Outline of Quality Control Flags

                               Shawn R. Smith
                        WOCE Surface Meteorology DAC
               Center for Ocean Atmospheric Prediction Studies
                          Florida State University

The quality control flags are single alphabetic characters for each data
value indicating quality of that specific value. Only those variables with a
qcindex have flag values (the qcindex is an integer pointer to the flag for
a selected variable). The flags are:

     A Original data had unknown units. The units indicated were
       determined using a climatology or other method.

     B Original data was out of the range bounds outlined (Table 1).

     C Time data are not sequential or date/time not valid.

     D Data failed TłTwłTd test.

     E Data failed resultant wind recomputation check. When the
       original data set includes the platform's speed and direction
       along with the platform relative wind speed and direction,
       recomputed earth relative wind speed and direction and compared to
       the reported earth relative wind speed and direction. A failed
       test occurs when the wind direction difference is > 10 degrees
       or the wind speed difference is >5 m/s.

     F Platform velocity unrealistic. Determined by platform position
       and speed data.

     G Data are greater than 4 standard deviations from the monthly
       climatological means in the da Silva et al. (1994) COADS
       climatology. The test is only applied to pressure, temperature,
       sea surface temperature, relative humidity, and wind speed data.

     H Discontinuity found in data

     I Interesting feature found in data. More specific information on
       the feature is contained in the data reports. Examples include:
       hurricanes passing station, sharp sea water temperature gradients,
       strong convective events, etc.

     J Data are of poor quality by visual inspection, DO NOT USE.

     K Data suspect/use with caution - this flag applies when the data
       look to have obvious errors, but no specific reason for the error
       can be determined.

     L Oceanographic platform passed over land/fixed platform moves
       dramatically.

     M Known instrument malfunction.

     N Flag currently not used.

     O Flag currently not used.

     P Position of platform or its movement are uncertain. Data should
       be used with caution.

     Q Flag currently not used.

     R Flag currently not used.

     S Spike in the data. Usually one or two data values (sometimes up to
       4 values) that are drastically out of the current data trend. 
       Spikes occur for many reasons including power surges, typos, data 
       logging problems, lightning strikes, etc.

     T Flag currently not used.

     U Flag currently not used.

     V Flag currently not used.

     W Flag currently not used.

     X Flag currently not used.

     Y Flag currently not used.

     Z Data passed evaluation

     Table 1: Range Bounds For Determining Use of Flag 'B'

     Variable                Lower Bound     Upper Bound     Units   Other
     ---------------------------------------------------------------------

     time                    1-1-1980        12-31-1999
     latitude                -90             90              degrees
     longitude               0               359             degrees
     platform heading        0               359             degrees
     platform speed          0               15              m/s     research vessels
                             0               0               m/s     stationary buoys
                             0               2               m/s     drifters
     plat. wind direction    0               360             degrees
     plat. wind speed        0               40              m/s
     wind direction          0               360             degrees
     wind speed              0               40              m/s
     pressure                950             1050            mb      Sea level
     air temperature         -10             40              deg Celsius
     wet bulb temperature    -10             40              deg Celsius
     dew point temperature   -10             40              deg Celsius
     sea temperature         0               35              deg Celsius
     relative humidity       0               100             percent
     radiation               0               1400            W/m2

     Reference:

     da Silva, A. M., C. C. Young, and S. Levitus, 1994: Atlas of
     Surface Marine Data, Volumes 1: Algorithms and Procedures. NOAA
     Atlas Series. In press.