Citation information for individual datasets is often provided in the metadata. However, not all datasets have this information embedded in the discovery metadata. On a general basis a citation of a dataset include the same components as any other citation:
author,
title,
year of publication,
publisher (for data this is often the archive where it is housed),
edition or version,
access information (a URL or persistent identifier, e.g. DOI if provided)
The information required to properly cite a dataset is normally provided in the discovery metadata the datasets.
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Brief user guide
The Data Access Portal has information in 3 columns. An outline of the content in these columns is provided above. When first entering the search interface, all potential datasets are listed. Datasets are indicated in the map and results tabulation elements which are located in the middle column. The order of results can be modified using the "Sort by" option in the left column. On top of this column is normally relevant guidance information to user presented as collapsible elements.
If the user want to refine the search, this can be done by constraining the bounding box search. This is done in the map - the listing of datasets is automatically updated. Date constraints can be added in the left column. For these to take effect, the user has to push the button marked search. In the left column it is also possible to specific text elements to search for in the datasets. Again pushing the button marked "Search" is necessary for these to take action. Complex search patterns can be constructed using logical operators through the drop down menu above the text field. Text strings that are not quoted are treated as separate words and will match any of the words (i.e. assuming the OR operator). Phrases may be prefixed with '-' to indicate no occurence of the phrase in the results.
Other elements indicated in the left and right columns are facet searches, i.e. these are keywords that are found in the datasets and all datasets that contain these specific keywords in the appropriate metadata elements are listed together. Further refinement can be done using full text, date or bounding box constraints. Individuals, organisations and data centres involved in generating or curating the datasets are listed in the facets in the right column.
This data set includes yearly snow melt onset dates over Arctic sea ice derived from Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave/Imager (SSM/I), and the Special Sensor Microwave Imager/Sounder (SSMIS) brightness temperature measurements. The data are gridded to the 25 km Northern Hemisphere Polar Stereographic projection and available from 1979 through 2022. One browse image is available for each year.
This data set also contains value-added statistics for each grid cell, including: mean melt onset date, latest (maximum) melt onset date, earliest (minimum) melt onset date, range of melt onset dates (the difference between maximum and minimum onset dates), and the standard deviation of melt onset dates. One browse image is also provided for each statistical field.
This archive of daily rawinsonde measurements of wind direction and speed, atmospheric pressure, humidity, air temperature, and geopotential height as well as surface-based observation of cloud cover (amount, type and height) from Soviet North Pole drifting stations was assembled under the direction of Dr. J. Kahl, with funding from the National Oceanic and Atmospheric Administration, the National Science Foundation, and the Electric Power Research Institute. Soundings were recorded from April 19, 1954 to July 31, 1990 at drifting stations located in the Arctic Ocean, north of approximately 70 degrees North. Data were obtained from several different sources. All of these data are ultimately derived from the set of bound volumes of handwritten tables kept at the Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia. Data are in 21 ASCII text format files with an average size of under 10 MB.
<p><font color="#FF0000">Note: This data set is now on HTTPS so references to CD-ROM are historic and no longer applicable.</font></p>
The Ice Altimetry System (IAS) data seet contains surface elevations of the Antarctic and Greenland ice sheets derived from Seasat and GEOSAT radar altimetry data. The Seasat data were collected for a continuous 90 days in 1978, at latitudes between 72 degrees South and 72 degrees North. GEOSAT was launched in 1985 and placed in a nearly identical orbit to Seasat, also at latitudes of between 72 degrees South and 72 degrees North. The orbit was designed to provide high-density measurements over the Earth's surface, at a maximum grid spacing of 2.7 kilometers at the equator and much denser spacing over polar ice sheets. Data were acquired between April 1985 and September 1986.
Initially acquired by the Johns Hopkins APL (Applied Physics Lab) satellite tracking facility, the raw altimetry satellite data from Seasat and GEOSAT were passed on to NASA, via the US Navy. NASA developed slope correction routines for the higher slopes over the ice sheets, relative to ocean surfaces. The data are height profile Level 3 data and gridded height Level 4 data provided by the Oceans and Ice branch of the Laboratory for Hydrospheric Physics of Goddard Space Flight Center. Elevations from the full data rate (i.e., one measurement every 662.5 m) are provided in georeferenced databases. These elevations are relative to the WGS-84 ellipsoid. Gridded elevations at 10-kilometer and 20-kilometer spacing are provided in the gridded data sets created from the GEOSAT and Seasat data, respectively. Software to extract and browse subsets of these data is included. The IAS software also allows the user to view contours created from the gridded data and groundtracks of the full-rate data.
Earth Observing System Data Information System, International Program for Antarctic Buoys, Earth Science Information Partners Program, World Climate Research Program (EOSDIS, IPAB, ESIP, WCRP)
Through participating research organizations in various countries, the World Climate Research Programme's (WCRP) International Programme for Antarctic Buoys (IPAB) maintains a network of drifting buoys in the Antarctic sea ice zone to support a better understanding of sea ice motion, meteorology, and oceanography. The IPAB Antarctic Drifting Buoy Data archive, spanning the years 1995 to 1998, includes measurements of buoy position, atmospheric pressure, air temperature, and sea surface temperature. Data are organized by daily and three-hour averages and are provided as raw, instantaneous, non-interpolated data values. Data were collected from buoys initially deployed in the following three study regions: East Antarctica; the Weddell Sea; and the Bellingshausen, Amundsen, and Ross Seas.
