GCIP LSA-E EAOP 1999 Fifteen Minute Precipitation Composite 1.0 General Description The Fifteen Minute Precipitation Composite is one of several precipitation datasets provided for the GEWEX Continental-Scale International Project (GCIP) Enhanced Annual Observing Period East (EAOP-E) 1999. This precipitation composite contains one data source (i.e., National Climatic Data Center (NCDC) Fifteen Minute Precipitation data (TD 3260)). Data from this source was quality controlled. This composite contains data for the EAOP-E 1999 domain and time period (01 October 1998 through 30 Sep 1999). The EAOP-E 1999 domain is approximately 76W to 90W longitude and 33N to 43N latitude. 2.0 Detailed Data Description 2.0.1 NCDC Fifteen Minute Precipitation Algorithms The NCDC Fifteen Minute Precipitation dataset (TD 3260) is formed by retaining both incremental and accumulative precipitation values from the raw precipitation data. Both incremental and accumulative values are contained in the EAOP-E 1999 15-minute precipitation composite. If an accumulation period began prior to but continued into the beginning of the EAOP-E 1999 time period, the precipitation values in that accumulation period were reset to missing values. An accumulation period that began near the end of the EAOP-E 1999 time period, but continued after the end of the EAOP-E 1999 time period would also have its precipitation values reset to missing. 2.1 Detailed Format Description The EAOP-E 1999 Fifteen Minute Precipitation Composite contains seven metadata parameters and three data parameters. The metadata parameters describe the date/time, network, station and location at which the data were collected. The three data parameters repeat once for each fifteen minutes from UTC 0000 through UTC hour 2345. Data reported for a designated 15-minute observation represents data collected during the previous 15-minutes. 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 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 15 Minute Precip Value Millimeters Quality Flag See list of Definitions QC Code See list of Definitions 2.2 Data Remarks None. 3.0 Quality Control Processing This precipitation composite contains one dataset (i.e., NCDC Fifteen Minute Precipitation data (TD 3260)). This dataset was Quality Controlled using the gross limit check method. Gross limit checks were used to determine the quality of the data in the EAOP-E 1999 Fifteen Minute Precipitation Composite. Data values less than 8 millimeters were flagged as good. Any data value greater than or equal to 8 millimeters but less than 18 millimeters was flagged as questionable. Any data value greater than or equal to 18 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 based on an isohyet analysis. The data were never changed, only flagged. Tables 1 and 2 contain the quality control flags and codes, 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 National Climatic Data center, 1986: 15 Minute Precipitation Data TD 3260. National Climatic Data Center, Asheville, NC, 19 pp.