PARCA Data @ NSIDC

Title Spatial Coverage Temporal Coverage Parameter(s)

Annual Accumulation Data from 1997 and 1998 PARCA Ice Cores

Dataset Summary

This data set contains annual accumulation data in water equivalent from 14 ice cores collected in 1997 and 16 ice cores collected in 1998. Data are provided in Microsoft Excel Format. Users of these data are encouraged to see the literature paper referenced below to aid them with the use of this data.

Details | Get Data

1998/01/01 to 1998/12/31 Snow Density, Depth Hoar, Isotopes, Snow Stratigraphy

Elevation Change of the Southern Greenland Ice Sheet from 1978-88

Dataset Summary

Southern Greenland ice sheet elevation change estimates are derived from SEASAT and GEOSAT radar altimetry data from 1978 to 1988. Data are confined to 61-72 deg N, 30-50 deg W, above 1700 m elevation. The addition of GEOSAT Geodetic Mission (GM) data results in twice as many crossover points and 50% greater coverage than previous studies. Coverage above 2000 m elevation is improved to 90%, and about 75% of the area between 1700 m and 2000 m is now covered. Data are in ASCII text format, available via FTP, and consist of elevation change rate (dH/dt, cm/year) and corresponding error estimates in 50 km grid cells.

Details | Get Data

N: 72, S: 61, E: -30, W: -52 1978/01/01 to 1988/12/31 Glacier Elevation/Ice Sheet Elevation, Ice Sheets

Greenland 5 km DEM, Ice Thickness, and Bedrock Elevation Grids

Dataset Summary

A Digital Elevation Model (DEM), ice thickness grid, and bedrock elevation grid of Greenland acquired as part of the PARCA program are available in ASCII text format at a 5 km grid spacing in a polar stereographic projection. DEM data are a combination of ERS-1 and Geosat satellite radar altimetry data, Airborne Topographic Mapper (ATM) data, and photogrammetric digital height data. Ice thickness data are based on approximately 700,000 data points collected in the 1990s from a University of Kansas airborne ice penetrating radar (IPR). Nearly 30,000 data points were collected in the 1970s from a Technical University of Denmark (TUD) airborne echo sounder. Bamber subtracted the ice thickness grid from the DEM to produce a grid of bedrock elevation values. Applications include studies of gravitational driving stress and ice volume (mass balance) of the Greenland Ice Sheet. Each of the three grids is approximately 1.5 MB. Data are available via FTP. Data access is unrestricted, but we recommend that users register with us. Registered users automatically receive e-mail notification of product updates and changes to processing.

Details | Get Data

N: 84, S: 60, E: -15, W: -72 1970/01/01 to 1970/12/01, 1993/01/01 to 1999/12/31 Glacier Elevation/Ice Sheet Elevation, Glacier Thickness/Ice Sheet Thickness, Glacier Topography/Ice Sheet Topography, Ice Depth/Thickness, Ice Sheets, Landforms, Topographical Relief, Topographic Effects

Greenland Climate Network (GC-Net) Automatic Weather Station Data

Dataset Summary

The Greenland Climate Network (GC-NET), established in spring 1994, currently consists of 18 stations with a distributed coverage over the Greenland ice sheet. The GC-Net emphasis is to monitor climatological and glaciological parameters at various locations on the ice sheet over a 10 year time period. The GC-Net Automatic Weather Stations (AWS) are equipped with instruments to measure surface energy and mass balance. Currently, the GC-NET archive contains 50 plus station years of measurements. These data have been quality controlled and calibrated. The objectives of the GC-Net AWS network are: (1) Assess daily, annual and interannual variability in accumulation rate, surface climatology and surface energy balance at selected locations on the ice sheet where high sensitivity of the ice sheet mass balance to climate anomalies is predicted from modeling results; (2) Assess accurate surface elevation, location, near-surface density at the AWS location with the option to revisit the locations in order to get temporal information for dynamic ice sheet modeling. The statistics are based on 12 critical parameters such as: incoming shortwave radiation, reflected shortwave radiation, net radiation, temperature-humidity-wind profile at two levels, wind direction, pressure and surface height. The possible data point count for all AWS and channels is 5.04574 106, whereas 4.72291 106 data were retrieved, resulting in an overall success rate of 93.6 percent. Recent six days of hourly surface meteorological ASCII data and plots are updated hourly on the WWW at: http://cires.colorado.edu/steffen/aws/current_GC-Net_plots.html. The GC-Net sites that are using GOES and ARGOS satellite data links are operationally updating automatically as of September 16 19

