Joint Seminar: Orographic-Convective Flows, Gravity-Waves, and Precipitation: Theoretical and Modeling Studies

To understand flows, gravity-waves, and precipitation over the mountainous area, a few theoretical and numerical studies will be introduced. Dynamical aspects of flows forced by either convective heating or a mountain have been extensively studied, but those forced by both convective heating and a mountain have been less studied. Here, the orographic-convective flows, gravity-wave reflection, and gravity-wave momentum fluxes in stably stratified hydrostatic and non-hydrostatic atmosphere are examined. The effects of the nonlinear interactions between orographically and convectively forced momentum fluxes and the non-hydrostatically forced additional gravity-wave components on total momentum flux are discussed. Numerical studies focus on the aerosol and mountain-geometric effects on orographic precipitation with different aerosol number concentrations and windward-widths of the bell-shaped mountain. For a detailed representation of drop size distributions, the WRF model that includes a bin microphysics scheme is used. A higher aerosol number concentration leads the decrease of total and maximum surface precipitation amounts and downward shifting of the location of the maximum surface precipitation amount. The aerosol effects on orographic precipitation are more clearly seen in the cases with the narrow windward-width. Additionally, using numerical simulations with different aerosol number concentrations, the aerosol effects on gravity-wave momentum fluxes over the precipitating mountain are examined. The modification of orographic-convective clouds and precipitation by aerosol number concentrations results in modification of convectively forced momentum fluxes, the nonlinear interactions between orographically and convectively forced momentum fluxes, and (as a result) of total momentum flux. The applicability of theoretical findings are verified through decomposition of the numerically simulated gravity-wave momentum fluxes.

Date

15.10.2019

Time

15:15 h

Place

Bundesstr. 53, room 101/102
Seminar Room 101/102, 1st floor, Bundesstr. 53, 20146 Hamburg, Hamburg

Speaker

Jaemyeong Seo, MPI

Chair

Dian Putrasahan

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