Summary:

The objective of this work was to construct a long-term data set of daily precipitation on half degree and one degree latitude/longitude grids over the global land areas. The analyses are defined by interpolating station observations from GTS (Global Telecommunications System) gauges using the algorithm of Shepard (1968). The algorithm of Shepard (1968) has been widely used to interpolate gauge observations of monthly, pentad, and daily precipitation (Rudolf 1993, Xie et al. 1996). This algorithm is used to interpolate the irregularly distributed station observations onto grid points. The weighting coefficients are inversely proportional to the gauge-grid point distance and are adjusted by a cosine function taking into account the directional isolation of each gauge relative to all other nearby gauges. There are 6 data files with this data set.

Additional Documentation:

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_gts_precip_daily_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.

Data Citation:

Cite this data set as follows:

Xie, P. and J. E. Janowiak. 2011. ISLSCP II Gauge-Based Analyses of Daily Precipitation over Global Land Areas. 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/1001

File Information:

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: 1.0 degree and 0.5 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 6 data files ( .zip) at 1.0 degree (1deg) and 0.5 degree (hdeg) resolution. There are also 2 changemap files at 1.0 degree and 0.5 degree resolution which provide the the spatial distribution of points which were removed or added ( ASCII map file).

File names and descriptions:  

• gts_dif-files_1deg.zip: When expanded to gts_precip_1d_YYYYMMDD.dif provides "differences" files at one degree spatial resolution showing the differences in the data from the Land/Water Mask. YYYY is the year from 1986 to 1995, MM is the month from 01 to 12, and DD is the day of month from 01 to 31.
• gts_dif-files_hdeg.zip: When expanded to gts_precip_hd_YYYYMMDD.dif provides "differences" files at half degree spatial resolution showing the differences in the data from the Land/Water Mask. YYYY is the year from 1986 to 1995, MM is the month from 01 to 12, and DD is the day of month from 01 to 31.
• gts_numguages_daily_1deg.zip: When expanded to gts_numguages_1d_YYYYMMDD.asc provides gridded number of rain guages used in the production of the daily precipitation rates data at one degree spatial resolution. YYYY is the year from 1986 to 1995, MM is the month from 01 to 12, and DD is the day of month from 01 to 31.
• gts_numguages_daily_hdeg.zip: When expanded to gts_numguages_1d_YYYYMMDD.asc provides gridded number of rain guages used in the production of the daily precipitation rates data at half degree spatial resolution. YYYY is the year from 1986 to 1995, MM is the month from 01 to 12, and DD is the day of month from 01 to 31.
• gts_precip_daily_1deg.zip: When expanded to gts_precip_1d_YYYYMMDD.asc provides daily precipitation rates at one degree spatial resolution. YYYY is the year from 1986 to 1995, MM is the month from 01 to 12, and DD is the day of month from 01 to 31. There is also 1 changemap file provided. This file also includes a changemap file gts_precip_1d_changemap.asc which provides the spatial distribution of those points that were removed or added (ASCII map file) after applying the land/water mask.
• gts_precip_daily_hdeg.zip: When expanded to gts_precip_1d_YYYYMMDD.asc provides daily precipitation rates at half degree spatial resolution. YYYY is the year from 1986 to 1995, MM is the month from 01 to 12, and DD is the day of month from 01 to 31. This file also includes a changemap file gts_precip_hd_changemap.asc which provides the spatial distribution of those points that were removed or added (ASCII map file) after applying the land/water mask.

Please refer to 1_gts_precip_daily_doc.pdf and 0_gts_precip_daily_readme.txt  for a more complete description of the data files and naming conventions.

References:

Shepard, D., 1968: A two dimensional interpolation function for regularly spaced data. 23rd National Conference of American Computing Machinery, Princeton, N.J.

Rudolf, B., 1993: Management and analysis of precipitation on a routine basis.Proc. Internat. WMO/IAHS/THE SYMP. On Precip. And Evap., Slovak Hydromet. Inst., Bratislava, Sep. 1993, 1,69-76.

Xie, P., and co-authors, 1996: Gauge-based monthly analysis of global land precipitation from 1971 to 1994. J. Geophy. Res., 101D14, 19023 – 19034.

Data Access:

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC)  [http://daac.ornl.gov].

Data Archive Contact Information:

E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952