Climatology of quiet time geomagnetic field variations at two locations in Antarctica

IF 1.5 4区地球科学 Q3 ECOLOGY Polar Science Pub Date : 2023-12-01 DOI:10.1016/j.polar.2023.100979

Geeta Vichare, Atul Kulkarni, Rahul Rawat, Gopi K. Seemala, Anoop K. Soman, Pritimay Patro

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Abstract

During geomagnetic quiet conditions, Indian Antarctic stations are considered to be located outside the auroral oval: Maitri (CGM coordinates: 63.3°S, 54.2°E) is equatorward and Bharati (CGM coordinates: 74.8°S, 98.4°E) is poleward of the auroral oval. Simultaneous observations of magnetic field variations at these two locations for 10-years (2013–2022) provide an opportunity to study quiet-time magnetic field patterns, if any. Geomagnetic quiet days with ΣKp ≤ 3 are selected, during which the lower values of solar wind and interplanetary parameters are also confirmed. Maitri station exhibits clear southern hemispheric solar quiet (Sq) type of magnetic field variation on geomagnetic quiet days in all seasons, indicating the influence of ionospheric dynamo due to thermospheric winds. Interestingly, Bharati station also displays regular and systematic magnetic field variations in all three components. The D-component at Bharati exhibits very strong variation at early morning hours (7–8 MLT), which is ∼2–4 times stronger than that of H-component, driving strong equatorward/northward currents during all seasons. Both stations show annual type of seasonal variation with peak amplitude during summer and least during winter. The schematic illustration of global and polar Sqs proposed here explains the results obtained through 10-years’ statistical study.

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南极两个地点静时地磁场变化的气候学

在地磁静止期间，印度南极站被认为位于极光椭圆之外：Maitri（CGM 坐标：南纬 63.3 度，东经 54.2 度）位于极光椭圆的赤道方向，Bharati（CGM 坐标：南纬 74.8 度，东经 98.4 度）位于极光椭圆的极地方向。对这两个地点的磁场变化进行为期 10 年（2013-2022 年）的同步观测，为研究安静时的磁场模式（如果有的话）提供了机会。选取了ΣKp≤3的地磁静止日，在此期间，太阳风和行星际参数的较低值也得到了证实。在所有季节的地磁静止日，Maitri 站都表现出明显的南半球太阳静止（Sq）型磁场变化，表明热层风对电离层动力的影响。有趣的是，巴拉蒂站也在所有三个分量中显示出有规律、有系统的磁场变化。巴拉蒂站的 D 分量在清晨时段（7-8 MLT）表现出非常强烈的变化，其强度是 H 分量的 2-4 倍，在所有季节都驱动着强大的赤道/北向洋流。两个站点都呈现出年型季节变化，夏季振幅最大，冬季最小。这里提出的全球和极地 Sqs 示意图解释了 10 年统计研究的结果。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Polar Science ECOLOGY-GEOSCIENCES, MULTIDISCIPLINARY

CiteScore

3.90

自引率

5.60%

发文量

期刊介绍： Polar Science is an international, peer-reviewed quarterly journal. It is dedicated to publishing original research articles for sciences relating to the polar regions of the Earth and other planets. Polar Science aims to cover 15 disciplines which are listed below; they cover most aspects of physical sciences, geosciences and life sciences, together with engineering and social sciences. Articles should attract the interest of broad polar science communities, and not be limited to the interests of those who work under specific research subjects. Polar Science also has an Open Archive whereby published articles are made freely available from ScienceDirect after an embargo period of 24 months from the date of publication. - Space and upper atmosphere physics - Atmospheric science/climatology - Glaciology - Oceanography/sea ice studies - Geology/petrology - Solid earth geophysics/seismology - Marine Earth science - Geomorphology/Cenozoic-Quaternary geology - Meteoritics - Terrestrial biology - Marine biology - Animal ecology - Environment - Polar Engineering - Humanities and social sciences.