The effects of lightning-produced NO_x and its vertical distribution on atmospheric chemistry: sensitivity simulations with MATCH-MPIC

The impact of different assumptions concerning the source magnitude as well as the vertical placement of lightning-produced nitrogen oxides is studied using the global chemistry transport model MATCH-MPIC. The responses of NO_x, O₃, OH, HNO₃ and peroxyacetyl-nitrate (PAN) are investigated. A marked sensitivity to both parameters is found. NO_x burdens globally can be enhanced by up to 100% depending on the vertical placement and source magnitude strength. In all cases, the largest enhancements occur in the tropical upper troposphere, where lifetimes of most trace gases are longer and where they thus become more susceptible to long-range transport by large-scale circulation patterns. Comparison with observations indicate that 0 and 20 Tg(N)/yr production rates of NO_x from lightning are too low and too high, respectively. However, no single intermediate production rate or vertical distribution can be singled out as best fitting the observations, due to the large scatter in the datasets. This underscores the need for further measurement campaigns in key regions, such as the tropical continents

STEREO and ACE Observations of Energetic Particles from Corotating Interaction Regions

Since early 2007, significant particle enhancements due to corotating interaction regions (CIRs) have regularly appeared at 1 AU without any appreciable contamination from solar energetic particles (SEPs). In 2009 the prevalence of CIRs diminished as the maximum speed of the high speed solar wind streams in the ecliptic decreased along with the tilt of the heliospheric current sheet. Observations of CIR time profiles at different longitudes from STEREO show delays between the Behind and Ahead spacecraft that are often roughly as expected from the corotation time lag, although small differences in the spacecraft latitudes introduce significant scatter in the time delays. In some cases different features seen at Ahead and Behind suggest that transient disturbances in the solar wind may alter connection to or transport from the shock, or that temporal changes occur in the CIR shock itself. H and He data from STEREO/LET at 1.8–6 MeV/nucleon show that 1) the CIR spectral index at these energies is ~−4, independent of intensity but with considerable variability, 2) the He/H ratio is ~0.03 for larger CIRs but varies systematically with energy and event intensity, and 3) although the correlation between the CIR MeV particle increases and solar wind speed is generally good, many times a high-speed stream is not associated with MeV particles, while at other times a recurring series of CIR particle increases appears only at higher energies and may be associated with current sheet crossings and low speed solar wind

Solar Energetic Particle Spectral Breaks

The five large solar particle events during October–November 2003 presented an opportunity to test shock acceleration models with in-situ observations. We use solar particle spectra of H to Fe ions, measured by instruments on ACE, SAMPEX, and GOES-11, to investigate the Q/M-dependence of spectral breaks in the 28 October 2003 event. We find that the break energies scale as (Q/M)^b with b ≈ 1.56 to 1.75, somewhat less than predicted. We also conclude that SEP spectra >100 MeV/nucleon are best fit by a double power-law shape. ©2005 American Institute of Physic

Applying TSEB-RTM on multiangular airborne hyperspectral imagery for evapotranspiration retrieval in a Mediterranean ecosystem at Las Majadas del Tietar Fluxnet site, Spain

Peer reviewe

Postural evaluation and balance analysis in nordic skiing beginners

Se trata de un estudio de diseño transversal con evaluación del control postural antes-después de un curso de iniciación al esquí nórdico (5 jornadas, 6h/día), a un grupo experimental de 25 sujetos, participantes de la formación, y un grupo control de 8 sujetos. Se pretende evaluar el efecto de un entrenamiento inicial de esquí nórdico sobre el control postural en jóvenes deportistas. La estabilidad corporal se evaluó por medio de un test estabilométrico, calculando el área de desviación del centro de presiones por medio de una plataforma de fuerzas con sensores electrónicos. No se aprecian diferencias significativas en el grado de mejora del equilibrio entre el grupo experimental y el grupo control. Nuevos estudios con una mayor exigencia en la formación en esquí nórdico y un mayor número de sujetos en el grupo control son requeridosCross-sectional study with evaluation of postural control before and after a course of initiation to Nordic skiing (5 days, 6 hours per day). The sample consisted of an experimental group of 25 subjects participated in the training and a control group of 8 subjects. It is intended to evaluate the effect of initial training of Nordic skiing on postural control in young athletes. The physical stability was evaluated by a stabilometric test, calculating the deviation of the area of the center of pressures by the use of a force platform with electronic sensors. No significant differences were observed in the degree of improvement of the balance between the experimental group and the control group. New studies with a greater emphasis on training in Nordic skiing and a greater number of subjects in the control group are require

Observations of the longitudinal spread of solar energetic particle events in solar cycle 24

With the twin STEREO spacecraft, significantly separated from L1-based satellites such as ACE, simultaneous multi-point measurements of solar energetic particle (SEP) events can be made for H-Fe ions from a few hundred keV/nuc to over 100 MeV/nuc and for electrons from tens to hundreds of keV. These observations allow studies of the longitudinal characteristics of SEP events to advance beyond statistical analysis of single point measurements. Although there have been few large SEP events thus far in cycle 24, there have been a number of smaller events that have been detected by more than one spacecraft. The composition of these SEP events, as indicated by the H/He and Fe/O abundance ratios, shows a dependence on longitudinal distance from the solar source in some events, at times with ratios varying by an order of magnitude. However, these variations are not organized by either the speed or width of the associated coronal mass ejections

STEREO Observations of Energetic Neutral Hydrogen Atoms During the 2006 December 5 Solar Flare

We report the discovery of energetic neutral hydrogen atoms (ENAs) emitted during the X9 solar event of 2006 December 5. Beginning ~1 hr following the onset of this E79 flare, the Low Energy Telescopes (LETs) on both the STEREO A and B spacecraft observed a sudden burst of 1.6-15 MeV protons beginning hours before the onset of the main solar energetic particle event at Earth. More than 70% of these particles arrived from a longitude within ±10° of the Sun, consistent with the measurement resolution. The derived emission profile at the Sun had onset and peak times remarkably similar to the GOES soft X-ray profile and continued for more than an hour. The observed arrival directions and energy spectrum argue strongly that the particle events < 5 MeV were due to ENAs. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. Possible origins for the production of ENAs in a large solar event are considered. We conclude that the observed ENAs were most likely produced in the high corona and that charge-transfer reactions between accelerated protons and partially stripped coronal ions are an important source of ENAs in solar events