CAPT: The Cloud-Associated Parameterizations Testbed

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Introduction

The Cloud-Associated Parameterizations Testbed (CAPT) aims to diagnose and improve the representation in climate models of cloud-associated physical processes. In the CAPT, weather forecast techniques are applied to climate models , with an emphasis on the simulations of the Community Atmosphere Model. We will be extending the concept of weather forecasts from the atmosphere to the fully coupled ocean-atmosphere model. Three foci of the project include:

• Comparing of model simulations to detailed process observations available from the ARM data
• Diagnosing the origin of errors in model simulations of climate
• Testing new model parameterizations in order to identify their strengths/weaknesses in simulating cloud-associated processes.

CAPT is a joint project of the Atmospheric System Research (ASR) and Regional and Global Climate Modeling (RGCM) Programs of the U.S. Department of Energy's Office of Science/Biological and Environmental Research (BER). We are using analyses of global weather from numerical weather prediction (NWP) centers, in conjunction with field observations such as those provided by the Atmospheric Radiation Measurement Climate Research Facility, to evaluate parameterizations of sub-gridscale processes in global climate models. Simply stated, we run realistically initialized climate models in forecast mode to determine their initial drift from the NWP analyses and/or from the available field data, thereby gaining insights on model parameterization deficiencies.

Prior to February 2010, CAPT was known as the CCPP-ARM Parameterization Testbed.