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--- kvalobs:kvalobs:qc13 [2019-06-11 13:45:56]
bjornn
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-====== QC1-3 ======
-There are three different checks
-  -Step check;
-  -Freeze check;
-  -Dip check.
-Only meteorological parameters with continuous observation values is controlled.
-==== QC1-3 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.
-Step-Up and Step-Down Check. \\
-This is a subroutine in Kvalobs check category QC1-3 that is to be found in a metadata table named: algorithms. \\
-kvQabase (in real time use as a daemon) is running this STEP_CHECK. \\
-This algorithm find the time resolution in the data to be checked. If the time resolution is not between 1 and 60 minutes it will jump out. \\
-Checking if the (absolute value) difference between the present value ($X[0]) and the previous value ($X[1]) exceeds threshold values. \\
-Operating with 2 sets of threshold values, one (high) put fs-flag to 2 and the other (max) to 8, if threshold values are exceeded. \\
-See the source code in:\\
-https://gitlab.met.no/obs/kvalobs/kvoss_intern/blob/master/kvmeta/algorithms/STEP_CHECK.pl
-==== QC1-3 FREEZE CHECK ====
-Error flags is attributed when the observation value is repeated in excess of the timeperiod specified for the parameter.
-See the source code in:\\
-https://gitlab.met.no/obs/kvalobs/kvoss_intern/blob/master/kvmeta/algorithms/FREEZE_CHECK.pl
-==== QC1-3 DIP 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.
-See the source code in:\\
-https://gitlab.met.no/obs/kvalobs/kvoss_intern/blob/master/kvmeta/algorithms/DIP_CHECK.pl
-Working examples:
-  -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.
-  -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.