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- Author or Editor: Verne H. Leverson x
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Abstract
On 23–24 September 1983 the vicinity of Prescott, Arizona, experienced a 36 h period of recurrent heavy rains. Measurement obtained from a supplemental precipitation survey of the storm-affected area are used to derive maximum 6 h and total storm (36 h) precipitation patterns. Rainfall depth-area-duration (DAD) data computed from the patterns are compared with three standards of precipitation severity: 1) documented extreme rainstorms in the southwestern United States, 2) precipitation-frequency values and 3) probable maximum precipitation (PMP) estimates. The comparisons show the Prescott storm to be an exceptional event that produced rainfall exceeding 100-yr amounts as well as some categories of PMP.
Abstract
On 23–24 September 1983 the vicinity of Prescott, Arizona, experienced a 36 h period of recurrent heavy rains. Measurement obtained from a supplemental precipitation survey of the storm-affected area are used to derive maximum 6 h and total storm (36 h) precipitation patterns. Rainfall depth-area-duration (DAD) data computed from the patterns are compared with three standards of precipitation severity: 1) documented extreme rainstorms in the southwestern United States, 2) precipitation-frequency values and 3) probable maximum precipitation (PMP) estimates. The comparisons show the Prescott storm to be an exceptional event that produced rainfall exceeding 100-yr amounts as well as some categories of PMP.
Abstract
During September 1974 in the Lower Florida Keys, the first successful penetrations of mature waterspouts were accomplished by a specially instrumented research aircraft. Throughout the course of each penetration, the measurement system recorded the temperature, the pressure and the three-dimensional velocity field near and within the visible funnel. Multiple penetrations of both cyclonic and anticyclonic waterspouts in various life-cycle stages were achieved. The results indicate that the waterspout funnel structure exhibits 1) a warm central core region, 2) positive vertical velocities of 5–10 m s−1 outside of the warm core, and 3) tangential velocities and horizontal pressure gradients with characteristics similar to but with magnitudes greater than those of the dust devil. A scale analysis of each term in the governing equations of motion suggests a simplified set of modeling equations. The simple Rankine-combined vortex model with cyclostrophic flow explains approximately 75% of the total measured pressure deficit. This compares favorably with Sinclair's (1966, 1973) earlier results for the dust devil vortex.
Abstract
During September 1974 in the Lower Florida Keys, the first successful penetrations of mature waterspouts were accomplished by a specially instrumented research aircraft. Throughout the course of each penetration, the measurement system recorded the temperature, the pressure and the three-dimensional velocity field near and within the visible funnel. Multiple penetrations of both cyclonic and anticyclonic waterspouts in various life-cycle stages were achieved. The results indicate that the waterspout funnel structure exhibits 1) a warm central core region, 2) positive vertical velocities of 5–10 m s−1 outside of the warm core, and 3) tangential velocities and horizontal pressure gradients with characteristics similar to but with magnitudes greater than those of the dust devil. A scale analysis of each term in the governing equations of motion suggests a simplified set of modeling equations. The simple Rankine-combined vortex model with cyclostrophic flow explains approximately 75% of the total measured pressure deficit. This compares favorably with Sinclair's (1966, 1973) earlier results for the dust devil vortex.
