Abstract: MODIS/Aqua Sea Ice Extent Daily L3 Global 1km EASE-Grid Night (MYD29P1N) data set contains fields for Ice Surface Temperature (IST) and IST Spatial Quality Assessment (QA) in Hierarchical Data Format-Earth Observing System (HDF-EOS) format, along with corresponding metadata. The field Sea Ice by Ice Surface Temperature that is in Version 4 (V004) was removed from Version 5 (V005. MOD29P1N V005, the latest version of the Moderate Resolution Imaging Spectroradiometer (MODIS) data, consists of 954 x 954 km files of 1 km resolution data gridded in the Lambert Azimuth Equal Area map projection. Data are stored in HDF-EOS format, and are available from 4 July 2002 to present via FTP. Data can also be obtained in GeoTIFF format by ordering the data through the Data Pool.
All MODIS/Aqua sea ice products are considered validated or at stage two meaning that accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation campaigns. Quality indicators for MODIS sea ice data can be found in the following three places: AutomaticQualityFlag and the ScienceQualityFlag metadata objects and their corresponding ... explanations: AutomaticQualityFlagExplanation and ScienceQualityFlagExplanation located in the CoreMetadata.0 global attributes; custom local attributes associated with each Scientific Data Set (SDS), for example Ice Surface Temperature; and the Pixel QA SDS that accompanies each data field, for example, Ice Surface Temperature Spatial QA. These quality indicators are generated during production or in post-production scientific and quality checks of the data product. The AutomaticQualityFlag is automatically set according to conditions for meeting data criteria in the sea ice algorithm. In most cases, the flag is set to either Passed or Suspect, and in rare instances, it may be set to Failed. Suspect means that a significant percentage of the data were anomalous and that further analysis should be done to determine the source of anomalies. The AutomaticQualityFlagExplanation contains a brief message explaining the reason for the setting of the AutomaticQualityFlag. The ScienceQualityFlag and the ScienceQualityFlagExplanation maybe updated after production, either after an automated QA program is run or after the data product is inspected by a qualified scientist. Content and explanation of this flag are dynamic so it should always be examined if present in the external metadata file. A sampling of products will be inspected. Random sampling or support of specific events, such as field campaigns, may also be conducted. The IST Spatial QA data field provides additional information on algorithm results for each pixel within a spatial context, and are used as a measure of usefulness for sea ice data. QA data are stored as coded integer values and tells if algorithm results were good or not, or if other defined conditions were encountered (Riggs, Hall, and Salomonson 2003).
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
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Postal Code: 80309-0449
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