January 9, 2026 Dataset Open Access

Sadikni, Remon; Kern, Stefan

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{"DOI":"10.25592/uhhfdm.18219","abstract":"<p><strong>Abstract:</strong>&nbsp;Reflectance measurements carried out at Terra MODIS bands 1, 3 and 4 are combined in a spectral un-mixing approach to estimate the melt-pond fraction on Arctic sea ice north of 60&deg;N for months June through August for the years 2000 through 2024. The resulting data set has daily temporal sampling and is offered on a polar-stereographic grid (true latitude is 70&deg;N) with 500 m x 500 m and 12.5 km x 12.5 km grid resolution. The data files contain, in addition to the melt-pond fraction, also the fraction of open water between the sea ice and the net sea-ice surface fraction, i.e. the fraction of sea ice without melt ponds. For information about the approach used and the validation of the data set offered here we refer to <a href=\"https://doi.org/10.5194/tc\u20106\u2010431\u20102012\">R&ouml;sel et al. (2012)</a> and Sadikni and Kern (2025).</p>\n\n<p><strong>TableOfContents:</strong></p>\n\n<ul>\n\t<li>500 m x 500 m product: grid-cell fraction of melt ponds (on sea ice); grid-cell fraction of sea ice without melt ponds; grid-cell fraction of open water</li>\n\t<li>12.5 km x 12.5 km product: grid-cell fraction of melt ponds (on sea ice); grid-cell fraction of sea ice without melt ponds; grid-cell fraction of open water; grid-cell_fraction_of_melt_ponds standard_deviation; grid-cell_fraction_of_sea_ice_without_melt_ponds standard_deviation; grid-cell_fraction_of_open_water standard_deviation; number of clear-sky 500 m grid cells; clear-sky mask</li>\n</ul>\n\n<p>While the 12.5 km x 12.5 km comes with latitude and longitude values for each grid cell, those of the 500 m x 500 m product are provided in a separate netCDF file.</p>\n\n<p>Note that the grid resolution of 12.5 km (and 500m) is only valid at the latitude at which the tangential plane of the polar stereographic projection touches the Earth&#39;s surface - here 70&deg;N. North of this latitude the actual grid cell area is smaller, south of it it is larger (see also&nbsp;<a href=\"https://nsidc.org/data/user-resources/help-center/guide-nsidcs-polar-stereographic-projection#anchor-grid-distortion\">https://nsidc.org/data/user-resources/help-center/guide-nsidcs-polar-stereographic-projection#anchor-grid-distortion</a>). In order to assist in the computation of the actual area (in km2) covered by melt ponds (or the other two surface types) we provide a netCDF file of the true area of each grid cell of the 12.5 km x 12.5 km product.</p>\n\n<p><strong>Technical Info:</strong></p>\n\n<ul>\n\t<li>500 m x 500 m product: dimensions: 13286 columns x 13293 rows; temporalExtent_startDate: 2000-06-01; temporalExtent_endDate: 2024-08-31; temporalResolution: daily; spatialResolution: 500; spatialResolutionUnit: meter; horizontalResolutionXdirection: 500; horizontalResolutionXdirectionUnit: meter; horizontalResolutionYdirection: 500; horizontalResolutionYdirectionUnit: meter; verticalResolution: none; verticalResolutionUnit: none; verticalStart: none; verticalEnd: none; instrumentName: Moderate Resolution Spectroradiometer (MODIS); instrumentType: 32-band imaging spectroradiometer; instrumentLocation: Earth Observation