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SUMMARY:Aerosol observational studies for climate research: from light abs
 orption to the kinetics of cloud droplet formation - Justin Langridge (Met
  Office)
DTSTART:20131014T131500Z
DTEND:20131014T143000Z
UID:TALK46359@talks.cam.ac.uk
CONTACT:Dr Amanda Maycock
DESCRIPTION:Aerosols play a major role in the climate system\, acting both
  directly to perturb radiative transfer and atmospheric heating by scatter
 ing and absorbing solar radiation\, and indirectly to modify cloud albedo 
 and lifetimes. This talk will present recent work relevant to aerosol dire
 ct effects\, motivated by the need to improve our fundamental understandin
 g of the optical behaviour of different aerosol types as a function of wav
 elength\, atmospheric age and environmental condition. \n\nNew instrumenta
 tion developed for the accurate and sensitive airborne measurement of aero
 sol absorption (using photoacoustic spectroscopy) and extinction (using ca
 vity ringdown spectroscopy) will be introduced and applications in three a
 reas presented. First\, airborne measurements from the California Basin wi
 ll be used to examine the impact of ageing on aerosol properties affecting
  climate and visibility in the Los Angeles plume. This analysis will highl
 ight the key role of semi-volatile component partitioning in this region. 
 Second\, ground-based observations from Boulder\, Colorado will be used to
  provide the first direct attribution of absorption to black carbon\, brow
 n carbon and absorption enhancement sources in a biomass burning plume. Th
 is study will highlight the importance of several absorption sources curre
 ntly missing from global climate model simulations. Third\, laboratory mea
 surements will be used to demonstrate the utility of photoacoustic spectro
 scopy for aerosol absorption measurement at high relative humidity\, for w
 hich no other direct methods currently exist. In addition to technical eva
 luation\, these measurements also provide new constraint of the water mass
  accommodation coefficient\, a key parameter controlling the kinetics of w
 ater condensation. Implications for potential kinetic limitations to cloud
  droplet formation will be discussed.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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