Emerging Modules for ESMs: Atmospheric chemistry Aerosols

1
Emerging Modules for ESMsAtmospheric chemistry
/ Aerosols

• For presentation at the Arctic System Model
  Workshop III
• David Plummer

2
Chemistry effects on climate system

• Unlike LLGHGs, ozone and aerosols can have
  important regional forcings

3
Antarctic ozone depletion

• trends over 1969-98 for temperature and
  geopotential height from radiosonde stations in
  Antarctica
• from Thompson and Solomon, Science, 2002

4
Antarctic ozone depletion

• trends in polar cap temperature (70S to pole)
  from 2001 to 2050
• Figure 1 from Son et al., Science, 2008

5
Antarctic ozone depletion

• difference in ocean zonal wind stress between
  runs with and without a prescribed Antarctic
  ozone depletion
• From Lenton et al., GRL, 2009
• decreased uptake of CO2 by 2.3 Pg-C between
  1987-2004

6
Arctic projections

• no ozone hole formation
• interaction of ozone with NH atmospheric
  circulation much more complex
• active area of research
• prescribed, monthly mean vs. prognostic

• 21st century temperature trends predicted by a
  suite of different CCMs
• From Butchart et al. (submitted to J. Clim)

7
Arctic RF

• pre-industrial to present day O3 RF at the
  tropopause
• from Mickley et al. 1999
• black carbon
• affects on surface albedo

8
Interaction with other ESM components

• experimental evidence for O3 damage to plants
• decreased productivity

• Sitch et al. 2007
• low and high sensitivity to O3

• reactive nitrogen (NOx) emitted and oxidized to
  HNO3
• NO3- deposition important nutrient
• OH, H2O2, O3 are powerful oxidants
• DMS, SO2, VOCs

9
Likely situation for GCMs in AR5

• several of the large centres have plans to run
  transient, coupled runs with interactive
  chemistry
• most likely simplified tropospheric chemistry
• prescribed or constrained stratospheric O3
• more consistency in approach to specifying
  Antarctic ozone trends