QC1-3 STEP CHECK

Gabriel Kielland

Controlling that the observation has a reasonable time development untill the time of observation.

There are three different checks

1. Step check;
2. Check on frozen value;
3. Dip check.

Only meteorological parameters with continuous observation values is controlled.

In the step check comparison between the present values and the previous one results in an error flag when the difference equals or exceeds the parameter specific threshold.

In the check on frozen value error flags is attributed when the observation value is repeated in excess of the number of times specified for the parameter.

The dip check is the QC2d-1 check. The error flag is attributed when the difference between the present values and the previous one plus the difference between the present values and the next one exceeds the parameter specific threshold.

Working examples:

1. Whenever a wind speed value is controlled, the latest prior value available observed during the previous 120 minutes (scaleable) is considered for step comparison. If the difference between the present and the prior value exceedes 40 m/s (scaleable) both values are flagged.
2. Whenever a wind speed value is controlled, all prior values available observed during the previous 900 minutes (scaleable) is considered for frozen value comparison. If there are less than 5 values (scaleable) available the control aborts. If the variation between the 5 latest values is less than 0.01 m/s the present value is flagged.

Last modified: Fri Dec 3 16:59:00 GMT 2004