diff -r 000000000000 -r 8306d3538de9 observed/lai/0_umd_landcover_readme.txt --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/observed/lai/0_umd_landcover_readme.txt Mon Jan 26 22:31:32 2009 -0500 @@ -0,0 +1,155 @@ + +############################################################################## +# University of Maryland Global Land Cover Classifications # +# at 0.25, 0.5 and 1 degree (1992-1993) # +############################################################################## + +The files in this directory were provided by Drs. Ruth DeFries and Matt Hansen +from the Department of Geography at the University of Maryland, College Park. +These are global, coarse resolution (1/4, 1/2 and 1 degree spatial resolutions) +land cover classifications (dominant type and fractional cover) generated using +data from the Advanced Very High Resolution Radiometer (AVHRR) (see Hansen et +al. 2000). + +The objective of this study was to create a land cover map derived from 1 +kilometer AVHRR data using all available bands and derived Normalized Difference +Vegetation Index (NDVI) and a full year of data (April 1992-March 1993). This +thematic map was resampled to 0.25, 0.5 and 1.0 degree grids for the +International Satellite Land Surface Climatology Project (ISLSCP) data +initiative II. During this re-processing, the original UMD land cover type and +fraction maps were adjusted to match the water/land fraction of the ISLSCP II +land/water mask. These maps were generated for use by modelers of global +biogeochemical cycles and others in need of an internally consistent, +global depiction of land cover. This 1km map was also one of the MODIS (Moderate +Resolution Imaging Spectroradiometer) at-launch land cover maps. + +The data set describes the geographic distributions of 13 classes of vegetation +cover (plus water and unclassified classes) based on a modified International +Geosphere-Biosphere Programme (IGBP) legend (Rasool 1992). The data set also +provides the fraction of each of the 15 classes within the coarser resolution +cells. The data set is provided at three spatial resolutions of 0.25, 0.5 and 1 +degrees in latitude and longitude. We refer the reader to the reference below +for more information on data processing of the original 1km data set. + +Please acknowledge Drs. DeFries and Hansen and the ISLSCP2 data collection when +these data are used. Please cite the following publications when these data are +used: + +Hansen, M. C., DeFries, R.S., Townshend, J.R.G., and Sohlberg, R., 2000, Global +land cover classification at 1km spatial resolution using a classification tree +approach, International Journal of Remote Sensing, 21, 1331-1364. + +Any problems encountered with the data set should be reported to Eric Brown de +Colstoun at ericbdc@ltpmail.gsfc.nasa.gov + +############################################################################## + +File Name Convention +-------------------- +The data sets in this directory are provided at three spatial resolutions of +0.25, 0.5 and 1 degrees lat./long. For each spatial resolution there is a land +cover type classification layer (with numbers from 0 to 14) and 15 associated +layers that provide the fraction, from 0 to 100, of each land cover type per +cell. The land cover type files are named umd_landcover_class_XX.asc, where XX +is qd, hd, or 1d, denoting a spatial resolution of 1/4, 1/2 or 1 degrees, +respectively. The fractional files are called umd_landcover_XX_cZZ.asc, where XX +is the same as above, and ZZ is a number from 00 to 14 which represents the land +cover type code as described below. As an example, the file named +umd_landcover_qd_c02.asc is the fraction of Evergreen Broadleaf Forest at a +quarter degree spatial resolution. This file is associated with the +umd_landcover_class_qd.asc land cover type file. + +############################################################################## + +ASCII File Format +------------------ +All of the files in the ISLSCP Initiative II data collection are in the ASCII, +or text format. The file format consists of numerical fields of varying length, +which are delimited by a single space and arranged in columns and rows. The +values in the land cover class type files are written as integers from 0 to 14. +All values in the land cover fraction files are written as real numbers. + +The files at different spatial resolutions each contain the following numbers of +columns and rows: + One degree: 360 columns by 180 rows + 1/2 degree: 720 columns by 360 rows + 1/4 degree: 1440 columns by 720 rows + +All files are gridded to a common equal-angle lat/long grid, where the +coordinates of the upper left corner of the files are located at 180oW, 90oN and +the lower right corner coordinates are located at 180oE, 90oS. Data in the files +are ordered from North to South and from West to East beginning at 180 degrees +West and 90 degrees North. + +The data files are PKZip compressed. On UNIX, they can be decompressed using the +"unzip -a" command. On Windows, they can be decompressed using WinZip or other +PKZip software. On the Macintosh, they can be decompressed using Stuffit +Expander. + +################################################################################ + +Land Cover Type Codes and Definitions +------------------------------------- +The following 15 classes are used. Note that here are no cells with a value of +13 (Urban and Builtup) in the 1degree land cover type file. + +0 = Water bodies: oceans, seas, lakes, reservoirs, and rivers. Can be either + fresh or salt water. This class is derived from a land/water mask. + +1 = Evergreen Needleleaf Forests: lands dominated by trees with a percent canopy + cover >60% and height exceeding 5m. Almost all trees remain green all year. + Canopy is never without green foliage. + +2 = Evergreen Broadleaf Forests: lands dominated by trees with a percent canopy + cover > 60% and height exceeding 5m. Almost all trees remain green all year. + Canopy is never without green foliage. + +3 = Deciduous Needleleaf Forest: lands dominated by trees with a percent canopy + cover >60% and height exceeding 5m. Trees shed their leaves simultaneously in + response to cold seasons. + +4 = Deciduous Broadleaf Forests: lands dominated by trees with a percent canopy + cover >60% and height exceeding 5m. Trees shed their leaves simultaneously in + response to dry or cold seasons. + +5 = Mixed Forests: lands dominated by trees with a percent canopy cover >60% and + height exceeding 5m. Consists of tree communities with interspersed mixtures or + mosaics of needleleaf and deciduous forest types. Neither type has <25% or >75% + landscape coverage. + +6 = Woodlands: lands with herbaceous or woody understories and tree canopy cover + of >40% and <60%. Trees exceed 5m in height and can be either evergreen or + deciduous. + +7 = Wooded Grasslands/Shrublands: lands with herbaceous or woody understories and + tree canopy cover of >10% and <40%. Trees exceed 5m in height and can be either + evergreen or deciduous. + +8 = Closed Bushlands or Shrublands: lands dominated by bushes or shrubs. Bush and + shrub percent canopy cover is >40%. Bushes do not exceed 5m in height. Shrubs + or bushes can be either evergreen or deciduous. Tree canopy cover is <10%. The + remaining cover is either barren or herbaceous. + +9 = Open Shrubland: lands dominated by shrubs. Shrub canopy cover is >10% and + <40%. Shrubs do not exceed 2m in height and can be either evergreen or + deciduous. The remaining cover is either barren or of annual herbaceous type. + +10 = Grasslands: lands with continuous herbaceous cover and <10% tree or shrub + canopy cover. + +11 = Croplands: lands with >80% of the landscape covered in crop-producing fields. + Note that perennial woody crops will be classified as the appropriate forest or + shrubs land cover type. + +12 = Barren: lands of exposed soil, sand, rocks, snow or ice which never have more + than 10% vegetated cover during any time of year. + +13 = Urban and Builtup: land covered by buildings and other man-made structures. + Note that this class is not mapped from the AVHRR imagery but is developed from + the populated places layer that is part of the Digital Chart of the World (Danko + 1992). + +14 = Unclassified: Points where the ISLSCP2 land/sea mask was labeled as land and + the UMD original data had sea and which could not be filled in from a 3 by 3 + average of surrounding cells. +