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Daily SSM/I Value Added Ice Edge
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Description of the data file:
A. Naming Conventions and General Information:
1. The following is an example filename of the data:
nic_autoc[yyyyjjj][hemisphere]_[pl]_[a]_[lowgrain].zip
where:
nic_autoc is the name of the product from NATICE.
[yyyyjjj] is 4 digits year, 3 digits julian.
[hemisphere] is north (n) or south (s) hemisphere.
[pl] is polygon.
[a] is version as described in WMO SIGRID 3.
[lowgrain] is lower resolution.
2. The following is how to unpack the data:
To unzip on windows, use winzip
To unzip on Linux, type: gunzip nic_autoc[yyyyjjj]_[pl]_[a]_[lowgrain].zip
There will be 3 files present: *.shp, *.shx, and *.dbf.
B. Resolution:
The resolution of the intial product is 25km. However, this resolution
is relative due to the nature of
the shape file in GIS software. Further, inputs to the data can range in
resolution from 200m to 25km.
These inputs
include RADARSAT, DMSPOLS, AVHRR, and QUIKSCAT. The SSM/I contour uses
the NAS A Team 2 algorithm and is contoured using the 10.1% value.
C. Analysis Process:
1. NIC ice analysts bring the SSM/I automated contour into the Sea Ice Mapping
System (SIMS)
as a shapefile
and verify the contour using imagery (Quickscat, SSM/I, Visible/IR, or RADARSAT)
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Analysts value add to the automated edge by adjusting the position of the
contour based on available
imagery.
2. The value-added iceedge shapefile, shoreline shapeline file and attri
bute shapefile are then merged
into a single coverage file. The coverage is
cleaned and quality controlled in Arctool
s Edit. An AML
is then run to create
the separate Northern and Southern hemispheric ice edge.
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If you have any comments, please E-mail the National Ice Center Liaison
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