SH23A-01
A BGK-Boltzmann Approach to Non-linear Cosmic-ray Diffusive Transport in Composite 2D and Slab MHD Turbulence
With the aid of particle simulations it was discovered that standard quasi-linear theory (QLT) cannot adequately describe the parallel and perpendicular diffusion of cosmic rays in 3D MHD solar wind turbulence, when the turbulence is modeled to a first approximation as a static combination of a dominant 2D component and a minor slab component. Recent non-linear theories based on a Taylor-Green-Kubo (TGK) formalism, such as the non- linear guiding center (NLGC) theory, and the weakly non-linear theory (WNLT) that uses assumptions consistent with extended QLT, proved to be much more successful because it takes into account the transverse diffusive motion of the particle guiding center as it follows a random field with a strong 2D component transverse to the mean field. Instead, we follow a BGK- Boltzmann approach (extended QLT) to investigate the non-linear diffusive transport of cosmic rays in combined 2D and slab MHD turbulence. Going beyond current NLGC theory and WNLT in scope, we derived a complete cosmic-ray transport theory that includes not only non-linear coupled expressions for parallel and perpendicular diffusion, but also drift, convection, adiabatic energy change and momentum diffusion transport coefficients. The BGK-Boltzmann approach enables one to derive tractable yet complicated expressions for all transport coefficients in both the weak and strong particle scattering limits. It will be shown that the WNLT for coupled parallel and perpendicular diffusion can be recovered by combining these two limits in such a way that there is weak particle scattering along the field but strong particle scattering across the magnetic field. The complexity of the WNLT expressions can be reduced to simple analytical expressions of parallel and perpendicular diffusion that reproduces well the rigidity dependence of particle simulations at low to medium rigidities. These expressions also prove to be consistent with well-known expressions for perpendicular diffusion in the literature. It is also discussed how large-scale gradient and curvature drifts get modified by turbulence and how stochastic particle acceleration changes when 2D turbulence is dominant.
SH23A-02
Gradients of Galactic Cosmic Rays: Ulysses KET Results
We study the spatial gradients of galactic cosmic rays in the inner heliosphere using data from the Kiel Electron Telescope (KET) aboard Ulysses and the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) for the time period from 1997 to 2007. This covers the solar minimum in the A>0- solar magnetic epoch, the solar magnetic reversal to an A<0-magnetic epoch at solar maximum and the declining phase of solar cycle 23. In order to calculate the galactic cosmic ray intensity distribution in the inner heliosphere we used the 125-250 MeV/nuc helium channel from KET and a combination of carbon channels from the CRIS instrument on ACE. Our analysis results in a radial and latitudinal intensity gradient of Gr=2.9±0.8%AU and Gθ=0.04±0.06% degree, respectively. Note, that in the current A<0-solar magnetic epoch a negative gradient was expected from previous observations in the outer heliosphere.
SH23A-03
Signatures of CMEs Shocks on LASCO Observations
We report on our efforts to establish reliable markers of CME-driven shocks in white light coronograph images. For this study, we looked at events during the ascending phase of solar cycle 23 when the overall morphology of the white light corona is simple. We isolated events that will be good candidates to drive a shock due to their high velocities (V>1500 km/s). The list includes 15 CMEs. For each event we calibrated the LASCO images and searched for indications of faint sharp fronts ahead of the bright CME front. We report our findings of the analysis of the front morphology, the distant streamer deflections, and the mass and energetics of these events. This work is funded by the LWS TR&T program
SH23A-04
Stream Interaction Regions and Interplanetary Coronal Mass Ejections at 5 AU
