Effects of Strong Magnetic Fields in Strange Baryonic Matter

We investigate the effects of very strong magnetic fields upon the equation of state of dense bayonic matter in which hyperons are present. In the presence of a magnetic field, the equation of state above nuclear density is significantly affected both by Landau quantization and magnetic moment interactions, but only for field strengths $B>5\times10^{18}$ G. The former tends to soften the EOS and increase proton and lepton abundances, while the latter produces an overall stiffening of the EOS. Each results in a supression of hyperons relative to the field-free case. The structure of a neutron star is, however, primarily determined by the magnetic field stress. We utilize existing general relativistic magneto-hydrostatic calculations to demonstrate that maximum average fields within a stable neutron are limited to values $B\le 1-3 \times10^{18}$ G. This is not large enough to significantly influence particle compositions or the matter pressure, unless fluctuations dominate the average field strengths in the interior or configurations with significantly larger field gradients are considered.Comment: 12 pages, 3 figures. To be submitted to Phys. Lett.

State of the climate in 2013

In 2013, the vast majority of the monitored climate variables reported here maintained trends established in recent decades. ENSO was in a neutral state during the entire year, remaining mostly on the cool side of neutral with modest impacts on regional weather patterns around the world. This follows several years dominated by the effects of either La Niña or El Niño events. According to several independent analyses, 2013 was again among the 10 warmest years on record at the global scale, both at the Earths surface and through the troposphere. Some regions in the Southern Hemisphere had record or near-record high temperatures for the year. Australia observed its hottest year on record, while Argentina and New Zealand reported their second and third hottest years, respectively. In Antarctica, Amundsen-Scott South Pole Station reported its highest annual temperature since records began in 1957. At the opposite pole, the Arctic observed its seventh warmest year since records began in the early 20th century. At 20-m depth, record high temperatures were measured at some permafrost stations on the North Slope of Alaska and in the Brooks Range. In the Northern Hemisphere extratropics, anomalous meridional atmospheric circulation occurred throughout much of the year, leading to marked regional extremes of both temperature and precipitation. Cold temperature anomalies during winter across Eurasia were followed by warm spring temperature anomalies, which were linked to a new record low Eurasian snow cover extent in May. Minimum sea ice extent in the Arctic was the sixth lowest since satellite observations began in 1979. Including 2013, all seven lowest extents on record have occurred in the past seven years. Antarctica, on the other hand, had above-average sea ice extent throughout 2013, with 116 days of new daily high extent records, including a new daily maximum sea ice area of 19.57 million km2 reached on 1 October. ENSO-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific had the largest impacts on the global sea surface temperature in 2013. The North Pacific reached a historic high temperature in 2013 and on balance the globally-averaged sea surface temperature was among the 10 highest on record. Overall, the salt content in nearsurface ocean waters increased while in intermediate waters it decreased. Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 mm yr-1 over the past two decades. A portion of this trend (0.5 mm yr-1) has been attributed to natural variability associated with the Pacific decadal oscillation as well as to ongoing contributions from the melting of glaciers and ice sheets and ocean warming. Global tropical cyclone frequency during 2013 was slightly above average with a total of 94 storms, although the North Atlantic Basin had its quietest hurricane season since 1994. In the Western North Pacific Basin, Super Typhoon Haiyan, the deadliest tropical cyclone of 2013, had 1-minute sustained winds estimated to be 170 kt (87.5 m s-1) on 7 November, the highest wind speed ever assigned to a tropical cyclone. High storm surge was also associated with Haiyan as it made landfall over the central Philippines, an area where sea level is currently at historic highs, increasing by 200 mm since 1970. In the atmosphere, carbon dioxide, methane, and nitrous oxide all continued to increase in 2013. As in previous years, each of these major greenhouse gases once again reached historic high concentrations. In the Arctic, carbon dioxide and methane increased at the same rate as the global increase. These increases are likely due to export from lower latitudes rather than a consequence of increases in Arctic sources, such as thawing permafrost. At Mauna Loa, Hawaii, for the first time since measurements began in 1958, the daily average mixing ratio of carbon dioxide exceeded 400 ppm on 9 May. The state of these variables, along with dozens of others, and the 2013 climate conditions of regions around the world are discussed in further detail in this 24th edition of the State of the Climate series. © 2014, American Meteorological Society. All rights reserved

Reduced heat transfer in saltwater by a magnetic field: do oceans have a “geomagnetic brake”?

Seawater is the major heat transporter in our global environment, covering more than two-thirds of the surface of the earth.With an average salinity of ∼3.5%, it is a moderate electric conductor, which is permanently in motion by thermal and hydrodynamicforces. The geomagnetic field exerts a Lorentz force on seawater that principally influences both the dissipation of turbulence and the flow properties by magnetic friction. Here we show by experiments on laboratory scale that convection in seawater is slowed down by an external static magnetic field and leads to a reduced heat flux resulting in an increased or decreased heat content in the volume in response to influx or drain of heat, respectively. Experimentally, the application of a vertical magnetic field of 60mT reduces the convective heat transport on the liquid-air surface within in 5min by about 8% perpendicular to the field and up to 14% parallel to it. The effect is strongly correlated with the magnetic interaction parameter of the system, which relates the magnetic to the viscous volume force. In the natural environment, the geomagnetic field is omnipresent. It is weaker by about three orders of magnitude compared with the magnetic field applied in the experiments. It has, however, an undisturbed and long-lasting impact on the convection, at low Reynolds numbers, in the large body of water in the deeper ocean below the mixed layer. There are no investigations regarding a possible contribution of this effect to natural saltwater flows, neither by proxy experiments nor by model calculations.The data presented raise the possibility that convective heat transport in the sea could be always slowed down by the geomagnetic field to a certain extent, besides it could be modulated by the geomagnetic secular variation on relatively short timescales like decades

World ocean annual mean absolute geostrophic velocity on marine geoid of EIGEN‐6C4 from WOA13

17 USC 105 interim-entered record; under review.The article of record as published may be found at http://dx.doi.org/10.1002/gdj3.124This data set was established from two open sources: (a) geoid undulation (N) from EIGEN-6C4, which is a static global combined gravity field model up to degree and order 2,190, and (b) ‘World ocean geostrophic velocity inverted from World Ocean Atlas 2013 with the P-vector method' (NCEI accession 0,121,576). With the given non-positive values of N in the oceans, absolute geostrophic currents (u, v) are easily obtained on N with 1°×1° resolution from the second data set except the equatorial zone (5oS – 5oN) due to the non-existence of the geostrophic balance. Altogether, the data set contains 15,868 (u, v) data pairs. The data set shows that the hypothetical situation that there would be no flow on the geoid does not exist.Research Office of the Naval Postgraduate SchoolIdentified in text as U.S. Government work