-------------------------------------------------- South America Gridded Precipitation Data Set Download Instructions and Release Notes -------------------------------------------------- CU/CIRES Climate Diagnostics Center (CDC) NOAA/ESRL/PSD Climate Analysis Branch (CAB) Current data set version: SA24 Data set updated: May 9, 2013 Release notes updated: May 20, 2013 Data set home page: http://www.esrl.noaa.gov/psd/people/brant.liebmann/south_america_precip.html DESCRIPTION ----------- This data set is gridded daily precipitation across South America, computed from historical gauge data from numerous official sources. Each grid point value on each date is computed by unweighted averaging of all stations with a valid record on that date, within a fixed surface distance of the nominal grid point coordinates. For further details, please refer to the journal article by Liebmann and Allured, 2005, referenced in item 7 below. DOWNLOADS --------- Both 1.0 and 2.5 degree gridded versions are available in Netcdf file format, by anonymous FTP at this address: ftp://ftp.cdc.noaa.gov/Datasets.other/south_america/ Files for the current data set version: 1 degree data: sa24.daily.1.1940-2012.nc (675 Mb) 2.5 degree data: sa24.daily.2.5.1940-2012.nc (113 Mb) Release notes: release-notes.sa24.3.txt (plain text) Journal article: SAprecipgrids.pdf (BAMS, 2005) VERSION HISTORY --------------- SA24, 2013-may-09: 1. Time coverage for Brazil was extended through December 2011, with a few areas reporting as recently as April 2012. SA23, 2011-sep-21: 1. Time coverage for Brazil was extended through December 2010, with a few areas reporting as recently as June 2011. SA22, 2011-feb-08: 1. Time coverage for Argentina was extended through December 2008. Spatial coverage for Argentina was improved significantly for 1960 through 2008. SA21, 2010-sep-07: 1. Time coverage was extended through 2009-dec-31. Coverage was updated for recent years in Bolivia, Brazil, Colombia, and la Provincia de Santa Fe, in northern Argentina. SA20, 2009-may-20: 1. Time coverage was extended through 2008-dec-31. Coverage through 2008 was added or infilled for Brazil only. Spatial coverage in 2008 is intermittent. 2. A new quality problem in source data for Brazil was discovered, but not fully corrected. This problem is estimated to affect about 1% of all Brazil stations, and to be insignificant within the gridded data. SA19, 2006-dec-07: 1. Time coverage was extended through 2006-aug-31. Spatial coverage was extended south to include the whole continent. 2. Extensive new spatial coverage from 1985 to 2006 was added for Guyana, Colombia, Ecuador, Peru, Bolivia, Paraguay, Chile, and Argentina. The added coverage is sparse at one degree resolution. However, many areas have some coverage where there was none in the previous version. 3. Source data for Brazil was extensively updated. Much of the updating in Brazil was infill stations that contributed to existing grid points rather than supplying new ones. New coverage for 2005 and 2006 was added. SA18, 2005-aug-04: 1. Source data from Brazil was extensively updated. Most of the updates were new data for 2004 and early 2005. There were a few added stations. There were a few corrections to historical data. 2. Averaging of station data at identical coordinates is now incorporated. The areas that are most significantly affected are Argentina, northeastern Brazil, and the Brazilian state of Sao Paulo. Also affected to a lesser degree are the Brazilian state of Amazonas, and occasional other other areas throughout the rest of the extent. 3. The array of daily observation counts is now included in each data file by default. Counts are the number of included observations AFTER averaging data at identical coordinates. SA17, 2004-aug-10: Preliminary release. Averaging of station data at identical coordinates is not yet incorporated. GENERAL RELEASE NOTES --------------------- 1. Data set home page and status: http://www.esrl.noaa.gov/psd/data/gridded/data.south_america_precip.html 2. This data set will be revised as source data are added, historical records are revised, and quality control methods are improved. 3. For information about NetCDF file format, access libraries, visualization software, utilities, and translators, please visit Unidata's NetCDF website: http://www.unidata.ucar.edu/software/netcdf/ For translation to plain text without programming, the program "ncdump" may be used. This simple utility program is included in normal distributions of NetCDF software from Unidata. 4. The data rich areas on the grids benefit from spatial smoothing of many nearby stations. However, many grid point values are based on a single station or a very small number of stations. This results in frequent "data noise" in sparsely populated grid points. This behavior includes zeros and abnormal high spikes due to individual storm events. This is especially common at the outer edges of the populated data regions. Users should take these conditions into account. 5. The time of day on each record in the Netcdf data files is a constant OZ. This time of day has no specific meaning, and is not related to observation times. For information about observation times, please refer to our main article (7) below, paragraph 6 within section "Quality Control". 6. If your application is sensitive to spatial or probabilistic patterns in the data, then consider these additional discussions: Robeson, S. M., and L. A. Ensor, 2006: Comments on "Daily Precipitation Grids for South America." Bull. Amer. Meteor. Soc., 87, 1095-1096. Liebmann, B., and D. Allured, 2006: Reply to Comments on "Daily Precipitation Grids for South America." Bull. Amer. Meteor. Soc., 87, 1096. http://journals.ametsoc.org/toc/bams/87/8 7. We request that the following article be cited if these data sets are used in publication: Liebmann, B., and D. Allured, 2005: Daily precipitation grids for South America. Bull. Amer. Meteor. Soc., 86, 1567-1570. The complete article is available on line, at any of these addresses: http://www.esrl.noaa.gov/psd/people/brant.liebmann/papers/SAprecipgrids.pdf ftp://ftp.cdc.noaa.gov/Datasets.other/south_america/SAprecipgrids.pdf http://journals.ametsoc.org/doi/abs/10.1175/BAMS-86-11-1567 http://dx.doi.org/10.1175/BAMS-86-11-1567 8. Contributions of additional daily station data would be most welcome and appreciated, especially for times and areas lacking coverage in the current version. Please send questions or comments about this data set to Brant Liebmann (mailto:brant.liebmann@noaa.gov ) or Dave Allured. Your feedback will help us to improve future versions. Release notes maintained by: Dave Allured NOAA/PSD/CIRES Climate Analysis Branch (CAB) http://www.esrl.noaa.gov/psd/psd1/ Boulder, Colorado USA 303-497-6825 mailto:dave.allured@noaa.gov