Effects of solar wind magnetosphere coupling recorded at different geomagnetic latitudes: Separation of directly-driven and storage/release systems

The effect on geomagnetic activity of solar wind speed, compared with that of the strength of the interplanetary magnetic field, differs with geomagnetic latitude. In this study we construct a new index based on monthly standard deviations in the H-component of the geomagnetic field for all geomagnetic latitudes. We demonstrate that for this index the response at auroral regions correlates best with interplanetary coupling functions which include the solar wind speed while mid- and low-latitude regions respond to variations in the interplanetary magnetic field strength. These results are used to isolate the responsible geomagnetic current systems

Present day challenges in understanding the geomagnetic hazard to national power grids

Power grids and pipeline networks at all latitudes are known to be at risk from the natural hazard of geomagnetically induced currents. At a recent workshop in South Africa, UK and South African scientists and engineers discussed the current understanding of this hazard, as it affects major power systems in Europe and Africa. They also summarised, to better inform the public and industry, what can be said with some certainty about the hazard and what research is yet required to develop useful tools for geomagnetic hazard mitigation

Jätemuovien konversio liikenteen polttoaineen raaka-aineeksi

Tiivistelmä. Maailmanlaajuisen jätemuoviongelman ratkaisemisen yhtenä vaihtoehtona on hyödyntää jätemuoveja liikenteen polttoaineiden valmistuksessa ja näin fossiilisen raakaöljyn korvaajana. Muovia valmistettiin vuonna 2018 maailmanlaajuisesti 359 miljoonaa tonnia, josta suurin osa päätyy ennemmin tai myöhemmin jätteeksi. Tässä työssä tehdyssä kirjallisuuskatsauksessa on vertailtu liikenteen polttoaineen raaka-aineena käytetyn fossiilisen raakaöljyn sekä jätemuovien kemiallisia ja fysikaalisia ominaisuuksia, joiden perusteella jätemuovien konversio liikenteen polttoaineeksi olisi mahdollista. Kirjallisuuskatsauksessa on myös eritelty yleisimmin käytettyjä jätemuovien nesteytysmenetelmiä. Menetelmien perusteella saatujen muoviöljyjen ominaisuuksia on vertailtu sekä toisiinsa, että raakaöljyn ominaisuuksiin. Työssä on kerrottu jätemuovien polttoaineeksi jalostamisen tämän hetkisiä suurimpia haasteita. Kirjallisuuskatsauksessa vertailtujen fossiilisen raakaöljyn ja muovien ominaisuudet ovat kemiallisesti samankaltaiset, joten jätemuovin muuntaminen polttoaineeksi olisi periaatteessa mahdollista. Muoveihin lisätään kuitenkin painoltaan jopa 70 % täyte- ja lisäaineita, joiden läsnäolo raaka-ainevirrassa aiheuttaa lisäkustannuksia jatkojalostusprosessiin. Jätemuovien nesteytykseen on kirjallisuudessa esitetty kolmea eri menetelmää: termistä pyrolyysia, katalyyttistä pyrolyysia ja kuumavesinesteytystä. Katalyytin käyttäminen pyrolyysissa laskee tarvittavaa prosessilämpötilaa ja tuottaa halutumpia hiilivetyjakeita, joskin nestemäinen öljysaanto jää pienemmäksi kuin termisessä pyrolyysissa. Kuumavesinesteytys on tuottanut tutkimuksissa hyviä öljysaantoja ja menetelmä sallii raaka-ainevirran kosteuden. Katalyyttinen pyrolyysi ja kuumavesiteknologia tuottavat muoviöljyyn enemmän olefiineja, kun toisaalta terminen pyrolyysi tuottaa enemmän parafiineja ja nafteeneja. Useista tutkimuksista ja koelaitoksista huolimatta jätemuovien konversiossa on vielä paljon haasteita. Raaka-ainevirrassa oleva PVC sekä muovien lisäaineiden aiheuttavat klooriyhdisteet täytyy poistaa prosessista jo varhaisessa vaiheessa, mikä on haasteellista. Useiden tutkimusten mukaan prosessit vaativat vielä paljon tutkimusta, jotta ne vakiintuisivat ja kaupallistuisivat

