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Argo Real-time Quality Control Process NOAA/AOML: Y.-H. DANESHZADEH, R. MOLINARI, R. SABINA, C. SCHMID CIMAS/UM: E. FORTEZA, X. XIA, H. YANG
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Guiding Philosophy of the international real-time DACs PROVIDE TO THE INTERNATIONAL OPERATIONAL AND RESEARCH OCEANIC COMMUNITIES PROFILES OF TEMPERATURE AND SALINITY RESULTING FROM ARGO FLOATS THAT MEET THE FOLLOWING CRITERIA: DATA HAVE BEEN MANAGED IN A UNIFORM MANNER DATA ARE FREE DATA ARE READILY ACCESSIBLE DATA ARE AVAILABLE WITHIN A TIMELY MANNER DATA HAVE BEEN QUALITY CONTROLLED TO REMOVE THE MOST EGREGIOUS ERRORS COST OF REAL TIME QUALITY CONTROL IS REASONABLE
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Number of profiles quality controlled per year
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Positions of the floats that have delivered data within the last 30 days Atlantic Data Coverage
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How an Argo float works
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Data flow
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Real-time processing system
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Delayed-mode processing system
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Automatic quality control 1.Platform Identification 2.Impossible Date (valid & not before 1997) 3.Impossible Location (-180 to 180, -90 to 90) 4.Position on Land (ETOPO5) 5.Impossible Speed (<=3m/s) 6.Global Range (-2.5 to 40C, 0 to 41 psu) 7.Regional Range (Red Sea, Mediterranean Sea) 8.Pressure Increasing 9.Spike (| V2 - (V3 + V1)/2 | - | (V3 - V1) / 2 ) Documents are at http://www.ifremer.fr/coriolis/cdc/argo_rfc.htm
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Regional Range tests, definitions Red Sea Temperature in range 21.7 to 40.0 o C Salinity in range 0.0 to 41.0 Mediterranean Sea Temperature in range 10.0 to 40 o C Salinity in range 0.0 to 40.0
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temperature Spike test examples Multiple-value spikes can be a problem. level temperature salinity
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Automatic quality control 10.Top and Bottom Spike (no top spike test, bottom spike test currently under development) 11.Gradient (| V2 - (V3 + V1)/2 |) 12.Digit Rollover test (part of decoders) 13.Stuck Value (e.g. all values of T the same) 14.Density Inversion (gradient must be >=0) 15.Grey List (decided by PI & Operator) 16.Gross Salinity or Temperature Sensor Drift Test (checks if values in the deep ocean change too much, dT >1 o C, dS >0.5 psu) Documents are at http://www.ifremer.fr/coriolis/cdc/argo_rfc.htm
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Bottom spike examples Currently no test is available to detect this problem.
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Gradient test examples If spikes are not excluded prior to application, then the test may flag some good points as bad. salinity level
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Density inversion test examples Flags wrong point because of three bad values around a good one. Current version: top to bottom.
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Density inversion test examples One flag at wrong point because of three bad values around a good one. New version: top to bottom and bottom to top.
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Automatic quality control 17.Visual QC: at AOML currently triggered by failure of any of the other tests on the profile data (except for grey list test). Additionally triggered by climatology/reanalysis test. 18.Frozen profile (>=5 almost identical consecutive profiles). 19.Deepest pressure test: pressure may not exceed nominal profile pressure given in the meta file by more than 10%. Documents are at http://www.ifremer.fr/coriolis/cdc/argo_rfc.htm
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Visual quality control Two cases of bad profiles that can not be detected by the standard Argo QC tests. For these a climatology test that triggers a visual QC can be very helpful. level temperature salinity
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Blue circles indicate that T (top) or S (bottom) failed the test. Results of frozen profile test Profile number pressure
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Quality control statistics
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http://www.aoml.noaa.gov/phod/ARGO/HomePage US Argo DAC web page at AOML
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