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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:32 |
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Conference: Bucharest University Faculty of Physics 2018 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
On improvements for the thermal convection prediction models
Authors:
Cristian Valer VRACIU(1), Bogdan ANTONESCU(2)
Affiliation:
1) University of Bucharest, Faculty of Physics, P.O. BOX MG-11, Bucharest-Magurele, Romania
2) National Institute of Research&Development for Optoelectronics - INOE 2000 409 Atomistilor St., RO - 77125, P.O. Box MG-5, Magurele, Ilfov, Romania
E-mail
cv_vraciu@yahoo.com
Keywords:
Thermal convection, Convection forecast, Turbulence of the thermals, Soaring
Abstract:
In the free flight activities, the forecast of the thermal convection is an important part of flight planning and competition tasks. At this point, it is not known how turbulence of the thermals affects the precision of its forecast or flight in the ascending currents. To integrate bulk Richardson number into the forecasting model, that gives at the conditions for thermals at mesoscale, needs to get some feedback from the glider pilots. The pilots can analyze during flights the difference between forecasting and reality depending on the predicted value of the Richardson number. This method can bring only minor corrections of the forecasts when the turbulence is normal (R ~ 0.5) but it can be a very useful information for pilots when the turbulence is out of the normal limits (laminar or very turbulent flow). Zakinyan et al. 2015, have developed a new theoretical model which allows the calculation with great accuracy of the vertical velocity of the thermals. Their model together with corrections related to glider flight in the thermal allows the forecasting of the vertical velocity depending on boundary layer stratification and overheat function at the surface. The gradient of temperature at the surface cannot be predicted at the required scale (<< 1km). Different vegetations types (averaged over scales on the order of tens of kilometres) can result in temperature gradients. Thus, an analysis needed in order to understand links exist between vegetation (or albedo associated with different vegetation types) mediated and overheated function at on the ground.
References:
Parton WJ (1984), Predicting soil temperature in a short grass step. Soil Sci 138:93-100
Stull RB (1988), An introduction to boundary layer meteorology. Kluwer Academic Publishers, The Netherlands
Vraciu CV, Stefan S (2017), Surface albedo and vegetation cover importance in atmospheric thermals genesis, Bucharest University Faculty of Physics 2017 Meeting
Zakinyan RG, Zakinyan AR, Lukinov AA (2015), Two-dimensional analytical model of dry air thermal convection. Meteorol Atmos Phys 127:451-455
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