Brief introduction to Dust module in SNUGCM

Atmospheric aerosols play an important role in the global climate system. But the examination of complex feedback between aerosol and climate is still insufficient. To increase the understanding of this complex system, the SNU/CES GCM has been extended by aerosol and cloud microphysics module. The aerosol module coupled online with a global climate model simulates trace gases and aerosol (dust, sulfate, BC, OC, sea salt and two internal mixtures) mass. – Now only dust aerosol is simulated. Simulated aerosol scatter and absorb solar radiation directly, forces climate model simulation. Cloud microphysics module comprises of aerosol activation for obtaining cloud condensation nuclei, precipitation microphysics with autoconversion and accretion, and parameterization for cloud drops distribution. Cloud optical properties varying with aerosol amount and chemical species can give an aerosol indirect forcing to climate model.

  Description of the aerosol module

 The Governing equation in the chemical transfer model is given by (Chang et al. 1987).

1(1)

, where C is the trace species concentration (ppm for gas, µg-3 for aerosol), V the three dimensional wind velocity vector and Ke the eddy diffusivity. Each term in equation (1) represents as:

    (a) time rate of change of pollutant concentration,

    (b)advection,

    (c) eddydiffusion,

    (d) productionfrom chemical reactions,

    (e) lossfrom chemical reactions,

    (f)emissions,

    (g) cloudmixing and aqueous-phase chemical production or loss,

    (h)aerosol process and

    (i) drydeposition

Table 1 Particle size division

Bin Number

Mid Radius (m)

1

0.10

2

0.16

3

0.25

4

0.40

5

0.64

6

1.01

7

1.60

8

2.53

9

4.03

10

6.40