Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB/dt Events at High Latitudes

We investigate sharp changes in magnetic field that can produce Geomagnetically Induced Currents (GICs) which damage pipelines and power grids. We use one-minute cadence SuperMAG observations to find the occurrence distribution of magnetic field “spikes.” Recent studies have determined recurrence statistics for extreme events and charted the local time distribution of spikes; however, their relation to solar activity and conditions in the solar wind is poorly understood. We study spike occurrence during solar cycles 23 and 24, roughly 1995 to 2020. We find three local time hotspots in occurrence: the pre-midnight region associated with substorm onsets, the dawn sector often associated with omega band activity, and the pre-noon sector associated with the Kelvin-Helmholtz instability (KHI) occurring at the magnetopause. Magnetic field perturbations are mainly North-South for substorms and KHI, and East-West for omega bands. Substorm spikes occur at all phases of the solar cycle, but maximize in the declining phase. Omega-band and KHI spikes are confined to solar maximum and the declining phase. Substorm spikes occur during moderate solar wind driving, omega band spikes during strong driving, and KHI spikes during quiet conditions but with high solar wind speed. We show that the shapes of these distributions do not depend on the magnitude of the spikes, so it appears that our results can be extrapolated to extreme events.publishedVersio

A2_2 Why So Blue?

We determine that the probable source of Dr Manhattan’s blue glow is the ionisation and excitation of nitrogen in the air around him. Through comparison with a filament lighbulb his minimum power output from photon production is estimated. Taking into account the dissociation and ionisation energies of each of the fluorescing molecules provides an upper limit on his power output. These limits are ≈ 470 W and ≈ 3300 W, respectively. Little to no information is given about Dr Manhattan’s physical properties in the source material, and these calculations require many assumptions and approximations

A2_3 The Great Eggscape

The movie “Chicken Run” sees a flock of chickens escape certain death by building an aircraft and flying out. By estimating the dimensions of this craft, “The Old Crate”, we calculated that atakeoff speed of 36ms−1 would be required for flight, which gave a kinetic energy of 130 KJ. Reviewing the movie showed that a total of 40 chickens power the craft through pedalling. Assuming 100% efficiency we calculated that the chickens could only supply 3.2 KJ of energy, hence, would not in fact escape their fate

Phosphorescent Energy Downshifting for Diminishing Surface Recombination in Silicon Nanowire Solar Cells

Molecularly engineered Ir(III) complexes can transfer energy from short-wavelength photons (lambda < 450 nm) to photons of longer wavelength (lambda > 500 nm), which can enhance the otherwise low internal quantum efficiency (IQE) of crystalline Si (c-Si) nanowire solar cells (NWSCs) in the shortwavelength region. Herein, we demonstrate a phosphorescent energy downshifting system using Ir(III) complexes at short wavelengths (300-450 nm) to diminish the severe surface recombination that occurs in c-Si NWSCs. The developed Ir(III) complexes can be considered promising energy converters because they exhibit superior intrinsic properties such as a high quantum yield, a large Stokes shift, a long exciton diffusion length in crystalline film, and a reproducible synthetic procedure. Using the developed 1011) complexes, highly crystalline energy downshifting layers were fabricated by ultrasonic spray deposition to enhance the photoluminescence efficiency by increasing the radiative decay. With the optimized energy downshifting layer, our 1cm(2) c-Si NWSCs with Ir(III) complexes exhibited a higher IQE value for short-wavelength light (300-450 nm) compared with that of bare Si NWSCs without Ir(III) complexes, resulting in a notable increase in the short-circuit current density (from 34.4 mA.cm(-2) to 36.5 mA.cm(-2) )

A2_9 Raindrops keep falling on my head

In this paper we attempt to find the density need for an object of raindrop size to kill a human if it were to land on their head. We conclude that the density of titanium, 4500 kg m−3, is the lower limit for what it would take to fracture the skull

Influence of Off-Sun-Earth Line Distance on the Accuracy of L1 Solar Wind Monitoring

Upstream solar wind measurements from near the L1 Lagrangian point are commonly used to investigate solar wind-magnetosphere coupling. The off-Sun-Earth line distance of such solar wind monitors can be large, up to 100 RE. We investigate how the correlation between measurements of the interplanetary magnetic field and associated ionospheric responses deteriorates as the off-Sun-Earth line distance increases. Specifically, we use the magnitude and polarity of the dayside region 0 field-aligned currents (R0 FACs) as a measure of interplanetary magnetic field (IMF) BY-associated magnetic tension effects on newly-reconnected field lines, related to the Svalgaard-Mansurov effect. The R0 FACs are derived from Advanced Magnetosphere and Planetary Electrodynamics Response Experiment measurements by a principal component analysis, for the years 2010–2016. We perform cross-correlation analyses between time-series of IMF BY, measured by the Wind spacecraft and propagated to the nose of the bow shock by the OMNI technique, and these R0 FAC measurements. Typically, in the summer hemisphere, cross-correlation coefficients between 0.6 and 0.9 are found. However, there is a reduction of order 0.1–0.15 in correlation coefficient between periods when Wind is close to (within 45 RE) and distant from (beyond 70 RE) the Sun-Earth line. We find a time-lag of around 17 min between predictions of the arrival of IMF features at the bow shock and their effect in the ionosphere, irrespective of the location of Wind.publishedVersio

A2_1 Zeus' Lightning Bolt

In this paper we calculate the heat capacity that would be required for the mythological Greek god Zeus to be able to comfortably hold a, hypothetical, `stationary lightning bolt'. Known properties of lightning and the human pain threshold were used to model the specic heat capacity required to elevate Zeus' hand temperature, from ambient to the upper limit of pain. In order for Zeus to be able to hold the lightning bolt, the calculated specic heat capacity that his hand must have was 3:33 * 10^10 J Kg-1 K-

A2_7 Rise (and Fall) of the Planet of the Apes

We determine the basic physical properties of a new astronomical body created by collecting the entire primate population of the Earth in orbit. We calculate the orbital distance at which the new satellite would exert a tidal force equal in magnitude to that of the moon on the Earth. At 7.2×10^4 m this is found to be three orders of magnitude smaller than the 2.7×10^7 m Roche limit and well within the body of the Earth, suggesting that there is no way such a primate satellite could significantly perturb the Earth

A2_4 'It appears to have gone into orbit, sir'

In this article we calculated the mass and acceleration due to gravity of a planetoid, featured in an episode of the BBC series `Red Dwarf', if a golf ball is hit into orbit. We then compared that result to the portrayal of the crew's movement around the planetoid's surface. We found that the mass of the planetoid is 1.4 x 104% of the mass of the Earth and its acceleration due to gravity is 0.05 m s-2

A2_6 Don't Weight For Me, Lois

This paper details the calculation of time dilation observers would perceive of the fictional comic book character, Superman, were he to fly to the star closest to Earth, Proxima Centauri. The Lorentz factor was calculated to be 5.025, assuming Superman was flying at 0.98 times the speed of light. In addition, we calculated that observers on Earth would perceive Superman flying overhead, to be 0.38m long, given a rest length of 1.905 m. The time Lois Lane would experience, stationary on Earth, if Superman were to fly to Proxima Centauri, at this top speed, would be 43.72 years. Superman, however would experience just 8.7 years to have passed. The relativistic mass of Superman, flying at this speed was also calculated to be 522.6 kg from a rest mass of 104 kg