Sunday, 6 January 2013
Exhibit Hall 3 (Austin Convention Center)
Five years of CloudSat 94-GHz cloud-profiling radar observations and collocated ECMWF environmental reanalyses are combined to investigate the morphological characteristics of deep-convective clouds over tropical (30°S - 30°N) oceans. After identifying deep-convective cloud objects in CloudSat data, we develop and apply a novel algorithm that relies on the profile of cloud-object width with height to differentiate between anvils and their corresponding convective cores. From these analyses, we investigate (1) the relationship between convective core width and corresponding anvil width, and (2) the relationships between these morphological quantities and other quantities such as sea-surface temperature, anvil optical depth, and cloud-top temperature. In the first investigation, we observe a consistent scaling relationship between convective core width and anvil width that has important implications for the parameterization of deep-convective clouds in climate models. In the second investigation, we observe dramatic changes in cloud morphology and optical properties with increasing sea-surface temperature. We observe that as sea-surface temperature increases, (a) convective cores, along with their corresponding anvils, become narrower; (b) the height of the algorithm-derived boundary between core and anvil rises; (c) anvil optical depth decreases non-negligibly; and (d) cloud-top temperature decreases sharply. These trends have important implications for climate sensitivity, as they suggest the presence of both a negative feedback (from (a)) and a positive feedback (from (d)).
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