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ERDDAP > info > nsidcSeaIceConc1850

Title Sum-
Institution Dataset ID
 data       graph  M    files  Sea Ice Extent and Concentration V2, NOAA/NSIDC, Arctic, 25km, 1850-Onward, Monthly    ?   F   I   M   background (external link) RSS Subscribe NOAA NSIDC nsidcSeaIceConc1850

The Dataset's Variables and Attributes

Row Type Variable Name Attribute Name Data Type Value
attribute NC_GLOBAL _NCProperties String version=2,netcdf=4.6.3,hdf5=1.10.5
attribute NC_GLOBAL cdm_data_type String Grid
attribute NC_GLOBAL citation String (external link)
attribute NC_GLOBAL comment String The data provided by PolarWatch are the gridded subset of the data package provided by NSIDC. Additional regional and arctic-wide ice extent, ice area, masks and ancillary data are available in the zip package from NSIDC at the source_url link.

The V2.0 extent and area values are slightly higher than those derived from V1.0. To create V1.1, inconsistencies in the V1.0 land mask were addressed by applying an -- if ever land, always land-- rule to grid cells. This had the effect of slightly expanding the land mask, so that the area covered by ocean cells, and thus the area that could contain sea ice, was proportionally reduced. The improved V2 land mask leaves more ocean cells in which ice may occur. In total, about 450,000 sq km of coastal ocean are added. V2.0 ice extent and area differ from extent and area derived using V1.0, simply because the V1.0 and V2.0 land areas are not the same. This difference is greatest in the winter months, when ice reaches a greater expanse of coastline. Most of the higher V2.0 extent and area values are the result of the changed land mask, with the change in input CDR source data version being an additional factor in the satellite era. There is a seasonal effect in the change attributable to the improved land mask. Metadata were alter to be in compliance with CF and ACDD standards.
attribute NC_GLOBAL contributor_email String,,
attribute NC_GLOBAL contributor_name String John E. Walsh, William L. Chapman, Florence Fetterer, J. S. Stewart
attribute NC_GLOBAL contributor_role String investigator, investigator, investigator, investigator
attribute NC_GLOBAL Conventions String CF-1.6, ACDD-1.3
attribute NC_GLOBAL creator_email String,,
attribute NC_GLOBAL creator_name String John E. Walsh, William L. Chapman, Florence Fetterer, J. S. Stewart
attribute NC_GLOBAL creator_type String group
attribute NC_GLOBAL dataset_doi String (external link)
attribute NC_GLOBAL date_created String 2019-09-03T00:00:00Z
attribute NC_GLOBAL date_issued String 2019-09-03T00:00:00Z
attribute NC_GLOBAL Easternmost_Easting double 359.875
attribute NC_GLOBAL geospatial_lat_max double 89.875
attribute NC_GLOBAL geospatial_lat_min double 30.125
attribute NC_GLOBAL geospatial_lat_resolution double 0.25
attribute NC_GLOBAL geospatial_lat_units String degrees_north
attribute NC_GLOBAL geospatial_lon_max double 359.875
attribute NC_GLOBAL geospatial_lon_min double 0.125
attribute NC_GLOBAL geospatial_lon_resolution double 0.25
attribute NC_GLOBAL geospatial_lon_units String degrees_east
attribute NC_GLOBAL history String Apr 19 2020: netCDF modified via nco tools to expand dimension of the grid_cell_area variable for compatability with ERDDAP: ncap2 -s gridcell_area_2d[time,latitude,longitude]= Gridcell_Area, Jan 27 2020: downloaded zip package including netCDF file from
attribute NC_GLOBAL id String g10010
attribute NC_GLOBAL infoUrl String (external link)
attribute NC_GLOBAL institution String NOAA NSIDC
attribute NC_GLOBAL instrument String SSM/I, visual observations
attribute NC_GLOBAL keywords String 1850, Earth Science > Cryosphere > Sea Ice > Ice Extent, Earth Science > Cryosphere > Sea Ice > Sea Ice Concentration, Earth Science > Oceans > Sea Ice > Ice Extent, historical, NSIDC, sea ice concentration
