Download - 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
