Cold sum

Technical description - Cold sum for route S by year and month

Technical description - Cold sum for route N by year and month

General description

These tables were prepared by Work Package 2 (Box B) as part of INSROP Phase 2 (See Working Paper no. 121). The tables include Year, Month and a number of fields with numeric names. These numbers refer to ship route segments included in the Tbl_1 shapefile set, which is a part of the dataset provided by INSROP Project I.4.2. These segments are an extract of 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.

3.1. Cold sum (parameter 1) and level ice thickness by the cold sum (parameter 6)

For calculating the cold sum (parameter 1) and level ice thickness by the cold sum (parameter 6) data of polar stations on mean air temperature over the 1953 to 1991 period are used. The initial values for calculation were selected from the monthly bulletins for 32 polar stations and were also taken from the charts of mean air temperature for a 10-day period at 18 additional points located near the selected routes. Parameter 1 was calculated for each of 50 points at the end of each month by summing up below zero air temperatures from the time of stable ice formation up to a stable air temperature transfer to above zero temperatures. Parameter 6 was calculated for each of 50 points by a known formula (Zubov, 1945):

H² + 50*H - 8*Sum(-t°) = 0,

where H is the ice thickness calculated by the cold sum: Sum(-t°)

The values of parameters 1 and 6 for each sub-segment of the selected routes were determined by linear interpolation using the most near 3 points.

Technical description - Cold sum for route S by year and month

Table source file name: p01_s.txt

Path: <NSR_DATA>\icesnow\workpackage2

Table type: DText table.

* Cold sum for route S by year and month

369 records, 144 descriptive fields.

Fields: [<Name>] -- <Alias> (type of field)

[Year] -- "Year" (Numeric, no decimals)

[Month] -- "Month" (Numeric, no decimals)

[1] -- "1" (Numeric, no decimals)

...

[142] -- "142" (Numeric, no decimals)

Technical description - Cold sum for route N by year and month

Table source file name: p01_n.txt