Efectos de la precipitación de partículas energéticas de origen solar en la atmosfera de la tierra

La Tierra es continuamente “bombardeada” por partículas energéticas cargadas procedentes del espacio exterior que penetran en la atmósfera y pueden influir en una variedad de procesos atmosféricos. El Sol emite ondas de radio, rayos X y partículas energéticas, además de la luz visible. El transporte de energía desde el Sol hacia la Tierra se produce de dos formas: (1) radiación electromagnética, que emite alrededor de 4 x 1033 erg/s irradiando la Tierra con 1,37x 10 3 W m-2 y (2) radiación corpuscular (el viento solar con el campo magnético interplanetario “congelado” en él y cualquier partícula solar energética que puede estar presente). El ingreso de partículas energéticas solares a la magnetosfera de la Tierra produce efectos sobre las especies químicas de la atmosfera alta y media cuando precipitan en las zonas aurorales de ambos hemisferios guiadas por el campo geomagnético. La ionosfera, como parte del entorno meteorológico espacial, juega un papel crucial a través de la modulación del circuito electrodinámico global, su acoplamiento a la magnetosfera y como medio clave para la comunicación, el sondeo y la navegación. Por tanto, una comprensión profunda de su variabilidad en todas las escalas de tiempo es un importante aporte al estudio de la meteorología espacial. Como consecuencia de la intensificación de la precipitación de partículas durante periodos de tormenta geomagnética, se produce un aumento de la ionización, la creación de nitrógeno impar (NOx) y de hidrógeno impar (HOx) en la atmósfera superior, afectando la química del ozono estratosférico. Por otro lado, los campos eléctricos de origen magnetosférico, las perturbaciones atmosféricas viajeras, la circulación termosférica, y los cambios de composición química, explican las características ionosféricas de la densidad electrónica durante las distintas fases de tormentas geomagnéticas y en diferentes latitudes.The Earth is continuously "bombarded" by energetic charged particles from outer space that penetrate the atmosphere and can influence a variety of atmospheric processes. The Sun emits radio waves, X-rays and energetic particles in addition to visible light. The energy transport from the Sun to the Earth occurs in two forms: (1) electromagnetic radiation, which emits about 4 x 1033 erg/s irradiating the Earth with 1.37x 10 3 W m-2 and (2) corpuscular radiation (the solar wind with the interplanetary magnetic field "frozen" into it and any energetic solar particles that may be present). The inflow of solar energetic particles into the Earth's magnetosphere produces effects on chemical species in the high and middle atmosphere as they precipitate into the auroral zones of the two hemispheres guided by the geomagnetic field. The ionosphere, as part of the space weather environment, plays a crucial role through modulation of the global electrodynamic circuitry, its coupling to the magnetosphere, and as a key medium for communication, sounding, and navigation. Therefore, a deep understanding of its variability on all time scales is an important contribution to the study of space weather. As a consequence of intensified particle precipitation during periods of geomagnetic storms, there is an increase in ionization, the creation of odd nitrogen (NOx) and odd hydrogen (HOx) in the upper atmosphere, affecting the chemistry of stratospheric ozone. Also, electric fields of magnetospheric origin, circulating atmospheric disturbances, thermospheric circulation, and chemical composition changes explain the ionospheric characteristics of the electron density during different phases of geomagnetic storms and at different latitudes.Asociación Argentina de Geofísicos y Geodesta

Comparative analysis of extreme ultraviolet solar radiation proxies during minimum activity levels

Four extreme ultraviolet (EUV) solar radiation proxies (Magnesium II core-to-wing ratio (MgII), Lyman α flux (Fα), 10.7-cm solar radio flux (F10.7), and sunspot number (Rz)) were analyzed during the last four consecutive solar activity minima to investigate how they differ during minimum periods and how well they represent solar EUV radiation. Their variability within each minimum and between minima was compared by considering monthly means. A comparison was also made of their role in filtering the effect of solar activity from the critical frequency of the ionospheric F2 layer, foF2, which at mid to low latitudes depends mainly on EUV solar radiation. The last two solar cycles showed unusually low EUV radiation levels according to the four proxies. Regarding the connection between the EUV “true” variation and that of solar proxies, according to the foF2 filtering analysis, MgII and Fα behaved in a more stable and suitable way, whereas Rz and F10.7 could be overestimating EUV levels during the last two minima, implying they would both underestimate the inter-minima difference of EUV when compared with the first two minima

Spitze Angle Changes during Rapid Geomagnetic Core Field Variation

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An Improved Stereoselective Synthesis of L-Alanosine

An improved, stereoselective synthesis of the natural, nonproteogenic amino acid L-alanosine has been developed, starting from the readily available and cheap substrate L-serine, in six steps and 49% overall yield. The process is very efficient, is suitable for large-scale production, and affords Lalanosine with properties comparable with those of the natural substance. In addition, the structural assignment concerning some previously reported synthetic alkylated derivatives of the natural amino acid has been definitively confirmed

Species diversification – which species should we use?

Large detector systems for particle and astroparticle physics; Particle tracking detectors; Gaseous detectors; Calorimeters; Cherenkov detectors; Particle identification methods; Photon detectors for UV. visible and IR photons; Detector alignment and calibration methods; Detector cooling and thermo-stabilization; Detector design and construction technologies and materials. The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems. as established by test beam measurements and simulation studies. is described. © 2008 IOP Publishing Ltd and SISSA