimeters from series of satellites (ERS-1, ERS-2 and Envisat) allow investigation the surface elevation changes of. [1] We here determine the surface elevation and the winter snow accumulation rate along a profile in the percolation zone of the Greenland Ice Sheet from data collected with ESA's Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) in spring The altimeter data show that in addition to a backscatter peak at the air‐snow interface a dominant second peak by:   Operation IceBridge is flying in Greenland to measure how much ice has melted over the course of the summer from the ice sheet.

The flights, which began on. Less ice, more ocean. That's the troubling conclusion emerging from new NASA research to study the condition of Greenland's ice sheet. Using a laser altimeter repeatedly flown across the surface of Greenland, experts say the edges of the ice found there may be.

Greenland's ice sheet, capable of raising sea levels by more than 20 feet, may be melting faster than scientists previously thought, according to two new scientific : Eric Zerkel. radar altimeter improves ice height and height change measurements in western Greenland waveform (the delay time variation in received power) over an ice cap or ice sheet depends on the topography.

All we know is that it must originate from somewhere within the signed to include a new mode of operation to address some of the limitations.

Since the late 's, NASA has been monitoring changes in the Greenland Ice Sheet. Recent analysis of data from both the ICESat satellite and an .Greenland Ice Sheet is of particular interest because: Study of polar ice sheets mass balance is critical for: • Greenland being located on the path of cyclones, is a good indicator of changes in the atmospheric circulation system • summer melting occurs over 1/4 to 1/3 of Greenland Ice Sheet surface.