Two major types of large-scale solar wind structures, stream interaction regions (SIRs) and interplanetary coronal mass ejections (ICMEs) are observed in the heliosphere. Both types of structures evolve as they propagate out from the Sun. Using Ulysses SWOOPS and VHM/FGM observations near 5 AU within +/- 10 degrees of the solar ecliptic plane, we have completed surveys of these two types of structures in 1992, 1997- 1998, and 2003-2005, which cover different phases of the solar activity cycle. About 70 precent of the SIRs in our survey are associated with shocks, many of which are reverse shocks. As at 1 AU, magnetic field and total perpendicular pressure (Pt) signatures are prominent for most SIRs, but some plasma signatures (e.g., a gradual and monotonic increase of velocity, a compression of proton number density, and a sharp increase of proton temperature) are not always apparent at larger radial distances. Most SIRs do not have sharp stream interfaces. The majority of ICMEs drive leading forward shocks. In previous work, we found 1 AU ICME observations could be sorted roughly into three categories, based on the temporal profile of Pt, and we interpreted the different categories as indicators of the impact parameter of the spacecraft with respect to the central causative flux rope. At 5 AU, we find such a sorting can not be applied to quite a few ICMEs, indicating ICMEs become more complicated as they propagate. In contrast with 1 AU ICMEs, several ICMEs seem to contain more than one flux rope, and these ropes differ in size, field strength, and even plasma content. Such events may be caused by the interaction of separate CMEs from the Sun, or may contain flux ropes formed by reconnection at the heliospheric current sheet between the Sun and 5 AU. Frequently, ICMEs and SIRs are merged and hard to separate. The number of such combined events decreases as solar activity declines. We quantitatively examine the occurrence rate, shock association rate, radial extent, and expansion velocity of these two types of solar wind disturbances and compare their behavior as a function of solar cycle and also with 1 AU Wind and ACE observations we have previously compiled in 2006 Solar Physics papers.
SH23A-05
Numerical Study of CME-like disturbances. 1-D simulations
We present a parametric study of ICME-like disturbances from close to the Sun (18 solar radii) to 1 AU. This is a 1-D HD model using the ZEUS 3D code (Stone and Norman, 1992). With this study we illuminate some basic aspects of the heliocentric evolution of these disturbances in the inner heliosphere. After their injection, the fast ICME-like disturbances present two deceleration steps: a slow deceleration propagation in the inner trajectory, and, after reaching a critical distance (at about .45 AU), an exponential deceleration propagation where the ICME- like velocity tends to equalize the ambient wind speed. This critical distance depends on the ICME initial parameters and the ambient wind characteristics.
SH23A-06
About the Las Acacias, Trelew and Vassouras Magnetic Observatories Monitoring the South Atlantic Magnetic Anomaly Region Response to an Interplanetary Coronal Mass Ejection
The South Atlantic Magnetic Anomaly (SAMA) Region presents evolutive characteristics very important as were observed by a variety of satelital sensors. Important Magnetic Observatories with digital record monitor the effects of the Sun-Earth interaction, such as San Juan de Puerto Rico (SJG), Kourou (KOU), Vassouras (VSS), Las Acacias (LAS), Trelew (TRW), Vernadsky (AIA), Hermanus (HER) and Huancayo (HUA). In the present work we present the features registered during the geomagnetic storm in January 21, 2005, produced by a geoeffective Coronal Mass Ejection (CME) whose Interplanetary Coronal Mass Ejection (ICME) was detected by the instrumental onboard the Advanced Composition Explorer (ACE) Sonde. We analize how the Magnetic Total Intensity records at VSS, TRW and LAS Observatories shows the effect of the entering particles to ionospherical dephts producing a field enhancement following the first Interplanetary Shock (IP) arrival of the ICME. This process manifest in the digital record as an increment over the magnetospheric Ring Current field effect and superinpossed effects over the Antarctic Auroral Electrojet. The analysis and comparison of the records demonstrate that the Ring Current effects are important in SJG and KOU but not in VSS, LAS and TRW observatories, concluding that SAMA region shows a enhancement of the ionospherical currents oposed to those generated at magnetospheric heighs. Moreover in TRW, 5 hours after the ICME shock arrival, shows the effect of the Antarctic Auroral Electrojet counteracting to fields generated by the Ring Current.