attribute NC_GLOBAL keywords_vocabulary String GCMD Science Keywords
attribute NC_GLOBAL license String The data may be used and redistributed for free but is not intended
for legal use, since it may contain inaccuracies. Neither the data
Contributor, ERD, NOAA, nor the United States Government, nor any
of their employees or contractors, makes any warranty, express or
implied, including warranties of merchantability and fitness for a
particular purpose, or assumes any legal liability for the accuracy,
completeness, or usefulness, of this information.
attribute NC_GLOBAL metadata_link String (external link)
attribute NC_GLOBAL naming_authority String data/org.nsidc
attribute NC_GLOBAL NCO String netCDF Operators version 4.7.9 (Homepage =, Code =
attribute NC_GLOBAL Northernmost_Northing double 89.875
attribute NC_GLOBAL platform String DMSP, ships
attribute NC_GLOBAL publisher_email String at
attribute NC_GLOBAL publisher_name String NOAA NMFS SWFSC ERD and NOAA NESDIS CoastWatch PolarWatch
attribute NC_GLOBAL publisher_type String institution
attribute NC_GLOBAL references String Walsh, J. E., W. L. Chapman, F. Fetterer, and J. S. Stewart. 2019. Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, Version 2. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi:
attribute NC_GLOBAL release_date String February 28, 2019
attribute NC_GLOBAL source String microwave satellite observations, visual observations
attribute NC_GLOBAL sourceUrl String (external link)
attribute NC_GLOBAL Southernmost_Northing double 30.125
attribute NC_GLOBAL summary String Observations from historical sources are the basis of this monthly gridded sea ice concentration product that begins in 1850. In 1979, these sources give way to a single source: concentration from satellite passive microwave data. The historical observations come in many forms: ship observations, compilations by naval oceanographers, analyses by national ice services, and others. Monthly sea ice concentration is given in a 1/4 degree latitude by 1/4 degree longitude grid. In addition to the concentration array, for each month a corresponding source array indicates where each of 16 possible sources is used.
attribute NC_GLOBAL time_coverage_end String 2017-12-16T12:00:00Z
attribute NC_GLOBAL time_coverage_resolution String P1M
attribute NC_GLOBAL time_coverage_start String 1850-01-15T12:00:00Z
attribute NC_GLOBAL title String Sea Ice Extent and Concentration V2, NOAA/NSIDC, Arctic, 25km, 1850-Onward, Monthly
attribute NC_GLOBAL version String 2.0
attribute NC_GLOBAL Westernmost_Easting double 0.125
dimension time   double nValues=2016, evenlySpaced=false, averageSpacing=30 days 10h 29m 36s
attribute time _ChunkSizes int 512
attribute time _CoordinateAxisType String Time
attribute time actual_range double -3.7855728E9, 1.5134256E9
attribute time axis String T
attribute time calendar String julian
attribute time coverage_content_type String coordinate
attribute time ioos_category String Time
attribute time long_name String Time
attribute time standard_name String time
attribute time time_origin String 01-JAN-1970 00:00:00
attribute time units String seconds since 1970-01-01T00:00:00Z
dimension latitude   float nValues=240, evenlySpaced=true, averageSpacing=-0.25
attribute latitude _CoordinateAxisType String Lat
attribute latitude actual_range float 30.125, 89.875
attribute latitude axis String Y
attribute latitude coverage_content_type String coordinate
attribute latitude ioos_category String Location
attribute latitude long_name String Latitude
attribute latitude standard_name String latitude
attribute latitude units String degrees_north
attribute latitude valid_max float 90.0
attribute latitude valid_min float 30.0
dimension longitude   float nValues=1440, evenlySpaced=true, averageSpacing=0.25
attribute longitude _CoordinateAxisType String Lon
attribute longitude actual_range float 0.125, 359.875
attribute longitude axis String X
