Mattia Marchio, Ph.D. Candidate 35th cycle, University of Trento, DICAM
1: Atmospheric Physics Group, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Italy; 2: C3A – Center Agriculture Food Environment, University of Trento, Italy
Diurnal wind systems typically develop in mountainous areas following the daytime heating and nighttime cooling of sloping surfaces. Common examples are valley and
slope winds. If valley winds have been deeply studied in the past, the same can not be said for slope winds, and in particular for their daytime component, usually called
upslope or anabatic wind. Thus, the physical mechanisms associated with the development of these winds, as well as the search for appropriate parameterization of turbulent
fluxes of mass, momentum, and heat over slopes are still open research topics.
A better understanding of the phenomena is desired for a series of applications in many fields, such as air quality (transport of pollutants, pollens, and other species),
agriculture (transport of droplets from spraying of pesticides in crops along slopes), civil protection (initiation of convection from slope winds as precursors of severe
precipitation events). Moreover, new parameterization of turbulent fluxes can be used in numerical weather prediction models to improve numerical weather forecasts in
complex terrain areas.The study is conducted through a combination of multiple approaches. Field data analysis, numerical model simulations, and studies on the derivation of new analytical
solutions can all help to provide a better and comprehensive understanding of the phenomena and will thus be used.
Field data from two stations of the recent i-Box campaign (Rotach et al. 2017, Stiperski et al. 2016) were analyzed. Sets of criteria for the selection of days with suitable
conditions for the development of valley winds were applied to detect days with the occurrence of slope winds given their similar nature but failed in the discrimination
(Figure 1). In addition, measurements representing the evolution of the up-slope flow structure from the early morning to the mid-afternoon are compared with
alternate success with an existing, simplified, analytical model (Zardi and Serafin 2015), which provides the evolution of the vertical profiles of temperature and along-slope
wind velocity as generated by a sinusoidal forcing representing the daily cycle of surface temperature (Figure 2). A new, improved analytical model is currently under
High-resolution numerical model simulations with advanced turbulence closures will be implemented for reproducing the properties of upslope flows under different
conditions (slope angle, surface properties, ambient stratification, thermal forcing, etc,) in view of deriving scaling properties and suitable structure functions.
- Rotach, M. W., Stiperski, I., Fuhrer, O., Goger, B., Gohm, A., Obleitner, F., Rau, G., Sfyri, E., & Vergeiner, J. (2017). Investigating Exchange Processes over Complex Topography: The Innsbruck Box (i-Box), Bulletin of the American Meteorological Society, 98(4), 787-805.
- Zardi, D. and Serafin, S. (2015), An analytic solution for time-periodic thermally driven slope flows. Quarterly Journal of the Royal Meteorological Society, 141: 1968-197
- Stiperski, I., Rotach, M.W. On the Measurement of Turbulence Over Complex Mountainous Terrain. Boundary-Layer Meteorol 159, 97–121 (2016).