Hummocked ice

Technical description

General description

Table name: Hummocked ice

7. THE AMOUNT OF HUMMOCKED SEA ICE.

This description below is based on the original one from AARI (See Expl.doc). The source tables referred to are included in the Data_7.xls spreadsheet in the \INSROP_GIS\Sourcedata\AARI-SOF 1996\tables folder.

The extent of the ice being covered by hummocks of all kinds expressed in tenths of the area of the zone under consideration is assumed to be the "amount of hummocked ice".

A brief description of initial data.

As initial information, specialised charts of the amount of hummocked sea ice for the period 1947-1989 generalised for 10-30 days are used. Data on these charts are presented in national conventional units. The scale below shows the correspondence between these units and the relative area covered by hummocks in percentage expression.

Conventional national units	Relative area covered by hummocks, %
0	0
1	0-20
2	20-40
3	40-60
4	60-80
5	80-100

Specialised charts of the amount of hummocked ice are based on airborne data and have the accuracy characteristics of the same type as the review charts of the ice situation (item 6.1). The accuracy of information presentation (in the used digital storage formats) is 25 km for the spatial position and not worse than 15% for the values of the relative area covered by hummocks. The data are available only for the periods of the year February-April, June-August. The total volume of initial information used is 433 charts.

A brief description of the processing/analysis method.

Data processing included:

- Expert control, correction and editing of the specialised charts.

- Digitising of data plotted on the charts using the national vector format KONTUR.

- Gridding of digital data from the KONTUR format to SIGRID format.

- Sampling of necessary data.

- Assessment of the occurrence frequency of the ranges of the amount of hummocked ice.

A brief description of the data transferred.

Data on the occurrence frequency of the ranges of the amount of hummocked ice are presented in the form of the ASCII file (tbl_12.txt) containing Table 12. Table 12 consists of the records including the following fields: No. of the point; month; the number of observations; the occurrence frequency (%) of the range 0%-0% (relative area occupied by hummocks); the occurrence frequency of the range 10%-20%; the occurrence frequency of the range 30%-40%; the occurrence frequency of the range 50%-60%; the occurrence frequency of the range 70%-80%; the occurrence frequency of the range 90%-100%; mean, minimum; maximum.

Technical description

Table source file name: hmkd_ice.dbf

Path: <NSR_DATA>\icesnow\aari_sof

Table type: dBASE table.

* Hummocked ice

167 records, 12 descriptive fields.

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

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

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

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

Number of observations

[C0_0] -- "0-0%" (Numeric, 1 decimal)

Frequency of occurrence of no hummocks

[C0_20] -- "0-20%" (Numeric, 1 decimal)

Frequency of occurrence of 0-20% of area being hummocked

[C20_40] -- "20-40%" (Numeric, 1 decimal)

Frequency of occurrence of 20-40% of area being hummocked

[C40_60] -- "40-60%" (Numeric, 1 decimal)

Frequency of occurrence of 40-60% of area being hummocked

[C60_80] -- "60-80%" (Numeric, 1 decimal)

Frequency of occurrence of 60-80% of area being hummocked

[C80_100] -- "80-100%" (Numeric, 1 decimal)

Frequency of occurrence of 80-100% of area being hummocked

[Mean] -- "Mean" (Numeric, 1 decimal)

Mean relative area (%) being covered by hummocked ice

[Min_] -- "Min." (Numeric, 1 decimal)

Minimum relative area (%) being covered by hummocked ice

[Max_] -- "Max." (Numeric, 1 decimal)

Maximum relative area (%) being covered by hummocked ice