attribute longitude coverage_content_type String coordinate
attribute longitude ioos_category String Location
attribute longitude long_name String Longitude
attribute longitude standard_name String longitude
attribute longitude units String degrees_east
attribute longitude valid_max float 360.0
attribute longitude valid_min float 0.0
variable seaice_conc   byte time, latitude, longitude
attribute seaice_conc _ChunkSizes int 1, 240, 1440
attribute seaice_conc colorBarMaximum double 100.0
attribute seaice_conc colorBarMinimum double 0.0
attribute seaice_conc colorBarPalette String KT_ice
attribute seaice_conc comment String Values are percent-concentration from 0 to 100. Sentinel value of 120 in the concentration field indicates land
attribute seaice_conc coverage_content_type String physicalMeasurement
attribute seaice_conc ioos_category String Ice Distribution
attribute seaice_conc long_name String Sea Ice Concentration (Percent)
attribute seaice_conc missing_value byte 120
attribute seaice_conc short_name String Concentration
attribute seaice_conc standard_name String sea_ice_area_fraction
attribute seaice_conc units String 1
variable seaice_source   byte time, latitude, longitude
attribute seaice_source _ChunkSizes int 1, 240, 1440
attribute seaice_source colorBarContinuous String false
attribute seaice_source colorBarMaximum double 19.0
attribute seaice_source colorBarMinimum double 0.0
attribute seaice_source colorBarNSections String 19
attribute seaice_source colorBarPalette String nsidc_seaIceSource
attribute seaice_source coverage_content_type String referenceInformation
attribute seaice_source ioos_category String Other
attribute seaice_source long_name String Source of Sea Ice Concentration Data
attribute seaice_source missing_value byte 0
attribute seaice_source name_source_00 String Land
attribute seaice_source name_source_01 String Satellite passive microwave
attribute seaice_source name_source_02 String Danish Meteorological Institute
attribute seaice_source name_source_03 String Dehn
attribute seaice_source name_source_04 String NAVO yearbooks
attribute seaice_source name_source_05 String AARI
attribute seaice_source name_source_06 String Hill
attribute seaice_source name_source_07 String Whaling Records - Complete Sea Ice
attribute seaice_source name_source_08 String Whaling Records - Partial Sea Ice
attribute seaice_source name_source_09 String Whaling Records - No Sea Ice
attribute seaice_source name_source_10 String DMI yearbook narrative
attribute seaice_source name_source_11 String ACSYS
attribute seaice_source name_source_12 String Walsh and Johnson
attribute seaice_source name_source_13 String JMA charts
attribute seaice_source name_source_14 String Kelly ice extent grids
attribute seaice_source name_source_15 String Landmask correction fill
attribute seaice_source name_source_16 String Change-of-landmask ocean
attribute seaice_source name_source_17 String Analog fill - spatial
attribute seaice_source name_source_18 String Analog fill - temporal
attribute seaice_source short_name String Seaice Source
attribute seaice_source standard_name String source
attribute seaice_source units String 1
variable gridcell_area_2d   float time, latitude, longitude
attribute gridcell_area_2d colorBarMinimum double 0.0
attribute gridcell_area_2d colorBarPalette String KT_amp
attribute gridcell_area_2d coverage_content_type String physicalMeasurement
attribute gridcell_area_2d ioos_category String Other
attribute gridcell_area_2d long_name String Grid Cell Area
attribute gridcell_area_2d short_name String Grid_Cell_Area
attribute gridcell_area_2d standard_name String cell_area
attribute gridcell_area_2d units String km^2

The information in the table above is also available in other file formats (.csv, .htmlTable, .itx, .json, .jsonlCSV1, .jsonlCSV, .jsonlKVP, .mat, .nc, .nccsv, .tsv, .xhtml) via a RESTful web service.

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