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Martin Köhler Department  of  Atmospheric Sciences University of California,  Los Angeles

Current Research:

My Ph.D. research focuses on the parameterization of cloudiness in an AGCM using a five phase bulk microphysics scheme. I shall finish it by the end of 1998 and will thereafter continue my favorite research on the evolution of layer clouds and their treatment in AGCMs with Leo Donner at GFDL, Princeton.  The following conference abstracts should give a good taste of my thesis approach towards an empirical cloudiness parameterization:

• The AMS annual meeting 1997 talk "Ice Cloud Formulation in Climate Modeling" summarizes our current state in the development of a bulk microphysics scheme of intermediate complexity for use in AGCMs, documents the sensitivity to uncertain parameters, and shows an initial CRM experiment designed to gain further understanding in the decay of ice clouds. (see html text or download postscript file)

Köhler, M. et al. 1997: Ice formulation in climate modeling. Seventh Conference on Climate Variations, 2-7 Feb. 1997, Long Beach, CA, Amer. Met. Soc., 237-242.
• The Tropical Meteorology meeting 1997 talk "Upgrading the cloud optical properties in the UCLA AGCM" describes the impact of moving to higher sophistication in cloud optical properties. A particular example is the sensitivity of stratus cloudiness over land to optical properties of those clouds. (see html text or download postscript file)

Köhler, M. and J.-L. F. Li 1997: Upgrading the Cloud Optical Properties in the UCLA AGCM. 22nd Conference on Hurricanes and Tropical Meteorology, 19-23 May 1997, Fort Collins, CO, Amer. Meteor. Soc. .
• The IAMAS meeting 1997 talk "Studying the Mechanisms involved in the Decay of Ice Clouds using a Cloud Resolving Model" focuses on the design of CRM experiments to better understand the generation, maintenance and decay of ice clouds. The results will be used in specifying as yet uncertain parameters in the AGCM bulk microphysics scheme. (see html text)

Köhler, M. et al. 1997: Studying the Mechanisms involved in the Decay of Ice Clouds using a Cloud Resolving Model. Joint Assemblies of IAMAS and IAPSO, 1-9 July, 1997, Melbourne, Australia.
• The Akio Arakawa Symposium 1998 talk "One the Decay of Ice Clouds and its Representation in AGCMs" examines the upward eddy fluxes of water in radiatively destabilized layer clouds.  Using CRM simulations. It is motivated, that those fluxes may significantly lengthen the life-time of cirrus clouds by partially offsetting the downward flux of falling precipitate. (see html text)

Köhler, M. 1998: One the Decay of Ice Clouds and its Representation in AGCMs.  Akio Arakawa Fest: General Circulation Model Development: Past, Present, and Future.  20-22 January, 1998, Los Angeles, California.
 

Research Colleagues:

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