• NSIDC reformatted digitized ice charts prepared by the Russian Arctic and Antarctic Research Institute from 1953 through 1990 into EASE-Grid to make them easier to use.
• Provides information when passive microwave data were not yet available (prior to 1973)
• Provides perhaps the most detailed analyses of ice conditions in the eastern Arctic
• A useful comparison set for analyses of SMMR- and SSM/I-derived ice concentrations, because passive microwave data were not used to produce the AARI charts
• More accurate and useful for studies of coastal polynyas and other relatively fine-scale features along the coast
• Disadvantages are that the area covered changes from one chart to the next, and temporal coverage is not consistent in the early years of the record.
• A similar version of this data set can be found on the EWG Sea Ice Atlas.

• The 12.5 km sea ice concentration product is generated using two algorithms: the enhanced NASA Team (NT2) algorithm (Markus and Cavalieri 2000) for the Arctic and the Bootstrap Basic Algorithm (BBA, Comiso 1995) for the Antarctic.
• The method for deriving snow depth from SSM/I data is described in Markus and Cavalieri (1998).

• The 25 km sea ice product is generated using two algorithms: the enhanced NASA Team (NT2) algorithm (Markus and Cavalieri 2000) in the Arctic and the AMSR Bootstrap Algorithm (ABA; Comiso, Cavalieri, and Markus 2003) in the Antarctic.
• The AMSR Bootstrap Algorithm (ABA; Comiso, Cavalieri, and Markus 2003) that makes use of the 6.9 GHz data to reduce temperature effects on V1937 data provides very similar results to those of the BBA algorithm used in the 12.5 km sea ice product, indicating that errors associated with temperature effects on the latter are relatively minor; however, ABA allows for the calculation of ice temperature, which in itself is an important climate parameter.

• Tabular compilation of a variety of drifting platform locations contains easy-to-use long-term platform drift records.
• Provides longest record on ice transport, ocean currents and wind patterns

• Provides information prior to the availibility of satellite coverage and greater temporal coverage than most ice chart-based data sets
• Prior to 1978, data come from early sea ice observations and ice charts.
• After 1978, data were obtained from passive microwave-derived concentration and extent using the NASA Team algorithm.
• Antarctic data are all from passive microwave using the NASA Team algorithm.
• There is a discontinuity in ice concentration (passive microwave derived concentrations are significantly lower than observational data in central Arctic), but no obvious discontinuity in ice extent in 1978.
• Useful for studies that require the longest time record possible and do not need the detail and higher resolution offered by satellite data sets
• Limitations of the data set:
  • Prior to 1953, data are primarily climatologies (leading to a discontinuity in extent and concentration in 1953)
  • Different sources of chart data have imprecise and variable concentration classifications.
  • Due to the inconsistent coverage of early chart data, concentration has been interpolated in space and time.

• This compilation of geolocated AVHRR satellite images contains albedo (reflectance) and infrared brightness temperature images selected to provide the best clear-sky views of surface conditions.
• Images were selected to avoid excessive cloudiness while still providing a time series of surface conditions at reasonable temporal frequency.
• Relatively fine detail of surface features makes the data set useful for studying ice edge conditions, presence and orientation of leads, and for comparison with other satellite products.
• Ancillary tables and browse images describe each image coverage.
• Calibration and image geolocation are likely more accurate in the AVHRR Polar Pathfinder products; however, the manual selection of clear-sky coverages used for this data set can save time for users interested in surface conditions.

• The readily available data record from moored ulS instruments begins in the late 1980s.
• This data set provides data for Antarctica.
• ACSYS distributes moored ulS data from the Arctic and provides a figure showing the distribution of moored ulS positions.
• See the references in the online documentation for information on ulS instruments, data processing procedures, and on scientific results.

• Continuous time series of daily averaged total ice concentrations derived from a modified version of the Bootstrap algorithm, which uses revised tie-points to provide more temporally consistent data between the various sensors (SMMR , F8, F11, and F13)
• Fewer false ice concentrations from weather effects in the open ocean and along land/ocean boundaries than with the standard algorithm
• Missing data, including small gaps in the time series, are temporally and spatially interpolated.
• Updated about once a year
• Especially useful for long time series analysis of ice extent

• Provides a wide range of measurements, including information on ocean, biophysics, meteorology and ice conditions as observed in the Norwegian and Greenland Seas

• Level 2 data. Users have access to all orbits rather than 24-hour averages.
• Only total ice is calculated for the Southern Hemisphere.