Details | Get Data

Surface Air Temperature, Air Temperature, Glacier Mass Balance/Ice Sheet Mass Balance, Terrain Elevation

Greenland Climate Network (GC-Net) Radiation for Arctic System Reanalysis

Dataset Summary

This data set provides incoming shortwave radiation measurements from fourteen stations of the Greenland Climate Network (GC-Net) distributed over the Greenland Ice Sheet. The original data were obtained from the GC-Net and subsequently quality controlled. The data span from 01 January 1995 through 09 May 2008. The data set is approximately 15 MB comprised of fourteen Network Common Data Form (netCDF) files. The data are available via FTP.

Details | Get Data

N: 80.75, S: 63.15, E: -42.5, W: -61.09 1995/01/01 to 2008/05/09 Solar Radiation

Greenland Ice Sheet Melt Characteristics Derived from Passive Microwave Data

Dataset Summary

The Greenland ice sheet melt extent data, acquired as part of the NASA Program for Arctic Regional Climate Assessment (PARCA), is a daily (or every other day, prior to August 1987) estimate of the spatial extent of wet snow on the Greenland ice sheet since 1979. It is derived from passive microwave satellite brightness temperature characteristics using the Cross-Polarized Gradient Ratio (XPGR) of Abdalati and Steffen (1997). It is physically based on the changes in microwave emission characteristics observable in data from the Scanning Multi-channel Microwave Radiometer (SMMR) and the Special Sensor Microwave/Imager (SSM/I) instruments when surface snow melts. It is not a direct measure of the snow wetness but rather is a binary indicator of the state of melt of each SMMR and SSM/I pixel on the ice sheet for each day of observation. It is, however, a useful proxy for the amount of melt that occurs on the Greenland ice sheet. The data are provided in a variety of formats including raw data in ASCII format, gridded daily data in binary format, and annual and complete time series climatologies in gridded binary and GeoTIFF format. All data are in a 60 x 109 pixel subset of the standard Northern Hemisphere polar stereographic grid with a 25 km resolution and are available via FTP.

Details | Get Data

N: 84, S: 60, E: -10, W: -73 1979/04/02 to 2007/12/31 Snow Melt

Greenland Ice Surface Elevations from NASA ATM Airborne Lidar

Dataset Summary

Scanning laser altimeters were flown over the Greenland icesheet during late spring or early summer from 1993 to 1999. Flights spanned the entire icesheet, sampling interior and coastal regions and several outlet glaciers. The data provided here are condensed from the original scanning lidar measurements to roughly one measurement per 75 m along the flight track, by fitting a plane to a set of points within a 70 meter by 150 meter subset. Each record in the resulting data set includes location, ellipsoid elevation, surface slope, and an RMS surface roughness. Flights from 1993 and 1994 were repeated in 1998 and 1999 to provide a measurement of the ice elevation change over a five-year period.

Details | Get Data

1993/01/01 to 1999/12/31 Glacier Elevation/Ice Sheet Elevation, Sea Ice Elevation, Sea Surface Slope, Surface Roughness

Greenland Radar Ice Sheet Thickness Measurements

Dataset Summary

Two 150-MHz coherent radar depth sounders were developed and flown over the Greenland ice sheet to obtain ice thickness measurements in support of PARCA investigations and the North Greenland Ice Core Project. These radar depth sounders are designed to use pulse compression techniques and coherent integration to obtain the high sensitivity required to measure the thickness of more than 4 km of cold ice. These systems are used to collect radar data over the interior and margins of the ice sheet and several outlet glaciers. Both radar systems are operated on the NASA P-3B aircraft equipped with GPS receivers. Radar data are tagged with GPS-derived location information and are collected in conjunction with laser altimeter measurements. All data collected from 1993 to 2014 have been processed, and ice thickness was derived with an accuracy of ± 10 m over 90 percent of the flight lines flown as a part of the PARCA initiative. Radar echo grams and derived ice thickness data are available via FTP.

