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  MADIS Meteorological Surface QC Summary Message Description

MADIS Meteorological Surface QC Summary Message Description


Overview

MADIS meteorological surface variables are quality-controlled by the Quality Control and Monitoring System, which collects statistics on observational errors encountered for NWS sea-level pressure, potential temperature, dewpoint, surface wind, and altimeter setting. The system provides the total number of observations for each variable, the number of observations that failed the QC checks, the station names for the failed observations, and the error and threshold values for each of the failed observations. The error is defined as the difference between the QC analysis value and the observed value, as computed in the spatial consistency check.

Statistics are calculated for all stations. Stations from different networks are kept statistically separate. Specifically, the following stratifications are maintained: "ASOS", "OTHER-MTR", (non-ASOS METARs), "MARITIME", "SAO", "CRN", "USHCN-M", and "NEPP". Mesonets are stratified by provider. For example, "MAP" for Multi-Agency Profiler. The statistics are available in the form of hourly QC messages. The following figure shows the MAP hourly message for 8 July 2004 at 1600 UTC.


             MAP HOURLY QUALITY CONTROL MESSAGE  (PAGE   1 OF   1)                        

  *********************************************************************************
  *  8-JUL-2004 *   SLP    * POT TEMP *  DEW PNT *    DD    *    FF    *   ALT    *
  *  1600 UTC   *   (MB)   * (DEG F)  *  (DEG F) *   (DEG)  *  (KNTS)  *   (MB)   *
  *********************************************************************************
  * TOTAL OBS   *      0   *      5   *      5   *      5   *      5   *      5   *
  *   QST OBS   *      0   *      1   *      0   *      0   *      0   *      5   *
  * PERCENT QST *   0.00   *  20.00   *   0.00   *   0.00   *   0.00   * 100.00   *
  *********************************************************************************
  *    ASTOR    *          *          *          *          *          *1007(   2)*
  *    CCDNH    *          *          *          *          *          *1002(   2)*
  *    CCOCA    *          *   7(   6)*          *          *          *1000(   4)*
  *    PSENH    *          *          *          *          *          *1002(   2)*
  *    PYMMA    *          *          *          *          *          *1002(   2)*
  *             *          *          *          *          *          *          *
  *             *          *          *          *          *          *          *
  *             *          *          *          *          *          *          *
  *             *          *          *          *          *          *          *
  *********************************************************************************
  ERROR = ANALYSIS - OBSERVATION            OB ERROR ( ERROR THRESHOLD )

Hourly QC message for Multi-Agency Profiler stations on 8 July 2004 at 1600 UTC. The stations listed had variables that were found bad by the spatial consistency check.

Statistics for the total number of observations ("TOTAL OBS"), the total number of observations that failed the QC checks ("QST OBS"), and the percentage of failed observations ("PERCENT QST") are given at the top of each page of the hourly message. "QST" represents "questionable" observations. Errors and threshold values for the failed observations are listed in the columns. In ASOS hourly messages, the stations are also stratified by NWS region.

Note that threshold values are not given for the surface wind errors in the above figure. Wind observations are tested by computing observation errors and threshold values for each of the u and v components of the wind. However, observation errors are converted to polar coordinates before display in the QC messages. If either of the u or v components fail, both direction and speed errors are computed.

Stations listed in the QC messages are either in error due to hardware or software failure, or are unrepresentative of the observation scale and, as such, are susceptible to diurnal, mesoscale, and terrain effects. To help distinguish between the two, daily, weekly, and monthly (4-week) summaries of the hourly QC messages are also provided. The summaries include the percentage of failed observations and the average error and rms error of the failed observations for individual stations and for all stations combined. The following figure shows the daily NOAA Profiler Network (NPN) QC message for 16 May 1997.


          NPN   DAILY QUALITY CONTROL MESSAGE (PAGE   1 OF   1)                

  *********************************************************************************
  *16-MAY-1997*   SLP    * POT TEMP *  DEW PNT *     DD     *    FF    *   ALT    *
  * 00-23 UTC *   (MB)   * (DEG F)  *  (DEG F) *    (DEG)   *  (KNTS)  *   (MB)   *
  *********************************************************************************
  * TOTAL OBS *    336   *    336   *    301   *     336    *    336   *     0    *
  *  QST OBS  *      0   *      0   *     11   *       0    *      0   *     0    *
  *PERCENT QST*   0.00   *   0.00   *   3.65   *    0.00    *   0.00   *  0.00    *
  *********************************************************************************
  *    PRCO2  *          *          *21/-20/ 85*            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *           *          *          *          *            *          *          *
  *********************************************************************************
  ERROR= ANALYSIS-OBSERVATION           RMS ERROR/MEAN ERROR/PERCENT QST

Daily QC message for NOAA Profiler Network (NPN) surface stations on 16 May 1997.

As with the hourly messages, all stations in the domain are used to calculate the statistics reported at the top of each page, but only stations that have failed the QC checks (at least once in the reporting period) are listed in the individual statistics. Stations with large percentages of failed observations are most likely experiencing hardware or software failures. For example, the QC message in the figure shows PRCO2 (Purcell, OK) as reporting bad dewpoint temperature observations 85% of the time. The rms errors for the station are also identical to the absolute value of the mean error, an indication that a persistent bias exists in the observations. The fact that the error is negative further indicates that the observations are biased high. With the information, the Profiler Control Center in Boulder was able to determine that the surface dewpoint sensor at Purcell had failed. The sensor has since been fixed, and the percentage of dewpoint observations failing the QC checks is back to zero.

Daily, weekly, and monthly summaries include only those stations with observations that have failed more than 25% of the time.


Last updated 16 June 2016