Shawn R. Smith
WOCE Surface Meteorology DAC
Center for Ocean Atmospheric Prediction Studies
Florida State University
The quality control flags are single alphabetic characters that
indicate the quality for each specific data 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:
| Flag | Definition |
| A |
Original data had unknown units. The units shown were determined using a climatology or some other method. |
| B | Original data were out of the range bounds outlined (Table 1). |
| C | Time data are not sequential or date/time not valid. |
| D |
Data failed T>=Tw>=Td test. In the free atmosphere, the value of the temperature is always greater than or equal to the wet-bulb temperature, which in turn is always greater than or equal to the dew point temperature. |
| E |
Data failed resultant wind recomputation check. When the data set includes the platform's heading, course, and speed along with the platform relative wind speed and direction, a program recomputes the earth relative wind speed and direction and compares the computed values to the reported earth relative wind speed and direction. A failed test occurs when the wind direction difference is > 20 degrees or the wind speed difference is > 2.5 m/s. |
| F |
Platform velocity unrealistic. Determined by analyzing latitude and longitude positions as well as reported platform speed data. |
| G |
Data are greater than 4 standard deviations from the COADS climatological means (da Silva et al. 1994). The test is only applied to pressure, temperature, sea 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 passes over land or fixed platform moves dramatically. |
| M | Known instrument malfunction. |
| O |
Original units differ from those listed in the convers_units variable attribute. See quality control report for details. |
| P | Position of platform or its movement are uncertain. Data should be used with caution. |
| Q | Questionable - data arrived at DAC already flagged as questionable/uncertain. |
| R |
Replaced with an interpolated value. Often done prior to arrival at the DAC. Flag is used to note condition. |
| S |
Spike in the data. Usually one or two sequential 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 | Time duplicate |
| Z | Data passed evaluation. |
Table 1: Range Bounds used in determining the use of flag B.
| Variable |
Lower Bound |
Upper Bound |
Units |
Other |
| time |
1-1-1980 |
12-31-2020 |
|
|
| latitude |
-90 |
90 |
degrees |
|
| longitude |
0 |
359.99 |
degrees E |
|
| platform heading |
0 |
359.9 |
degrees |
|
| platform course |
0 |
359.9 |
degrees |
|
| platform speed |
0 |
15 |
m/s |
research vessels |
| wind direction |
0 |
360 |
degrees |
|
| wind speed |
0 |
40 |
m/s |
|
| pressure |
950 |
1050 |
mb |
Sea level |
| air temperature |
-10 |
40 |
degree C |
|
| wet bulb temperature |
-10 |
40 |
degree C |
|
| dew point temperature |
-10 |
40 |
degree C |
|
| sea temperature |
0 |
35 |
degree C |
|
| relative humidity |
0 |
100 |
percent |
|
| specific humidity |
0 |
48 |
g/kg |
|
| rain rate |
0 |
150 |
mm/hr |
|
| radiation |
0 |
1400 |
W/m2 |
|
Reference:
da Silva, A. M., C. C. Young, and S. Levitus, 1994: Atlas of Surface
Marine Data, Volume 1: Algorithms and Procedures. NOAA Atlas Series. In
press.