This table was created from the ice-stat file as prepared by INSROP project
I.5.8. The table records refer to the routes_c shapefile set, which includes
points defining the ship routes as defined in INSROP Working paper no. 108 (1998),
prepared by Work Package 1 (Box B) as part of INSROP Phase 2.
Sea ice conditions
Ice concentration, thickness, and pressure are the major direct factors
influencing ship speed. Ice concentration was extracted from AARI 10-day Arctic Ocean
EASE-Grid Sea Ice Observations. These gridded ice charts represent a
reformatting by the National Snow and Ice Data Center (NSIDC), of information contained
in Russian Arctic and Antarctic Research Institute (AARI) digital sea ice
charts. AARI digitized arctic sea ice concentrations and stages of development from
original source charts as part of an international data exchange program. The
AARI source charts were developed from aircraft and satellite observations made
for shipping purposes; they provide extremely detailed information. AARI
encoded these paper charts in digital Sea Ice Grid (SIGRID) format. But due to the
difficulties of vizualizing, extracting, and working with data in SIGRID, NSIDC
is now providing AARI data in NSIDC's Equal Area SSM/I Earth (EASE) Grid. The
EASE-Grid format makes it easier to compare observed ice concentration or ice
types with the same parameters derived from satellite data. AARI sea ice data in
the EASE-Grid North azimutal projection are gridded at a 12.5-km resolution, for
both western (24°W to 110°E) and eastern (105°E to 130°W) sectors. Data extend
from 1953 through 1990, and are available via ftp (URL:
http://www-nsidc.colorado.edu/NSIDC/CATALOG/ENTRIES/nsi-0050.html in compressed tar format.
In the EASE-Grid presentation, the original SIGRID data have been condensed to
five layers: total sea ice concentration, multi-year ice concentration,
first-year ice concentration, and new ice concentration. The fast-ice area is also
shown in the fifth layer. Project I.5.8 have processed this information and
extracted ice concentrations for each point along the transitional routes.
The probability of occurrence of ice thickness for each point of the NSR is
presented in this Table. The information presented is a combination of the data
given in the conc-ice_a.dbf file and the data presented in Tables 1.1-1.5 of the
INSROP report "Natural Conditions along the Selected Routes" by Ashik et al.,
1998. The conc-ice_a.dbf file includes statistics of ice concentration for
different ice age categories. It includes total ice concentration, concentration of
multi-year, first-year, thin, and fast ice.
Path: <NSR_DATA>\icesnow\i_5_8
Table type: dBASE table.
* Ice thickness statistics
4020 records, 10 descriptive fields.
Fields: [<Name>] -- <Alias> (type of field)
[No] -- "No" (Numeric, no decimals)
Point number
[Month] -- "Month" (Numeric, no decimals)
Month number
[Maximum] -- "Maximum" (Numeric, no decimals)
Maximum ice thickness (cm)
[Minimum] -- "Minimum" (Numeric, no decimals)
Minimum ice thickness (cm)
[Mean] -- "Mean" (Numeric, no decimals)
Mean ice thickness (cm)
[None] -- "No ice" (Numeric, no decimals)
Frequency of occurence (%) of no ice
[Th_120] -- "Th < 120 cm" (Numeric, no decimals)
Frequency of occurence (%) of ice thickness < 120 cm
[Th120_180] -- "120 cm < Th < 180 cm" (Numeric, no decimals)
Frequency of occurence (%) of ice thickness between 120 and 180 cm
[Th180_240] -- "180 cm < Th < 240 cm" (Numeric, no decimals)
Frequency of occurence (%) of ice thickness between 180 and 240 cm
[Th_240] -- "240 cm < Th" (Numeric, no decimals)
Frequency of occurence (%) of ice thickness > 240 cm
Ice thickness statistics