SH23A-07
Space Weather Impact on Pipeline in La Plata City, Argentine
In the Sun-Earth connection, some of the most important characteristic events involved are the Coronal Mass Ejections (CME) and the high speed particle streams events coming from the Coronal Holes at the Sun. These interplanetary events produce effects on space and ground-based technology. In the present work, the geomagnetic storm recorded at Las Acacias Digital Magnetic Observatory (LAS, Lat.:-35º.0; Long.: 302º.3) produced by a particle stream from a solar coronal hole and their relationship with the induction effects caused on a pipeline in the shore of La Plata city, Argentine. The result shows an increase of the induced current correlated with the registered geomagnetic storm. Also, the magnetically calm days are analized. It is concluded that the amplitude of induced current intensity verifies a logarithmic relation with the amplitude of total magnetic intensity recorded in Las Acacias Observatory.
SH23A-08
Study of Radio sources and interferences detected by MEXART
The Mexican Array Radio Telescope (MEXART) is a radio telescope that will perform studies of solar wind disturbances using the Interplanetary Scintillation (IPS) technique. The radiotelescope is its final calibration stage, and in this work we report two testings: the interference signals detected around the operation frequency, and the transit of the main radio sources detected by individual lines of 64 dipoles. These radio sources are: Sun, Casiopea, Crab nebula, Cygnus and Virgo. These testings allow us to know the response of the array elements in order to calibrate them. The final operation of the MEXART requires that the signal detected and transmitted by each East-West line of 64 dipoles arrives at the butler matrix (control room) with the same phase and amplitude.
SH23A-09
Solar Cycle Dynamics of the Quasi-Biennial Periodicities Associated With the Coupling of a Double Solar Dynamo
In this work we report an analysis of various indices of solar magnetic variability of closed and open field, concentrating particularly in the quasi-biennial peridicities (1.7-2.5 years). The wavelet technique is used in the time series of the solar indices to find the significant periodicities of our study, we also use other wavelet analysis already made. We consider the theory of a double solar dynamo, with its low frequency component located at the base of the covection zone, and its high frequency component in the upper part, coupled by the helicity (alfa effect). In this context, we obtain a classification of the couplings between the low and high frequency components per cycle along cycles 17 to 23, based on the strength and regularity of the quasi-biennial periodicities
SH23A-10
The First Space Weather Forecast Models from the Center for Integrated Space Weather Modeling
One main objective of the Center for Integrated Space Weather Modeling (CISM) is to develop forecast models (FM) for the Sun-Earth chain, and to mature them close to the operational stage. The Sun-Earth chain comprises empirical and physical models. Among the former is the Planetary Equivalent Amplitude FM with a 1 to 7 day prediction of the daily Ap and a 3 to 24 hour prediction of the running 3 hourly ap. We employ a linear filter technique which is driven by real-time ACE solar wind speed and AFWA Ap/ap data. Among the latter is the Ambient Solar Wind FM with a 1 to 5 day prediction of solar wind parameters in 6 hour intervals. It is driven by daily NSO/SOLIS synoptic maps. We employ the Wang-Sheeley-Arge algorithm to transform these into inner boundary conditions for the ideal MHD code ENLIL, which propagates the solar wind structures out to Earth and beyond. We are also preparing a Geospace FM with short-range predictions for magnetospheric and ionospheric parameters, which is driven by real-time ACE measurements. The transition from science to forecast model follows along these main steps: the science model is validated against various metrics, software engineering matures the transition candidate, and useful forecast products are derived from the forecast model.
SH23A-11
Evolution of the spectrum of velocity and magnetic fluctuations in the solar wind
Recent work has shown that at 1 AU from the Sun the power spectrum of the magnetic field has the -5/3 spectral slope expected for Kolmogorov turbulence, but that the velocity has closer to a -3/2 spectrum. The latter slope is predicted for magnetically dominated turbulence, but if this were the case one might expect that the magnetic spectrum would be most likely to have the -3/2 slope. An alternative perspective is that the -3/2 is accidental and transient, and that the -5/3 slope is the eventual state of the all the fluctuations. Here we present spectra from Helios, Wind, Voyager, and other spacecraft to support the evolutionary view. If this is the correct interpretation of the results, then the question still arises of why the velocity evolves at a different rate from the magnetic field. This talk will not answer this question, but will begin to quantify the obersvational evidence.