GIDS-1 Hourly Precipitation Composite 1.0 General Description The Hourly Precipitation Composite is one of two precipitation datasets provided as part of the GEWEX Continental-scale International Project (GCIP) Initial Dataset One (GIDS-1). This precipitation composite was formed from three data sources (i.e., GIDS-1 area subset of the STORM-FEST Hourly Precipitation Composite data, NCDC Hourly Precipitation data, and the precipitation extracted from the GIDS-1 Hourly Surface Composite). Data from the three sources (over a thousand stations) were merged and quality controlled to form this precipitation composite. This composite contains data for the GIDS-1 time period (01 February 1992 through 30 April 1992) and for the GIDS-1 area of interest, only. The GIDS-1 area is approximately 85W to 106W longitude and 30N to 45N latitude. 2.0 Detailed Data Description The Hourly Precipitation Composite format contains seven metadata parameters followed by three data parameters. The metadata parameters describe the station location and time at which the data was collected. The three data parameters repeat once for each UTC hour from 0000 through UTC hour 2300. 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 UCAR/Office of Field Project Support (UCAR/OFPS) quality control 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 3.0 Quality Control Processing This precipitation composite was formed from three sub-datasets (i.e., NCDC Hourly Precipitation data, GIDS-1 area of STORM-FEST Hourly Precipitation Composite data, and the precipitation extracted from the GIDS-1 Hourly Surface Composite). Each of these sub-datasets was Quality Controlled independently. Gross limit checks were used to determine the quality of the NCDC Hourly Precipitation data and the precipitation data extracted from the GIDS-1 Hourly Surface Composite. Data values less than 25 millimeters were flagged as good. Any data value greater than or equal to 25 millimeters but less than 75 millimeters was flagged as questionable. Any data value greater than or equal to 75 millimeters was flagged as unlikely. Several questionable and unlikely data values were also manually inspected. After inspection, the quality control code and flag may have been manually updated to better reflect the likelihood of the actual occurrence of the precipitation value. The data were never changed, only flagged. Tables of the possible quality control codes and flags and their meanings are listed below. The GIDS-1 area of STORM-FEST Hourly Precipitation Composite data was extracted directly. The quality control applied during the STORM-FEST project was retained. Gross limit checks, as described above, were applied during the STORM-FEST precipitation data processing. After the three sub-datasets were merged to form the GIDS-1 Hourly Precipitation Composite, a statistics program was executed to ensure that the quality of the individual sub-datasets had been retained. Quality Control Flag Description 0 No qualifier required 1 Accumulation period 2 End of Accumulation period 3 Deleted value. Original data was unreadable. 4-6 Reserved. 7 Missing value 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 9999.99 millimeters or was negative. T Trace precipitation amount recorded 4.0 References For additional station information, refer to the station list provided as a seperate dataset in CODIAC.