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Title Sum-
Institution Dataset ID
 data       graph  M    Data from a local source.    ?   F   I   M   background (external link) RSS Subscribe ??? SNAP_SEA_ICE_ATLAS

The Dataset's Variables and Attributes

Row Type Variable Name Attribute Name Data Type Value
attribute NC_GLOBAL _CoordSysBuilder String ucar.nc2.internal.dataset.conv.CF1Convention
attribute NC_GLOBAL acknowledgement String The Historical Sea Ice Atlas was a joint project funded by the Alaska Ocean Observing System (AOOS), the Alaska Center for Climate Assessment and Policy (ACCAP) and the Scenarios Network for Alaska and Arctic Planning (SNAP). This work was funded by the National Ocean Service at the National Oceanic and Atmospheric Administration (NOAA) through AOOS grant #NA11NOS0120020. Work was performed at UAF by the International Arctic Research Center's ACCAP (funded by the NOAA Office of Oceanic and Atmospheric Research) and SNAP, with assistance from the University of Illinois, Urbana-Champaign.
attribute NC_GLOBAL cdm_data_type String Grid
attribute NC_GLOBAL Conventions String CF-1.6, COARDS, Unidata Dataset Discovery v1.0
attribute NC_GLOBAL creator_email String takurkowski at
attribute NC_GLOBAL creator_name String Tom Kurkowski
attribute NC_GLOBAL creator_url String (external link)
attribute NC_GLOBAL date_created String 2022-02-01T22:58:00Z
attribute NC_GLOBAL date_issued String 2022-02-01T22:58:00Z
attribute NC_GLOBAL Easternmost_Easting double -119.875
attribute NC_GLOBAL GDAL String GDAL 2.2.1, released 2017/06/23
attribute NC_GLOBAL GDAL_AREA_OR_POINT String Area
attribute NC_GLOBAL geospatial_lat_max double 80.125
attribute NC_GLOBAL geospatial_lat_min double 40.125
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 -119.875
attribute NC_GLOBAL geospatial_lon_min double -179.875
attribute NC_GLOBAL geospatial_lon_resolution double 0.25
attribute NC_GLOBAL geospatial_lon_units String degrees_east
attribute NC_GLOBAL history String Tue Feb 01 13:52:51 2022: GDAL CreateCopy( nc/, ... )
attribute NC_GLOBAL id String seaiceatlas
attribute NC_GLOBAL infoUrl String ???
attribute NC_GLOBAL institution String ???
attribute NC_GLOBAL keywords String alaska, concentration, data, distribution, estimates, ice, ice distribution, local, monthly, observed, sea, source, waters
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_Conventions String CF-1.6, COARDS, Unidata Dataset Discovery v1.0
attribute NC_GLOBAL metadata_link String (external link)
attribute NC_GLOBAL model String SNAP Sea Ice Atlas
attribute NC_GLOBAL naming_authority String edu.uaf.snap
attribute NC_GLOBAL Northernmost_Northing double 80.125
attribute NC_GLOBAL processing_level String This data set includes weekly (January 1954 to December 2013) and monthly (January 1850 to December 2020) midpoint historical sea ice concentration (0 - 100%) estimates at 1/4 x 1/4 degree spatial resolution for the ocean region around the state of Alaska, USA. This value-added dataset was developed by compiling the below historical data sources into spatially and temporally standardized datasets. Gaps in temporal or spatial resolutions were filled in with spatial and temporal analog month approaches. Note the monthly values from January 1954 - December 2013 are the week 2 values from the weekly time series. They are provided in the monthly time series for ease of use in monthly midpoint analyses. The January 2014 - February 2017 monthly time series data have been regridded and processed to match the January 1954 - December 2013 series from the NSIDC 0051 Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data, Version 1, which were accessed from the NSIDC website ( The further post-processing and regridding of the NSIDC product to the extent / crs / origin / resolution of the existing data, was a non-standard process. It involved initially warping the polar stereographic data to a pacific centered WGS84 crs, converting the sea ice concentration values to points and performing a spline interpolation across the entire domain. This interpolated raster was then filled further around the land-sea divide where there was a mismatch