Aerial Observations of the East African Low-Level Jet stream

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  • 1 Department of Astro-Geophysics, University of Colorando, Boulder, CO 80309
  • | 2 Department of Atmospheric Science, St. Louis University, St. Louis, MO 63156
  • | 3 National Center for Atmospheric research, Boulder, CO 80307
  • | 4 Department of Meteorology, University of Wisconsin, Madison, WI 53706
  • | 5 Meteorological Department, Nairobi, Kenya
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Abstract

This paper describes observation of the East African low-level jet stream obtained during June and July 1977 with a long-range research aircraft. We present results based on the real-time display of data on board the aircraft during the research flights. The jet stream core was located at about 40°E between 1 and 2 km altitude. The jet had a very sharp horizontal shear layer to the west of the core, with less pronounced shear to the east extending out over the ocean. Although flowing persistently from the south, it experienced a strong diurnal change over land. In addition, other changes in structure on a longer time scale were observed. This article presents the kinematic and thermal structure of the jet, and the low-level flow further upstream. Based on these data, the estimated cross-equational water vapor flux across the equator was found to be much higher than previously thought.

Abstract

This paper describes observation of the East African low-level jet stream obtained during June and July 1977 with a long-range research aircraft. We present results based on the real-time display of data on board the aircraft during the research flights. The jet stream core was located at about 40°E between 1 and 2 km altitude. The jet had a very sharp horizontal shear layer to the west of the core, with less pronounced shear to the east extending out over the ocean. Although flowing persistently from the south, it experienced a strong diurnal change over land. In addition, other changes in structure on a longer time scale were observed. This article presents the kinematic and thermal structure of the jet, and the low-level flow further upstream. Based on these data, the estimated cross-equational water vapor flux across the equator was found to be much higher than previously thought.

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