Changes in the metabolome of Picea balfouriana embryogenic tissues that were linked to different levels of 6-BAP by gas chromatography-mass spectrometry approach

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Propagation of a shock-related disturbance in the Earth's magnetosphere

The Grand Unified Magnetosphere-Ionosphere Coupling Simulation, version 4, magnetohydrodynamic simulation of the interplanetary shock event on 9 November 2002 is used to determine the shock-associated disturbance propagation characteristics inside the Earth's magnetosphere. Interaction of an interplanetary fast forward shock with the magnetopause caused a shock-related disturbance inside the magnetosphere that propagated at a speed significantly higher than that in the solar wind or magnetosheath. The propagation direction of the disturbance was calculated from the Rankine-Hugoniot conditions, velocity and magnetic coplanarity, and minimum variance analysis and is shown to vary in different regions of the magnetosphere. Furthermore, the impulse disturbance wave mode changes as the plasma and field conditions change inside the magnetosphere. These results bring important new information about the propagation processes that is not directly obtainable from point measurements made by (even several) spacecraft. On the other hand, comparison of ionospheric observations from the IMAGE magnetometer chain with geosynchronous data allow us to also interpret the double step structure observed at dayside geosynchronous orbit, which is below the simulation resolution. This combination provides us with quite a complete view on shock propagation inside the magnetosphere.Peer reviewe

Jensen-Shannon Complexity and Permutation Entropy Analysis of Geomagnetic Auroral Currents

In this study we determine whether auroral westward currents can be characterized by low-dimensional chaotic attractors through the use of the complexity-entropy methodology developed by Rosso et al. (2007, https:// doi.org/10.1103/PhysRevLett.99.154102) and based on the permutation entropy developed by Bandt and Pompe (2002, https://doi.org/10.1103/PhysRevLett.88.174102) . Our results indicate that geomagnetic auroral indices are indistinguishable from stochastic processes from time scales ranging from a few minutes to 10 hr and for embedded dimensions d <8. Our results are inconsistent with earlier studies of Baker et al. (1990, https://doi.org/10.1029/GL017i001p00041), Pavlos et al. (1992), D. Roberts et al. (1991, https://doi.org/10.1029/91GL00021), D. A. Roberts (1991, https://doLorg/10.1029/91JA01088), and Vassiliadis et al. (1990, https://doi.org/10.1029/GL017i011 p01841, 1991, https://doi.org/10.1029/91GL01378) indicating that auroral geomagnetic indices could be reduced to low-dimensional systems with chaotic dynamics.Peer reviewe

Evaluation of the Tail Current Contribution to \u3cem\u3eDst\u3c/em\u3e

The Dst index is produced using low-latitude ground magnetic field measurements and frequently is used as an estimate of the energy density of the ring current carried mainly by energetic (∼10-200 keV) ions relatively close to the Earth. However, other magnetospheric current systems can cause field perturbations at the Earth\u27s surface: for example, dayside magnetopause currents are known to contribute to the Dst index. It has also been suggested that the nightside tail current sheet can significantly affect the Dst index during high magnetic activity periods when the currents are intense and flow relatively close to the Earth. In this study, several disturbed periods are input into Tsyganenko magnetic field models. From the time series of the external and internal fields an artificial Dst index is computed using the same procedure followed in the actual Dst calculation. A tail region in the magnetosphere is explicitly defined and the T96 and T89 models are used to calculate the effect of current within this tail region on ground measurements and therefore on Dst. The results are then compared with the measured Dst to determine the tail current contribution to Dst. It is found that for a geomagnetic storm and a storm-time substorm with Dst of ~80 nT the tail current contribution is between 22 and 26 nT. The same analysis is also applied to several isolated non-storm-time substorms, yielding a nearly linear relationship between Dst and the tail current contribution. This contribution is approximately one quarter of Dst