Idealised Simulations of Daytime Pollution Transport in a Steep Valley and its Sensitivity to Thermal Stratification and Surface Albedo
- 140 Downloads
Numerical simulations of tracer transport in an idealised, east-west aligned valley are performed with the Regional Atmospheric Modeling System (RAMS), both two-dimensional and three-dimensional. The results are qualitatively consistent with wintertime observations in the Austrian Inn Valley. The simulations show an asymmetry in wind circulation and tracer distribution between the valley sidewalls according to the orientation of the slope with respect to the sun. Two-dimensional sensitivity experiments are run to investigate the influence of vertical inhomogeneities in thermal stratification and vegetation coverage on the slope-wind circulation and therewith the tracer transport. It is shown that a transition to a layer of higher stability or to a region with higher surface albedo causes a reduction of the mass flux in the upslope-wind layer and due to mass continuity a quasi-horizontal transport out of the slope-wind layer.
KeywordsAnabatic winds Cross-valley winds Numerical modelling Tracer transport
Unable to display preview. Download preview PDF.
- Gohm A, Harnisch F, Fix A (2006) Boundary layer structure in the Inn Valley during high air pollution (INNAP). In: Extended abstract of the 12th conference on mountain meteorology. Santa Fe, New Mexico. http://ams.confex.com/ams/pdfpapers/114458.pdf Accessed 24 Apr 2009
- Gohm A, Harnisch F, Vergeiner J, Obleitner F, Schnitzhofer R, Hansel A, Fix A, Neininger B, Emeis S, Schäfer K (2009) Air pollution transport in an Alpine valley: results from airborne and ground-based observations. Boundary-Layer Meteorol. doi: 10.1007/s10546-009-9371-9
- Hanna SR, Strimaitis DG (1990) Rugged terrain effects on diffusion. In: Blumen W (ed) Atmospheric processes over complex terrain, meteorological monographs, vol 23. American Meteorological Society, pp 109–143Google Scholar
- Heimann D, de Franceschi M, Emeis S, Lercher P, Seibert P (eds) (2007) Air pollution, traffic noise and related health effects in the Alpine space—a guide for authorities and consulters. ALPNAP comprehensive report. Università degli Studi di Trento, Dipartimento di Ingegneria Civile e Ambientale, Trento, Italy, 335 ppGoogle Scholar
- Lehner M (2008) Idealized sensitivity study of pollution transport over Alpine terrain. Master’s thesis, Institute of Meteorology and Geophysics, University of Innsbruck, 160 ppGoogle Scholar
- Lilly DK (1962) On the numerical simulation of buoyant convection. Tellus XIV:148–172Google Scholar
- Louis JF, Tiedtke M, Geleyn J-F (1981) A short history of the operational PBL—parameterization at ECMWF. In: Proc workshop on planetary boundary layer parameterization. ECMWF, Reading, United Kingdom, pp 59–79Google Scholar
- McNider RT, Pielke RA (1984) Numerical simulation of slope and mountain flows. J Clim Appl Meteorol 23: 1441–1453Google Scholar
- Vosper SB, Brown AR (2008) Numerical simulations of sheltering in valleys: the formation of nighttime cold-air pools. Boundary-Layer Meteorol. doi: 10.1007/s10546-008-9272-3
- Zängl G, Gohm A, Obleitner F (2007) The impact of the PBL scheme and the vertical distribution of model layers on simulations of Alpine foehn. Meteorol Atmos Phys. doi: 10.1007/s00703-007-0276-1