A STUDY OF VERTICAL VELOCITIES IN THE VICINITY OF JET STREAMS

Abstract

Three-hour average vertical velocity values are computed at the 500-and 300-mb levels under the assumption of adiabatic motion by the ?isobaric? technique. The patterns of the isolines of vertical velocity (isanabats) are shown for several upper flow patterns. Vertical velocity values of 10 cm sec?1 are found to be common at both levels, and a maximum value of 25 cm sec?1 is given. Computational errors are felt to be smaller by an order of magnitude. The strong isanabatic centers are shown to lie in or near the jet stream, indicating that the jet is an important vertical transport mechanism. Cloud observations show good qualitative agreement with the computations. Limited evidence, based on a study of the vertical velocity patterns over the Northern Hemisphere for a ten-day period, indicates that the mean circulation around the jet stream is thermally indirect.