Details | Get Data

N: -90, S: -90, E: 0, W: 0, N: 76, S: 76, E: -42, W: -42 1993/01/01 to 2014/12/31 Ice Depth/Thickness, Glacier Thickness/Ice Sheet Thickness

Hydrologic Outlets of the Greenland Ice Sheet

Dataset Summary

The Hydrologic Outlets of the Greenland Ice Sheet data set contains GIS point shapefiles that include 891 observed and potential hydrologic outlets of the Greenland Ice Sheet, as identified by Lewis and Smith (2009), using satellite imagery. There are 460 observed hydrologic outlets that include proglacial streams and rivers emerging from the ice sheet (length scale >1 km), proglacial lakes touching the ice edge or clearly connected to it via streams or rivers (length scale >3 km), and sediment-rich plumes exiting tidewater glaciers into fjords. Also, there are 431 potential hydrologic outlets that include point locations with release of meltwater from fjords without obvious sediment discharge, as well as locations where the ice sheet directly connects to the ocean that cannot be proven to release meltwater. Meltwater features along the entire edge of the ice sheet were mapped via photo interpretation of GoogleEarth and Landsat ETM+ 15 m panchromatic data. The exact acquisition dates of the imagery are not available; however, owing to the light and relatively snow-free conditions seen in the GoogleEarth and Landsat images, it is presumed that they were taken during the summer season. Neither Landsat or GoogleEarth images were available for a section of ice sheet within the northern Tunu region; therefore, that region was excluded from the study. This excluded area represents approximately 0.9 percent of the ice sheet perimeter. Data are available via FTP, and can be read in any GIS software. The following journal article provides documentation for this data set: Lewis, Sarah and Laurence Smith. 2009. Hydrologic Drainage of the Greenland Ice Sheet. Hydrological Processes doi: 10.1002/hyp.7343. This journal article can be accessed from the Documentation link at the top of this Web page.

Details | Get Data

N: 85.02649, S: 59.58015, E: -8.96739, W: -80.79734 1991/01/01 to 2000/12/31 Discharge/Flow, Drainage, Runoff, Snow Melt

Hydrologic Sub-basins of Greenland

Dataset Summary

The Hydrologic Sub-basins of Greenland data set contains Geographic Information System (GIS) polygon shapefiles that include 293 hydrologic sub-basins of the Greenland Ice Sheet, as created by Lewis and Smith (2009). Five km Digital Elevation Models (DEMs) of ice-surface and bedrock topography (Bamber et al. 2001) were used to estimate the hydraulic potentiometric surface for Greenland, which accounts for the effects of ice overburden pressure, such as hydrostatic pressure, surface topography, and underlying bedrock topography (Paterson 1994). Using the 5 km potentiometric grid, a modeled basin network for Greenland's ice sheet was created using the hydrological tools within ESRI ArcGIS (ArcInfo 9.2). Although the GIS initially generated more than 293 basins, basins less than 100 km2 in size, as well as basins located completely outside of the ice sheet extent, were removed from the data set. Data are available via FTP, and can be read in any GIS software. The following journal article provides documentation for this data set: Lewis, Sarah and Laurence Smith. 2009. Hydrologic Drainage of the Greenland Ice Sheet. Hydrological Processes DOI: 10.1002/hyp.7343. This journal article can be accessed from the Documentation link at the top of this Web page.

Details | Get Data

N: 85.57962, S: 59.25085, E: -6.7577, W: -80.9178 Discharge/Flow, Drainage, Glacier Topography/Ice Sheet Topography, Runoff

