HR: 0800h
AN: A31C-0084    [Abstracts]
TI: Size Distribution of Sea-Salt Emissions as a Function of Relative Humidity
AU: * Zhang, K M
EM: maxzhang@ucdavis.edu
AF: University of California, Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616 United States
AU: Knipping, E M
EM: eknippin@epri.com
AF: EPRI, 3412 Hillview Ave, Palo Alto, CA 94304 United States
AU: Wexler, A S
EM: aswexler@ucdavis.edu
AF: University of California, Department of Mechanical and Aeronautical Engineering, Department of Civil and Environmental Engineering and Department of Land, Air, and Water Resources, University of California, Davis, CA 95616 United States
AU: Bhave, P V
EM: bhave.prakash@epamail.epa.gov
AF: NOAA, Atmospheric Sciences Modeling Division, National Oceanic and Atmospheric Administration, Air Resources Laboratory, Research Triangle Pa, NC 27711 United States
AU: Tonnesen, G S
EM: tonnesen@mail.cert.ucr.edu
AF: University of California, 6Center for Environmental Research and Technology, University of California, Riverside, CA 92521 United States
AB: Here we introduced a simple method for correcting sea-salt particle-size distributions as a function of relative humidity. Distinct from previous approaches, our derivation uses particle size at formation as the reference state rather than dry particle size. The correction factors, corresponding to the size at formation and the size at 80% RH, are given as polynomial functions of local relative humidity which are straightforward to implement. Without major compromises, the correction factors are thermodynamically accurate and can be applied between 0.45 and 0.99 RH. Since the thermodynamic properties of sea-salt electrolytes are weakly dependent on ambient temperature, these factors can be regarded as temperature independent. The correction factor w.r.t. to the size at 80% RH is in excellent agreement with those from Fitzgerald's and Gerber's growth equations; while the correction factor w.r.t. the size at formation has the advantage of being independent of dry size and relative humidity at formation. The resultant sea-salt emissions can be used directly in atmospheric model simulations at urban, regional and global scales without further correction. Application of this method to several common open-ocean and surf-zone sea-salt-particle source functions is described.
DE: 4842 Modeling
DE: 4504 Air/sea interactions (0312)
DE: 4801 Aerosols (0305)
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0355 Thermosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting