Archiv: magnetic poles


15.09.2020 - 14:25 [ National Aeronautics and Space Administration ]

NASA Researchers Track Slowly Splitting ‚Dent‘ in Earth’s Magnetic Field

(17.08.2020)

Earth’s magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. But over South America and the southern Atlantic Ocean, an unusually weak spot in the field – called the South Atlantic Anomaly, or SAA – allows these particles to dip closer to the surface than normal. Particle radiation in this region can knock out onboard computers and interfere with the data collection of satellites that pass through it – a key reason why NASA scientists want to track and study the anomaly.

The South Atlantic Anomaly is also of interest to NASA’s Earth scientists who monitor the changes in magnetic field strength there, both for how such changes affect Earth’s atmosphere and as an indicator of what’s happening to Earth’s magnetic fields, deep inside the globe.

15.09.2020 - 14:19 [ Sky News ]

NASA investigates mysterious South Atlantic Anomaly

(18.08.2020)

Scientists at NASA are investigating the mysterious South Atlantic Anomaly, a region of weakness in the Earth’s magnetic field that is growing in size.

On average, the planet’s magnetic field has lost almost 10% of its strength over the last two centuries – but there is a large localised region of weakness stretching from Africa to South America.

15.09.2020 - 14:11 [ Nature.com ]

Rapid geomagnetic changes inferred from Earth observations and numerical simulations

(06.07.2020)

Rapid changes in field direction have also attracted significant attention, particularly in the context of polarity reversals18. Historically, the fastest directional changes were attributed to lava flows at Steens Mountain, though these results are now thought to be untenable19. Currently, the fastest directional changes noted are those recorded by sediments in central Italy20, where angular changes in the Virtual Geomagnetic Pole position (P^V) reach values of ∂P^V/∂t∼1∘yr−1. These rates are about a factor of 10 faster than values of ∂P^V/∂t∼0.1∘yr−1 for the modern field, similar to the difference in rates of intensity change between the modern field and spikes.

15.09.2020 - 14:05 [ ScienceDaily.com ]

Earth’s magnetic field can change 10 times faster than previously thought

(06.07.2020)

The clearest example of this in their study is a sharp change in the geomagnetic field direction of roughly 2.5 degrees per year 39,000 years ago. This shift was associated with a locally weak field strength, in a confined spatial region just off the west coast of Central America, and followed the global Laschamp excursion — a short reversal of the Earth’s magnetic field roughly 41,000 years ago.

02.01.2020 - 12:13 [ ibtimes.com ]

Earth’s Magnetic Field is Weakening And Could Collapse Eventually, Expert Warns

(26.12.2019)

Hardwick noted that SWARM revealed that the magnetic field over certain areas of Earth has decreased dramatically. However, in certain areas, it appears to have strengthened.

“What SWARM has actually found is that after 2.5 years of observation, the Earth’s magnetic field has weakened by about 3.5 [percent] at high latitudes over North America, while it has strengthened about 2 [percent] over Asia,” he wrote on Quora. “In other words, it wiggles and wobbles.”

02.01.2020 - 11:44 [ Harvard.edu ]

Earth’s inner core nucleation paradox

(April 2018)

Using constraints from experiments, simulations, and theory, we show that spontaneous crystallization in a homogeneous liquid iron alloy at Earth’s core pressures requires a critical supercooling of order 1000 K, which is too large to be a plausible mechanism for the origin of Earth’s inner core. We consider mechanisms that can lower the nucleation barrier substantially. Each has caveats, yet the inner core exists: this is the nucleation paradox.

02.01.2020 - 11:37 [ LiveScience.com ]

Earth’s Inner Core Shouldn’t Technically Exist

(09.02.2018)

In their paper, the researchers proposed one possibility: Perhaps a massive nugget of solid metal alloy dropped from the mantle and plunged into the liquid core.

02.01.2020 - 11:32 [ ScienceDaily.com ]

Challenging core belief: Have we misunderstood how Earth’s solid center formed?

(07.02.2018)

It is widely accepted that the Earth’s inner core formed about a billion years ago when a solid, super-hot iron nugget spontaneously began to crystallize inside a 4,200-mile-wide ball of liquid metal at the planet’s center.

One problem: That’s not possible-or, at least, has never been easily explained-according to a new paper published in Earth and Planetary Science Letters from a team of scientists at Case Western Reserve University.