Ice Velocities Around the 2000 Meter Traverse in Greenland

Dataset Summary

This data set contains traverse measurements used to infer the mass balance of central parts of the ice sheet upslope from the traverse, and results from this work have been published in Thomas et al., [1998] and 2000, with comparisons of these results with those from repeat altimetry in Thomas et al. (2001). Ongoing projects using these data include: Collaboration with J. Bamber to increase the spatial resolution of our mass-balance estimates in order to identify causes for major imbalance in parts of southern Greenland, and use of the ice velocities to infer basal conditions along the traverse. During 1993-1997 a line of stakes about 30 km apart was established completely around the ice sheet approximately along the 2000 m elevation contour except in the south west, where it was higher because of high mountains, nunataks, and crevasses [Thomas et al., 1998 and 2000]. Each station was precisely surveyed by GPS, with resurvey one or two years later, to yield estimates of ice velocity. Station locations were marked by aluminum poles approximately 2 meters long, inserted close to vertically into the snow surface to a depth of about 1 meter. A second and, in areas of very high accumulation, a third pole was added to the lower pole using connecting sections and hose clamps. At each station, a GPS receiver was set atop the lower pole, by attaching a short length of aluminum rod to the base of the receiver and inserting this into the marker pole. Most stations were installed and surveyed via Twin Otter aircraft, during brief (about 10 minute) stops for station installation, and GPS mounting etc. The GPS receivers were left to operate for a minimum of 40 minutes, and more commonly a few hours. Up to 10 stations were visited during a one-day flight from a nearby coastal station. The GPS data from each day were processed by a point-positioning analysis for the longest-occupied station, with differential solutions for the others relative to this. Errors on resulting horizontal locations were about +/- 2 cm for the longest-occupied station, increasing to about +/- 10 cm for the shortest occupancy, with vertical errors approximately double these values. Additional errors were introduced by tilting of the marker poles during the 1-2 year interim between surveys, increasing the uncertainty by perhaps 5 cm. Consequently, derived velocities are accurate to better than +/- 0.2 m/yr. The data were acquired with support from NASA's Polar Research Program, and users requesting the data are asked to provide a brief description of their application of the data. This will help provide NASA with an assessment of the scientific benefits resulting from their support of such efforts.

Details | Get Data

1993/01/01 to 1997/12/31 Ice Velocity, Glacier Mass Balance/Ice Sheet Mass Balance

Mass-Balance Estimates by Comparing Ice Discharge Across the 2000 m Traverse

Dataset Summary

Ice-sheet mass balance can be inferred from comparison between total net accumulation and total ice discharge, and this data set contains results from such a comparison for higher-elevation parts of the Greenland ice sheet. During 1993-1997, velocities were measured at a line of stakes about 30 km apart completely around the ice sheet approximately along the 2000 m elevation contour except in the south west, where it was higher because of high mountains, nunataks, and crevasses [Thomas et al., 2000]. More information on these velocities can be found on our web site. Ice thickness was also measured along the traverse by a low-frequency ice-sounding radar [Gogineni et al., 1998]. Snow accumulation was from existing estimates [Ohmura and Reeh, 1991], supplemented by recent German and PARCA measurements and with estimates of total precipitation at weather stations for coastal accumulation rates. Each estimate refers to the time period over which measurements were made, ranging from years to centuries, but the overall set of results is heavily influenced by results from recent PARCA cores, most of which refer to the past two or three decades. Total snow accumulation within catchment areas corresponding to selected groups of stakes, expressed as a volume flux of ice, was compared to ice discharge between the stake locations. This was calculated as the product of ice thickness and velocity integrated between the stakes, after correcting for the ratio (R) between surface and column-averaged velocity, based on model simulations of the velocity/depth profile [Huybrechts, 1996]. Errors for small catchment areas are quite large because of uncertainties in local accumulation rates, the size of the catchment area, and R [Thomas et al., 1998]. For areas larger than about 100,000 sq km, the random nature of these errors reduces their overall effect to less than seven percent of the snow-accumulation rate, and considerably less for the entire region under study [Thomas et al., 2000]. Snow-accumulation rates range from less than 0.1 m of water equivalent per year in the northeast to more than one meter per year in parts of the southeast, with an average value for the entire ice sheet of about 0.3 m/yr [Bales et al., this issue]. The data set presented here is in tabular form, with a listing for individual gates of: station locations forming the gates; velocities, ice thicknesses and R estimates at the gates; total upstream accumulation; and resulting estimates of average ice-thickening rates (dH/dt) for the catchment areas appropriate to the gates. Because errors in dH/dt are large for single gates, additional Tables are provided giving:
  1. Values for larger ice-sheet catchment areas (approximately 30,000 sq km) formed by including several adjacent gates.
  2. Values for 12 larger gates (up to >100,000 sq km) that represent regions of the ice sheet with distinctive patterns of dH/dt. These estimates are compared to independent estimates from altimetry measurements in Thomas et al.
Errors in accumulation rates are the largest source of uncertainty in these mass-balance estimates, but they are progressively reduced as more information is acquired. The data presented here were compiled before all PARCA accumulation measurements had been analyzed, so they include different estimates of dH/dt based on accumulation estimates ranging from those in Ohmura and Reeh [1991] to our own attempts to improve these using then available PARCA data, and details of these can be found on our web site. Consequently, the dH/dt estimates provided here will be progressively improved as our estimates of snow accumulation also improve. Ongoing work with these data include:
  • Investigation of the regions that are significantly out of balance, in an attempt to identify causes for the imbalance.
  • Progressive updating of the dH/dt estimates using improved accumulation estimates, flow lines based on better maps of ice-sheet topography, and better estimates of R. This will be continued into the GLAS mission, using accumulation estimates from atmospheric analyses, for comparison with GLAS measurements of surface-elevation change.

