UK Hourly Weather data - Columns in the WH table


Table Description - Columns in the WH table - How to start filtering the rows of data out Additional Notes


The surface observation data are in a simple ASCII format.

Table Description:

This entity contains SYNOPs and METARs measured during the hour ending at the stated date and time. The identifier is climatological station number, DCNN or WMO station number, or ICAO-id. It also contains sunshine duration measured during the hour ending at the specified time. Hourly sunshine is reported using Metform 3445, and the value is reported as "hour beginning". The MIDAS ingestion software makes the necessary transformation so that the observations are stored at "hour ending", consistent with other hourly data.

Columns in the WH table (104 parameters from 2010, 102 parameters before 2010):

For the convenience of users, the 104 WH file column headers are available for download in Excel or as a comma separated text file

PK Attribute Description / Units / Precision
* ob_time Date and time of observation
* id  
* id_type Identifier type
* met_domain_name Message type
* version_num Observation version number - Use the row with '1', as this has been quality checked by the Met Office
  src_id Unique source identifier or station site number
  rec_st_ind State indicator for the record**
  wind_speed_unit_id Wind speed unit code
  src_opr_type Source operation type code - 1 is for a manual observation; 7 is for an automatic observation.
  wind_direction Wind direction from which the wind blows, measured in Degrees (true). The entry for an east wind is 090, that for a south wind is 180 and so on clockwise. Note that zero values in both wind speec and wind direction fields indicate that there was no wind blowing at the time of observation. More
  wind_speed Wind speed
knots. Wind mast elevations from selected stations are available here (MIDAS users only).
  prst_wx_id Present weather code - definition
Important Note: Check the src_opr_type value to determine the type of observation amade (Manual or Automatic). When there is a 1 in the src_opr_type column this is a manual observation where the present weather has been included and reported using WMO table 4677. If there is a 7 in the src_opr_type column then this is an automatic observation reported using code from WMO table 4680.
  past_wx_id_1 Past weather code #1 - This is a number between 0-9 which details what the weather has been like in the last 6 hours for observations at 00, 06, 12, 1800 UTC, the last 3 hours for observations at 03, 09, 15, 2100 UTC and the previous hour at any other times. The past weather is only recorded when a manual observation is done at the station. definition
  past_wx_id_2 Past weather code #2 - Same principle as above but is used to cover two codes or just one code occurring throughout the appropriate period. If more than 2 codes apply for the period then the 2 highest are used. So for example if it rained for a whole hour at the 1000 UTC ob then the code would be 66. If there was rain and drizzle during the period it would be 65 and if cloud was covering more than half the sky during the period it would be 22. The past weather is always coded as two digits which are separated into id_1 and id_2 in MIDAS. definition
  cld_ttl_amt_id Total cloud amount code - definition
oktas
  low_cld_type_id Low cloud type code - definition
  med_cld_type_id Medium cloud type code - definition
  hi_cld_type_id High cloud type code - definition
  cld_base_amt_id Cloud base amount code - definition
  cld_base_ht Cloud base height
decametres
  visibility Visibility
decametres
  msl_pressure Mean sea level air pressure
Unit=1 hpa to the nearest 0.1 hpa
Precision aneroid barometers are now in general use for measuring pressure and a correction for altitude is applied to obtain the value at mean sea level (MSL). Please see additional notes below.
  cld_amt_id_1 Layer cloud amount code #1 - definition
  cloud_type_id_1 Cloud type code #1 - definition
  cld_base_ht_id_1 Cloud base height code #1
decametres
  cld_amt_id_2 Layer cloud amount code #2 - definition
  cloud_type_id_2 Cloud type code #2 - definition
  cld_base_ht_id_2 Cloud base height code #2
decametres
  cld_amt_id_3 Layer cloud amount code #3 - definition
  cloud_type_id_3 Cloud type code #3 - definition
  cld_base_ht_id_3 Cloud base height code #3
decametres
  cld_amt_id_4 Layer cloud amount code #4 - definition
  cloud_type_id_4 Cloud type code #4 - definition
  cld_base_ht_id_4 Cloud base height code #4
decametres
  vert_vsby Vertical visibility
decametres
  air_temperature Air temperature
Unit=1 deg C to the nearest 0.1 deg C
  dewpoint Dewpoint temperature - is the temperature to which the air must be cooled to produce saturation with respect to water at its existing atmospheric pressure and humidity - more...
Unit=1 deg C to the nearest 0.1 deg C
  wetb_temp Wet bulb temperature - is the lowest temperature that can be obtained by evaporating water into the air. It measures the humidity of the air - more...
Unit=1 deg C to the nearest 0.1 deg C
  stn_pres Station air pressure
Atmospheric pressure as measured at the station level. Correction for altitude is not applied.
