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- Author or Editor: E. Paul Mcclain x
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Abstract
Revised means, frequency distributions and other statistics based on ten years of January temperature observations at the 200-, 100- and 50-mb levels are presented for four arctic stations. The frequency distributions are shown to be markedly bimodal, a characteristic that becomes more pronounced with increasing height and latitude. Thermal conditions in the arctic and antarctic stratospheres are compared with the aid of recent IGY data.
Abstract
Revised means, frequency distributions and other statistics based on ten years of January temperature observations at the 200-, 100- and 50-mb levels are presented for four arctic stations. The frequency distributions are shown to be markedly bimodal, a characteristic that becomes more pronounced with increasing height and latitude. Thermal conditions in the arctic and antarctic stratospheres are compared with the aid of recent IGY data.
Abstract
Some effects of the western mountain complex of North America on cyclones are investigated from the standpoint of how the vorticity tendency field might be influenced by orographically-induced vertical motion and divergence. A detailed case study is presented which includes computations of terms in the vorticity tendency equation during a lee cyclogenesis. The local increases in low-level vorticity which occurred during formation of the lee trough and cyclone were primarily due to horizontal convergence, while the horizontal and vertical advection of vorticity opposed the increases; the contribution of the tipping term was generally negligible. The study also provides evidence that orographic effects are insufficient to explain the genesis of major cyclonic storms.
Abstract
Some effects of the western mountain complex of North America on cyclones are investigated from the standpoint of how the vorticity tendency field might be influenced by orographically-induced vertical motion and divergence. A detailed case study is presented which includes computations of terms in the vorticity tendency equation during a lee cyclogenesis. The local increases in low-level vorticity which occurred during formation of the lee trough and cyclone were primarily due to horizontal convergence, while the horizontal and vertical advection of vorticity opposed the increases; the contribution of the tipping term was generally negligible. The study also provides evidence that orographic effects are insufficient to explain the genesis of major cyclonic storms.
Abstract
The thermal structure of the troposphere and lower stratosphere during the movement eastward of several Pacific troughs is examined primarily from the standpoint of the distribution of baroclinity within a vertical plane extending across the northwestern and north central United States. Baroclinity is defined and then expressed in a form suitable to the potential-temperature cross-sections employed in this study. Dominating features of the thermal field are two types of baroclinic zones: (1) broad and essentially non-frontal zones which form the leading and trailing edges of deep, rapidly moving cold domes in the middle and upper troposphere; (2) narrow, frontal type zones comprising the leading or trailing edges of either slowly-moving, low-level cold domes or rapidly-moving, upper-level ones. There is evidence that the non-frontal baroclinic zones are equally as important, both dynamically and synoptically, as the frontal ones.
Abstract
The thermal structure of the troposphere and lower stratosphere during the movement eastward of several Pacific troughs is examined primarily from the standpoint of the distribution of baroclinity within a vertical plane extending across the northwestern and north central United States. Baroclinity is defined and then expressed in a form suitable to the potential-temperature cross-sections employed in this study. Dominating features of the thermal field are two types of baroclinic zones: (1) broad and essentially non-frontal zones which form the leading and trailing edges of deep, rapidly moving cold domes in the middle and upper troposphere; (2) narrow, frontal type zones comprising the leading or trailing edges of either slowly-moving, low-level cold domes or rapidly-moving, upper-level ones. There is evidence that the non-frontal baroclinic zones are equally as important, both dynamically and synoptically, as the frontal ones.
