数据集包括：
1、permaice（冻土类型图）
2、subsea(海底界线矢量图)
3、treeline(林线矢量图)
4、nhipa(栅格图)
5、llipa(栅格图)
Permaice包括属性字段：
Num_code（冻土属性编码）
Combo(冻土属性）
extent（冻土范围）
content(含冰量）
属性对照如下：
（1）冻土属性对照表：
0 （No information ）
1 - chf （Continuous permafrost extent with high ground ice content and thick overburden）
2 - dhf （Discontinuous permafrost extent with high ground ice content and thick overburden ）
3 - shf （Sporadic permafrost extent with high ground ice content and thick overburden ）
4 - ihf （Isolated patches of permafrost extent with high ground ice content and thick overburden ）
5 - cmf （Continuous permafrost extent with medium ground ice content and thick overburden ）
6 - dmf （Discontinuous permafrost extent with medium ground ice content and thick overburden ）
7 - smf （Sporadic permafrost extent with medium ground ice content and thick overburden ）
8 - imf （Isolated patches of permafrost extent with medium ground ice content and thick overburden）
9 - clf （Continuous permafrost extent with low ground ice content and thick overburden ）
10 - dlf （Discontinuous permafrost extent with low ground ice content and thick overburden ）
11 - slf （Sporadic permafrost extent with low ground ice content and thick overburden ）
12 - ilf （Isolated patches of permafrost extent with low ground ice content and thick overburden）
13 - chr （Continuous permafrost extent with high ground ice content and thin overburden and exposed bedrock ）
14 - dhr （Discontinuous permafrost extent with high ground ice content and thin overburden and exposed bedrock ）
15 - shr （Sporadic permafrost extent with high ground ice content and thin overburden and exposed bedrock ）
16 - ihr （Isolated patches of permafrost extent with high ground ice content and thin overburden and exposed bedrock）
17 - clr （Continuous permafrost extent with low ground ice content and thin overburden and exposed bedrock ）
18 - dlr （Discontinuous permafrost extent with low ground ice content and thin overburden and exposed bedrock ）
19 - slr （Sporadic permafrost extent with low ground ice content and thin overburden and exposed bedrock）
20 - ilr （Isolated patches of permafrost extent with low ground ice content and thin overburden and exposed bedrock ）
21 - g （Glaciers）
22 - r （Relict permafrost）
23 - l （Inland lakes ）
24 - o （Ocean/inland seas ）
25 - ld （Land）
（2）冻土范围对照表
c = continuous (90-100%)
d = discontinuous (50- 90%)
s = sporadic (10- 50%)
i = isolated patches ( 0 - 10%)
（3）含冰量对照表
h = high (>20% for "f" landform codes) (>10% for "r" landform codes)
m = medium (10-20%)
l = low (0-10%)
Projection of the shapefiles is:
PROJCS["Sphere_ARC_INFO_Lambert_Azimuthal_Equal_Area",
GEOGCS["GCS_Sphere_ARC_INFO",
DATUM["Sphere_ARC_INFO", SPHEROID["Sphere_ARC_INFO",6370997.0,0.0]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Azimuthal_Equal_Area"],
PARAMETER["False_Easting",0.0],
PARAMETER["False_Northing",0.0],
PARAMETER["longitude_of_center",180.0],
PARAMETER["latitude_of_center",90.0],
UNIT["Meter",1.0]]
Projection for the raster (*.byte) files is:
Projection: Lambert Azimuthal
Units: meters
Spheroid: defined
Major Axis: 6371228.00000
Minor Axis: 6371228.000
Parameters:
radius of the sphere of reference: 6371228.00000
longitude of center of projection: 0
latitude of center of projection: 90
false easting (meters): 0.00000
false northing (meters): 0.00000
数字矢量化
数据集通过严格的人工审核控制质量
Brown, J., O.J. Ferrians, Jr., J.A. Heginbottom, and E.S. Melnikov. 1998, revised February 2001. Circum-arctic map of permafrost and ground ice conditions. Boulder, CO: National Snow and Ice Data Center. Digital media.
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