Abstract
With the global aerosol-climate model ECHAM5-HAM we investigate the potential influence
of organic aerosol originating from the ocean on aerosol mass and chemical composition
and the droplet concentration and size of marine clouds. We present sensitivity
simulations in which the uptake of organic matter in the marine aerosol is prescribed for
each aerosol mode with varying organic mass and mixing state, and with a geographical
distribution and seasonality similar to the oceanic emission of dimethyl sulfide.
Measurements of aerosol mass and chemical composition serve to evaluate the representativity
of the model initializations. Good agreement with the measurements is
obtained when organic matter is added to the Aitken, accumulation and coarse modes
simultaneously. Representing marine organics in the model leads to higher cloud drop
number concentrations, smaller cloud drop effective radii, and a better agreement with
remote sensing measurements. The mixing state of the organics and the other aerosol
matter, i.e., internal or external depending on the formation process of aerosol organ
ics, is an important factor for this. We estimate that globally about 75 TgCyr−1 of
organic matter from marine origin enters the aerosol phase. An approximate 35% of
this occurs through formation of secondary organic aerosol and 65% through emission
of primary particles.
| Original language | Undefined/Unknown |
|---|---|
| Pages (from-to) | 5675-5700 |
| Number of pages | 26 |
| Journal | Atmospheric Chemistry and Physics Discussions |
| Volume | 7 |
| Publication status | Published - 2007 |