| PK | Attribute | Description / Units |
| * | id | |
| * | id_type | Identifier type |
| * | ob_time | Date and time of observation |
| * | met_domain_name | Message type |
| src_id | Unique source identifier or station site number | |
| wmo_region_code | '1' - '7' '1' Africa; '2' Asia; '3' South America; '4' North and Central America; '5' South-west Pacific; '6' Europe; '7' Antarctic |
|
| rec_st_ind | State Indicator for the record** | |
| wind_direction | Degs true | |
| wind_speed | Knots | |
| prst_wx_id | Present weather code | |
| past_wx_id_1 | Past weather code #1 | |
| past_wx_id_2 | Past weather code #2 | |
| cld_ttl_amt_id | Total cloud amount code oktas |
|
| cld_base_amt_id | Cloud base amount code | |
| cld_base_ht | Cloud base height code decametres |
|
| low_cld_type_id | Low cloud type code | |
| med_cld_type_id | Medium cloud type code | |
| hi_cld_type_id | High cloud type code | |
| wind_speed_unit_id | Wind speed unit code describes how the wind reading was made and what units it was stored in (before converted to knots in MIDAS). | |
| visibility | Decametres (Visibility unit information in the MIDAS User guide) | |
| air_temperature | Surface air temperature 0.1 deg C |
|
| wetb_temp | Wet bulb temperature 0.1 deg C | |
| dewpoint | Dewpoint temperature 0.1 deg C |
|
| stn_pres | Station air pressure 0.1 hpa |
|
| pres_sfc | Pressure surface | |
| pres_sfc_ht | Height of pressure surface | |
| msl_pressure | Mean sea level air pressure 0.1 hpa |
|
| pres_tdcy_amt | Air pressure tendency | |
| prcp_ob_hr_cnt | Precipitation hour count | |
| prcp_amt | Precipitation amount millimetres |
|
| cld_amt_id_1 | Layer cloud amount code #1 | |
| cloud_type_id_1 | Cloud type code #1 | |
| cld_base_ht_id_1 | Cloud base height code #1 decametres |
|
| cld_amt_id_2 | Layer cloud amount code #2 | |
| cloud_type_id_2 | Cloud type code #2 | |
| cld_base_ht_it_2 | Cloud base height code #2 decametres |
|
| cld_amt_id_3 | Layer cloud amount code #3 | |
| cloud_type_id_3 | Cloud type code #3 | |
| cld_base_ht_id_3 | Cloud base height code #3 decametres |
|
| max_air_temp | Maximum air temperature. The period of maximum and minimum temperatures are defined by WMO Regional Reporting Practices. | |
| min_air_temp | Minimum air temperature. The period of maximum and minimum temperatures are defined by WMO Regional Reporting Practices. | |
| ground_state_id | Ground state id | |
| min_grss_temp | Grass temperature | |
| snow_depth | Snow depth | |
| sun_ob_hr_cnt | Sunshine observation hour count | |
| sun_dur | Sunshine duration | |
| q24hr_prcp_amt | 24hr precipitation amount millimetres |
|
| q24hr_pres_tdcy_amt | 24hr air pressure tendency | |
| vert_vsby | Vertical visibility decametres |
|
| src_opr_type | Source operation type code - refers to whether the observation is manual or automatic 1 = Manned Observation, 7 group included in observation 2 = Manned Observation, 7 group omitted (no significant weather) 3 = Manned Observation, 7 group omitted (not observed, not available) 4 = Automatic Observation, 7 group included (code taken from WMO table 4677) 5 = Automatic Observation, 7 group omitted (no significant weather) 6 = Automatic Observation, 7 group omitted (not observed, not available) 7 = Automatic Observation, 7 group included (code taken from WMO table 4677) Code 2 shoudl be used when present weather code is 00,01,02,03 AND past weather code is 00,11,22. |
|
| gust_spd_type_code | Gust speed type code 0 = 10 minute gust 1 = As past weather, etc. See 910 - 914 of code 3778 in WMO documentation |
|
| max_gust_speed | Maximum gust speed | |
| runway_name | Runway name | |
| rnwy_vis_rnge | Runway visual range | |
| alt_pres | Altimeter pressure 0.1 hpa |
|
| qc_flag_list_1 | QC bit flags for 9 specified items - please see note below for details. | |
| qc_flag_list_2 | Please see note below for details. | |
| MIDAS Version Number | (from 2016-11-01) Please see MIDAS Version Number note below for details. |
NOTES:
The Met Office MIDAS Team is not responsible for the quality of the global weather data. This data is not flagged in the same way that data from the weather hrly and temp drnl tables etc would be flagged. In these tables the data is flagged by element but in the global weather table it is not as simple.
