Section 2.0 contains a detailed description of the instrumentation, siting, and algorithms used by the source network to collect the data. Section 2.1 contains a detailed description of the format of the composite dataset. Please review Section 2.2 for information on data processing, and for specific issues that affect the data. See Section 3.0 below for the quality control processing performed by the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS) on this dataset. Section 4.0 contains references.
Data from cooperators networks such as NCEP/EMC has hundreds of reporting locations which change from incremental to accumulator and back to incremental. Others changed a couple of times and have now settled on accumulators.
Anyone using this data must be aware of the dynamic changes in the network of sites that are processed by HADS and be aware of the potential lag time from when a change is implemented to when NCEP/EMC becomes aware of the change. This is far, far from a stable environment.
To help users in identifying these changes, UCAR/JOSS checks the NCEP/EMC 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/EMC 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.
Due to a coding error in the conversion of the LDMSFCMETR data to QCF format, the record for the last hour of the last day an LDMSFCMETR station reported during the BAMEX time of interest was inadvertently deleted. As most LDMSFCMETR stations report for the entire BAMEX TOI, most of these missing records occur on July 6, 2003. A total of 783 records were deleted (one for each LDMSFCMETR station). As the LDMSFCMETR hourly precipitation was extracted from the LDMSFCMETR hourly surface data, the last hourly precipitation value for each LDMSFCMETR station is missing from this BAMEX 2003 Precipitation (Hourly) Multi-Network Composite. This bug affects the BAMEX 2003 Surface Meteorological (Hourly) Multi-Network Composite (but NOT the BAMEX 2003 Surface Meteorological (Miscellaneous) Multi-Network Composite), and thus the BAMEX 2003 Precipitation (Hourly) Multi-Network Composite and BAMEX 2003 Precipitation (Daily) Multi-Network Composite as well.
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
UCAR/JOSS checks the NCEP/EMC 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/EMC network to "questionable". For more information on the quality control performed on this network by UCAR/JOSS, please see section 3.0 below.
Due to a coding error in the conversion of the LDMSFCMETR data to QCF format, the record for the last hour of the last day an LDMSFCMETR station reported during the BAMEX time of interest was inadvertently deleted. As most LDMSFCMETR stations report for the entire BAMEX TOI, most of these missing records occur on July 6, 2003. A total of 783 records were deleted (one for each LDMSFCMETR station). As the LDMSFCMETR hourly precipitation was extracted from the LDMSFCMETR hourly surface data, the last hourly precipitation value for each LDMSFCMETR station is missing from this BAMEX 2003 Precipitation (Hourly) Multi-Network Composite. This bug affects the BAMEX 2003 Surface Meteorological (Hourly) Multi-Network Composite (but NOT the BAMEX 2003 Surface Meteorological (Miscellaneous) Multi-Network Composite), and thus the BAMEX 2003 Precipitation (Hourly) Multi-Network Composite and BAMEX 2003 Precipitation (Daily) Multi-Network Composite as well.
Gross limit checks were used to determine the quality of the data in the BAMEX 2003 Hourly Precipitation Composite. 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. 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. UCAR/JOSS checks the NCEP/EMC 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/EMC 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 flags and codes, respectively. After the datasets were merged to form the BAMEX 2003 Hourly Precipitation Composite, a statistics program was executed to ensure that the quality of the individual datasets had been retained.
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.