02.01.2020 - 11:23 [ Sciencedirect.com ]

Extreme geomagnetic reversal frequency during the Middle Cambrian as revealed by the magnetostratigraphy of the Khorbusuonka section (northeastern Siberia)

(15.12.2019)

A geomagnetic reversal frequency of 26 reversals per Myr is therefore estimated for the Drumian, reduced to 15 reversals per Myr if only the polarity intervals defined by at least two consecutive samples are retained. This is an extreme reversal rate, similar to that reported for the Late Ediacaran (late Precambrian), ∼50 Myr earlier, and proposed to be potentially linked to a late nucleation of the inner core.

02.01.2020 - 10:32 [ CNN ]

Earth’s magnetic north pole is heading for Russia and scientists are puzzled

(18.12.2019)

A weakened magnetic field allows more cosmic radiation from space to strike our atmosphere, which creates more beryllium.

The actual reversal took less than 4,000 years — a drop in the bucket when compared to Earth’s timeline so far. But leading up to that reversal were 18,000 years of instability, including two temporary and partial reversals. This is twice as long as expected.

05.06.2019 - 20:00 [ Phys.org ]

Earth’s magnetic poles could start to flip. What happens then?

(07.12.2018)

‚The geomagnetic field has been decaying for the last 3,000 years,‘ said Dr. Nicolas Thouveny from the European Centre for Research and Teaching of Environmental Geosciences (CEREGE) in Aix-en-Provence, France. ‚If it continues to fall down at this rate, in less than one millennium we will be in a critical (period).‘

29.04.2019 - 13:21 [ Geophysical Research Letters 35(16) / researchgate.net ]

Magnetic effect on CO 2 solubility in seawater: A possible link between geomagnetic field variations and climate

(August 2008)

Correlations between geomagnetic-field and climate parameters have been suggested repeatedly, but possible links are controversially discussed. Here we test if weak (Earth-strength) magnetic fields can affect climatically relevant properties of seawater. We found the solubility of air in seawater to be by 15% lower under reduced magneticfield (20 mT) compared to normal field conditions (50 mT). The magnetic-field effect on CO2 solubility is twice as large, from which we surmise that geomagnetic field variations modulate the carbon exchange between atmosphere and ocean. A 1% reduction in magnetic dipole moment may release up to ten times more CO2 from the surface ocean than is emitted by subaerial volcanism.

29.04.2019 - 13:15 [ Stanford University ]

ON THE WEAKENING OF THE POLAR MAGNETIC FIELDS DURING SOLAR CYCLE 23

(20. Dezember 2009)

The Sun’s polar fields are currently ∼40% weaker than they were during the previous three sunspot minima. This weakening has been accompanied by a corresponding decrease in the interplanetary magnetic field (IMF) strength, by a ∼20% shrinkage in the polar coronal-hole areas, and by a reduction in the solar-wind mass flux over the poles. It has also been reflected in coronal streamer structure and the heliospheric current sheet, which only showed the expected flattening into the equatorial plane after sunspot numbers fell to unusually low values in mid-2008. From latitude–time plots of the photospheric field, it has long been apparent that the polar fields are formed through the transport of trailing-polarity flux from the sunspot latitudes to the poles.

29.04.2019 - 12:48 [ Nature.com ]

Earth’s magnetic field is acting up and geologists don’t know why

(9. Januar 2019)

The magnetic pole is moving so quickly that it has forced the world’s geomagnetism experts into a rare move.

On 15 January, they are set to update the World Magnetic Model, which describes the planet’s magnetic field and underlies all modern navigation, from the systems that steer ships at sea to Google Maps on smartphones.

29.04.2019 - 12:35 [ British Geological Survey ]

World Magnetic Model (WMM)

The World Magnetic Model (WMM) is a standard model of the core and large-scale crustal magnetic field. It is used extensively for navigation and in attitude and heading referencing systems by the UK Ministry of Defence, the US Department of Defense, the North Atlantic Treaty Organization and the International Hydrographic Organization.

(…)

The WMM is a model of the core and large-scale crustal fields only. However the satellite data contain unwanted signals such as small-scale crustal, external ionospheric and magnetospheric and their induced counterparts. These fields would have added noise to the WMM2015 SV model and could have biased its estimates.

BGS employed two techniques to avoid the contamination caused by external magnetic fields. Firstly we rejected those data most contaminated by these sources, as identified by a combination of local time, geomagnetic indices and solar wind data. ……..