UK Daily Weather Observations data - .dwx (weather observations) file format

PLEASE NOTE: The file format described below refers to the Met Office Land Surface data (1900-2000) dataset which has been superseded by the Met Office MIDAS dataset (1853-present) at the BADC.

The surface observation data are in a simple ASCII format.

A list of UK stations for which the BADC holds .dwx files is available (.dwx stations).

The file name convention is (STATION_NAME)(YEAR).(MESSAGE_TYPE).(FILE_EXTENSION)

STATION_NAMES is the complete station name.
YEAR is the year expressed in full, ie 1998.
Description of the message types is available.
The file extension is .dwx meaning that the file contains daily weather observations.

These .dwx files contain daily weather observations measured on a 24 hour time scale. The file headers END_HOUR and COUNT define the observation period.
Sunshine duration, snow day, hail day, thunder day and gale day are usually for the period 0000-2359Z (i.e. END_HOUR=2359 and COUNT=24). Concrete state, lying snow, snow depth, fresh snow depth and fresh mountain snowfall are "spot" values, usually at 0900Z, i.e. END_HOUR=0900 and COUNT=0.

-999 indicates a missing value.

The first line of the data file are the fields headers (which are detailed in the table below).

The fields in the .dwx data files are :

HEADER
PARAMETER FIELDS COLUMNS UNITS COMMENTS/DESCRIPTION

ID Station Ref. Number 1 1-8 - Station identification

IDTYPE - 2 9-17 - Station identification

MET_DOM Met. Domain 3 18-28 - Message types

YEAR Year 4 29-35 - 4 characters

MONTH Month 5 36-43 - 1 or 2 characters (from 1 to 12)

DAY Day 6 44-51 - 1 or 2 characters (from 1 to 31max)

END_HOUR Hour 7 52-61 - Observation end time

COUNT Hour count 8 62-69 - See COUNT definition

SUN Sunshine duration 9 70-77 0.1 hour See Met Office documentation

CONC State of concrete slab 10 78-83 WMO Code State of a concrete slab (e.g. dry, wet, frozen, etc) of specified standard dimensions and composition at the observing station.

SNOW_L Snow lying 11 84-91 WMO code Snow lying is counted, provided that the snow covers at least one-half of the ground easily visible from the station and the altitude of this ground does not differ by more than 30m from that of the station. In judging if at least one-half of the ground is snow covered no account is taken of bare patches under trees or of aeras occupied by water.

SNOW_D Snow depth 12 92-99 cm -

FRSH_SNOW Fresh snow amount 13 100-110 cm -

SNOW_DAY Day of snow 14 111-120 WMO Code -

HAIL_DAY Day of hail 15 121-130 WMO Code A day of hail is defined as one when pieces of ice, 5mm or more in diameter are observed to fall. The hailstones can fall separately or be agglomerated into irregular lumps.

THUN_DAY Day of thunder 16 131-139 WMO Code A day of thunder is counted when thunder is heard.

GALE_DAY Day of gale 17 140-149 WMO code A day of gale is counted when a mean wind speed reaches or exceeds or is estimated to have reached or exceeded, 34kn (force 8 on the Beaufort scale) over a period of at least several minutes (10 mn in the case of a station equipped with an anemograph).

General information about the Climate Network is available in the documentation provided by the Met Office.

HEADER	PARAMETER	FIELDS	COLUMNS	UNITS	COMMENTS/DESCRIPTION
ID	Station Ref. Number	1	1-8	-	Station identification
IDTYPE	-	2	9-17	-	Station identification
MET_DOM	Met. Domain	3	18-28	-	Message types
YEAR	Year	4	29-35	-	4 characters
MONTH	Month	5	36-43	-	1 or 2 characters (from 1 to 12)
DAY	Day	6	44-51	-	1 or 2 characters (from 1 to 31max)
END_HOUR	Hour	7	52-61	-	Observation end time
COUNT	Hour count	8	62-69	-	See COUNT definition
SUN	Sunshine duration	9	70-77	0.1 hour	See Met Office documentation
CONC	State of concrete slab	10	78-83	WMO Code	State of a concrete slab (e.g. dry, wet, frozen, etc) of specified standard dimensions and composition at the observing station.
SNOW_L	Snow lying	11	84-91	WMO code	Snow lying is counted, provided that the snow covers at least one-half of the ground easily visible from the station and the altitude of this ground does not differ by more than 30m from that of the station. In judging if at least one-half of the ground is snow covered no account is taken of bare patches under trees or of aeras occupied by water.
SNOW_D	Snow depth	12	92-99	cm	-
FRSH_SNOW	Fresh snow amount	13	100-110	cm	-
SNOW_DAY	Day of snow	14	111-120	WMO Code	-
HAIL_DAY	Day of hail	15	121-130	WMO Code	A day of hail is defined as one when pieces of ice, 5mm or more in diameter are observed to fall. The hailstones can fall separately or be agglomerated into irregular lumps.
THUN_DAY	Day of thunder	16	131-139	WMO Code	A day of thunder is counted when thunder is heard.
GALE_DAY	Day of gale	17	140-149	WMO code	A day of gale is counted when a mean wind speed reaches or exceeds or is estimated to have reached or exceeded, 34kn (force 8 on the Beaufort scale) over a period of at least several minutes (10 mn in the case of a station equipped with an anemograph).