The effect of the equatorially symmetric zonal winds of Saturn on its gravitational field

doi:10.1088/1674-4527/18/4/39

	The effect of the equatorially symmetric zonal winds of Saturn on its gravitational field
	Kong, Dali 1,2; Zhang, Keke 2,3; Schubert, Gerald 4; Anderson, John D.5
刊名	RESEARCH IN ASTRONOMY AND ASTROPHYSICS
	2018-04-01
卷号	18 期号:4 页码:8
关键词	gravitation planets and satellites: individual (Saturn) planets and satellites: interiors
ISSN号	1674-4527
DOI	10.1088/1674-4527/18/4/39
通讯作者	Zhang, Keke(kzhang@ex.ac.uk)
英文摘要	The penetration depth of Saturn's cloud-level winds into its interior is unknown. A possible way of estimating the depth is through measurement of the effect of the winds on the planet's gravitational field. We use a self-consistent perturbation approach to study how the equatorially symmetric zonal winds of Saturn contribute to its gravitational field. An important advantage of this approach is that the variation of its gravitational field solely caused by the winds can be isolated and identified because the leading-order problem accounts exactly for rotational distortion, thereby determining the irregular shape and internal structure of the hydrostatic Saturn. We assume that (i) the zonal winds are maintained by thermal convection in the form of non-axisymmetric columnar rolls and (ii) the internal structure of the winds, because of the Taylor-Proundman theorem, can be uniquely determined by the observed cloud-level winds. We calculate both the variation Delta J(n), n = 2, 4, 6 ... of the axisymmetric gravitational coefficients J(n) caused by the zonal winds and the non-axisymmetric gravitational coefficients Delta J(nm) produced by the columnar rolls, where m is the azimuthal wavenumber of the rolls. We consider three different cases characterized by the penetration depth 0.36 R-S, 0.2 R-S and 0.1 R-S, where R-S is the equatorial radius of Saturn at the 1-bar pressure level. We find that the high-degree gravitational coefficient (J(12) + Delta J(12)) is dominated, in all the three cases, by the effect of the zonal flow with vertical bar Delta J(12)/J(12)vertical bar > 100% and that the size of the non-axisymmetric coefficients Delta J(mn) directly reflects the depth and scale of the flow taking place in the Saturnian interior.
WOS关键词	CONVECTION ; JUPITER ; SIGNATURE ; PLANETS ; MODEL
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	NATL ASTRONOMICAL OBSERVATORIES, CHIN ACAD SCIENCES
WOS记录号	WOS:000430282700003
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/22487]
专题	中国科学院紫金山天文台
通讯作者	Zhang, Keke
作者单位	1.Chinese Acad Sci, Shanghai Astron Observ, Key Lab Planetary Sci, Shanghai 200030, Peoples R China 2.Univ Exeter, Coll Engn Math & Phys Sci, Exeter EX4 4QF, Devon, England 3.Macau Univ Sci & Technol, Lunar & Planetary Sci Lab, Macau, Peoples R China 4.Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA 5.Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA
推荐引用方式 GB/T 7714	Kong, Dali,Zhang, Keke,Schubert, Gerald,et al. The effect of the equatorially symmetric zonal winds of Saturn on its gravitational field[J]. RESEARCH IN ASTRONOMY AND ASTROPHYSICS,2018,18(4):8.
APA	Kong, Dali,Zhang, Keke,Schubert, Gerald,&Anderson, John D..(2018).The effect of the equatorially symmetric zonal winds of Saturn on its gravitational field.RESEARCH IN ASTRONOMY AND ASTROPHYSICS,18(4),8.
MLA	Kong, Dali,et al."The effect of the equatorially symmetric zonal winds of Saturn on its gravitational field".RESEARCH IN ASTRONOMY AND ASTROPHYSICS 18.4(2018):8.