water vapour measurments

Liam Tallis

IntroductionKnow the vertical distribution of water

vapour in the atmosphereProfile for input into radiative transfer

schemesNeed to know this profile accurately

SourcesProduce a profile of water distribution in the

atmosphereExample Day: 18th September 2008

RadiosondesDry bulb, wet bulb

and relative humidityEasy to derive lots of

other things from these

Additional launches performed during campaign

Average values for geographic area

55.9km

52.2km

Dropsondes

Dropped from FAAM aircraftRegarded as more accurate than radiosonde

Limited Height ProfileSamples relatively small geographical area

10:26:06

08:27:43

10:28:04

10:47:56

08:32:55

10:42:33

7.9km

GPS Water Vapour

HATPROHumidity and Temperature Profilers

Partial availability whilst campaign was running at Camborne

Vertical profileTemperatureRelative humidity

Microtops II Sunphotometer“The water vapour

measurement is based on a pair of radiometric measurements in the IR band. The 940nm filter is located in a strong water vapour absorption band, while the 1020nm filter is affected only by aerosol scattering.”

Microtops II Sunphotometer

Aircraft MeasurementsFAAM Aircraft has

numerous instruments on board recording information of use to use

General Eastern chilled mirror probe

Lyman-alpha total water content probe

Numerical ModelsMet Office Model Fields

Relative Humidity (%)ECMWF Model Field

Specific Humidity (kg kg-1)

Longitude, Latitude, Pressure, Time

Need to extract the required information at each level

As useful as “real” data?

Cross ComparisonRadiosonde

FAAM Aircra

ft

GPS Integrat

ed Water Vapour

HATPRO

Microtops

Dropsonde

Numerical

Models

Cross ComparisonTime

Radiosonde

Microtops

GPS HATPRODropsond

eAltitud

eUT kg m-2 kg m-2 kg m-2 kg m-2 kg m-2 m             

05:00 15.8   14.6 16.5    08:28         14.9 626008:33         14.8 625009:00 14.3   13.3 15.9    09:25   12        10:26         14.8 107010:28         14 107010:42         14 910110:48         15 885011:00 15.0   14.3 16.6    11:15   13        12:00 14.3   15.6 16.3    12:35   12