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Water Vapour Measurments. Liam Tallis. Introduction. Know the vertical distribution of water vapour in the atmosphere Profile for input into radiative transfer schemes Need to know this profile accurately Sources Produce a profile of water distribution in the atmosphere
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Water Vapour Measurments Liam Tallis
Introduction • Know the vertical distribution of water vapour in the atmosphere • Profile for input into radiative transfer schemes • Need to know this profile accurately • Sources • Produce a profile of water distribution in the atmosphere • Example Day: 18th September 2008
Radiosondes • Dry bulb, wet bulb and relative humidity • Easy 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 aircraft • Regarded as more accurate than radiosonde • Limited Height Profile • Samples relatively small geographical area
10:26:06 08:27:43 10:28:04 10:47:56 08:32:55 10:42:33
HATPRO • Humidity and Temperature Profilers • Partial availability whilst campaign was running at Camborne • Vertical profile • Temperature • Relative 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.”
Aircraft Measurements • FAAM Aircraft has numerous instruments on board recording information of use to use • General Eastern chilled mirror probe • Lyman-alpha total water content probe
Numerical Models • Met 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 Comparison Dropsonde Radiosonde Numerical Models Microtops HATPRO GPS Integrated Water Vapour FAAM Aircraft