Dust as a Tracer of Climate Change in Antarctica and as modulator of Phytoplankton Activity

1
Dust as a Tracer of Climate Change in Antarctica
and as modulator of Phytoplankton Activity

• Ice core records show a correlation of dust
  deposition and temperature changes (Recent and in
  geological times)

• Phytoplankton activity is very sensitive to
  changes in nutrient availability (particularly in
  the Southern Ocean)

McConnell et al, PNAS, 2007
Artificially seeded Fe in the SO
Chlorophyll visible for several days afterwards
Soiree Experiment, Edward et al, Nature 407,
727-730(12 October 2000) doi10.1038/35037555
2
A combination of MODIS and OMI observations shows
dust traveling a long way in the South Atlantic

• Observation of dust in the SO is very difficult
  because
• Very cloudy --- gt very few clear sky retrievals
  ----- gt sampling problem
• Dust activity is episodic and in pulses.
• Only a combination of satellite retrievals can
  help to understand dust transport and detection
  in the SO as this example shows.

3
Indirect Effects from Degassing Volcanoes can be
comparable to human effects
Anthropogenic (a) ,Volcano (b), DMS (c )
Radiative forcing- Graf et al, 1997

• Weakly explosive volcanoes play an important role
  in the sulfur cycle and radiative forcing.
• Estimation is model dependent due to
  parameterization and emissions height inventory
• Very poor global characterization of degassing
  activity of volcanoes.

4
Observations of the impact of weak volcanic
activity on clouds

• A natural laboratory for studying the indirect
  effect
• First observation of a naturally occurring
  phenomena similar to man-made ship-tracks
• Used two-satellite platforms to characterize the
  event.