scholarly journals The State of the Solar Wind, Magnetosphere, and Ionosphere During the Maunder Minimum

2018 ◽  
Vol 13 (S340) ◽  
pp. 247-250
Author(s):  
Pete Riley ◽  
Roberto Lionello ◽  
Jon A. Linker ◽  
Mathew J. Owens
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
Maunder Minimum ◽  
The State ◽  
Solar Wind Density ◽  
Direct Observations ◽  
Upper Limit ◽  
Maximum Electron Density ◽  
Order Of Magnitude ◽  
Feasible Solutions

AbstractBoth direct observations and reconstructions from various datasets, suggest that conditions were radically different during the Maunder Minimum (MM) than during the space era. Using an MHD model, we develop a set of feasible solutions to infer the properties of the solar wind during this interval. Additionally, we use these results to drive a global magnetospheric model. Finally, using the 2008/2009 solar minimum as an upper limit for MM conditions, we use results from the International Reference Ionosphere (ILI) model to speculate on the state of the ionosphere. The results describe interplanetary, magnetospheric, and ionospheric conditions that were substantially different than today. For example: (1) the solar wind density and magnetic field strength were an order of magnitude lower; (2) the Earth’s magnetopause and shock standoff distances were a factor of two larger; and (3) the maximum electron density in the ionosphere was substantially lower.

A neural network-based mid-term prognosis of geomagnetic storms that uses pre-storm effects related to current sheets and magnetic islands

2021 ◽  
Author(s):  
Mikhail Fridman
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
High Speed ◽  
Geomagnetic Storms ◽  
Magnetic Islands ◽  
Solar Wind Density ◽  
Short Term ◽  
Storm Effects ◽  
Term Forecast ◽  
Advance Time

<p>Mid-term prognoses of geomagnetic storms require an improvement since theу are known to have rather low accuracy which does not exceed 40% in solar minimum. We claim that the problem lies in the approach. Current mid-term forecasts are typically built using the same paradigm as short-term ones and suggest an analysis of the solar wind conditions typical for geomagnetic storms. According to this approach, there is a 20-60 minute delay between the arrival of a geoeffective flow/stream to L1 and the arrival of the signal from the spacecraft to Earth, which gives a necessary advance time for a short-term prognosis. For the mid-term forecast with an advance time from 3 hours to 3 days, this is not enough. Therefore, we have suggested finding precursors of geomagnetic storms observed in the solar wind. Such precursors are variations in the solar wind density and the interplanetary magnetic field in the ULF range associated with crossings of magnetic cavities in front of the arriving geoeffective high-speed streams and flows (Khabarova et al., 2015, 2016, 2018; Adhikari et al., 2019). Despite some preliminary studies have shown that this might be a perspective way to create a mid-term prognosis (Khabarova 2007; Khabarova & Yermolaev, 2007), the problem of automatization of the prognosis remained unsolved.</p>

scholarly journals Mirror mode waves in Venus's magnetosheath: solar minimum vs. solar maximum

2016 ◽  
Vol 34 (11) ◽  
pp. 1099-1108 ◽  
Author(s):  
Martin Volwerk ◽  
Daniel Schmid ◽  
Bruce T. Tsurutani ◽  
Magda Delva ◽  
Ferdinand Plaschke ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
Solar Wind Velocity ◽  
Solar Maximum ◽  
Flow Line ◽  
Bow Shock ◽  
Solar Wind Density ◽  
Solar Uv ◽  
Mirror Mode ◽  
Possible Cause

Abstract. The observational rate of mirror mode waves in Venus's magnetosheath for solar maximum conditions is studied and compared with previous results for solar minimum conditions. It is found that the number of mirror mode events is approximately 14 % higher for solar maximum than for solar minimum. A possible cause is the increase in solar UV radiation, ionizing more neutrals from Venus's exosphere and the outward displacement of the bow shock during solar maximum. Also, the solar wind properties (speed, density) differ for solar minimum and maximum. The maximum observational rate, however, over Venus's magnetosheath remains almost the same, with only differences in the distribution along the flow line. This may be caused by the interplay of a decreasing solar wind density and a slightly higher solar wind velocity for this solar maximum. The distribution of strengths of the mirror mode waves is shown to be exponentially falling off, with (almost) the same coefficient for solar maximum and minimum. The plasma conditions in Venus's magnetosheath are different for solar minimum as compared to solar maximum. For solar minimum, mirror mode waves are created directly behind where the bow shock will decay, whereas for solar maximum all created mirror modes can grow.