Satellite (EOS) Terra; instrumentProvider: NOAA/NASA</li>\n\t<li>12.5 km x 12.5 km product:&nbsp;dimensions: 531 columns x 531 rows; temporalExtent_startDate: 2000-06-01; temporalExtent_endDate: 2024-08-31; temporalResolution: daily; spatialResolution: 12500; spatialResolutionUnit: meter; horizontalResolutionXdirection: 12500; horizontalResolutionXdirectionUnit: meter; horizontalResolutionYdirection: 12500; horizontalResolutionYdirectionUnit: meter; verticalResolution: none; verticalResolutionUnit: none; verticalStart: none; verticalEnd: none; instrumentName: Moderate Resolution Spectroradiometer (MODIS); instrumentType: 32-band imaging spectroradiometer; instrumentLocation: Earth Observation Satellite (EOS) Terra; instrumentProvider: NOAA/NASA</li>\n</ul>\n\n<p>Missing data (either because the MOD09GA product has gaps or because the melt-pond fraction retrieval failed): 2000-08-06 to 2000-08-17; 2001-06-16 to 2001-07-02; 2002-06-15 to 2002-06-19; 2002-07-11; 2004-06-20 to 2004-06-22; 2005-07-21; 2008-08-06 to 2008-08-08; 2008-08-11; 2008-08-22; 2010-06-17; 2010-08-01; 2010-08-16; 2013-06-09; 2013-06-15; 2014-08-02; 2016-06-07; 2016-06-08; 2016-06-11; 2016-08-12; 2018-08-04; 2021-08-11; 2024-06-21; 2024-06-22; 2024-06-25.</p>\n\n<p><strong>Methods:</strong> For a description of the methods used see Sadikni and Kern, 2025.</p>\n\n<p><strong>Units:</strong></p>\n\n<ul>\n\t<li>500 m x 500 m product: 1, 1, 1</li>\n\t<li>12500 m x 12500 m product: 1, 1, 1, 1, 1, 1, 1, 1</li>\n</ul>\n\n<p><strong>geoLocations:</strong> westBoundLongitude: -180.0 degrees East; eastBoundLongitude: 180.0 degrees East; southBoundLatitude: 60.0 degrees North; northBoundLatitude: 90.0 degrees North; geoLocationPlace: northern hemisphere</p>\n\n<p><strong>Size:</strong></p>\n\n<ul>\n\t<li>500 m x 500 m product: Single file: 2.1 GigaByte; zip-file or one month: 1.5 to 4.0 GigaByte (depends on gaps due to cloud cover); total volume (as unpacked netCDF): 4.87 TeraByte&nbsp;</li>\n\t<li>12.5 km x 12.5 km product: Single daily file: ~10 MegaByte; annually aggregated file: ~670 MegaByte; zip-file of one month: 60 to 100 MegaByte (depends on gaps due to cloud cover);&nbsp; total volume (as unpacked netCDF): 22.8 GigaByte</li>\n</ul>\n\n<p><strong>Format:</strong> netCDF</p>\n\n<p><strong>DataSources:&nbsp;</strong>MODerate resolution Imaging Spectroradiometer MODIS aboard the Earth Observation Satellite (EOS) Terra collection 6.1 product MOD09A1 of the surface spectral reflectance:&nbsp;<a href=\"https://lpdaac.usgs.gov/products/mod09gav061/\">https://lpdaac.usgs.gov/products/mod09gav061/</a> (last access: Dec. 6, 2024).</p>\n\n<p><strong>Contact:</strong>&nbsp;<a href=\"mailto:remon.sadikni@uni-hamburg.de\">remon.sadikni (at) uni-hamburg.de</a>;&nbsp;<a href=\"mailto:stefan.kern@uni-hamburg.de\">stefan.kern (at) uni-hamburg.de</a></p>\n\n<p><strong>Web page:</strong> <a href=\"https://www.cen.uni-hamburg.de/en/icdc/data/cryosphere/arctic-meltponds.html\">https://www.cen.uni-hamburg.de/en/icdc/data/cryosphere/arctic-meltponds.html</a></p>","author":[{"family":"Sadikni, Remon"},{"family":"Kern, Stefan"}],"id":"18219","issued":{"date-parts":[[2026,1,9]]},"language":"eng","title":"Daily melt-pond fraction on Arctic sea ice from TERRA MODIS visible imagery","type":"dataset","version":"2026_fv0.01"}