QC flag list 1 gives a bit flag for the following 15 values listed:
pres_tdcy, prcp_amt, cld_amt_id_1, cloud_type_id_1, cld_base_ht_id_1, cld_amt_id_2, cloud_type_id_2, cld_base_ht_id_2, cld_amt_id_3, cloud_type_id_3, cld_base_ht_id_3, max_air_temp, min_air_temp, q24hr_prcp_amt, q24hr_pres_tdcy_amt
QC flag list 2 gives a bit flag for the following 16 values listed:
wind_speed_unit_id, wind_speed, wind_direction, prst_wx_id, past_wx_id_1, past_wx_id_2, cld_ttl_amt_id, cld_base_amt_id, cld_base_ht, low_cld_type_id, med_cld_type_id, hi_cld_type_id, visibility, air_temperature, dewpoint, msl_pressure
The bit flag is based on a binary number generated from the 16 different bit sets shown below:
Bit set Description
0 (0) MetDB quality control performed
1 (1) Data correction performed 1 = performed
2 (2) MetDB suspect flag. MetDB flag=tendency flag)
3 (4) Spare
4 (8) MetDB hydrostatic check performed
5 (16) MetDB interpolation check performed
6 (32) MetDB substitution/correction applied
7 (64) spare
8 (128) rejected by forecasters (1=rejected)
9 (256) spare
10 (512) used in assimilation
11 (1024) checked by model quality control (at least
background check)(1=not checked)
12 (2048) A priori rejection (rejected prior to knowledge of observed value; i.e. permanent rejection or deactivation)
13 (4096) model mode 1 quality control flag (background check)
14 (8192) model mode 2 quality control flag ('buddy' check)
15 (16384) model final quality control flag
*binary number in brackets
The QC flag number found in MIDAS could just correspond to one flag or multiple flags (ie bit set 5 (16) and bit set 6 (32)) which would equal 48. However this is just for the whole observation and does not specify which of the elements have caused these flags to be set. If any of bits 13 to 15 have flags set then this indicates that the observation has failed the quality control check.
MIDAS Version Number (from 2016-11-01):
From 1st November 2016 the number of columns increased to 58 following the addition of a 'version' number for the global weather data held within MIDAS. This follows some additional QC checks carried out within the MIDAS system that were introduced at this time. When data first arrive within the MIDAS system they are given a version number '1'. Subsequentally, the version number 0 is used for a data line which denotes that QC has happened within the MIDAS system and an adjustment to the orignial data line has been made. The original data line is stored with a version number 0 and the amended line with version 1. Thus, only those lines with a version 0 can be taken has having had MIDAS QC run on them and the associated version 1 line is the updated value. Where only a version 1 line exists this may either be before MIDAS system QC has been run on the data or that it has run and no issued have been found with the data.
| Element | Condition | Value to be set to V0 | Value to be set to V0 |
| Air temperature* | air temp > +60 or <-70 | Air temperature | |
| Dewpoint* | dewpoint > +60 or <-70 | Wetbulb | Dewpoint |
| Max air temp* | max air temp > +60 or <-70 | Max air temp | |
| Min air temp* | min air temp > +60 or <-70 | Min air temp | |
| Wind direction | wind direction > 360 | Wind speed | Wind direction |
| Dewpoint | Dewpoint > air temperature | Wetbulb | Dewpoint |
| Present weather | wx & total cloud when wx between 50 and 75 ,80 & 99 and ttl cloud = 0 | Total cloud | |
| Present weather | Past weather 2 is greater than past weather 1 | Past weather 1 | Past weather 2 |