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Mass transport across a temperature inversion

1977; American Geophysical Union; Volume: 82; Issue: 24 Linguagem: Inglês

10.1029/jc082i024p03463

2156-2202

J. Goodman, Albert J. Miller,

Atmospheric Ozone and Climate

There is significant vertical transport of mass both within and across the base of the U.S. west coast temperature inversion. The vertical flux has been determined from a variety of observations made on Mt. Sutro Tower, in the heart of San Francisco: (1) increased concentration of trace elements in aerosols above the inversion base; (2) correlation between the diurnal variations of the concentration of condensation nuclei below and just above the inversion base; (3) a rate of decrease with height in the concentration of sea salt nuclei that does not change significantly above the inversion base; and (4) mixing of fluorescent particles, released upwind of the tower both below and above the inversion base, across and within the inversion. The vertical transport, approximately 15 cm s−1 is ascribed to the action of stable internal gravity waves moving through a layer of strong vertical shear of the horizontal wind. Horizontal mixing near their crests results in a net vertical pumping of mass. The apparent vertical diffusion coefficient is larger than would be expected for the observed Richardson number, although it decreases with increasing Richardson number.