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[空间天气]空间环境--地球磁场变化 专帖

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更多 发布于:2014-06-28 10:08

图片:1 (2).jpg




地球磁场呈现显著走弱迹象

The first set of high-resolution results from ESA’s three-satellite Swarm constellation reveals the most recent changes in the magnetic field that protects us from cosmic radiation and charged particles that bombard Earth.
Magnetic field is in a permanent state of flux. Magnetic north wanders, andevery few hundred thousand years the polarity flips so that a compass would point south instead of north. Moreover, the strength of the magnetic field constantly changes – and it is currently showing signs of significant weakening. (ESA)
Measurements made by Swarm over the past six months confirm the general trend of the field’s weakening, with the most dramatic declines over the Western Hemisphere. But in other areas, such as the southern Indian Ocean, the magnetic field has strengthened since January.
The field is particularly weak over the South Atlantic Ocean – known as the South Atlantic Anomaly and the latest measurements confirm the movement of magnetic North towards Siberia.
The weak field has indirectly caused many temporary satellite ‘hiccups’ (called Single Event Upsets) as the satellites are exposed to strong radiation over this area. (ESA)
This animation shows changes in Earth’s magnetic field from January to June 2014 as measured by ESA’s Swarm trio of satellites:


图片:2.jpg



Snapshot’ of the main magnetic field at Earth’s surface as of June 2014 based on Swarm data. The measurements are dominated by the magnetic contribution from Earth’s core (about 95%) while the contributions from other sources (the mantle, crust, oceans, ionosphere and magnetosphere) make up the rest. Red represents areas where the magnetic field is stronger, while blues show areas where it is weaker. image copyright: ESA/DTU Space


图片:3.jpg



Swarm is ESA's first Earth observation constellation of satellites. The three identical satellites are launched together on one rocket. Two satellites orbit almost side-by-side at the same altitude – initially at about 460 km, descending to around 300 km over the lifetime of the mission. The third satellite is in a higher orbit of 530 km and at a slightly different inclination. The satellites’ orbits drift, resulting in the upper satellite crossing the path of the lower two at an angle of 90° in the third year of operations.
The different orbits along with satellites’ various instruments optimise the sampling in space and time, distinguishing between the effects of different sources and strengths of magnetism. Image copyright: ESA/AOES Medialab





Swarm was launched in November 2013 and is providing unprecedented insights into the complex workings of Earth’s magnetic field. The objective of the Swarm mission is to provide the best-ever survey of the geomagnetic field and its temporal evolution as well as the electric field in the atmosphere using a constellation of 3 identical satellites carrying sophisticated magnetometers and electric field instruments.
Its first results were presented today, June 19th, at the ‘Third Swarm Science Meeting’ in Copenhagen, Denmark.
“These initial results demonstrate the excellent performance of Swarm,” said Rune Floberghagen, ESA’s Swarm Mission Manager. “With unprecedented resolution, the data also exhibit Swarm’s capability to map fine-scale features of the magnetic field.”
Over the coming months, scientists will analyse the data to unravel the magnetic contributions from other sources, namely the mantle, crust, oceans, ionosphere and magnetosphere.
This will provide new insight into many natural processes, from those occurring deep inside our planet to space weather triggered by solar activity. In turn, this information will yield a better understanding of why the magnetic field is weakening.


如果地球磁场是不变的,那么指南针就会不偏不倚地指向北方。但实际不是这样的。研究人员早就发现地球磁场正在发生变化。地球北磁极按惯例移动,每年高达40千米,从而导致指南针推着时间的推移而发生偏转。而且,从19世纪以来,全球磁场已经减弱了10%。

欧洲航天局Swarm卫星群的最新研究表明,地球磁场变化比先前预想的更快。在下图中,蓝色描述了地磁场弱的区域,红色显示了磁场强的区域:

图片:1.jpg




Swarm卫星群数据,并结合CHAMP和rsted卫星观测,清楚地显示了北美高纬地区磁场已经减弱了约3.5%,而亚洲增强了约2%。磁场最弱的区域--南大西洋异常区--已经稳定地向西移动,并且进一步减弱了约2%。这些变化发生在1999年到2016年中期之间相对短暂的时间内。


地球磁场保护我们免受太阳风暴和宇宙射线的伤害。地磁场的减弱意味着更多的辐射可以穿透到我们的大气层中。事实上,Spaceweather.com常规发射的高空气球探测到了加利福尼亚上空的宇宙射线正在增强。也许正是北美上空磁场的衰退造成了这一趋势。


