Mesoscale Meteorology - Theories, Observations and Models

Mesometeorology was defined by Ligda in 1951 to include phe nomena which are too large to be observed by in situ sensors at a single station but too small to be defined adequately by conven tional station networks. The scientific, economic, and social im portance of weather events on the scales of 10-1000 km is not a new discovery, but only recently have the weather services, research laboratories, and academic scientists of the world begun to concen trate attention on these phenomena. An Advanced Study Institute was organized by the present editors to provide a focus and forum for review and dissemination of the current state of basic and ap plied research across the broad and somewhat indefinite span (see Emanuel's first paper for one version) of this subject. We believe this objective was largely fulfilled, although not all relevant subjects were given attention equal to their perceived significance. The smaller and more intense mesoscale phenomena, especially con vective clouds and storms, were excellently treated from a variety of viewpoints, while the important area of regional scale simula tion and prediction received less emphasis. A fascinating discus sion and mathematical treatment of a seemingly obscure cloud phe nomena in Australia, the "morning glory", suggests that it may have much more generality and importance than is first apparent. New insights are obtained on the long-puzzling problem of the true nature and significance of turbulent entrainment into cumulus clouds.

1. Mesoscale Processes and Variability. - a) On the Dynamical Definition(s) of Mesoscale . - b) Mesoscale Variability of the Atmosphere. - 2. Regional and Cyclonic Scale Motions and Prediction Models. - a) Synoptic-Scale Forcing of Mesoscale Processes. - b) Cyclogenesis in the Lee of the Alps. - c) Several Methods for Initializing Mesoscale Forecast Models. - d) Initialization of Mesoscale Models: The Possible Impact of Remotely Sensed Data. - e) On the Effect of the Planetary Boundary Layer Parameterizations in Mesoscale Numerical Weather Prediction. - 3. Fronts. - a) Observations of Fronts. - b) Frontogenesis During the November 15, 1980 Storm of STREX. - c) An Energy-Theory for the Propagation of Gravity Currents. - 4. Mesoscale Instabilities. - a) Symmetric Instability. - b) Conditional Symmetric Instability: A Theory for Rainbands Within Extratropical Cyclones. - c) A Review of Meso-scale Disturbances in Cold Air Masses. - d) Radar Observations of Snowbands in Finland A Preliminary Report. - 5. Buoyancy (Gravity) Waves and Topographic Forcing. - a) Linear Theory of Internal Gravity Waves and Mountain Waves. - b) Mesoscale Mountain Waves: Theory and Observations. - c) Topographic Forcing. - d) The Morning Glory: A Nonlinear Wave Phenomenon. - e) The Formation of the Morning Glory. - 6. Buoyant Convection. - a) Cumulus Clouds: Early Aircraft Observations and Entrainment Hypotheses. - b) Cumulus Role in Tropical Circulations. - c) Cumulus Clouds: Interactions Between Laboratory Experiments and Observations as Foundations for Models. - d) Cumulus Clouds: Numerical Models, Observations and Entrainment. - e) Editor s Comments on Dr. Simpson s. Lectures. - f) The Dynamics and Simulation of Organized Deep Convection. - g) Bénard Convection and Effects of Rotation. - h) Prediction of SevereConvection. - i) Dynamics of Rotating Thunderstorms. - j) A Case Study of Elevated Convection in an Unsaturated Large-scale Environment. - k) Elementary Aspects of the Interaction Between Cumulus Convection and the Large-scale Environment. - l) Condensation Parameterization in a Convection Model. - m) Matching Three-Dimensional Convection Models with Doppler Radar Observations. - 7. Boundary Layers. - a) Lectures on the Planetary Boundary Layer. - b) Planetary Boundary Layer Parameterization and Turbulence Closure. - c) Flow in Valleys: Observations. - d) Numerical Modeling of the Planetary Boundary Layer. - e) Anti-Clockwise Rotation of the Wind Hodograph and Its Relation to Thermal Forcing. - f) The Effects of Boundary Layer Modification on the Initiation of Convection During AVE-SESAME, 1979. - 8. Observing Technology. - a)/Three-Dimensional Wind Field Analysis from Doppler Radar Data. - b) Satellite Data: Analysis Techniques and Applications to Meteorology.