(links to browse directories on our ftp site)

• Daily averaged total sea ice concentrations for the Arctic and the Antarctic
• Standard algorithm weather filter removes most false ice concentrations over open ocean that result from atmospheric effects.
• Land contamination effects not eliminated
• Updated approximately quarterly

• The "EWG Sea Ice Atlas" is our most comprehensive Arctic sea ice data set derived from ice charts and related information.
• Offers the most complete collection available of data derived from operational ice centers in the U.S. and Russia
• Intended to make operational data more useful for sea ice and climate research
• Data are available in EASE-Grid and ArcInfo, as well as the original SIGRID format.
• Data were manually assimilated from a variety of satellite and in situ sources.
• While the data are arguably more accurate than ice edge and concentration derived from satellite passive microwave data, the level of detail and accuracy varies in both time and space.
• More information on operational products is available from the National Ice Center and the Arctic and Antarctic Research Institute.
• Also includes sea ice draft statistics from 14 selected submarine cruises between 1977 and 1993. Most of these data are available from the data set Submarine Upward Looking Sonar Ice Draft Profile Data and Statistics, which we recommend you use if you are interested in more than the 14 cruises available on the Atlas.

• By agreement with NOAA, NSIDC archives and makes the Interactive Multisensor Snow and Ice Mapping System (IMS) products available on a daily basis. The IMS product is produced in near-real time to meet a daily operational need.
• The IMS product is considered operational, but OSDPD does not guarantee availability or timely delivery of data via the OSDPD Web server, and NSIDC does not guarantee availability of this product via the NSIDC Web server. These servers should not be used to support operational observation, forecasting, emergency, or disaster mitigation operations, either public or private. Users with real-time operational needs should contact the Satellite Analysis Branch (SAB) Snow Product Lead within the NOAA/NESDIS/OSDPD/SSD/Interactive Processing Branch at 301-763-8142 or ssdhelpdesk@noaa.gov and request access to the operational server.

• Meteorological and ice drift data dating back to 1979
• Data cover the largest area of any single source data set of in situ meteorological measurements for the high-latitude Arctic Ocean.
• Raw data are transmitted from buoys using the ARGOS telemetry system and then broadcast on the Global Telecommunications System.
• Buoy drift tracks can be used to study ice dynamics.
• NSIDC archives these data and maintains documentation; however, data are processed and distributed by the IABP at the University of Washington's Polar Science Center.

• Data are distributed in near real time for use in operational meteorological analyses.
• In addition to the standard parameters, some files also contain total daily ice velocity components and an ice flag to indicate percentage of sea ice concentration.
• Processing is ongoing, and data through 2000 will be available in the future.

• The Meltpond2000 project was the first in a series of Arctic and Antarctic aircraft campaigns to validate sea ice algorithms developed for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), primarily to quantify errors in AMSR-E sea ice products resulting from the presence of melt ponds. The objective was to compare sea ice concentrations derived from AMSR-E algorithms but using Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) radiances, with coincident observations from aircraft sensors and high-resolution satellite imagery.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• The sea ice algorithm uses a Normalized Difference Snow Index (NDSI) modified for sea ice to distinguish sea ice from open ocean, based on reflective and thermal characteristics.

• Data sources for the Romanov atlases are described as the AARI Sever expeditions (1940s to 1980s), the AARI North Pole drift stations (1937-1991), the US-USSR joint research Polar Experiment (POLEX) program (1972-1981), ice reconnaissance flight reports, and literature in the public domain ("Executive Summary," Atlas of Ice and Snow of the Arctic Basin and Siberian Shelf Seas, 1995). NSIDC has published the data from aircraft landings only and has not included extensive data from the North Pole program. The source of each year's observations is uncertain.
• NSIDC received files that possibly are observations from Sever and North Pole station aircraft landing locations. These files apparently contain snow and ice observations from many but not all Sever stations and possibly from North Pole stations. Note that the Sever data and North Pole data are indistinguishable in the data files.
• NSIDC only distributes the raw, ungridded observations from aircraft landings on Arctic pack ice.

• Area covered by sea ice in Arctic and Antarctic sectors was computed by digitizing the ice edge from Joint Ice Center (now the U.S. Navy/NOAA/ Coast Guard National Ice Center) weekly charts, and summing the area within the edge for 10° longitude sectors.
• The National Ice Center creates ice charts by manually assimilating information from a variety of sources, including satellite and in situ observations (reconnaissance flights, ship reports).
• Satellite observations comprise almost 100% of the the Southern Hemisphere data.
• Roughly 65% of austral winter data are from passive microwave sensors, and 35% are from visible or infrared band instruments. For austral summer data, the ratio is reversed.
• The data set is of interest to those studying variability in sea ice extent by region.

