This Excel Workbook summarizes the overall Spring sea ice lead statistics covering the offshore area from Northern Alaska (West of Wainwright) to the Northwest Canada (East of the Mackenzie Delta) for the study area for the study area which ranges from approximately 130 to 164 degrees West and 68.5 to 74 degrees North.
These data were compiled by the University of Alaska Fairbanks to meet contract requirements for the US Mineral Management Service: Mapping and Characterization of Recurring Spring Leads and Landfast ice in the Beaufort and Chukchi Seas (AK-03-06)
ground condition
Any hardcopies or published information utilizing these data sets shall clearly indicate their source. If the user has modified the data in any way they are obligated to describe the types of modifications that they have performed. User specifically agrees not to misrepresent these datasets, nor to imply that any changes that they made were approved by the University of Alaska.
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The funding for this effort was provided by the US Mineral Management Service for Mapping and Characterization of Recurring Spring Leads and Landfast ice in the Beaufort and Chukchi Seas (AK-03-06, MMS-71707)
Lead statistics were based on the results of binarized segmentation processing of AVHRR data.
Complete.
The International Observatory of the North (ION) uses satellite navigation and attitude parameters for scene navigation (with additional ground control) to produce adequate results (with errors <3 km) for geolocated AVHRR imagery. ION data sets were used as a base map to derive the lead segmentation.
Visual inspection. Distance measurement tools.
AVHRR data was geolocated, calibrated and reprojected in GeoTIFF format using TeraScan software. A coast mask is applied in ENVI. The fraction of leads within each pixel is then determined based on the brightness temperatures or reflectances of open water and the surrounding thick ice, as described by Lindsay and Rothrock (Arctic sea ice leads from advanced very high resolution radiometer images. Journal of Geophysical Research, 100(C3), 4533-4544, 1995). Here, we have corrected for regional differences in surface temperature and reflectance as well as thin cloud cover by determining the fraction of leads within a moving 50 by 50 pixel (55 x 55 km) square window, with the fraction of thick ice based on the upper and lower quartile reflectance and brightness temperature, respectively. For a few cases of more expansive stretches of open water, manual adjustments of open water extent have been made. The resulting image indicating the fraction of open water is then binarized about a threshold corresponding to an open water fraction of 25% in each pixel, with pixels containing less open water designated as ice and those at or above 25% designated as leads. This information is then brought into NIH Image for derivation of lead location, shape and size statistics, open water fractions and other information for the different study subregions. The statistics were compiled in a Microsoft Excel Workbook with associated graphs.
903 Koyukuk Dr., P.O. Box 757320
Internal Object Identifier
ESRI ArcCatalog
Internal Object Identifier
ESRI ArcCatalog
Season
UAF
Ice Season (December-June)
UAF
File Name associated with AVHRR image
UAF
AVHRR File Name (t = thermal, v = visual, Year (YY format), Day of Year
UAF
Regions of MMS study area
UAF
Regions of MMS Study Area (West, East, East Central, West Central)
UAF
Day of Year
Julian Calender
Day of Year
Julian Calender
Days since Sept 1
Julian Calender
Days since Sept 1
Julian Calender
Number of Leads
NIH Image/Scion Image software
Number of Leads
NIH Image/Scion Image software
Mean of Lead Area in square km
NIH Image/Scion Image software
Mean of Lead Area in square km
NIH Image/Scion Image software
Mean of Lead Perimeter in km
NIH Image/Scion Image software
Mean of Lead Perimeter in km
NIH Image/Scion Image software
Mean of Lead Major Axis in km
NIH Image/Scion Image software
Mean of Lead Major Axis in km
NIH Image/Scion Image software
MEAN_OF_LEAD_MINOR_AXIS
NIH Image/Scion Image software
MEAN_OF_LEAD_MINOR_AXIS
NIH Image/Scion Image software
Standard Deviation of Lead Area
NIH Image/Scion Image software
Standard Deviation of Lead Area
NIH Image/Scion Image software
Standard Deviation of Lead Perimeter
NIH Image/Scion Image software
Standard Deviation of Lead Perimeter
NIH Image/Scion Image software
Standard Deviation of Lead Major Axis
NIH Image/Scion Image software
Standard Deviation of Lead Major Axis
NIH Image/Scion Image software
Standard Deviation of Lead Minor Axis
NIH Image/Scion Image software
Standard Deviation of Lead Minor Axis
NIH Image/Scion Image software
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Microsoft Office XP Excel Workbook
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