I. Cheng, N. Achilleos, X. Blanco-Cano, C. Bertucci, N. Sergis, C. Paranicas, P. Guio
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MM waves were found from 4 to 19 hr local time (partly due to data coverage), and distances of 0–12 <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>R</mi>\n <mi>S</mi>\n </msub>\n </mrow>\n <annotation> ${\\mathrm{R}}_{\\mathrm{S}}$</annotation>\n </semantics></math> from the magnetopause (MP). The occurrence of MM dips was more frequent near the MP and magnetosheath flanks, analogous to the Jovian system. MM dips exhibited a minimum field strength saturation <span></span><math>\n <semantics>\n <mrow>\n <mo>∼</mo>\n </mrow>\n <annotation> ${\\sim} $</annotation>\n </semantics></math> 0.5 nT, with the largest dip inferred to be in mirror-stable plasma. Notably, larger amplitude MM dips were typically found nearer the MP boundary which increases <span></span><math>\n <semantics>\n <mrow>\n <mi>Δ</mi>\n <mi>β</mi>\n </mrow>\n <annotation> ${\\Delta }\\beta $</annotation>\n </semantics></math> across the boundary thus increasing the magnetic shear necessary for the onset of MP reconnection. Thus, MM waves may be important in plasma dynamics near Saturn's magnetopause.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032584","citationCount":"0","resultStr":"{\"title\":\"Waves and Instabilities in Saturn's Magnetosheath: 1 Mirror Mode Waves and Their Impact on Magnetopause Reconnection\",\"authors\":\"I. Cheng, N. Achilleos, X. Blanco-Cano, C. Bertucci, N. Sergis, C. 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MM waves were found from 4 to 19 hr local time (partly due to data coverage), and distances of 0–12 <span></span><math>\\n <semantics>\\n <mrow>\\n <msub>\\n <mi>R</mi>\\n <mi>S</mi>\\n </msub>\\n </mrow>\\n <annotation> ${\\\\mathrm{R}}_{\\\\mathrm{S}}$</annotation>\\n </semantics></math> from the magnetopause (MP). The occurrence of MM dips was more frequent near the MP and magnetosheath flanks, analogous to the Jovian system. MM dips exhibited a minimum field strength saturation <span></span><math>\\n <semantics>\\n <mrow>\\n <mo>∼</mo>\\n </mrow>\\n <annotation> ${\\\\sim} $</annotation>\\n </semantics></math> 0.5 nT, with the largest dip inferred to be in mirror-stable plasma. 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引用次数: 0
摘要
卡西尼号在 2004 年至 2012 年期间穿越了 1,589 次土星磁鞘,我们利用这些土星磁鞘的综合目录对镜像模式(MM)波进行了统计研究,并评估了它们在影响磁层顶(MP)的磁再连接方面所起的作用。在许多行星磁层、磁鞘、彗星和太阳风中都观测到了镜像模式波。了解它们生长和主导的条件可以揭示它们在影响等离子体动力学中的作用。利用对磁场和等离子体数据进行阈值化处理的方法,可以确定 MM 波的候选者。研究发现了这些波在不同地点和条件下的磁场特征和出现分布。在当地时间 4 至 19 小时(部分原因是数据覆盖范围),距离磁极点 0-12 R S ${\mathrm{R}}_{\mathrm{S}}$ 的范围内发现了 MM 波。在磁层顶和磁鞘侧翼附近,MM 凹陷的出现更为频繁,这与汝维亚系统类似。MM倾角的最小场强饱和度为0.5 nT,推断最大倾角出现在镜像稳定等离子体中。值得注意的是,更大振幅的MM波通常出现在靠近MP边界的地方,这增加了边界上的Δ β $\{Delta }\beta $,从而增加了MP重联发生所需的磁剪切。因此,MM 波可能是土星磁极附近等离子体动力学的重要因素。
Waves and Instabilities in Saturn's Magnetosheath: 1 Mirror Mode Waves and Their Impact on Magnetopause Reconnection
A comprehensive catalog of 1,589 Saturn magnetosheath traversals by Cassini between 2004 and 2012 was used to perform a statistical study of mirror mode (MM) waves and assess their role in influencing magnetic reconnection at the magnetopause (MP). MM waves have been observed in many planetary magnetospheres and magnetosheaths, comets and the solar wind. Understanding the conditions under which they grow and dominate can reveal their role in influencing plasma dynamics. Using a thresholding method on both magnetic field and plasma data, MM wave candidates can be identified. The magnetic field characteristics and occurrence distributions of these waves against different locations and conditions were found. MM waves were found from 4 to 19 hr local time (partly due to data coverage), and distances of 0–12 from the magnetopause (MP). The occurrence of MM dips was more frequent near the MP and magnetosheath flanks, analogous to the Jovian system. MM dips exhibited a minimum field strength saturation 0.5 nT, with the largest dip inferred to be in mirror-stable plasma. Notably, larger amplitude MM dips were typically found nearer the MP boundary which increases across the boundary thus increasing the magnetic shear necessary for the onset of MP reconnection. Thus, MM waves may be important in plasma dynamics near Saturn's magnetopause.