Mixing in Earth's outer core causes geomagnetic dipole to collapse
4 Jul 2009, 1422 Hrs

Add comment          Mail          Print          Write to Editor

Washington, July 4 Scientists have performed numerical calculations that show how convective mixing flows in the Earth's liquid outer core can cause the geomagnetic dipole to collapse.

For the past 160 years, the Earth's magnetic dipole has been weakening at a rate of nearly six percent per century.

To gain an improved understanding of the mechanisms contributing to the dipole moment collapse, Lijun Liu, from California Institute of Technology, and Peter Olson from Johns Hopkins University, US, have performed numerical calculations to show that mixing in Earth's outer core is the culprit.

Their simulations show that as fluid mixes in the outer core, magnetic energy is transferred from the dipole to smaller scales, producing patches of reversed magnetic field at the core-mantle boundary and weakening the dipole.

They demonstrated that the rate of dipole moment decay is weakly sensitive to the particular mixing flow pattern, but varies with the magnetic Reynolds number, a measure of the velocity of the flow.

In particular, the researchers found that a mixing flow in the outer core with magnetic Reynolds number in the range of 200, which they suggest is a physically reasonable range, could account for the historically measured rate of decrease of the geomagnetic dipole moment. (ANI)

Related Latest

Physicist identifies mysterious core left by exploding star Long-term antidepressant drug use causes rise in prescriptions: Study British Fascist leader's appearance causes furore at BBC HQ U2 stars phone astronauts in outer space! Global warming causes rise of gigantic mucus-like sea blobs 20 injured in Durga puja tent collapse in Tripura Girl's death after vaccination for cervical cancer causes fear Here's what causes arteries to clog up BBC causes outrage with call for age of consent to be 13 A bad vacation causes more grief than buying poor-quality goods

Related Latest

Two police officers embark on bicycle rally to spread message of unity Madhu Koda to remain in hospital for another day Middle order has not performed consistently in the series, says Dhoni TMC-CPM workers clash, Maoists kill three ahead of CM's visit in Midnapore Fake currency worth Rs 900,000 seized in Punjab Allahabad hosts Ganga Water Rally to accelerate tourism industry in Uttar Pradesh Over 60 percent turnout in Assembly by-polls; 53 percent in Firozabad LS poll Madhu Koda's associate sent to ten days in Enforcement Directorate custody Congress-NCP alliance forms government in Maharashtra for the second time Gold lovers in Chennai see gold as a promising investment

• Two police officers embark on bicycle rally to spread message of unity
• Madhu Koda to remain in hospital for another day
• Middle order has not performed consistently in the series, says Dhoni
• TMC-CPM workers clash, Maoists kill three ahead of CM's visit in Midnapore
• Over 60 percent turnout in Assembly by-polls; 53 percent in Firozabad LS poll

• बीकानेर महापौर चुनावः एक विश्लेषण
• Deepawali: The Festival Of Lights
• Nine tips for nine nights
• need new prevention tech for HIV, other STIs and UP
• "Good health is India's basic need": Easier said than done Mr Prime Minister!