SOME NEW DATA ON THE LONGITUDINAL DIMENSIONS OF PLANETARY WAVES

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  • 1 U. S. Weather Bureau, Washington, D. C.
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Abstract

Statistics of planetary wave number and wave length as observed on 5-day mean 700-mb charts are presented for each ten degrees of latitude between 30N and 70N for each month of the year. These statistics show that there tend to be fewer waves around latitude circles in the colder half of the year. As might be expected from the variation in the length of latitude circles, there are more waves at tower latitudes than at high latitudes, but wave lengths are actually longer at middle and low latitudes than at high latitudes. The monthly and latitudinal variations in the longitudinal dimensions of waves are explained to a moderate degree by variations in physical parameters suggested by theoretical and laboratory models. Specifically, it has been found that wave length exhibits a direct relationship to thermal Rossby number, zonal wind speed in mid-troposphere, and static stability.

Abstract

Statistics of planetary wave number and wave length as observed on 5-day mean 700-mb charts are presented for each ten degrees of latitude between 30N and 70N for each month of the year. These statistics show that there tend to be fewer waves around latitude circles in the colder half of the year. As might be expected from the variation in the length of latitude circles, there are more waves at tower latitudes than at high latitudes, but wave lengths are actually longer at middle and low latitudes than at high latitudes. The monthly and latitudinal variations in the longitudinal dimensions of waves are explained to a moderate degree by variations in physical parameters suggested by theoretical and laboratory models. Specifically, it has been found that wave length exhibits a direct relationship to thermal Rossby number, zonal wind speed in mid-troposphere, and static stability.

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