forrest@0
|
1 |
|
forrest@0
|
2 |
##############################################################################
|
forrest@0
|
3 |
# University of Maryland Global Land Cover Classifications #
|
forrest@0
|
4 |
# at 0.25, 0.5 and 1 degree (1992-1993) #
|
forrest@0
|
5 |
##############################################################################
|
forrest@0
|
6 |
|
forrest@0
|
7 |
The files in this directory were provided by Drs. Ruth DeFries and Matt Hansen
|
forrest@0
|
8 |
from the Department of Geography at the University of Maryland, College Park.
|
forrest@0
|
9 |
These are global, coarse resolution (1/4, 1/2 and 1 degree spatial resolutions)
|
forrest@0
|
10 |
land cover classifications (dominant type and fractional cover) generated using
|
forrest@0
|
11 |
data from the Advanced Very High Resolution Radiometer (AVHRR) (see Hansen et
|
forrest@0
|
12 |
al. 2000).
|
forrest@0
|
13 |
|
forrest@0
|
14 |
The objective of this study was to create a land cover map derived from 1
|
forrest@0
|
15 |
kilometer AVHRR data using all available bands and derived Normalized Difference
|
forrest@0
|
16 |
Vegetation Index (NDVI) and a full year of data (April 1992-March 1993). This
|
forrest@0
|
17 |
thematic map was resampled to 0.25, 0.5 and 1.0 degree grids for the
|
forrest@0
|
18 |
International Satellite Land Surface Climatology Project (ISLSCP) data
|
forrest@0
|
19 |
initiative II. During this re-processing, the original UMD land cover type and
|
forrest@0
|
20 |
fraction maps were adjusted to match the water/land fraction of the ISLSCP II
|
forrest@0
|
21 |
land/water mask. These maps were generated for use by modelers of global
|
forrest@0
|
22 |
biogeochemical cycles and others in need of an internally consistent,
|
forrest@0
|
23 |
global depiction of land cover. This 1km map was also one of the MODIS (Moderate
|
forrest@0
|
24 |
Resolution Imaging Spectroradiometer) at-launch land cover maps.
|
forrest@0
|
25 |
|
forrest@0
|
26 |
The data set describes the geographic distributions of 13 classes of vegetation
|
forrest@0
|
27 |
cover (plus water and unclassified classes) based on a modified International
|
forrest@0
|
28 |
Geosphere-Biosphere Programme (IGBP) legend (Rasool 1992). The data set also
|
forrest@0
|
29 |
provides the fraction of each of the 15 classes within the coarser resolution
|
forrest@0
|
30 |
cells. The data set is provided at three spatial resolutions of 0.25, 0.5 and 1
|
forrest@0
|
31 |
degrees in latitude and longitude. We refer the reader to the reference below
|
forrest@0
|
32 |
for more information on data processing of the original 1km data set.
|
forrest@0
|
33 |
|
forrest@0
|
34 |
Please acknowledge Drs. DeFries and Hansen and the ISLSCP2 data collection when
|
forrest@0
|
35 |
these data are used. Please cite the following publications when these data are
|
forrest@0
|
36 |
used:
|
forrest@0
|
37 |
|
forrest@0
|
38 |
Hansen, M. C., DeFries, R.S., Townshend, J.R.G., and Sohlberg, R., 2000, Global
|
forrest@0
|
39 |
land cover classification at 1km spatial resolution using a classification tree
|
forrest@0
|
40 |
approach, International Journal of Remote Sensing, 21, 1331-1364.
