Whether the process has occured or not is indicated by the version number (1 is the one to use).
To show the progress of the data through the quality control the various variables will have an associated _q value (e.g. prcp_amnt and prcp_amnt_q). This _q value will have different values for each record.
NOTE: While the Met Office MIDAS system overwrites the existing entry in their database the BADC's MIDAS entries do not as we take snapshots of the the MIDAS database from time to time leading to duplicate entries occuring in our archive.
The _q value will have a number of possible values which relate to the form of quality control carried out on each value and these can be related to a look up table. This _q attribute is a five digit number (of the form MESQL), where each digit describes one aspect of the quality of a meteorological element.
| M | qc_marker | A combination of two flags to indicate accumulations, and/or a trace of rainfall |
| E | qc_estimate | Indicates 1 of up to 8 remarks about an estimate |
| S | qc_status | Indicates 1 of up to 8 possible descriptions of the value of the element (e.g. reason for suspecting a value) |
| Q | qc_query | Indicates 1 of up to 8 statements about the original value (e.g. a reason for correcting a data value) |
| L | qc_level | Indicates which of 10 possible stages of QC has been reached |
qc_marker (code_id 8021) when set, indicates a precipitation trace or an accumulated value (e.g. rainfall or maximum temperature over more than one day; maximum gust speed over more than one hour).
| 0 | NULL |
| 1 | Trace of precipitation |
| 2 | Accumulation |
| -2 | Accumulated trace of precipitation |
qc_estimate (code_id 8022) provides information about an estimated or corrected value. In this context an "estimate" is a value either derived by the QC teams where the observer or the automatic instrument has not provided a value, or has been provided retrospectively from the observing station after the original report was ingested with the element in question missing.
| 0 | Value is not an estimate or correction, or information on the estimate/correction is not available |
| 1 | Estimate/correction derived automatically from a program with no manual intervention |
| 2 | Estimate/corrected value has been set manually (with or without assistance from a program) |
| 3 | Estimate/correction has been obtained retrospectively from the observer/station |
| 4 | Precipitation estimate/correction has been derived from a snow/rain equivalence, or trace estimate/correction has been set for consistency with present weather |
| 5 | Correction has been obtained by changing units of measurement |
| 6 | Correction has been obtained by applying a systematic adjustment |
| 7 | Measurement impossible, because of snow, etc. |
qc_status (code_id 8023) indicates the status of the data value.
| 0 | Observed and not suspect |
| 1 | Observed and suspect (i.e. has failed the latest QC check), or there are strong grounds for suspecting the accuracy of the observation |
| 2 | An estimate where the original value is not available |
| 3 | An estimate where the original value is missing and cannot be retrieved |
| 4 | An unreliable estimate (used in radiation QC) |
| 5 | A correction (a reported value is assumed to be in error) |
| 6 | Value reverted to original |
| 7 | Original value verified by observer |
qc_query (code_id 8024) gives information about the original (as reported) value.
| 0 | Original value is/was not queried, or no information available |
| 1 | Failed SDB or MetDB QC check |
| 2 | Failed MIDAS validation |
| 3 | Failed climate QC marine position or movement check |
| 4 | Failed climate QC range check |
| 5 | Failed climate QC internal consistency check |
| 6 | Failed climate QC sequence check |
| 7 | Failed climate QC areal check |
qc_level (code_id 8025) indicates the climate QC stage reached. Level 0 - no processing; Level 9 - normal processing complete. The number of values between will vary with the element, and with time as QC procedures change. This item will not indicate the application or otherwise of MIDAS validation checks, nor whether visual checks of data have been carried out, e.g. of data on forms.
| 0 | Initial climate QC program not run |
| 1 | Initial climate QC program has run |
| 2 | Initial QC queries processed |
| 3 | Spare |
| 4 | Further range or internal consistency or sequence checks job(s) run and queries processed |
| 5 | Spare |
| 6 | Final (or only) areal or buddy job run and queries processed |
| 7 | Spare |
| 8 | Final (or only) monthly job(s) run and queries processed |
| 9 | Normal QC complete |
Basically the _q flag is made up of a number which has up to 5 digits. Each digit should be treated separately as each digit corresponds to a different part of the QC flagging (see above tables). Here the (up to) five digits correspond to the 5 letters of MESQL i.e. a value of just '1' correspondes to - - - - 1 i.e. 4 blanks and a 1 in the M E S Q L columns.
| NULL | |
| A | Not originally reported in 1949 codes |
| B | Nominal cloud height |
| C | Height measured |
| D | Amount originally measured in tenths |
| E | Amount is derived from METAR code NsNsNs |
| F | Values from LCBR (ix = 5, 6 or 7) |
| NULL | |
| A | Reading from autographic instrument |
| B | Amount due to dew, fog or frost |
| C | Amount due to snowfall |
| D | Rainfall converted from inches |
| E | Snow depth originally measured in inches |
| NULL | |
| A | Measured by barometer not calibrated in millibars, or from barograph |
| B | Measured in whole units |
| NULL | |
| A | Reading from autographic instrument |
| B | Original measured in degrees Fahrenheit |
| C | Original measured to nearest whole degree Fahrenheit |
| D | Original measured to nearest 0.5 degree Fahrenheit |
| E | Original measured to nearest whole degree Celsius |
| F | Original measured to nearest 0.5 degree Celsius |
| G | Iced Wetbulb (previously Spare) |
| H | Wet bulb not frozen, registering below 0.0 degrees Celsius |
| J | Wet bulb wick is assumed to have dried out |
| K | Wet bulb is derived from air temperature and dew point |
| L | Iced Wetbulb derived from air/dewpoint temp (previously Spare) |
| M | Aspirated |
| N | Aspirated and original in degrees Fahrenheit |
| P | Aspirated and original to nearest whole degree Fahrenheit |
| Q | Aspirated and original to nearest 0.5 degree Fahrenheit |
| R | Aspirated and original to nearest whole degree Celsius |
| S | Aspirated and original to nearest 0.5 degree Celsius |
| T | Max / min obtained from SAWS hourly values |
| U | Original temperature measured in 0.1 degrees F, and depth in inches |
| V | Original temperature measured in whole degrees F, and depth in inches |
| W | Original temperature measured in 0.1 degrees F, and depth at 24 inches |
| X | Original temperature measured in whole degrees F, and depth at 24 inches |
| Y | Original temperature measured in 0.1 degrees F, and depth at 48 inches |
| Z | Original temperature measured in whole degrees F, and depth at 48 inches |
| NULL | |
| A | Measured rather than estimated |
Weather (past and present) (code_id 8012)
| NULL | |
| A | Derived from "AB" codes |
| B | Present weather is derived from code 4680 |
| C | Present weather is derived from code 4678 |
Speed / Direction (code_id 8013)
| NULL | |
| A | Speed originally estimated in metres/sec |
| B | Speed originally estimated in knots |
| C | Speed originally measured in metres/sec |
| D | Speed originally measured in knots |
| E | Speed originally measured in miles per hour |
| F | Converted from kilometres to whole knots |
| G | Mean wind derived from run of wind - unspecified units |
| H | Mean wind derived from run of wind, converted from kilometres to whole knots |
| J | Direction converted from 8 point compass |
| K | Direction converted from 16 point compass |
| L | Direction converted from 32 point compass |
| M | Speed originally Beaufort scale |
| NULL | |
| A | Stationary |
| B | Position reported to within 30 minutes |
| C | Position reported to within 10 minutes |
| D | Position reported to within 5 minutes |
| E | Position reported from dead reckoning from previous position |
| F | OWS not in area |
| G | Observation time calculated from Local Apparent Time |