尽管这些变化听起来很引人注目,但是相比地球磁场过去发生的变化,这些还是温柔的。有时候磁场完全翻转,南北极互换位置。这样的反转,在古老岩石的磁性中有记录,是不可预测的。它们平均每300,000年不定期发生一次,最近的一次发生在780,000年前。我们是否可以延期到下一次?没人知道。


Swarm由3颗卫星组成,每颗卫星配备了矢量磁力计,可以从轨道高度到地心边缘一路感应到地球磁场。卫星群预计能持续运行至少到2017年,并有可能超出预期,
[invensys于2017-09-26 19:17编辑了帖子]
2条评分, 金钱 +1 威望 +1
  • yrch007
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    这么快就要准备磁极倒转了吗。。。
    2014-06-29 18:37
  • yrch007
    金钱 +1
    这么快就要准备磁极倒转了吗。。。
    2014-06-29 18:37
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发布于:2014-06-28 10:40
要倒置了么?可以拍大片了。
欢迎访问<a href="http://bbs.typhoon.gov.cn" target="_blank">台风论坛</a>。
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发布于:2014-06-29 14:53
懒得慢慢看英文,有没有翻译?
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发布于:2014-06-29 18:37
这么快就要准备磁极倒转了吗。。。
炎热无风的夏天
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发布于:2017-09-26 10:31
Swarm卫星最新数据显示西半球磁场减弱

欧洲空间局(ESA)的三颗SWARM卫星产生的第一批高分辨率结果揭示了地球磁场的近期变化。2013年发射的Swarm卫星为地球磁场的复杂工作原理提供了前所未有的新见解,地球磁场保护我们不受到宇宙辐射和带电粒子的轰击。

过去6个月进行的测量证实了地球磁场正在逐渐减弱的趋势,且西半球的减弱程度最为剧烈。而其它地区,例如南印度洋,磁场自1月起有所增强。最新的测量也证实了磁场朝北西伯利亚地区的移动。

图片:1.jpg

红色阴影部分代表磁场增强地区,蓝色则显示了在过去6个月磁场减弱的地区(2014年)。

这些变化是基于源于地球内核的磁场信号。在接下来的几个月内,科学家将分析数据以揭开磁场其他来源的影响,也即地幔、地壳、海洋、电离层和磁气圈。这将为很多自然过程提供新的见解,从发生在地球深处的过程,到由太阳活动引发的空间天气。而这些信息反过来又将提供对磁场为何减弱的更好地理解。

“这些初期结果展示了Swarm良好的性能表现,”欧洲空间局Swarm任务经理鲁恩·弗洛伯格哈根(Rune Floberghagen)这样说道。“利用前所未有的高分辨率,数据还展示了Swarm具备绘制磁场精细尺度特征的能力。”初期结果被展示在6月19日在丹麦哥本哈根召开的第三届Swarm科学会议上。

丹麦高等教育科学部部长索菲·卡斯滕·尼尔森(Sofie Carsten Nielsen)强调了丹麦在这一项目里做出的贡献。Swarm延续了丹麦“阿斯泰兹”(Orsted)号人造卫星和德国CHAMP卫星的传奇,阿斯泰兹卫星目前仍可运行。Swarm的核心设备——矢量磁场磁强计——是由丹麦科技大学提供的。

丹麦国家空间研究院DTU Space在Swarm卫星应用和研究机构中起着主导作用,后者会基于Swarm数据提供高级模型,这些Swarm数据描述了被测量的场的每一个来源。DTU Space与10余所欧洲和加拿大研究院有研究合作。

[invensys于2017-10-01 08:52编辑了帖子]
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发布于:2017-09-26 15:58
伯克兰电流在北半球更强劲,也随季节而异

图片:2.png




ESA’s Swarm mission has discovered that this seasonal variation of Birkeland currents, strong electric currents in the upper atmosphere, is not the same in the north and south polar regions.


Named after Kristian Birkeland, the scientist a century ago who first postulated that the ‘northern lights’ were linked to electrically charged particles in the solar wind, these currents flow along Earth’s magnetic field lines in the polar regions. Magnetic field measurements from ESA’s Swarm satellite constellation are allowing scientists to understand more about these powerful currents, which carry up to 1 TW of electric power to the upper atmosphere. This is about 30 times the energy consumed in New York during a heatwave.
It is important to understand the interplay between these Birkeland currents and the solar wind that bombards our planet and that can potentially cause power and communication blackouts.
New findings show how three years of measurements from the mission were combined with measurements from Germany’s earlier Champ satellite to produce global climatological maps of these currents, ESA announced.
Moreover, these results show differences between currents in the northern and southern hemisphere, how they change with the season and how they vary according to the strength of the solar wind.

