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D. L. McNaughton

Abstract

It is suggested the Bowen's meteor hypothesis has special relevance in the Southern Hemisphere, because of its comparatively small area of land and the fairly slow interhemispheric exchange of air. The latter is discussed in the light of tritium measurements in Rhodesian rain. The existence of calendar singularities is established in Rhodesian rainfall records, the pattern repeating itself in the hail records of years which do not overlap those used for the rainfalls. Salisbury and Bulawayo derive almost coincident peaks with rain falling in completely different years, indicating that a secondary rather than primary weather mechanism is responsible for some of the singularities. Others are associated with pressure fluctuations over South Africa.

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Vladimir N. Kapustin
,
Antony D. Clarke
,
Steven G. Howell
,
Cameron S. McNaughton
,
Vera L. Brekhovskikh
, and
Jingchuan Zhou

Abstract

Topography-induced steady-state accelerated wind flow in the Alenuihaha Channel between the islands of Hawaii and Maui provides about 100 km of fetch with winds that can nearly double over trade wind speed. Here ship- and aircraft-based observations of meteorological parameters and aerosols in Hawaii’s orographic natural “wind tunnel” are used for the study of sea salt aerosol (SSA) production, evolution, and related optical effects under clean oceanic conditions. There are certain advantages of channel measurements, such as a broad and uniform upstream area usually filled with background aerosol, stationary flow, and known fetch, but also some difficulties, like vigorous entrainment and persistent presence of organized structures (rolls). It is found that marine boundary layer (MBL) rolls are a common occurrence near the Hawaiian Islands even when cloud streets are not visible in satellite imagery. The presence of rolls tends to enhance the variability of ambient aerosol concentration and probably affects production of primary sea salt aerosol and entrainment from above. The possibility of channel measurements of the size-dependent flux of SSA is explored using a concentration buildup method as surface wind speeds range from 7 to 11 m s−1. Production of SSA particles with dry diameter as small as 0.18 μm was observed. General agreement with reported SSA fluxes was found.

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D. J. McNaughton
,
N. E. Bowne
,
R. L. Dennis
,
R. R. Draxler
,
S. R. Hanna
,
T. Palma
,
S. L. Marsh
,
W. T. Pennell
,
R. L. Peterson
,
J. V. Ramsdell
,
S. T. Rao
, and
R. J. Yamartino

The Eighth Joint Conference on Applications of Air Pollution Meteorology with the Air and Waste Management Association was held in conjunction with the AMS 74th Annual Meeting in Nashville, Tennessee, on 23–28 January 1994. Sessions at the meeting covered a broad range of topics including the dispersion environment, meteorology in emissions determination, long-range and mesoscale pollutant transport and fate, meteorology and photochemistry, advanced dispersion models and modeling systems, model evaluation, complex flows affecting dispersion near structures, and coastal and complex terrain issues. Papers followed some recurrent themes but many reported applications of new technology that provide new opportunities to see atmospheric characteristics and complexities for the first time. Innovative techniques were described in data analysis and presentation and modeling.

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