Extended Abstract (336K)P1.17
Use of in-situ observations of Arctic clouds to understand impacts of mixed-phase clouds on single-scattering: properties: applications to climate studies
Greg McFarquhar, University of Illinois, Urbana, IL; and G. Zhang
Although it is well known that mixed-phase clouds occur frequently in spring and fall at the Arctic, the microphysical mixtures of water and ice that constitute these clouds and their effects on the single-scattering properties of such clouds are not well known. In-situ observations obtained during the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) and the FIRE Arctic Cloud Experiment (ACE) are used to examine the sizes, shapes, and phases of cloud particles in those clouds that are identified as having both phases present in an approximately 2 km path length. The mean scattering properties of such distributions are then computed by weighting the single-scattering properties of different shapes, sizes, and phases of cloud particles calculated using an improved geometric ray-tracing method according to scattering cross-section and number concentration. The results of these calculations are then compared against the mean scattering properties computed using parameterizations that are currently implemented in large-scale global models. The differences between the properties and parameterizations are interpreted in terms of variances in cloud radiative forcings that would be predicted by such models.
Poster Session 1, Climate Modeling and Observed Climate Change (Hall 4AB)
Tuesday, 13 January 2004, 9:45 AM-11:00 AM, Hall 4AB
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