WMO
Atlas_Stage
Stages
Code
WMO Abbrev.
NWS Ice Classification
Code
New Ice
1
N
N
1
Nilas
2
N
(not reported)
Young
3
YN
YNG
2
Gray
4
G
(not reported)
Gray-White
5
GW
(not reported)
First Year
6
FY
FY
3
First Year Thin
7
FL
FL
4
First Year Thin (First Stage)
8
FL
(not reported)
First Year Thin (Second Stage)
9
FL
(not reported)
Medium First Year
1.
FM
FM
5
Thick First Year
4.
FT
(does not occur in Cook Inlet)
Old
7.
(does not occur in Cook Inlet)
Second Year
8.
SY
(does not occur in Cook Inlet)
Multi-Year
9.
MY
(does not occur in Cook Inlet)
Ice of Land Origin
*.
(not reported)
Atlas_Conc
The numerical equivalent assigned by the GIS technician for ice con-
centration. We rounded the mean value to the higher integer if the
reported concentration spanned more than two tenths.
Date
The date of the NWS ice analysis chart.
Conf
The confidence level assigned by the NWS, appearing as high, moder-
ate, or low, which was based on the quality of the data used to produce
the report. This rating does not appear on every chart, but when it did, it
was recorded in this field.
The next phase of our work involved changing the ArcView shape files to a Mercator
projection with its central meridian at 155W and the latitude of true scale at 60N. We
used ArcView's Spatial Analyst extension to convert the themes to ArcInfo grids repre-
senting our atlas concentrations and stages. We organized the grid sets into half-month
groupings, with the 1st to 15th of each month comprising the first half, and the 16th to
the end of the month making up the second half.
In our third phase we performed the statistical calculations and created composite
summary maps for each half-month period. Weighting all available grid sets equally for
each half-month period, we calculated the mean and standard deviation values of stage
and concentration in every grid cell. This was done using ArcInfo's Map Algebra Tools.
We reclassified the resulting values into integers according to the following schemes
(where V = cell value).
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