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RISOn the Deformation Term in the Quasigeostrophic Omega Equation
Publisher: American Meteorological Society
Abstract: It is a common diagnostic, synoptic practice to consider the Trenberth?Sutcliffe approximation to the quasigeostrophic (QG) omega equation, which relates upward vertical motion to regions of cyclonic vorticity advection ...
Quasigeostrophic Forcing of Ascent in the Occluded Sector of Cyclones and the Trowal Airstream
Publisher: American Meteorological Society
Abstract: A numerical model-based analysis of the quasigeostrophic forcing for ascent in the occluded quadrant of three cyclones is presented based upon a natural coordinate partitioning of the Q vector into its along- and ...
The Separate Roles of Geostrophic Vorticity and Deformation in the Midlatitude Occlusion Process
Publisher: American Meteorological Society
Abstract: Separate vector expressions for the rate of change of direction of the potential temperature gradient vector resulting from the geostrophic vorticity and geostrophic deformation, referred to as QVR and QDR, respectively, ...
The Role of Shearwise and Transverse Quasigeostrophic Vertical Motions in the Midlatitude Cyclone Life Cycle
Publisher: American Meteorological Society
Abstract: The total quasigeostrophic (QG) vertical motion field is partitioned into transverse and shearwise couplets oriented parallel to, and along, the geostrophic vertical shear, respectively. The physical role played by each ...
Lower-Tropospheric Height Tendencies Associated with the Shearwise and Transverse Components of Quasigeostrophic Vertical Motion
Publisher: American Meteorological Society
Abstract: The recent suggestion that lower-tropospheric cyclogenesis is predominantly a result of column stretching associated with the updraft portion of the shearwise quasigeostrophic (QG) vertical motion is quantified through ...
The Structure and Evolution of a Continental Winter Cyclone. Part I: Frontal Structure and the Occlusion Process
Publisher: American Meteorological Society
Abstract: The frontal structure and occlusion process in a cyclone of moderate intensity that affected the central United States in January 1995 is examined. The deep warm-frontal zone associated with this cyclone had a lateral ...
The Structure and Evolution of a Continental Winter Cyclone. Part II: Frontal Forcing of an Extreme Snow Event
Publisher: American Meteorological Society
Abstract: The production of a narrow, heavy, occasionally convective snowband that fell within a modest surface cyclone on 19 January 1995 is examined using gridded model output from a successful numerical simulation performed using ...
Contraction of the Northern Hemisphere, Lower-Tropospheric, Wintertime Cold Pool over the Past 66 Years
Publisher: American Meteorological Society
Abstract: mploying reanalysis datasets, several threshold temperatures at 850 hPa are used to measure the wintertime [December?February (DJF)] areal extent of the lower-tropospheric, Northern Hemisphere, cold-air pool over the past ...
A Pacific Moisture Conveyor Belt and Its Relationship to a Significant Precipitation Event in the Semiarid Southwestern United States
Publisher: American Meteorological Society
Abstract: In this study the term moisture conveyor belt (MCB) is defined as an elongated band of enhanced poleward water vapor fluxes (WVFs) above the PBL that is rooted in the Tropics. This new terminology is illustrated through ...
Surface Cyclolysis in the North Pacific Ocean. Part II: Piecewise Potential Vorticity Diagnosis of a Rapid Cyclolysis Event
Publisher: American Meteorological Society
Abstract: Employing output from a successful numerical simulation, piecewise potential vorticity inversion is used to diagnose a rapid surface cyclolysis event that occurred south of the Aleutian Islands in late October 1996. The ...