Understanding the Mechanisms and Effects of ice Nucleation in Tropical Cyclones
Abstract
The Tropical Cloud Systems and Processes (TCSP) experiment in July 2005 was conducted to investigate the genesis and intensification of tropical cyclones in the Caribbean and eastern Pacific. A full range of thermodynamic, radiative and kinematic process scales involved in the early evolution of these storms, ranging from the microphysical through the synoptic, have potential to influence the development and evolution of tropical cyclones and hurricanes. Hurricane formation and behavior is a multi-scale problem: The hurricane vortex is hundreds of miles in horizontal scale, while the embedded convective clouds are on the order of one mile (cloud scale). Our study is focused on the role of interactions between tropospheric aerosols and clouds. These interactions are addressed with an Explicit Microphysics Model (EMM) and with relevant in situ field data from July 2005 cases. There is no aerosol data from TCSP but from the GFDL atmospheric model with on-line aerosols. To compensate for this lack of in-situ measurements, the simulated aerosol properties (size distribution, mass column, optical thickness) are evaluated with data from ground-based and remote sensing instruments. EMM has the unique capability of predicting particle properties (shape, bulk density, size) without categorization assumptions and to predict the particle size distributions. Model simulations illustrate the linkage between aerosol and ice particle properties in cirrus, and sensitivity to ambient conditions. Particular focus is given to the competition between the homogeneous freezing of aerosol and that of cloud-droplets. Such results are relevant for improving the representation of microphysical processes in cloud resolving models, hurricane, and in climate models.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2006
- Bibcode:
- 2006AGUSM.A43D..03A
- Keywords:
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- 3364 Synoptic-scale meteorology;
- 0321 Cloud/radiation interaction;
- 3311 Clouds and aerosols;
- 3314 Convective processes