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