Identifying the role of different physical processes in evolving climate anomalies is a basic component of CDC's research, and is complementary to research to ascertain that physical processes are properly represented in climate models. All five areas of physical process research (Sections 4.1-4.6) will continue to emphasize physical connections and their variations across a broad range of time scales. For example, the linear AAM model does a good job with intraseasonal variations but not with interannual variability. Stochastic (El Niño) and oscillatory (the QBO) interannual modes can be included in the model and their interactions with intraseasonal variations examined. Indeed, synoptic analyses indicate a link between the transport of momentum across 35N by an interannual mode such as ENSO and excitation of an intraseasonal mid-latitude mode linked with the mountains. Such potential scale interactions of the large scale circulation are of interest both scientifically and for monitoring and prediction purposes.

Air-sea interactions studies related to the MJO will continue with a range of coupled models. One focus will be on proper simulation of the seasonal cycle in the tropics, especially over the Indian Ocean. Model experiments will be designed to test the role of air-sea interaction on the character of monsoonal precipitation fluctuations over South America, including its potential predictability.

Parameterizations of subgrid scale processes in clouds will be implemented in the GFDL Flexible Modeling System, making it more usable for diagnostic studies, and possibly improving its climate. Moist convective parameterizations will be developed and tested to account for the observed variations found across a broad range of time scales and physical environments. Issues of continued interest for parameterization schemes include: the role of cumulus friction simulated in cloud-resolving models, the non-equilibrium behavior of the diurnal cycle of convection over tropical land masses (Fig. 4.4), and the convective organization on relatively small scales (e.g., Fig. 4.2) by gravity waves.

Future research in these areas will benefit from new global datasets, from observations made during field projects, and from new climate model datasets. Improving the understanding of basic physical processes will remain essential for diagnosing current climate events, and for evaluating predictions of atmosphere and coupled ocean-atmosphere phenomena.

Contributed by: J. Bergman, H. Hendon, H.-P. Huang, B. Liebmann, B. Mapes, M. Newman, R. Pincus, P. D. Sardeshmukh, T. Shinoda, and K. Weickmann.

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