Unit=1 hpa to the nearest 0.1 hpa. Please see Additional notes below.
  alt_pres Altimeter pressure
Unit=1 hpa to the nearest 0.1 hpa. Please see Additional notes below.
  ground_state_id Ground state code
  q10mnt_mxgst_spd 10 minute maximum gust speed
knots
  cavok_flag cavok flag
  cs_hr_sun_dur Campbell-Stokes hour sunshine duration - This gives the hourly readings taken from the old Campbell Stokes Recorder
  wmo_hr_sun_dur This gives the readings from the newer automatic sun sensor which has now replaced the Campbell Stokes Recorder. See list of UK stations recording sun hour data
  wind_direction_q QC code - wind direction**
  wind_speed_q QC code - wind speed**
  prst_wx_id_q QC code - present weather code**
  past_wx_id_1_q QC code - past weather code #1**
  past_wx_id_2_q QC code - past weather code #2**
  cld_ttl_amt_id_q QC code - cloud total amount**
  low_cld_type_id_q QC code - low cloud type code**
  med_cld_type_id_q QC code - medium cloud type code**
  hi_cld_type_id_q QC code - high cloud type code**
  cld_base_amt_id_q QC code - cloud base amount**
  cld_base_ht_q QC code - cloud base height**
  visibility_q QC code - visibility**
  msl_pressure_q QC code - msl pressure**
  air_temperature_q QC code - air temperature**
  dewpoint_q QC code - dewpoint**
  wetb_temp_q QC code - wet bulb**
  ground_state_id_q QC code - ground state code**
  cld_amt_id_1_q QC code - layer cloud amount #1**
  cloud_type_id_1_q QC code - cloud type code #1**
  cld_base_ht_id_1_q QC code - cloud base ht code #1**
  cld_amt_id_2_q QC code - layer cloud amount #2**
  cloud_type_id_2_q QC code - cloud type code #2**
  cld_base_ht_id_2_q QC code - cloud base ht code #2**
  cld_amt_id_3_q QC code - layer cloud amount #3**
  cloud_type_id_3_q QC code - cloud type code #3**
  cld_base_ht_id_3_q QC code - cloud base ht code #3**
  cld_amt_id_4_q QC code - layer cloud amount #4**
  cloud_type_id_4_q QC code - cloud type code #4**
  cld_base_ht_id_4_q QC code - cloud base ht code #4**
  vert_vsby_q QC code - vertical visibility**
  stn_pres_q QC code - station pressure**
  alt_pres_q QC code - altimeter pressure**
  q10mnt_mxgst_spd_q QC code - 10 min max gust speed**
  cs_hr_sun_dur_q  
  wmo_hr_sun_dur_q  
  meto_stmp_time Met Office receipt stamp time
  midas_stmp_etime Elapsed time to storage in MIDAS
minutes
  wind_direction_j Descriptor - wind direction**
  wind_speed_j Descriptor - wind speed**
  prst_wx_id_j Descriptor - present weather**
  past_wx_id_1_j Descriptor - past weather #1**
  past_wx_id_2_j Descriptor - past weather #2**
  cld_amt_id_j Descriptor - cloud total amt**
  cld_ht_j Descriptor - cloud base ht**
  visibility_j Descriptor - visibility**
  msl_pressure_j Descriptor - msl pressure**
  air_temperature_j Descriptor - air temperature**
  dewpoint_j Descriptor - dewpoint**
  wetb_temp_j Descriptor - wet bulb**
  vert_vsby_j Descriptor - vertical vis**
  stn_pres_j Descriptor - station pressure**
  alt_pres_j Descriptor - altimeter press**
  q10mnt_mxgst_spd_j Descriptor - 10 min max gust**
  rltv_hum Calculated relative humidity
  rltv_hum_j Descriptor - relative humidity**
  snow_depth Snow depth
cm
  snow_depth_q QC code - snow depth**
  drv_hr_sun_dur
(only in files from 2010 onwards)
Derived hourly sunshine duration
This value is calculated using the MMS global radiation minute values which are each entered into a formula which determines whether each minute is 'sunshine'. An hourly sunshine value between 0 and 1 is then given based on the number of sunshine minutes. For example: 30 sunshine minutes - 30/60 = 0.5 hours; 20 sunshine minutes - 20/60 = 0.3333 hours (rounded to 0.3 hours).
This is NOT to be confused or compared with the WMO hourly sunshine duration found in the daily weather table. This is calculated from the sunshine sensor directly and is not linked to the global radiation value like the derived figure. Both however do give a value between 0 and 1 and are in increments of 0.1
  drv_hr_sun_dur_q
(Only in files from 2010 onwards)
QC code - derived hourly sunshine duration**


** Details available to registered users only.

More information about the Met Office surface data is available in the documentation provided by the Met Office.

How to start filtering the rows of data out:

  1. As the data arrive at the Met Office it undergoes quality control to check that the data are correct and consistent with the surrounding data points. Whether the process has occured or not is indicated by the version number (1 is the one to use as indicated in the table above).

  2. To show the progress of the data through the quality control the various variables will have an associated _q value (e.g. air_temperature_q). This _q value will have different values for each record (see details in table above).

  3. While the Met Office MIDAS system overwrites the existing entry in their database the BADC's MIDAS entries do not as the BADC takes snapshots of the the MIDAS database from time to time leading to duplicate entries occuring in our archive. If duplicate records are found, check the associated meto_stmp_time to determine which record is the most recent one - this is the one to use and the other(s) can be ignored.


Additional notes