This data set contains elevation and elevation-based parameters at 1.0 and 0.5-degree spatial resolutions that were developed to support a wide variety of global modeling activities through the International Satellite Land Surface Climatology Project (ISLSCP) Initiative II data collection. These coarse scale data have sufficient statistical information (up to fourth moment) to allow a good statistical description of the sub-cell distribution of any particular elevation parameter (i.e. elevation, slope and aspect). The database used in the development effort was the HYDRO1k product (http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/HYDRO1K) with a native spatial resolution of 1 km, a high resolution database of global coverage of standard elevation-based derivatives (slope, aspect, elevation, compound topographic index, etc.).
This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, it's derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named 1_hydro1k_elevation_doc.pdf.
ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.
ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [http://www.gewex.org/] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.
Related Data Sets:
Cite this data set as follows:
Verdin, K. L. 2011. ISLSCP II HYDRO1k Elevation-derived Products. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/1007
The archived data sets for ISLSCP II have been organized by categories. This data set is in the Hydrology, Soils, and Topography category-- a collection of hydroclimatology and surface elevation data sets.
Data Set Spatial Extent: Global gridded
Westernmost Longitude: -180 W
Easternmost Longitude: 180 E
Northernmost Latitude: 90 N
Southernmost Latitude: -90 S
Projection: Geographic
Data Set Spatial Resolution: one degree and half degree in both latitude and longitude
Data Set Temporal Extent: 1986 through 1995
Data File Format
All of the data files in each data set within the ISLSCP Initiative II data collection are in ASCII GRID format. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. There are 2 data files ( .zip) in 1 degree (1d) and half degree (hd) resolution:
When extrapolated, each file contains 24 ASCII files pertaining to elevation and elevation-based products, a changemap file, and a landmask file for a total of 26 files:
8 Elevation Products: The mean, median, minimum, maximum, range, standard deviation, skewness, and kurtosis of the 1-km values.
5 Slope Products: The mean, median, standard deviation, skewness, and kurtosis of the 1-km values .
5 Aspect Products: Aggregated from 1-km data with the mean, median, standard deviation, skewness, and kurtosis provided.
6 Compound Topographic Index (CTI) Products: The maximum, mean, median, standard deviation, skewness, and kurtosis.
In addition, both .zip files contain an ASCII changemap file and an ASCII landmask file:
Please refer to the table below and the 1_hydro1k_elevation_doc.pdf for further explanation of the file naming conventions and data descriptions.
| File Name | Description |
|---|---|
| aspect_kurt | Kurtosis of the aspects within each cell |
| aspect_mean | Mean aspect of each cell |
| aspect_median | Median aspect of each cell |
| aspect_skew | Skewness in aspect for each cell |
| aspect_stdev | Standard deviation in aspect for each cell |
| cti_kurt | Kurtosis in CTI for each cell |
| cti_max | Maximum CTI within each cell |
| cti_mean | Mean CTI within each cell |
| cti_median | Median CTI within each cell |
| cti_skew | Skewness in CTI for each cell |
| cti_stdev | Standard deviation in CTI for each cell |
| elev_kurt | Kurtosis in elevation values within each cell |
| elev_max | Maximum elevation value within each cell |
| elev_mean | Mean elevation value within each cell |
| elev_median | Median elevation value within each cell |
| elev_min | Minimum elevation value within each cell |
| elev_range | Range of elevation values within each cell |
| elev_skew | Skewness in elevation values within each cell |
| elev_stddev | Standard deviation of the elevation values within each cell |
| landmask | Original land/water mask used in the aggregation of HYDRO1k |
| landmask_dif | Differences between the ISLSCP II land/water mask and the original land/water mask |
| slope_kurt | Kurtosis of the slopes within each cell |
| slope_mean | Mean slope within each cell |
| slope_median | Median slope within each cell |
| slope_skew | Skewness of the slopes within each cell |
| slope_stddev | Standard deviation of the slopes within each cell |
For additional information, please refer to :
* 0_hydro1k_elevation_readme.txt
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) [http://daac.ornl.gov].
E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952