between the NSIDC mask and the Sea Ice Atlas mask. The filling was performed by taking the average of the surrounding sea ice concentration pixels and filling the missing locations. These locations have been flagged in the source band (band 2) to keep track of what was modified from the NSIDC 0051 for this purpose. These data are a compilation of data from many sources integrated into a single gridded product. The sources of data for each grid cell have changed over the years from infrequent land/sea observations, to observationally derived charts, to satellite data for the most recent decades. Temporal and spatial gaps within observed data are filled with analog month approaches. Please note that large portions of the pre-1953, and almost all of the pre-1900 data, are either analog or interpolated data and the user is cautioned to use these data with care. The temporal and spatial inhomogeneities in the data sources that went into the construction of this dataset require that any historical analysis of the data is done with caution and an understanding of the limitations of the data. Methods of data compilation varied by data source, but included visual interpretation of hard copy map notation and legends, scanning, digitization, geo-rectification into digital geospatial products, reprojection, and also resampling into a common resolution. To standardize the data onto a common spatial grid, the resampling methodology utilized the centroid of the target 1/4 x 1/4 grid cell as the location to extract the value from the underlying data source.
attribute NC_GLOBAL project String Historical Sea Ice Atlas
attribute NC_GLOBAL publisher_email String janzen at
attribute NC_GLOBAL publisher_institution String Alaska Ocean Observing System
attribute NC_GLOBAL publisher_name String Alaska Ocean Observing System
attribute NC_GLOBAL publisher_url String (external link)
attribute NC_GLOBAL sourceUrl String (local files)
attribute NC_GLOBAL Southernmost_Northing double 40.125
attribute NC_GLOBAL standard_name_vocabulary String CF-12
attribute NC_GLOBAL summary String Data from a local source.
attribute NC_GLOBAL time_coverage_end String 2018-12-15T12:00:00Z
attribute NC_GLOBAL time_coverage_start String 1850-01-15T12:00:00Z
attribute NC_GLOBAL title String Data from a local source.
attribute NC_GLOBAL Westernmost_Easting double -179.875
dimension time   double nValues=2028, evenlySpaced=false, averageSpacing=30 days 10h 28m 43s
attribute time _ChunkSizes uint 1024
attribute time _CoordinateAxisType String Time
attribute time actual_range double -3.7855728E9, 1.5448752E9
attribute time axis String T
attribute time calendar String gregorian
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   double nValues=161, evenlySpaced=true, averageSpacing=0.25
attribute latitude _ChunkSizes uint 40
attribute latitude _CoordinateAxisType String Lat
attribute latitude actual_range double 40.125, 80.125
attribute latitude axis String Y
attribute latitude ioos_category String Location
attribute latitude long_name String Latitude
attribute latitude standard_name String latitude
attribute latitude units String degrees_north
dimension longitude   double nValues=241, evenlySpaced=true, averageSpacing=0.25
attribute longitude _ChunkSizes uint 60
attribute longitude _CoordinateAxisType String Lon
attribute longitude actual_range double -179.875, -119.875
attribute longitude axis String X
attribute longitude ioos_category String Location
attribute longitude long_name String Longitude
attribute longitude standard_name String longitude
attribute longitude units String degrees_east
variable sic_con_pct   float time, latitude, longitude
attribute sic_con_pct _ChunkSizes uint 10, 40, 60
attribute sic_con_pct _FillValue float -2.14748365E9
attribute sic_con_pct colorBarMaximum double 100.0
attribute sic_con_pct colorBarMinimum double 0.0
attribute sic_con_pct grid_mapping String crs
attribute sic_con_pct ioos_category String Ice Distribution
attribute sic_con_pct long_name String Sea Ice Concentration
attribute sic_con_pct units String percent

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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