图片:1.jpg


Three years of measurements from ESA’s Swarm mission have been combined with measurements from Germany’s earlier Champ satellite to produce global climatological maps of Birkeland currents. These currents tend to be weak for a northwards interplanetary field and strong for a southwards field. Importantly, these new results also reveal that the strength of the currents is not the same in both hemispheres. These hemispheric differences may relate to asymmetry in Earth’s main magnetic field. Credit: DTU/BSS


“Interaction between Earth’s magnetic field and the interplanetary magnetic field – meaning part of the Sun’s magnetic field carried by solar wind – depends on how the interplanetary field is orientated.
While this sounds complicated, it means that hardly any solar wind can enter the magnetosphere and arrive at Earth if the interplanetary magnetic field points north, parallel to Earth’s magnetic field," Karl Laundal, from the Birkeland Centre for Space Science, explained.

“On the other hand, if the interplanetary field points south, the opposite is true and this allows a connection to be made with Earth’s magnetic field. Part of the energy in solar wind then further energizes the charged particles that are responsible for the visible light displays of the auroras,” Laundal said.
Birkeland currents, therefore, tend to be weak for a northwards interplanetary field and strong for a southwards field.
Importantly, these new results also reveal that the strength of the currents is not the same in both hemispheres. These hemispheric differences may relate to asymmetry in Earth’s main magnetic field.
In fact, the two geomagnetic poles are not geometrically opposite to one another, and the magnetic field intensity is also not the same in the north as in the south.

图片:2.jpg




Seasonal asymmetry of Birkeland currents in detail. Credit: DTU/BSS
“The main reason for this probably has to do with differences in Earth’s main field. Such differences imply that the ionosphere–magnetosphere coupling is different in the two hemispheres. In particular, the magnetic pole is more offset with respect to the geographic pole in the south compared to north, which leads to different variations in sunlight in the ‘magnetic hemispheres’. Because of these differences, the two hemispheres do not respond symmetrically to solar wind driving or changing seasons," Laundal said.
“Swarm is a fantastic tool for space science studies. The high-quality measurements and the fact that there are three satellites working in concert hold many new clues about how our home planet interacts with the space around it. It’s a fascinating time."
[invensys于2017-09-26 16:01编辑了帖子]
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发布于:2017-09-26 19:00
SWARM项目与正在减弱的地球磁场

图片:4.jpg


保护地球的一层保护罩正在减弱,从而让有害的太阳风粒子可以侵入地球大气层。

这一保护层便是地球的磁层,它从地球表面向外延伸至数千公里的地方,有效阻挡有害宇宙射线的侵袭,并对我们生活的方方面面——从全球通讯到天气模式构成影响。


图片:3.jpg


减弱的地球磁层意味着一旦发生太阳活动,将出现更加强烈的极光现象

图片:5.jpg


地球磁层从地球表面向外延伸至数千公里的地方,有效阻挡有害宇宙射线的侵袭

欧洲空间局(ESA)执行的“SWARM”项目旨在对地球磁层发生的变化进行监测。在轨运行一年之后,该项目收集的数据正让我们得以一窥这一地球保护层正在发生的细微变化。

图片:1.jpg


欧空局的SWARM卫星极化旨在对地球磁层的变化开展探测。在轨运行一年之后,项目得到了初步结果。图像显示的是根据SWARM项目数据构建的地壳(底部)和地核(中心)的磁场模型

SWARM项目的主要任务是测量并分析来自地核,地幔,地壳,海洋,电离层以及磁层所产生的不同磁信号。该计划预计将持续4年时间,将可以提供不同层面的自然过程,从地球深层内部到太阳活动与空间天气的各类观测信息,目前该项目还剩余3年的在轨运行时间。整个项目一共包括3颗完全相同的卫星,但为了改善项目的空间与时间分辨率,它们各自的轨道存在差异,并且还会在任务期间进行变轨。

SWARM是首个利用“磁力梯度”开展探测的项目,其做法是将两颗卫星并排放置在相距仅100公里的轨道上协同运行。这样做将能够对源自地壳内磁性岩石产生的磁信号细节进行观测。


来自丹麦“DTU 航天”的尼尔斯·奥尔森(Nils Olsen)表示:“我们对于该项目得到的初步结果感到非常满意。这不仅是因为该项目验证了磁力梯度概念的可行性,它们还证明了我们的卫星在磁场信号测量方面具备的高度精确性。”


SWARM卫星星座也让科学家们能够更加容易地对由地核产生的地球主磁场开展观测,这一强大的磁场保护着我们,阻挡有害的宇宙射线侵入地球大气层。SWARM项目主要提出人之一的高瑟·霍罗特(Gauthier Hulot)表示:“我们地球的磁场主要是由地球的外核所产生的。”


