<p>The region where the Earth's internal magnetic field is weakest is known as the South Atlantic Anomaly (SAA). In this region at Earth's surface, the field is approximately one third the strength of the region of maximum strength (near the North and South magnetic dip poles), so roughly 20,000nanoTesla versus 60,000nanoTesla.</p>

<p>The weaker field seen at Earth's surface is caused by opposite polarity field at the surface of Earth's outer core (inwards instead of outwards like in the rest of the Southern hemisphere). It allows the radiation belts closer to Earth's surface, and allows charged particles to penetrate lower into Earth's atmosphere, increasing the risk to satellites flying through the region.</p>

<p><a href="https://i.sstatic.net/oCGe2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/oCGe2.png" alt="The inner radiation belt is closest to Earth&#39;s surface over the SAA"></a></p>

<blockquote>
  <p><a href="https://commons.wikimedia.org/wiki/File:South_Atlantic_Anomaly.png" rel="nofollow noreferrer">Source: NASA, via wikimedia</a></p>
</blockquote>

<p><a href="https://epod.typepad.com/.a/6a0105371bb32c970b0120a55b6770970c-pi" rel="nofollow noreferrer"><img src="https://epod.typepad.com/.a/6a0105371bb32c970b0120a55b6770970c-pi" alt="Electrical upsets of TOPEX/Poseidon satellite, clustered around SAA"></a></p>

<blockquote>
  <p><a href="https://epod.usra.edu/blog/2002/06/south-atlantic-anomaly.html" rel="nofollow noreferrer">Source: USRA</a> The weaker region of field over the SAA allows the radiation belts closer to the surface, so increases the occurrence of electrical upsets (yellow dots in the image) on satellites flying through the region, here the TOPEX/Poseidon satellite. The contours are magnetic field intensity in nanoTesla.</p>
</blockquote>

CC BY-SA 4.0
2020-03-03T09:22:32.227Z
Can you add sources for those figures?  Or did you produce them?
gerrit
CC BY-SA 4.0
2020-03-02T11:59:12.157Z
2020-03-03T17:02:54.763Z
2020-03-03T17:02:54.763Z
WJB
<p>The picture below shows how a magnetosphere has defined points on the solid magnet and on the moon where cosmic radiation has a window, gap, or focal point. I'm not sure what to call these areas? </p>

<p>Where on Earth are these areas? Is there a map where the magnetosphere or local natural magnetic fields has this same effect?</p>

<p><a href="https://i.sstatic.net/67lZM.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/67lZM.jpg" alt="enter image description here"></a></p>

<mapping><magnetosphere>
Where are the magnetopheres weak points on Earth?
Muze
# Where are the magnetopheres weak points on Earth?

(Asked by: username_0 on 2019-08-05)

The picture below shows how a magnetosphere has defined points on the solid magnet and on the moon where cosmic radiation has a window, gap, or focal point. I'm not sure what to call these areas?

Where on Earth are these areas? Is there a map where the magnetosphere or local natural magnetic fields has this same effect?

[![enter image description here](https://i.sstatic.net/67lZM.jpg)](https://i.sstatic.net/67lZM.jpg)

**Tags:** mapping, magnetosphere


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## 1 answers

### Answer by username_1 on 2020-03-02. Score: 3 | Accepted answer

The region where the Earth's internal magnetic field is weakest is known as the South Atlantic Anomaly (SAA). In this region at Earth's surface, the field is approximately one third the strength of the region of maximum strength (near the North and South magnetic dip poles), so roughly 20,000nanoTesla versus 60,000nanoTesla.

The weaker field seen at Earth's surface is caused by opposite polarity field at the surface of Earth's outer core (inwards instead of outwards like in the rest of the Southern hemisphere). It allows the radiation belts closer to Earth's surface, and allows charged particles to penetrate lower into Earth's atmosphere, increasing the risk to satellites flying through the region.

[![The inner radiation belt is closest to Earth's surface over the SAA](https://i.sstatic.net/oCGe2.png)](https://i.sstatic.net/oCGe2.png)

> [Source: NASA, via wikimedia](https://commons.wikimedia.org/wiki/File:South_Atlantic_Anomaly.png)

[![Electrical upsets of TOPEX/Poseidon satellite, clustered around SAA](https://epod.typepad.com/.a/6a0105371bb32c970b0120a55b6770970c-pi)](https://epod.typepad.com/.a/6a0105371bb32c970b0120a55b6770970c-pi)

> [Source: USRA](https://epod.usra.edu/blog/2002/06/south-atlantic-anomaly.html) The weaker region of field over the SAA allows the radiation belts closer to the surface, so increases the occurrence of electrical upsets (yellow dots in the image) on satellites flying through the region, here the TOPEX/Poseidon satellite. The contours are magnetic field intensity in nanoTesla.

> **Comments:**
> **username_2**: Can you add sources for those figures?  Or did you produce them?  

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