GCIP LSA-NW EAOP 2000 NCEP/CPC Hourly Precipitation Data in QC format 1.0 General Description The National Centers for Environmental Prediction/Climate Prediction Center (NCEP/CPC) Hourly Precipitation data in QC format is one of several precipitation datasets provided in the GEWEX Continental-Scale International Project (GCIP) Large Scale Area-North West (LSA-NW) Enhanced Annual Observing Period (EAOP) 2000. Gross Limit quality control checks were applied to this data. This dataset contains data for the GCIP LSA-NW EAOP-00 domain and time period (01 April 2000 through 31 March 2001). The GCIP LSA-NW EAOP-00 domain is approximately 90W to 115W longitude and 36N to 51N latitude. 2.0 Detailed Data Description National Centers for Environmental Prediction/Climate Prediction Center (NCEP/CPC) Algorithms The Climate Prediction Center (CPC) is a component of the National Centers for Environmental Prediction (NCEP). The NCEP/CPC Hourly Precipitation dataset was formed by extracting incremental precipitation values that fell on the hour. The value reported for any hourly observation represents data collected during the previous 60 minutes. All raw precipitation data, including data that do not fall on the hour, can be found on codiac in the GCIP/EOP Surface: Precipitation NCEP/CPC Gage Only Hourly Dataset. UCAR/JOSS checks the NCEP/CPC hourly precipitation data for possible accumulated values and resets the UCAR/JOSS Quality Control flags for all "unchecked", "good", and "trace" accumulated precipitation values in the NCEP/CPC network to "questionable". For this purpose, UCAR/JOSS defines accumulated precipitation to be six identical, sequential hourly precipitation values potentially followed by additional identical values or values that increase over time. 2.1 Detailed Format Description The NCEP/CPC GCIP LSA-NW EAOP-00 Hourly Precipitation Data contains seven metadata parameters and three data parameters. The metadata parameters describe the date/time, network, station, and location at which the data was collected. The three data parameters repeat once for each UTC hour from 0000 through UTC hour 2300. Data reported for a designated hour represents data collected during the previous hour. All times are reported in UTC, and precipitation data values are reported in millimeters. A Quality Flag and a QC Code are assigned to each data value during the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS) Quality Control (QC) processing. For a list of possible Quality Flag and QC Code values see the Quality Control Section 3.0. The table below details each parameter. Parameters Units ---------------------- ---------------------------------- Date of Observation UTC Time of Observation UTC Network Identifier Abbreviation of platform name Station Identifier Network Dependent Latitude Decimal degrees, South is negative Longitude Decimal degrees, West is negative Station Occurrence Unitless Hourly Precip Value Millimeters Quality Flag See list of Definitions QC Code See list of Definitions 2.2 Data Remarks UCAR/JOSS checks the NCEP/CPC hourly precipitation data for possible accumulated values and resets the UCAR/JOSS Quality Control flags for all "unchecked", "good", and "trace" accumulated precipitation values in the NCEP/CPC network to "questionable". For more information on the quality control performed on this network by UCAR/JOSS, please see section 3.0 below. 3.0 Quality Control Processing Gross limit checks were used to determine the quality of the data in the GCIP LSA-NW EAOP-00 Hourly Precipitation Data. Data values less than 20 millimeters were flagged as good. Any data value greater than or equal to 20 millimeters but less than 50 millimeters was flagged as questionable. Any data value greater than or equal to 50 millimeters was flagged as unlikely. UCAR/JOSS checks the NCEP/CPC hourly precipitation data for possible accumulated values and resets the UCAR/JOSS Quality Control flags for all "unchecked", "good", and "trace" accumulated precipitation values in the NCEP/CPC network to "questionable". For this purpose, UCAR/JOSS defines accumulated precipitation to be six identical, sequential hourly precipitation values potentially followed by additional identical values or values that increase over time. The data were never changed, only flagged. Tables 1 and 2 contain the quality control codes and flags, respectively. Table 1 Quality Control Flag Description --------------------------- -------------------------------------------- 0 No qualifier required 1 Accumulation period 2 End of Accumulation period 3 Deleted value. Original data was unreadable. 4 Trace of precipitation. 5 Probable amount as a result of melting frozen precipitation. 6 Suspect amount relative to time or period of occurrence. 7 Missing value Table 2 QC Code Description ----------------- ------------------------------------------ U Unchecked G Good M Normally recorded but missing D Questionable B Unlikely N Not available or Not observed. X Glitch E Estimated C Reported value exceeds output format field size or was negative precipitation. T Trace precipitation amount recorded. I Derived parameter can not be computed due to insufficient data. 4.0 References None.