The dynamical influence of large‐scale heat sources and sinks on the quasi‐stationary mean motions of the atmosphere

The classical convective theory for the influence of large-scale zonally asymmetric heating and cooling on the quasi-stationary mean motions is re-examined and shown to be inconsistent with observation. Scale considerations indicate that the classical mechanism cannot be applied to heating on a scale larger than that responsible for sea-breezes. In analogy with the theory of orographically produced stationary disturbances, heat sources and sinks of planetary dimensions produce quasi-static and quasi-geostrophic perturbations. A thermally active model is constructed in which all motions except those of large scale are filtered out a priori. The small perturbations produced by an idealized large-scale distribution of heat sources and sinks acting on a horizontally uniform baroclinic zonal current confined between rigid horizontal planes are then studied. The influence of surface friction is taken into account. Calculations are also performed on a model with no friction and on the assumption that entropy is advected horizontally. The results generally show good agreement with those for the more general model. When the stratosphere is taken into account, the disturbances in the upper troposphere are reduced in magnitude. The conditions for resonance in the absence of friction are determined. The passage through the resonant state is shown to modify significantly the character of the motions. The observed normals are discussed at some length in light of the theoretical computations. It is found that the magnitude and spatial distribution of the model disturbances display substantial correspondence with observation when allowance is made for orographic effects. Finally a method is suggested for quantitatively deducing the three-dimensional field of non-adiabatic heating and cooling from the observed normal maps by dynamical considerations.

[1]  R. S. Scorer,et al.  Theory of waves in the lee of mountains , 1949 .

[2]  J. Neumann,et al.  Numerical Integration of the Barotropic Vorticity Equation , 1950 .

[3]  J. Namias.  Evolution of monthly mean circulation and weather patterns , 1948 .

[4]  R. Sutcliffe.  Mean upper contour patterns of the northern hemisphere — the thermal-synoptic view-point , 1951 .

[5]  J. S. Sawyer,et al.  Dynamics of flow patterns in extra‐tropical regions , 1951 .

[6]  R. Elliott,et al.  A STUDY OF THE EFFECTS OF LARGE BLOCKING HIGHS ON THE GENERAL CIRCULATION IN THE NORTHERN-HEMISPHERE WESTERLIES , 1949 .

[7]  H. Wexler.  COOLING IN THE LOWER ATMOSPHERE AND THE STRUCTURE OF POLAR CONTINENTAL AIR , 1936 .

[8]  B. Haurwitz.  Comments on the Sea-Breeze Circulation. , 1947 .

[9]  J. London.  THE DISTRIBUTION OF RADIATIONAL TEMPERATURE CHANGE IN THE NORTHERN HEMISPHERE DURING MARCH , 1952 .

[10]  R. C. Sutcliffe,et al.  A contribution to the problem of development , 1947 .

[11]  B. Bolin.  On the Influence of the Earth's Orography on the General Character of the Westerlies , 1950 .

[12]  P. A. Sheppard,et al.  A note on the eddy transport of angular momentum , 1951 .

[13]  J. G. Charney,et al.  THE DYNAMICS OF LONG WAVES IN A BAROCLINIC WESTERLY CURRENT , 1947 .

[14]  C. S. Durst,et al.  Physical and Dynamical Meteorology , 1935 .

[15]  W. Jacobs.  THE ENERGY ACQUIRED BY THE ATMOSPHERE OVER THE OCEANS THROUGH CONDENSATION AND THROUGH HEATING FROM THE SEA SURFACE , 1949 .

[16]  W. Jacobs.  SOURCES OF ATMOSPHERIC HEAT AND MOISTURE OVER THE NORTH PACIFIC AND NORTH ATLANTIC OCEANS , 1943 .

[17]  Paul Queney,et al.  The Problem of Air Flow Over Mountains: A Summary of Theoretical Studies , 1948 .

[18]  J. Namias.  The Annual Course of Month-to-Month Persistence in Climatic Anomalies* , 1952 .

[19]  J. G. Charney,et al.  A Numerical Method for Predicting the Perturbations of the Middle Latitude Westerlies , 1949 .

[20]  C. Rossby.  Relation between variations in the intensity of the zonal circulation of the atmosphere and the displacements of the semi-permanent centers of action , 1939 .

[21]  G. Kuiper.  The atmospheres of the earth and planets. , 1952 .