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Numerical Modeling of Terrestrial Planet Temperature Distribution Effect on Polar Vortex Forming: Venus Modeling

Molaverdikhani, Karan | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40489 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud
  7. Abstract:
  8. A global rotating atmosphere with polar vortex and super rotation is simulated using a simplified Venus General Circulation Model (GCM). The polar vortex is maintained strongly by meridional circulation develops in the form of a simple Hadley cell, extending from the equator to the pole in both hemispheres and rotation terrestrial planet. Venus Total Polar Vortex Parameter (PVP) was defined like globally integrated super-rotation but at polar skullcaps (60-90 deg). Venus Polar Vortex Parameter is PVP=1.5 that’s qualitatively similar to observed polar vortex. Then with study in terrestrial planet and Titan modeling, we appointed the Polar Vortex Parameter and critical limit of Polar Vortex existence. The Polar Vortex is one of the complicated phenomena in planets and moons which have atmosphere. But for the reason that these events happen in poles, so conventional modeling and numerical grids don’t have a suitable. In this paper with selecting a numerical model in global circulation modeling (GCM, as Lee offer) and try to improve it in dynamic core parts, add polar filtering and change the grids from B to C Arakawa, we calculate the polar vortex of Venus in this way. After survey of the Venus modeling, we use the modified modular method with development in entrance data for supposition Earth (single Hadley cell Earth), Mars and also mystery moon of Saturn (Titan), until we appointment the Polar Vortex Parameter (PVP) and critical limit of Polar Vortex existence. In this GCM, a sigma coordinate is used in the vertical with maximum level space about 3 km (typical of the current Venus GCMs), with both winds and temperatures defined at the same levels. On horizontal grids, the prognostic variables are located on an Arakawa C-grid. Forcing in the model is provided by Newtonian cooling and Rayleigh friction parameterizations and a model stabilizing fourth-order numerical diffusion. A polar Fourier filter is applied to the tendencies of all the prognostic variables from mean latitude to pole at both hemispheres. Also, in these results, Northern is the referenced pole. Temperature difference at day and night is the very important factor with effects on the eastern-western hemispheres atmosphere dynamic. We use similar Lee mean temperature profile but with developments on night and Polar Regions.
  9. Keywords:
  10. Numerical Modeling ; Variable Infiltration Capacity (VIC)Model ; Polar Vortex ; Polar Filter

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