CPC Gauge-Based Analysis of Daily Precipitation over CONUS 1) Product Name CPC Unified Gauge-Based Analysis of Daily Precipitation over CONUS 2) Background This data set is part of products suite from the CPC Unified Precipitation Project that are underway at NOAA Climate Prediction Center (CPC). The primary goal of the project is to create a suite of unified precipitation products with consistent quantity and improved quality by combining all information sources available at CPC and by taking advantage of the optimal interpolation (OI) objective analysis technique. The gauge analysis here covers the Conteminous United States on a fine-resolution and is quantitatively consistent with that covering the global land on a coarser resolution. 3) Coverage and Resolution Space : 0.25deg lat / lon; CONUS Time : Daily; Jan.1, 1979 - Present 4) Cautions and Alerts * The analysis quality varies with the gauge network density. Users are encouraged to take advantage of the network density information included in the data file; * Daily accumulation ends at 12Z. 5) Data Files * Document files are in sub-directory /DOCU * Retrospective version data files are in sub-directory /v1.0 * Real-time version data files are in sub-directory /RT * Data files for each calendar year are stored in a sub-directory 'yyyy' where 'yyyy' is a 4-digit integer; * Under each yearly sub-directory, analysis data for each day is included in a single GrADS formatted data file named: PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.yyyymmdd ; or PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.yyyymmddRT where 'yyyymmdd' denotes the target year, month, and date. 'RT' at the end of the file name indicates that the analysis for the day is based on the real-time station data and the analysis will be reprocessed later on when enhanced station data are available. * In each daily file, there are two fields: analyzed field of daily precipitation in 0.1mm; and number of gauges available in each 0.25deg lat/lon grid box. * The CONUS field starts from the 0.25deg lat/lon grid box centering at (129.875W; 20.125N), going from west to east first, and then south to north. * Both the CONUS fields are written as 4-byte real numbers in LITTLE_ENDIAN byte order. You may need to swap the byte order if you are working with a big_endian machine (such as an SGI). * The following GrADS control files for the daily data are available: PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.ctl PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.RT.ctl (Real-Time updates) 6) References: (Interpolation algorithm) Xie_et_al_2007_JHM_EAG.pdf Xie, P., A. Yatagai, M. Chen, T. Hayasaka, Y. Fukushima, C. Liu, and S. Yang (2007), A gauge-based analysis of daily precipitation over East Asia, J. Hydrometeorol., 8, 607. 626. (Gauge Algorithm Evaluation) Chen_et_al_2008_JGR_Gauge_Algo.pdf Chen, M., W. Shi, P. Xie, V. B. S. Silva, V E. Kousky, R. Wayne Higgins, and J. E. Janowiak (2008), Assessing objective techniques for gauge-based analyses of global daily precipitation, J. Geophys. Res., 113, D04110, doi:10.1029/2007JD009132. (Construction of the Daily Gauge Analysis) Chen_et_al_2008_Daily_Gauge_Anal.pdf Chen, M., P. Xie, and Co-authors (2008), CPC Unified Gauge-based Analysis of Global Daily Precipiation, Western Pacific Geophysics Meeting, Cairns, Australia, 29 July - 1 August, 2008. 8) Contacts Dr. Pingping Xie Climate Prediction Center 5200 Auth Road, #605 Camp Springs, MD 20746 USA E-Mail: Pingping.Xie@noaa.gov Tel. (301)763-8000, #7572 Dr. Wei Shi Climate Prediction Center 5200 Auth Road, #605 Camp Springs, MD 20746 USA E-Mail: Wei.Shi@noaa.gov Tel. (301)763-8000, #7545 Dr. Mingyue Chen Climate Prediction Center 5200 Auth Road, #605 Camp Springs, MD 20746 USA E-Mail: Mingyue.Chen@noaa.gov Tel. (301)763-8000, #7506