SGP 1997 NCDC Summary of the Day Co-operative Dataset 1.0 General Description The National Climatic Data Center (NCDC) Summary of the Day Co-operative Dataset is one of several surface datasets provided for the Southern Great Plains (SGP) 1997 project. This NCDC Co-operative Observer (COOP) dataset contains data from sixty-two stations for the SGP 1997 time period (18 June 1997 through 18 July 1997) and in the SGP 1997 domain (approximately 97W to 99W longitude and 34.5N to 37N latitude). 2.0 Detailed Data Description The observations in this dataset are primarily those from the cooperative network, augmented by observations from principal observing stations operated by the National Weather Service (NWS) and other sites having highly trained observers. The primary thrust of the cooperative observing program today is the recording of 24-hour precipitation amounts, but approximately 55% of the stations also record maximum and minimum temperatures. The observations are for the 24-hr period ending at the time of observation. Observer convenience or special program needs mean that observing times vary from station to station. However, the vast majority of observations are taken near either 7:00 AM or 7:00 PM local time. Details of procedures and recording practices of the observers are documented in the "National Weather Service Observing Handbook No. 2". The daily observations were processed at the National Climatic Data Center (NCDC) using computerized editing procedures. The data were subjected to internal consistency checks, compared against climatological limits, checked serially, and evaluated against surrounding stations. Quality control flags were appended to each element to show how they fared during the edit procedures and to indicate what, if any, action was taken. The data then, consist of observed values and, as necessary, best guess estimates (NCDC, 1991). 2.1 Detailed Format Description The NCDC Summary of the Day Co-operative Dataset (TD-3200) contains eight metadata parameters and fifteen data parameters and flags. The metadata parameters describe the date/time, network, station and location at which the data were collected. All times are UTC. Data values are valid for the 24 hours preceding the time of observation. Table 1 below details the data parameters. The data parameters have two associated NCDC Quality Control (QC) Flags. A description of the possible QC flag values is listed in Tables 2 and 3. For general information regarding the NCDC Summary of the Day Co-operative data, refer to document "TD-3200 Summary of Day Co-operative" (NCDC, 1991). Table 1 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 Station Elevation Meters Maximum Temperature, QC1, QC2 flags Celsius Minimum Temperature, QC1, QC2 flags Celsius Total Snow Depth, QC1, QC2 flags Meters Total Precipitation, QC1, QC2 flags Millimeters Daily Snow Fall, QC1, QC2 flags Meters Table 2 QC1 flag value Description -------------- ----------- 0 Reserved 1 Accumulated amount since last measurement 2 Accumulated amount includes estimated value 3 Estimated 4 Value has been manually validated 5 Included in a subsequent value 6 Trace 7 Expert system edited not validated 8 Expert system approved edited value 9 Flag not needed 11-255 Reserved Table 3 QC2 flag value Description -------------- ----------- 0 Reserved 1 Valid data element 2 Valid data element from unknown source 3 Invalid data element replacement follows 4 Invalid data element no replacement follows 5 Validity unknown, not checked 6 Original value has been replaced by numeric value 7 Substituted TOBS for TMAX or TMIN 8 Time Shifted Value 9 Precipitation estimated by snowfall 10 Transposed digits 11 Changed units 12 Adjusted TMAX or TMIN by a multiple of + or - 10 degrees. 13 Changed algebraic sign 14 Moved decimal point 15 Rescaling other than 12, 13, or 14 16 Subjectively derived value 17 Extracted from an accumulated value 18 Switched to TMAX and or TMIN 19 Switched TOBS with TMAX or TMIN 20 Substitution of 3 nearest station mean 21 Switched snow and precipitation data value 22 Added snowfall to snow depth 23 Switched snowfall and snow depth 24 Precipitation not reported; estimated as "0" 25 Manually edited value 26 Failed internal consistency check 27 Failed areal consistency check (beginning Oct 92) 28-255 Reserved 2.2 Data Remarks The NCDC Co-operative Summary of the Day hour of observation varies by station. A value of -1.0 for snow fall or snow depth indicates a trace value was recorded. 3.0 Quality Control Processing Quality Control for this data was provided by NCDC. No additional QC was performed by University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS) on this dataset. 4.0 References National Climatic Data Center, 1991: Surface Land Daily Cooperative; Summary of the Day TD-3200. National Climatic Data Center, Asheville, NC, 25pp. NOAA, National Weather Service, 1989: National Weather Service Observing Handbook No. 2, Cooperative Station Observations. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service, Silver Spring, MD. 83 pp.