کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5487426 | 1523509 | 2017 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Reversal and amplification of zonal flows by boundary enforced thermal wind
ترجمه فارسی عنوان
معکوس کردن و تقویت جریان های ناحیه ای توسط باد حرارتی اعمال شده توسط مرز
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کلمات کلیدی
جریان زون، ژئواستروفی، باد های گرم ناهنجاری شار حرارتی،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
علوم فضا و نجوم
چکیده انگلیسی
Zonal flows in rapidly-rotating celestial objects such as the Sun, gas or ice giants form in a variety of surface patterns and amplitudes. Whereas the differential rotation on the Sun, Jupiter and Saturn features a super-rotating equatorial region, the ice giants, Neptune and Uranus harbour an equatorial jet slower than the planetary rotation. Global numerical models covering the optically thick, deep-reaching and rapidly rotating convective envelopes of gas giants reproduce successfully the prograde jet at the equator. In such models, convective columns shaped by the dominant Coriolis force typically exhibit a consistent prograde tilt. Hence angular momentum is pumped away from the rotation axis via Reynolds stresses. Those models are found to be strongly geostrophic, hence a modulation of the zonal flow structure along the axis of rotation, e.g. introduced by persistent latitudinal temperature gradients, seems of minor importance. Within our study we stimulate these thermal gradients and the resulting ageostrophic flows by applying an axisymmetric and equatorially symmetric outer boundary heat flux anomaly (Y20) with variable amplitude and sign. Such a forcing pattern mimics the thermal effect of intense solar or stellar irradiation. Our results suggest that the ageostrophic flows are linearly amplified with the forcing amplitude qâ leading to a more pronounced dimple of the equatorial jet (alike Jupiter). The geostrophic flow contributions, however, are suppressed for weak qâ, but inverted and re-amplified once qâ exceeds a critical value. The inverse geostrophic differential rotation is consistently maintained by now also inversely tilted columns and reminiscent of zonal flow profiles observed for the ice giants. Analysis of the main force balance and parameter studies further foster these results.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Icarus - Volume 282, 15 January 2017, Pages 380-392
Journal: Icarus - Volume 282, 15 January 2017, Pages 380-392
نویسندگان
W. Dietrich, T. Gastine, J. Wicht,