The PALMS instrument (Particle Analysis by Laser Mass Spectrometry) participated in three Costa Rica aircraft campaigns from 2004 to 2007: Pre-AVE, CR-AVE, and TC4. PALMS measures the chemical composition of individual aerosol particles with diameters >300 nm. Aerosol types were often observed in discrete vertical layers in the troposphere. In some cases, aerosols within the TTL (tropical tropopause layer) showed little resemblance to those in the convective region below or the stratosphere above. TTL aerosol composition was dominated by highly oxidized carbonaceous material. Sulfate was often the principal aerosol component in the convective region. In marine-influenced areas, this sulfate was acidic, whereas sulfate in the TTL was largely neutralized, probably by ammonium. Although all three missions were based from the same site, key features of the aerosol chemistry varied among the missions due to differences in regional convection and sources of air. These variations in aerosol composition may help give insight into mechanisms for air entering the TTL. Additionally, aerosol organic content and the extent of sulfate neutralization have implications for cirrus formation in the TTL.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0305 Aerosols and particles (0345;
- 0365 Troposphere: composition and chemistry;
- 0368 Troposphere: constituent transport and chemistry