The total annual freezing and thawing indices are defined as the
cumulative number of degree-days when air temperatures are below and
above zero degrees Celsius. The total annual freezing index has been
widely used to predict permafrost distribution; estimate the
maximum thickness of sea, lake, and river ice, and the maximum depth of
ground-frost penetration; and classify snow types. The annual total
thawing index has been used to predict permafrost distribution and to
estimate the maximum depth of thaw in frozen ground. Both total
freezing and thawing indices are important parameters for engineering
design in cold regions.
Data coverage is global. The data set contains the total annual freezing and thawing indices with a spatial resolution of 0.5 degrees
latitude by 0.5 degrees longitude. Two data files are available, for
the freeze and thaw indices respectively, in flat binary format. Each
file is approximately 1 MB in size. The total annual freezing and
thawing indexes were calculated based upon the monthly mean air
temperature by Legates and Willmott (1990).
Earth Observing System Data Information System, Earth Science Information Partners Program, NOAA/NASA Pathfinder Program (EOSDIS, ESIP, NOAA/NASA PATHFINDER)
As of 1 February 2022, this data set is retired and no longer available for download. We recommend using the MEaSUREs Calibrated Enhanced-Resolution Passive Microwave Daily EASE-Grid 2.0 Brightness Temperature ESDR, Version 1 data set, located at https://nsidc.org/data/nsidc-0630/versions/1, as an alternative.
This Level-3 Equal-Area Scalable Earth-Grid (EASE-Grid) Brightness Temperature data set, collected since 09 July 1987, is a part of the NOAA/NASA Pathfinder Program. The data set consists of gridded data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager/Sounder (SSMIS) in three equal-area projections: Northern Hemisphere, Southern Hemisphere, and full global.
The AMSR Level-2A product (AA_L2A) contains brightness temperatures at 6.9 GHz, 10.65 GHz, 18.7 GHz, 23.8 GHz, 36.5 GHz, 89.0 GHz, 50.3 GHz, and 52.8GHz. Data are resampled to be spatially consistent except for the 50.3GHz and 52.8GHz data, and therefore are available at a variety of resolutions that correspond to the footprint sizes of the observations such as 56 km, 38 km, 24 km, 21 km, 12 km, and 5.4 km, respectively.
The Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) instrument on the NASA EOS Aqua satellite provides global passive microwave measurements of the Earth. NSIDC produces AMSR-E gridded brightness temperature data by interpolating AMSR-E data (6.9 GHz, 10.7 GHz, 18.7 GHz, 23.8 GHz, 36.5 GHz, and 89.0 GHz) to the output grids from swath space using an Inverse Distance Squared (ID2) method. AMSR-E/Aqua L2A Global Swath Spatially-Resampled Brightness Temperatures (AE_L2A) input source data are used.
These data are provided in three EASE-Grid projections (north and south Lambert azimuthal and global cylindrical) at 25 km resolution, and in one global cylindrical, equidistant latitude-longitude projection at 0.25 degree (quarter-degree) resolution.
The Antarctic atlas consists of 28 digital elevation maps which cover all of Antarctica north of 72.1 degrees south at a resolution of three kilometers. Each map contains surface elevations and coordinates for one atlas page covering 16 degrees of longitude. Data were acquired by the Geodetic Satellite (GEOSAT) Geodetic Mission (GM) from March 1985 through September 1986 and are available in both Universal Transverse Mercator (UTM) coordinates, and in latitude and longitude coordinates.
Data were mapped using the UTM projection in atlas form to decrease the distortion that usually occurs at the poles. Many features of the Antarctic Ice Sheet are shown in more detail than in previous digital elevation models, especially along the margin of the East Antarctic Ice Sheet. A geostatistical mapping technique (Herzfeld et al. 1993) improved the accuracy of surface elevations compared to previous GEOSAT elevation data sets. This atlas will facilitate the monitoring of changes in surface elevation that could indicate mass changes in the Antarctic Ice Sheet.
The Near-real-time Ice and Snow Extent (NISE) data set provides daily, global maps of sea ice concentrations and snow extent. These data are not suitable for time series, anomalies, or trends analyses. They are meant to provide a best estimate of current ice and snow conditions based on information and algorithms available at the time the data are acquired. Near-real-time products are not intended for operational use in assessing sea ice conditions for navigation.
This NISE Version 5 product contains DMSP-F18, SSMIS-derived sea ice concentrations and snow extents derived from the Special Sensor Microwave Imager/Sounder (SSMIS) aboard the Defense Meteorological Satellite Program (DMSP) F18 satellite. For DMSP-F16, SSMIS-derived data, see <a href="https://doi.org/10.5067/JAQDJKPX0S60"> NISE Version 3</a>. For DMSP-F17, SSMIS-derived data, see <a href="https://nsidc.org/data/nise/versions/4"> NISE Version 4</a>. For the older, DMSP-F13, Special Sensor Microwave Imager (SSMI) derived data, see <a href="https://doi.org/10.5067/4FSODMDM1WEJ">NISE Version 2</a>.