• These data cover the period during which the standard sea ice data are being processed by Remote Sensing Systems, Inc. and are not available for distribution. This is typically three to six months before the present.
• Typically available within 1-2 days following the time of SSM/I image acquisition
• More recent coverage than is available from the standard sea ice data set
• Derived from brightness temperatures that have not received the same types of quality control applied to the standard sea ice data set
• Users wanting to detail trends in sea ice concentration and extent should exercise caution with these data, and are encouraged to use the other standard sea ice products when near-real time coverage is not an issue.

(links to registration form to access data and browse imagery)

• Typically available within 1-2 days following the time of SSM/I image acquisition
• Derived from brightness temperatures that have not received the same types of quality control that are applied to the standard sea ice data set
• Developed to assist in generation of EOS satellite products that require knowledge of snow and ice coverage
• Data are useful for near real-time investigations of changes in sea ice concentration in conjunction with variations in snow cover.
• Masks are applied to minimize erroneous retrievals of sea ice over open ocean and along coastlines.
• Users wanting to detail trends in sea ice concentration and extent should exercise caution with these data, and are encouraged to use the other standard sea ice products when near-real time coverage is not an issue.

• Includes monthly, multiyear monthly, and yearly sea ice concentration grids generated from ESMR data
• Since ESMR provided only one spectral channel, a different algorithm was used to derive ice concentrations compared to the algorithms used for SMMR and SSM/I-derived products.
• ESMR provides additional detail and coverage to augment other data sets.
• ESMR data show variations within the interior portions of the ice pack. Such regions are not typically mapped in detail in ice charts.

• Includes gridded brightness temperatures and ice concentrations for all SMMR channels
• SMMR provides two lower-frequency channels at 6.6 GHz and 10.78 GHz, but lacks SSM/I's 85 GHz channel.
• Lower-frequency channels are not used in the NASA Team algorithm, but they provide additional information on surface conditions that can be used for studies of surface temperature and variations in ice type.

• Snow cover extent is based on the digital NOAA-NESDIS Weekly Northern Hemisphere Snow Charts, revised by D. Robinson (Rutgers University) and regridded to the EASE-Grid.
• Original NOAA-NESDIS weekly snow charts are derived from the manual interpretation of AVHRR, GOES, and other visible-band satellite data.
• Sea ice extent is based on the NSIDC polar stereographic sea ice concentration grids derived from SMMR and SSM/I passive microwave brightness temperature data.
• This data set was designed to represent large-scale seasonal fluctuations in snow cover and sea ice extent, and is most appropriate for large area studies.

• Daily and mean ice motion grids combine data from AVHRR, SMMR, SSM/I, and drifting buoys.

• Daily and monthly sea ice concentrations for the Arctic and Antarctic
• Modified calibration coefficients designed to provide a consistent sea ice record
• Additional weather filtering to remove remaining false ice concentrations not eliminated using the standard algorithm weather filter
• Methods to reduce land contamination effects
• Missing data, including small gaps in the time series, are temporally and spatially interpolated.
• Useful for long time series analysis of ice extent

• The Sea Ice Index consists of graphics showing trends and anomalies in monthly mean Arctic and Antarctic sea ice concentration and extent, with a table of monthly mean extent in millions of square km.
• The NSIDC Near Real-Time DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations and the DMSP SSM/I Daily and Monthly Polar Gridded Sea Ice Concentrations data sets are used to generate the monthly mean, trend, and anomaly images.
• The product is intended to help researchers illustrate sea ice conditions, and to inform users with general questions about recent ice concentration and extent.

• Data consist of broadband (400-1000 nm) and narrow band albedos for individual ponds under varying documented cloud conditions, along with other information such as pond depth and bottom characteristics for more than 500 sea ice melt ponds near Cornwallis Island.
• The melt ponds were on first-year, multiyear, and land fast ice, although the multiyear data are limited.
• While the data set is somewhat limited in time and space, it is exceptional in the number of ponds measured and the detail about the pond and radiative conditions.
• Useful for theoretical modeling of melt pond hydrology and radiative processes
• The associated technical report fully describes the data set and contains analysis summaries, including the time progression of pond depth and reflectance curves for ponds under different conditions.

• Textual and graphical value-added products assist in investigations of variability and trends of sea ice cover.
• These products may not contain the most recent data; therefore, caution is suggested, particularly with the ocean masks and sea ice climatologies, since they may not be representative of ice cover conditions outside the time period used to produce the data.
• trends and anomalies derived from Goddard Space Flight Center (GSFC) sea ice products provide a continuous time series from 1979 onward, but they are updated infrequently.
• trends and anomalies derived from NSIDC sea ice products provide a shorter time series (1987 forward), but they are updated every three to six months.
• The combined ESMR-SMMR-SSM/I product offers the longest continuous time series (1973 to 2002), but has limited use and uses other data to fill in data gaps in the satellite record.