|
forrest@0
|
41 |
|
forrest@0
|
42 |
Any problems encountered with the data set should be reported to Eric Brown de
|
forrest@0
|
43 |
Colstoun at ericbdc@ltpmail.gsfc.nasa.gov
|
forrest@0
|
44 |
|
forrest@0
|
45 |
##############################################################################
|
forrest@0
|
46 |
|
forrest@0
|
47 |
File Name Convention
|
forrest@0
|
48 |
--------------------
|
forrest@0
|
49 |
The data sets in this directory are provided at three spatial resolutions of
|
forrest@0
|
50 |
0.25, 0.5 and 1 degrees lat./long. For each spatial resolution there is a land
|
forrest@0
|
51 |
cover type classification layer (with numbers from 0 to 14) and 15 associated
|
forrest@0
|
52 |
layers that provide the fraction, from 0 to 100, of each land cover type per
|
forrest@0
|
53 |
cell. The land cover type files are named umd_landcover_class_XX.asc, where XX
|
forrest@0
|
54 |
is qd, hd, or 1d, denoting a spatial resolution of 1/4, 1/2 or 1 degrees,
|
forrest@0
|
55 |
respectively. The fractional files are called umd_landcover_XX_cZZ.asc, where XX
|
forrest@0
|
56 |
is the same as above, and ZZ is a number from 00 to 14 which represents the land
|
forrest@0
|
57 |
cover type code as described below. As an example, the file named
|
forrest@0
|
58 |
umd_landcover_qd_c02.asc is the fraction of Evergreen Broadleaf Forest at a
|
forrest@0
|
59 |
quarter degree spatial resolution. This file is associated with the
|
forrest@0
|
60 |
umd_landcover_class_qd.asc land cover type file.
|
forrest@0
|
61 |
|
forrest@0
|
62 |
##############################################################################
|
forrest@0
|
63 |
|
forrest@0
|
64 |
ASCII File Format
|
forrest@0
|
65 |
------------------
|
forrest@0
|
66 |
All of the files in the ISLSCP Initiative II data collection are in the ASCII,
|
forrest@0
|
67 |
or text format. The file format consists of numerical fields of varying length,
|
forrest@0
|
68 |
which are delimited by a single space and arranged in columns and rows. The
|
forrest@0
|
69 |
values in the land cover class type files are written as integers from 0 to 14.
|
forrest@0
|
70 |
All values in the land cover fraction files are written as real numbers.
|
forrest@0
|
71 |
|
forrest@0
|
72 |
The files at different spatial resolutions each contain the following numbers of
|
forrest@0
|
73 |
columns and rows:
|
forrest@0
|
74 |
One degree: 360 columns by 180 rows
|
forrest@0
|
75 |
1/2 degree: 720 columns by 360 rows
|
forrest@0
|
76 |
1/4 degree: 1440 columns by 720 rows
|
forrest@0
|
77 |
|
forrest@0
|
78 |
All files are gridded to a common equal-angle lat/long grid, where the
|
forrest@0
|
79 |
coordinates of the upper left corner of the files are located at 180oW, 90oN and
|
forrest@0
|
80 |
the lower right corner coordinates are located at 180oE, 90oS. Data in the files
|
forrest@0
|
81 |
are ordered from North to South and from West to East beginning at 180 degrees
|
forrest@0
|
82 |
West and 90 degrees North.
|
forrest@0
|
83 |
|
forrest@0
|
84 |
The data files are PKZip compressed. On UNIX, they can be decompressed using the
|
forrest@0
|
85 |
"unzip -a" command. On Windows, they can be decompressed using WinZip or other
|
forrest@0
|
86 |
PKZip software. On the Macintosh, they can be decompressed using Stuffit
|
forrest@0
|
87 |
Expander.
|
forrest@0
|
88 |
|
forrest@0
|
89 |
################################################################################
|
forrest@0
|
90 |
|
forrest@0
|
91 |
Land Cover Type Codes and Definitions
|
forrest@0
|
92 |
-------------------------------------
|
forrest@0
|
93 |
The following 15 classes are used. Note that here are no cells with a value of
|
forrest@0
|
94 |
13 (Urban and Builtup) in the 1degree land cover type file.
|
forrest@0
|
95 |
|
forrest@0
|
96 |
0 = Water bodies: oceans, seas, lakes, reservoirs, and rivers. Can be either
|
forrest@0
|
97 |
fresh or salt water. This class is derived from a land/water mask.
|
forrest@0
|
98 |
|
forrest@0
|
99 |
1 = Evergreen Needleleaf Forests: lands dominated by trees with a percent canopy
|
forrest@0
|
100 |
cover >60% and height exceeding 5m. Almost all trees remain green all year.
|
forrest@0
|
101 |
Canopy is never without green foliage.
|
forrest@0
|
102 |
|
forrest@0
|
103 |
2 = Evergreen Broadleaf Forests: lands dominated by trees with a percent canopy
|
forrest@0
|
104 |
cover > 60% and height exceeding 5m. Almost all trees remain green all year.