scholarly journals Time scale of the largest imaginable magnetic storm

2013 ◽  
Vol 20 (1) ◽  
pp. 19-23 ◽  
Author(s):  
V. M. Vasyliūnas
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Storm ◽  
Energy Content ◽  
Horizontal Magnetic Field ◽  
Order Of Magnitude ◽  
Magnetosphere Plasma ◽  
Time Required ◽  
Parameter Values ◽  
Magnetic Field Perturbation

Abstract. The depression of the horizontal magnetic field at Earth's equator for the largest imaginable magnetic storm has been estimated (Vasyliūnas, 2011a) as −Dst ~ 2500 nT, from the assumption that the total pressure in the magnetosphere (plasma plus magnetic field perturbation) is limited, in order of magnitude, by the minimum pressure of Earth's dipole field at the location of each flux tube. The obvious related question is how long it would take the solar wind to supply the energy content of this largest storm. The maximum rate of energy input from the solar wind to the magnetosphere can be evaluated on the basis either of magnetotail stress balance or of polar cap potential saturation, giving an estimate of the time required to build up the largest storm, which (for solar-wind and magnetospheric parameter values typical of observed superstorms) is roughly between ~2 and ~6 h.

scholarly journals State-Owned Jute Mills in Bangladesh: Problems and Possible Way-Out

2021 ◽  
Vol 16 (4) ◽  
pp. 63
Author(s):  
Mohammad Mobarak Hossain ◽  
Nasrin Sultana Nishu
Keyword(s):  
Research Work ◽  
International Market ◽  
The State ◽  
Government Policies ◽  
Primary Data ◽  
Skilled Workers ◽  
Depth Interview ◽  
The World ◽  
Feasible Solutions ◽  
Secondary Information

Historically, jute is known as the golden fibre of Bangladesh, a leading cash crop and major export item for Bangladesh. Unfortunately, the production and export of jute have been declining since the 1970s due to the various internal and external problems. The Bangladesh government has recently declared to shut down the production at all state-owned jute mills. This paper aims to determine the reasons behind the state-owned jute mills failure and feasible solutions to unravel the problems. An in-depth interview with 10 (ten) industry experts was conducted to collect primary data. Secondary information has been collected from different books, websites, articles and newspapers. The demand for various and versatile jute products has been increasing globally over the last two decades. Still, in Bangladesh, the jute sector's development is no longer satisfactory to retain its glorious position towards the world because of having some major problems such as mismanagement and corruption of BJMC, lack of modern machinery, lack of skilled workers, weak marketing and government policies etc. Most state-owned jute mills under BJMC are stuck in dishonesty and lavishness alongside ageing infrastructure. They have been incurring losses for years, turning profits in just four of the last 48 years. Reform and restructuring of BJMC, modernizing factory with the latest technology, providing enough training to employees, investment in research work, improvement in the production process, efficient marketing strategy and appropriate government policies might help the state-owned jute mills to regain its position in the national and international market. There are no reasons to shut down the production where reformation is adequate to make the state-owned jute mills profitable. At least, the time to shut down state-owned jute mills is not right due to the Coronavirus pandemic.

scholarly journals MESSENGER observations of planetary ion enhancements at Mercury’s northern magnetospheric cusp during Flux Transfer Event Showers

2021 ◽  
Author(s):  
Weijie Sun ◽  
James Slavin ◽  
Anna Milillo ◽  
Ryan Dewey ◽  
Stefano Orsini ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Transfer Event ◽  
Order Of Magnitude ◽  
In Situ Observations ◽  
Flux Transfer ◽  
Magnetospheric Cusp ◽  
Upward Moving ◽  
Entry Layer

Abstract At Mercury, several processes can release ions and neutrals out of the planet’s surface. Here we present enhancements of dayside planetary ions in the solar wind entry layer during flux transfer event (FTE) “showers” near Mercury’s northern magnetospheric cusp. In this entry layer, solar wind ions are accelerated and move downward (i.e. planetward) toward the cusps, which sputter upward-moving planetary ions within 1 minute. The precipitation rate is enhanced by an order of magnitude during FTE showers and the neutral density of the exosphere can vary by >10% due to this FTE-driven sputtering. These in situ observations of enhanced planetary ions in the entry layer likely correspond to an escape channel of Mercury’s planetary ions, and the large-scale variations of the exosphere observed on minute-timescales by ground-based telescopes. Comprehensive, future multi-point measurements made by BepiColombo will greatly enhance our understanding of the processes contributing to Mercury’s dynamic exosphere and magnetosphere.

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