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#            Global Gridded Monthly Sea Ice Concentrations                   #
#       at 1/4, 1/2 and 1 Degree Spatial Resolutions (1986-1995)             #
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File Name Convention
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The following files are included in this data set:

sea_ice_data_XX_YYYY.csv: Original files submitted by the Principal Investigator 
in tabular format. These original data contain gridded monthly sea ice 
concentrations, in percent, arranged within 10 yearly files. XX is qd, hd, or 1d 
indicating a spatial resolution of one quarter, one half, or 1 degree, 
respectively, in both latitude and longitude. YYYY is the year from 1986 to 
1995. These files are in the "sea_ice_data" directory. See below for complete 
file description.

sea_ice_map_1d_YYYYMM00.asc: 120 files with the 1 degree monthly gridded sea ice 
concentrations arranged on a global grid. YYYY is the year from 1986 to 1995 and 
MM is the month from 01 to 12. The 00 means this is a monthly average. These 
files are in the "sea_ice_map" directory. NOTE***: At this revision, these files 
are only available at a 1 degree spatial resolution. 

sea_ice_mask_diffs_1d.asc: Gridded file with values describing the differences
between the 1 degree ISLSCP II land/water mask and the 1 degree original land/water
mask. The values here can be 0, 1, or 2 (see below for description).

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ASCII File Format
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1) Original Files (sea_ice_data_XX_YYYY.csv)
All of the files in the ISLSCP Initiative II data collection are in the ASCII, 
or text format. The original data files sea_ice_data_XX_YYYY.csv all have a 
total of 15 columns separated by a single comma and a number of rows that ranges 
from 10511 (File "sea_ice_data_1d_1986.csv") to 182399 (File 
"sea_ice_data_qd_1995.csv"). No data are written to the tables for cells which had 
0% sea ice for the entire year. Only numerical fields are included as described 
below. The contents for each column are given below:

LON: Longitude for the center of a cell in decimal degrees

LAT: Latitude for the center of a cell in decimal degrees

JAN: Average sea ice concentration in percent for the month of January of the 
year YYYY.

FEB: Average sea ice concentration in percent for the month of February of the 
year YYYY.

...

DEC: Average sea ice concentration in percent for the month of December of the 
year YYYY.

LAND_MASK: Value of the 1 degree ISLSCP II land/water mask (0 = Water; 1 = Land)


2) "Mapped" Files
The file format for the "mapped" monthly sea ice concentration files 
"sea_ice_map_1d_YYYYMM00.asc" and the "sea_ice_mask_diffs_1d.asc" files consists 
of numerical fields of varying length, which are delimited by a single space and
arranged in columns and rows. The files each contain 360 columns by 180 rows. All 
values in these files are written as real numbers. Land cells in the 
"sea_ice_map_1d_YYYYMM00.asc" files are given the value -88.

For the "sea_ice_mask_diffs_1d.asc" file the values range from 0 to 2 and mean the 
following:
0 = Data sets agree over land or water
1 = ISLSCP II 1 degree mask is water and original 1 degree data show land (92 
    points)
2 = ISLSCP II 1 degree mask is land and original 1 degree data show water (532 
    points)

These files are all gridded to a common equal-angle lat/long grid, where the 
coordinates of the upper left corner of the files are located at 180 degrees W, 
90 degrees N and the lower right corner coordinates are located at 180 degrees E,
90 degrees S. Data in the files are ordered from North to South and from West to
East beginning at 180 degrees West and 90 degrees North.