Modelling sea salt aerosol and its direct and indirect effects on climate

X. Ma (1) , K. von Salzen (1) , J. Li (1)

1 CCCma - Canadian Centre for Climate Modelling and Analysis

A size-dependent sea salt aerosol parameterization was developed based on the piecewise log-normal approximation (PLA) for aerosol size distributions. Results of this parameterization from simulations with a global climate model produce good agreement with observations at the surface and for vertically-integrated volume size distributions. The global and annual mean of the sea salt burden is 10.1 mg m^?2. The direct radiative forcing is calculated to be ?1.52 and ?0.60 W m^?2 for clear sky and all sky, respectively. The first indirect radiative forcing is about twice as large as the direct forcing for all-sky (?1.34 W m^?2). The results also show that the total indirect forcing of sea salt is ?2.9 W m^?2 if climatic feedbacks are taken into account. The sensitivity of the forcings to changes in the burdens and sizes of sea salt particles was also investigated based on additional simulations with a different sea salt source function.

Domaines: Océan, Atmosphère

X. Ma, K. von Salzen, J. Li. Modelling sea salt aerosol and its direct and indirect effects on climate. Atmospheric Chemistry and Physics Discussions, 2007, 7 (5), pp.14939-14987. ⟨hal-00303146⟩