TURBULENT DISPERSION OF AIRCRAFT EXHAUSTS IN REGIONS OF BREAKING GRAVITY-WAVES

This study describes the three-dimensional dispersion of aircraft exha usts released into regions of overturning and breaking gravity waves b elow a critical level. The principal concept is to estimate effective diffusivities of a passive scalar by combining previous numerical appr oaches to the plume dispersion in the free atmosphere and to the break down of internal gravity waves at those altitudes. Here, it could be s hown that the possible high vertical diffusivity of 6 m(2) s(-1) contr ibutes considerably to an efficient vertical mixing of aircraft exhaus ts or other species, e.g. trace gases. The effective Vertical diffusio n coefficient of the entire breaking event is calculated to be D-v(eff ) approximate to 0.5 m(2) s(-1). (C) 1998 Elsevier Science Ltd. All ri ghts reserved.