HR: 0800h
AN: C21B-0470    [Abstracts]
TI: Impurities in Snow: Effects on Spectral Albedo of Prairie Snowpacks
AU: * Morris, J N
EM: jenmorris@tamu.edu
AF: Texas A&M University, Department of Geography, College Station, TX 77843, United States
AU: Klein, A G
EM: klein@geog.tamu.edu
AF: Texas A&M University, Department of Geography, College Station, TX 77843, United States
AB: While extensive research on soot in snow has been done in the Polar Regions, there remains a lack of observations addressing the effect of soot on snow albedo in North American prairie snowpacks which causes uncertainty to the overall global effect that soot in snow has on climate. Measurements of snow impurities in freshly fallen prairie snowpacks in northwestern Iowa and central Texas collected from February 28 - March 5, 2007 and April 6, 2007, respectively. Two significant snowfall events occurred in northwestern Iowa during the study; the second snowfall event produced the most severe blizzard conditions in northwestern Iowa in the last thirty years. An unusual snowfall event in central Texas offered a unique sampling opportunity Several types of sites were sampled during the field campaign; this includes: frozen lakes with minimal human impact, agricultural fields impacted by agricultural dust, and human impacted sample sites. At twelve sites in northwestern Iowa samples were collected on multiple days and for both snow events to examine changes in snow impurities over time. At all site locations snow samples, temperature, density, and grain size were recorded. Snow reflectance and snow radiance was collected at a subset of the sites with an ASD VNIR Spectroradiometer (350 - 1500 nm). Snow impurities of light-absorbing particulate matter were measured by filtering the meltwater through a nuclepore 0.4 micrometer filter. Impurity concentration was determined by comparing the filters against a set of standards. A photometer will provide a more exact determination of snow impurities in the near future. Preliminary soot observations indicate prairie snow pack concentrations ranging from 1 ngC/g to 236 ngC/g with an average of 61.4 ngC/g. These measurements are within range of previously published values in the Arctic and can lower snow albedo. Differences in soot concentrations were observed between the two Iowa snowfall events. Impurity concentrations measured for the central Texas snowfall were higher than either of the Iowa snowfalls. As expected, spectral albedo was found to decrease with increasing impurities.
DE: 0700 CRYOSPHERE (4540)
DE: 0736 Snow (1827, 1863)
DE: 0758 Remote sensing
DE: 0770 Properties
SC: Cryosphere [C]
MN: 2007 Fall Meeting