Omega Diagnosis of a Cold Vortex with Severe Convection

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  • 1 Department of Geophysics, Peking University, Beijing, China
  • | 2 NOAA, Environmental Research Laboratories, Weather Research Program, Boulder, Colorado
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Abstract

A real-time quasi-geostrophic omega diagnostic scheme, based on Hoskins' Q-vector analysis and developed by Barnes, was applied to a cold mesoscale vortex with severe convection over northeast China in summer. The limited area model used at the Beijing Weather Center did not predict this event because the baroclinic forcing was rather weak, but the Q-vector analysis clearly indicated the forcing 12 h before. In addition to Barnes' diagnostics, we estimate divergence tendency in low levels through computation of the rotational component of the Q-vector. Combined with the diagnosed stability tendency, moisture analysis, and low-level wind convergence zone, the convective area can be identified. This microcomputer diagnostic-graphics scheme, when coupled with intelligent use of conventional data, has potential as an aid for local short-range weather forecasting.

Abstract

A real-time quasi-geostrophic omega diagnostic scheme, based on Hoskins' Q-vector analysis and developed by Barnes, was applied to a cold mesoscale vortex with severe convection over northeast China in summer. The limited area model used at the Beijing Weather Center did not predict this event because the baroclinic forcing was rather weak, but the Q-vector analysis clearly indicated the forcing 12 h before. In addition to Barnes' diagnostics, we estimate divergence tendency in low levels through computation of the rotational component of the Q-vector. Combined with the diagnosed stability tendency, moisture analysis, and low-level wind convergence zone, the convective area can be identified. This microcomputer diagnostic-graphics scheme, when coupled with intelligent use of conventional data, has potential as an aid for local short-range weather forecasting.

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