他说:“SWARM项目的探测结果对地球磁场的细节进行了监测并发现它正在减弱,这将削弱我们拥有的保护层。最终,我们将有能力对地球磁场未来十年内的变化做出预测。”

图片:2.jpg


地球高层大气,电离层与磁层,它们构成一个紧密联系且相互作用的系统。SWARM项目旨在加深科学家们对于近地电流系统与过程的理解
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发布于:2017-10-15 12:02
2015年,地磁南北两极位置

图片:1.gif


图片:2.gif




earNorth geomagnetic poleSouth geomagnetic poleNorth magnetic poleSouth magnetic poleDipole moment
1022Am2
Lat.Long.Lat.Long.Lat.Long.Lat.Long.
190078.7N68.8W78.7S111.2E70.5N96.2W71.7S148.3E8.32
190578.7N68.7W78.7S111.3E70.7N96.5W71.5S148.5E8.30
191078.7N68.7W78.7S111.3E70.8N96.7W71.2S148.6E8.27
191578.6N68.6W78.6S111.4E71.0N97.0W70.8S148.5E8.24
192078.6N68.4W78.6S111.6E71.3N97.4W70.4S148.2E8.20
192578.6N68.3W78.6S111.7E71.8N98.0W70.0S147.6E8.16
193078.6N68.3W78.6S111.7E72.3N98.7W69.5S146.8E8.13
193578.6N68.4W78.6S111.6E72.8N99.3W69.1S145.8E8.11
194078.5N68.5W78.5S111.5E73.3N99.9W68.6S144.6E8.09
194578.5N68.5W78.5S111.5E73.9N100.2W68.2S144.4E8.08
195078.5N68.8W78.5S111.2E74.6N100.9W67.9S143.5E8.06
195578.5N69.2W78.5S110.8E75.2N101.4W67.2S141.5E8.05
196078.6N69.5W78.6S110.5E75.3N101.0W66.7S140.2E8.03
196578.6N69.9W78.6S110.1E75.6N101.3W66.3S139.5E8.00
197078.7N70.2W78.7S109.8E75.9N101.0W66.0S139.4E7.97
197578.8N70.5W78.8S109.5E76.2N100.6W65.7S139.5E7.94
198078.9N70.8W78.9S109.2E76.9N101.7W65.4S139.3E7.91
198579.0N70.9W79.0S109.1E77.4N102.6W65.1S139.2E7.87
199079.2N71.1W79.2S108.9E78.1N103.7W64.9S138.9E7.84
199579.4N71.4W79.4S108.6E79.0N105.3W64.8S138.7E7.81
200079.6N71.6W79.6S108.4E81.0N109.6W64.7S138.3E7.79
200579.8N71.8W79.8S108.2E83.2N118.2W64.5S137.8E7.77
201080.1N72.2W80.1S107.8E85.0N132.8W64.4S137.3E7.75
201180.1N72.3W80.1S107.7E85.4N137.4W64.4S137.2E7.74
201280.2N72.4W80.2S107.6E85.7N142.5W64.4S137.0E7.74
201380.3N72.5W80.3S107.5E85.9N148.0W64.3S136.9E7.73
201480.3N72.5W80.3S107.5E86.1N153.9W64.3S136.7E7.73
201580.4N72.6W80.4S107.4E86.3N160.0W64.3S136.6E7.72
201680.4N72.7W80.4S107.3E86.4N166.3W64.2S136.4E7.72
201780.5N72.8W80.5S107.2E86.5N172.6W64.2S136.3E7.72
201880.5N73.0W80.5S107.0E86.5N178.8W64.2S136.1E7.71
201980.6N73.1W80.6S106.9E86.4N175.3E64.1S135.9E7.71
202080.6N73.2W80.6S106.8E86.4N169.8E64.1S135.8E7.70
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发布于:2017-10-15 12:05
地磁1600-2000年强弱变化

图片:1.gif

[invensys于2017-10-15 12:21编辑了帖子]
NASA. NOAA. USGS. NSIDC. ESA. National Geographic. Discovery.
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invensys
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9楼#
发布于:2017-11-12 09:53
地球的磁场在我们的脚下约3 000公里的铁磁体产生,穿过整个行星并穿过太空 - 保护生命和卫星免受来自太阳的有害辐射。 但这种屏蔽效应远不是恒定的,因为场强在时间和空间上都有显著的变化。

图片:1.jpg

2010年(左)和公元前1000年(右)地球磁场的强度


https://theconversation.com/mysterious-geomagnetic-spike-3-000-years-ago-challenges-our-understanding-of-the-earths-interior-86638
[invensys于2017-11-12 09:56编辑了帖子]
NASA. NOAA. USGS. NSIDC. ESA. National Geographic. Discovery.
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