|
forrest@0
|
105 |
Canopy is never without green foliage.
|
forrest@0
|
106 |
|
forrest@0
|
107 |
3 = Deciduous Needleleaf Forest: lands dominated by trees with a percent canopy
|
forrest@0
|
108 |
cover >60% and height exceeding 5m. Trees shed their leaves simultaneously in
|
forrest@0
|
109 |
response to cold seasons.
|
forrest@0
|
110 |
|
forrest@0
|
111 |
4 = Deciduous Broadleaf Forests: lands dominated by trees with a percent canopy
|
forrest@0
|
112 |
cover >60% and height exceeding 5m. Trees shed their leaves simultaneously in
|
forrest@0
|
113 |
response to dry or cold seasons.
|
forrest@0
|
114 |
|
forrest@0
|
115 |
5 = Mixed Forests: lands dominated by trees with a percent canopy cover >60% and
|
forrest@0
|
116 |
height exceeding 5m. Consists of tree communities with interspersed mixtures or
|
forrest@0
|
117 |
mosaics of needleleaf and deciduous forest types. Neither type has <25% or >75%
|
forrest@0
|
118 |
landscape coverage.
|
forrest@0
|
119 |
|
forrest@0
|
120 |
6 = Woodlands: lands with herbaceous or woody understories and tree canopy cover
|
forrest@0
|
121 |
of >40% and <60%. Trees exceed 5m in height and can be either evergreen or
|
forrest@0
|
122 |
deciduous.
|
forrest@0
|
123 |
|
forrest@0
|
124 |
7 = Wooded Grasslands/Shrublands: lands with herbaceous or woody understories and
|
forrest@0
|
125 |
tree canopy cover of >10% and <40%. Trees exceed 5m in height and can be either
|
forrest@0
|
126 |
evergreen or deciduous.
|
forrest@0
|
127 |
|
forrest@0
|
128 |
8 = Closed Bushlands or Shrublands: lands dominated by bushes or shrubs. Bush and
|
forrest@0
|
129 |
shrub percent canopy cover is >40%. Bushes do not exceed 5m in height. Shrubs
|
forrest@0
|
130 |
or bushes can be either evergreen or deciduous. Tree canopy cover is <10%. The
|
forrest@0
|
131 |
remaining cover is either barren or herbaceous.
|
forrest@0
|
132 |
|
forrest@0
|
133 |
9 = Open Shrubland: lands dominated by shrubs. Shrub canopy cover is >10% and
|
forrest@0
|
134 |
<40%. Shrubs do not exceed 2m in height and can be either evergreen or
|
forrest@0
|
135 |
deciduous. The remaining cover is either barren or of annual herbaceous type.
|
forrest@0
|
136 |
|
forrest@0
|
137 |
10 = Grasslands: lands with continuous herbaceous cover and <10% tree or shrub
|
forrest@0
|
138 |
canopy cover.
|
forrest@0
|
139 |
|
forrest@0
|
140 |
11 = Croplands: lands with >80% of the landscape covered in crop-producing fields.
|
forrest@0
|
141 |
Note that perennial woody crops will be classified as the appropriate forest or
|
forrest@0
|
142 |
shrubs land cover type.
|
forrest@0
|
143 |
|
forrest@0
|
144 |
12 = Barren: lands of exposed soil, sand, rocks, snow or ice which never have more
|
forrest@0
|
145 |
than 10% vegetated cover during any time of year.
|
forrest@0
|
146 |
|
forrest@0
|
147 |
13 = Urban and Builtup: land covered by buildings and other man-made structures.
|
forrest@0
|
148 |
Note that this class is not mapped from the AVHRR imagery but is developed from
|
forrest@0
|
149 |
the populated places layer that is part of the Digital Chart of the World (Danko
|
forrest@0
|
150 |
1992).
|
forrest@0
|
151 |
|
forrest@0
|
152 |
14 = Unclassified: Points where the ISLSCP2 land/sea mask was labeled as land and
|
forrest@0
|
153 |
the UMD original data had sea and which could not be filled in from a 3 by 3
|
forrest@0
|
154 |
average of surrounding cells.
|
forrest@0
|
155 |
|