A gridded climatological monthly-mean data base of Arctic water vapor characteristics has been assembled by combining fixed station data with data from soundings taken over the Arctic Ocean from ships and Russian drifting stations.
Variables provided include temperature, specific humidity, zonal vapor flux, meridional vapor flux, zonal wind speed, and meridional wind speed, available for 15 pressure levels extending from the surface (1,000 mb) to 300 mb. Sea level pressure and geopotential height are provided for the 850 mb, 700 mb, 500 mb and 300 mb levels. Precipitable water, vertically integrated zonal vapor flux and vertically integrated meridional vapor flux are available for five layers: surface to 850 mb, 850 to 700 mb, 700 to 500 mb, 500 to 400 mb and 400 to 300 mb.
Coverage of the rawinsonde archives extends from 1954 through 1990 for data from the Russian North Pole series of drifting ice stations over the Arctic Ocean; from 1976 through 1991 for fixed-station data obtained from the National Center for Atmospheric Research; and from about 1958 through 1991 for fixed-station data obtained from the Historical Arctic Rawinsonde Archive.
All variables were obtained through interpolation of the raw sounding data, with the exception of sea level pressure and geopotential height. The files are structured in monthly data arrays over a subsection of the National Meteorological Center grid (octagonal grid format) centered over the pole, extending to approximately 65 degrees North on each side and about 55 degrees North at the corners.
NOAA/NASA Pathfinder Program, Earth Science Information Partners Program, Earth Observing System Data Information System (NOAA/NASA PATHFINDER, ESIP, EOSDIS)
The Pathfinder Program, sponsored by the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA), is tasked to produce long-term data sets for global change research. The Special Sensor Microwave/Imager (SSM/I) Pathfinder Level 2 Land Products data set has been generated using the land classification algorithms developed by Neale, and the land surface temperature algorithms developed by McFarland. This data set includes both the land classification and land surface temperature products. The Pathfinder Level 2 Land Products data set is in swath format. Coverage is global land surface, and covers 1 August 1987 through 31 March 1988.
The SSM/I Pathfinder Level 3 Land Products data set has been generated using the Level 2 data described above. The Level 2 data were interpolated to a longitude-latitude grid with a resolution of one degree. For the Benchmark Period, the data were averaged over periods of five days (a pentad) or one month, although, for the land classification product, the most commonly occurring land class (the mode of the distribution within each bin) was chosen as the class for that bin and for the period. The data set, including both pentad and monthly grids, covers 1 August 1987 through 31 December 1988.
As of 26 September 2019, this data set is retired and no longer available for download. This data set was retired because other passive microwave data sets with longer temporal records are available at NSIDC. We recommend <a href="https://nsidc.org/data/amsre">the suite of AMSR-E products available at NSIDC</a> as an alternative.
This data set provides a Digital Elevation Model (DEM) for Antarctica to 81.5 degrees south latitude, at a resolution of 5 km. Approximately twenty million data points were used to generate this data set. Data points were derived from ERS-1 radar altimetry during the geodetic phase from March 1994 to May 1995.
As of 31 August 2022, this data set is retired and no longer available for download. We recommend using <a href="https://nsidc.org/data/nsidc-0630">MEaSUREs Calibrated Enhanced-Resolution Passive Microwave Daily EASE-Grid 2.0 Brightness Temperature ESDR, Version 1</a> data set as an alternative. This data set provides daily, near-real-time Special Sensor Microwave Imager/Sounder (SSMIS) brightness temperatures in the Equal-Area Scalable Earth-Grid (EASE-Grid). The data set consists of gridded data in two projections: Northern Hemisphere and Southern Hemisphere. The data lag by one day and provide 365 days of near-real-time data. The spatial resolution is 25 km for all channels. Data are contained in flat binary files.
The SMMR Antenna Temperatures (Nimbus-7) data set consists of antenna temperatures from passive microwave radiometers aboard NOAA's Nimbus-7 satellite. The instrument is the Scanning Multichannel Microwave Radiometer (SMMR). Each file consists of one days worth of data in swath format, i.e. the portion of the Earth's surface viewed by the scanning radiometer. Antenna temperature data are available from NSIDC from October 1978 to August 1987. SMMR was a ten channel passive microwave instrument using six conventional Dicke-type radiometers. It delivered orthogonally polarized antenna temperature data at five frequencies: 6.6, 10.69, 18.0 21.0 and 37.0 GHz. The two 37.0 GHz radiometers operated
continuously for each polarization. The other radiometers alternated polarizations on alternate scans. The size of each daily file is 35 MBytes. The data are distributed on FTP.
The scanner operated only on alternate days, due to spacecraft power limitations. There are typically at least 14 days of coverage per month, although major data gaps occur in August: in August, 1982, the 4th, 8th, and 16th are missing for both polar regions; in August,
1984, the 13th through the 23rd are missing for both polar regions.