Details | Get Data

1993/01/01 to 1997/12/31 Ice Velocity, Glacier Mass Balance/Ice Sheet Mass Balance

Modelled Precipitation Over Greenland

Dataset Summary

This data set includes the annual total precipitation from 1985 to 1999 and monthly total precipitation from January 1985 to December 1999. The data is derived from a dynamic model using the omega equation which describes vertical atmospheric motion. The data are arrayed in a 67 x 69 grid with a grid length of 50 km. Two versions of the data are available in separate directories (ver1 and ver2). Data are in ASCII files named yy.sum for annual total precipitation (mm), yymm.sum for monthly total precipitation (mm), and yy1-yy2.mean for annual mean precipitation from yy1 to yy2. Latitude and longitude data for the grid points and topological data are also available.

Details | Get Data

N: 72.5796, S: 72.5796, E: -38.4592, W: -38.4592 1985/01/01 to 1999/12/31 Precipitation Amount, Precipitation Rate

Program for Arctic Regional Climate Assessment (PARCA) Data Sets

Dataset Summary

PARCA began in 1993 with the primary goal of measuring and understanding the mass balance of the Greenland Ice Sheet. Approximately 25 investigations used in situ measurements and satellite and aircraft remote sensing to study this issue. Measurements include surface elevation and ice thickness change rates from aircraft laser altimetry, shallow to intermediate ice cores (for average accumulation rates and their temporal and spatial variability), velocity around the ice-sheet perimeter at an elevation of about 2000 meters, local ice thickening/thinning rates, and climatological observations from automatic weather stations. Satellite data used include elevation change from radar altimetry; mapping of snow facies and zones of summer melt from passive and active microwave; ice velocities from interferometric synthetic aperture radar (SAR) and from repeat high-resolution visible and SAR imagery; mapping surface and 10-m temperatures, accumulation rates, and surface albedo from microwave and AVHRR data. Data are available either by FTP or through investigator Web sites. Questions about investigator data should be directed to the individual technical contacts responsible for each data set. The National Snow and Ice Data Center (NSIDC) provides summaries and links to these data as a service to our users.

Details | Get Data

Ablation Zones/Accumulation Zones, Air Temperature, Glacier Elevation/Ice Sheet Elevation, Glacier Topography/Ice Sheet Topography, Humidity, Ice Depth/Thickness, Ice Growth/Melt, Ice Sheets, Ice Velocity, Incoming Solar Radiation, Landforms, Net Radiation, Precipitation Amount, Radar Backscatter, Radar Imagery, Reflectance, Return Power, Sigma Naught, Snow Cover, Snow Density, Snow Depth, Snow/Ice Temperature, Snow Melt, Snow Water Equivalent, Solar Radiation, Surface Air Temperature, Surface Roughness, Surface Winds, Terrain Elevation, Topographical Relief, Topographic Effects

Scatterometer Climate Record Pathfinder Data

Dataset Summary

This data set contains mean normalized backscatter coefficient (sigma-naught); backscatter variance; and other associated data files from Seasat SASS carrying a Ku-band scatterometer (1978), European Space Agency (ESA) Earth Remote Sensing (ERS) -1 and -2 missions carrying a C-band scatterometer (1992-2001), the NASA Scatterometer (NSCAT) mission (1996-1997), SeaWinds on QuikSCAT (1999-2009), SeaWinds on ADEOS-II/Midori2 (2003), and the ESA Advanced scatterometer (ASCAT) (2009+). Global, overlapping swath data were accumulated over a fixed interval of time. The data were then gridded, binned, and averaged, before it was processed using the Scatterometer Image Reconstruction (SIR) and SIR w/filtering algorithms developed at Brigham Young University.

Details | Get Data

N: 90, S: -90, E: 180, W: -180 1978/01/01 Brightness Temperature, Radar Backscatter