Dr
Thomas Kaempfer
(AF Colenco Ltd / CRREL)
08/06/2011, 09:15
The micro-structure of a sintered and porous material impacts its chemical and physical properties. In particular, sintering ice-crystals evolving from snow to firn alter the characteristics of the snowpack. We study the link between micro-structure and properties by numerical modeling based on
experimental X-ray micro-tomography data or using discrete element model (DEM) snow as geometrical...
Dr
Martina Roeselova
(Institute of Organic Chemistry and Biochemistry ASCR Prague)
08/06/2011, 09:45
We present the results of molecular dynamics simulations in which ice Ih slabs with free basal, prismatic, 28 degrees pyramidal, and 14 degrees pyramidal facets are exposed to vapor. All simulations were carried out at 250 K using a six-site intermolecular potential. Characteristics common to all facets include spontaneous development of a quasi-liquid layer (QLL) within ~10 ns, and QLL...
Thorsten Bartels-Rausch
(Paul Scherrer Institut)
08/06/2011, 10:00
Recent laboratory experiments that investigated the interaction of atmospheric trace gases with ice surfaces under tropospheric conditions are presented. Key-Questions are
a) the importance of surface versus bulk uptake of trace gases
b) the effect of trace gas adsorption on the quasiliquid layer
c) the influence of the presence of an additional, coadsorbing trace gas on the...
08/06/2011, 10:15
Dr
Martin King
(Royal Holloway University of London)
08/06/2011, 11:30
Photolysis of chemicals within snowpacks can produce radical species that initiate oxidation reactions within the snowpack and may be responsible for chemical fluxes from the snowpack.
Photolysis rate coefficients as a function of solar zenith angle, snowpack depth and snowpack layer structure are reported using a radiative-transfer model constrained by field measurements of the solar...
Ms
Maria Zatko
(University of Washington)
08/06/2011, 11:45
The photolysis of nitrate (NO3-) in snowpack is a source of NOx to the overlying atmosphere, with implications for the oxidizing capacity of polar atmospheres and the preservation of chemicals in the ice core record. A snowpack radiative transfer model with updated optical properties in the UV [Warren and Clarke, 2008] leads to an e-folding depth of actinic flux in snowpack of 60 cm...
Laurens Ganzeveld
(1Earth System Sciences - Climate Change group, department of Environmental Sciences, Wageningen University and Research Centre, Wageningen, Netherlands)
08/06/2011, 13:30
Research on snowpack processes and atmosphere-snow gas exchange has demonstrated that chemical and physical interactions between the snowpack and the overlaying atmosphere have a substantial impact on the composition of the lower troposphere. These observations also imply that deposition, e.g. of ozone to the snowpack and the potential release of reactive oxidized nitrogen, NOx, possibly...
Dr
Kenjiro Toyota
(York University / Environment Canada)
08/06/2011, 14:00
Reactive halogens, especially bromine, are known to play a major role in the rapid loss of both ozone and gaseous elemental mercury (GEM) in the polar boundary layer during the spring. Measurements of relevant chemical species in the field and from satellites have shown that reactive bromine is released to the high-latitude atmosphere extensively and most notably from the ice-covered ocean....
Dr
Apostolos Voulgarakis
(NASA Goddard Institute for Space Studies at Columbia University, New York, USA)
08/06/2011, 14:15
Climate projections suggest that a complete Arctic sea-ice retreat is likely in the future during summer. Less ice will
cause less light reflection and slower tropospheric photolysis. We use a tropospheric chemistry model to examine
how oxidation may differ over an ice-free Arctic. We find that late-summer OH concentrations can decrease by
30–60% at polar latitudes, while effects on local...
