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Screen Observations: Details

Field Descriptions

DRY_BULB: Degrees Celsius (deg C)
The air temperature at the time the measurement is taken.

WET_BULB: Degrees Celsius (deg C)
The wet bulb temperature at the time measurement is taken.

DEWPOINT: Degrees Celsius (deg C)
The air temperature at which dew starts to form. The temperature to which a given air parcel must be cooled at constant pressure and constant water vapour content in order for saturation to occur.

RELATIVE_HUMIDITY: Percent (%)
The ratio of the vapour pressure of the air to the saturated vapour pressure.

DRY_BULB_REL: "*"
Reliability of Dry Bulb; "*" if estimated else NULL.

WET_BULB_REL: "*"
Reliability of Wet Bulb; "*" if estimated else NULL.

ORIG_DRY_BULB: code
Source of Dry Bulb observations data; D=Daily Climate, S=Synop, E=Environmental Data Recorder, M=Metar.

ORIG_WET_BULB: code
source of Wet Bulb / Dewpoint obs data; D=Daily Climate, S=Synop, E=Environmental Data Recorder, M=Metar.

Notes

• Sources are:
  • D = Daily Climate
  • E = Environmental Data Recorder,
  • S = Synop
  • M = Metar
  • H = Clitel Hourly
  
  
• For Dry_Bulb the order of precedence of sources (orig_dry_bulb) are... (Best overwrites) D > E > S > M (poorest)


• For the rest, the order of precedence of sources (orig_wet_bulb) are... (Best overwrites) D > E > S > M (poorest)


• Daily Climate provides 9am local time values in tenth degree, for dry-bulb and wet-bulb.


• EDR provides hourly values in tenth degree, for dry-bulb, wet-bulb and/or RH if available.


• Synop provides 3 or 6-hourly values in either whole or tenth degree depending on an indicator, for dry-bulb and dewpoint.


• Metar provides hourly values in whole degrees, for dry-bulb and dewpoint.


• Clitel hourly values are a mean over the the one minute preceeding the hour. For 'Clitel" true hourly means use the Max Min Mean Temperature datatype.


• The Dry-bulb temperature is always present, but the humidity measurements MAY be missing.


• Given one or more of Wet-bulb, Dewpoint, or RH, the missing values are calculated with reference to the given Dry_bulb temperature.

Statistics

Screen obs statistics are compiled in the "MTHLY_STATS" and "ANNUAL_STATS" tables for:

• Code 02: Mean Air Temperature
• Code 16: Mean Vapour Pressure
• Code 64: Mean 9am Relative Humidity
• Code 65: Mean 9am Temperature

See also: