Mineral Dust and its Microphysical Interactions with Clouds - Mineral Dust: A Key Player in the Earth System - page 298

Table 12.1 (continued)

Campaign Focus Major findings

ACE-Asia, Trochkine
et al. ( 2003 )

Examination of the
composition of mineral
particles in source region
and comparing them with
those after long-range
transport

The main difference between
particles collected in China and
Japan was that 40-45 % of
mineral particles in Japan were
internally mixed with sulfate

Data from MODIS,
AMSR-E, and
CERES, Li et al.
( 2010 )

Mineral dust impacts on
warm clouds

Clouds are affected strongly by the
dust aerosols coming from the
Saharan region
Statistically significant impacts on
clouds for only some of the
segregated cloud classes

Gwangju, Korea, Kim and
Park ( 2012 )

Hygroscopicity and volatility
of dust particles
originating from the Gobi
Desert

Particles were aged, internally
mixed with hygroscopic and
volatile species characteristic
transport pathway
“Less polluted” dust particles
attributed to interaction with
sea salt and/or cloud
processing, while “highly
polluted” particles linked to
interaction with anthropogenic
pollutants and heterogeneous
reactions

12.5 Field Observations of Mineral Dust as IN

Mineral dusts were identified as IN in the early years of ice nucleation research.
For example, Kumai ( 1961 ) identified the particles often found at the center of
snowflakes as mineral dust using electron microscopy. These results were consistent
with fog chamber studies where various mineral dusts were found to be effective
at triggering glaciation in a supercooled fog (Pruppacher and Klett 1997 ;Mason
1971 ). This early picture is reinforced by contemporary measurements of ice crystal
residues in a range of environments.
As part of the CRYSTAL-FACE (Cirrus Regional Study of Tropical Anvils and
Cirrus Layers-Florida Area Cirrus Experiment), DeMott et al. ( 2003b )usedan
airborne continuous flow diffusion chamber (CFDC) to expose ambient aerosol
to a supersaturated environment (the processing conditions were 36.5 ı Cand
123 % RH i ). They showed that the highest IN concentrations in the measurements
over Florida occurred within plumes of mineral dust from the Sahara. This was
clear evidence that mineral dust could significantly contribute to IN populations
at great distances from source. More direct evidence that mineral dust makes up a
significant proportion of heterogeneous IN came from the mountain top atmospheric
observatory at Storm Peak in Colorado. DeMott et al. ( 2003a )usedaCFDCto
activate IN in ambient air under conditions pertinent to cirrus; these ice crystals were