How far are we from a ‘Standard Model’ of the solar dynamo?

Over the last few years, dynamo theorists seem to be converging on a basic scenario as to how the solar dynamo operates. The strong toroidal component of the magnetic field is produced in the tachocline, from where it rises due to magnetic buoyancy to produce active regions at the solar surface. The decay of tilted bipolar active regions at the surface gives rise to the poloidal component, which is first advected poleward by the meridional circulation and then taken below the surface to the tachocline where it can be stretched to produce the toroidal component. The mathematical formulation of this basic model, however, involves the specification of some parameters which are still uncertain. We review these remaining uncertainties which have resulted in disagreements amongst various research groups and have made it impossible to still arrive at something that can be called a standard model of the solar dynamo.     

The Solar Magnetic Field as a Coronal Hole Extension Forms: Effects of Magnetic Helicity and Boundary Conditions

An analytical solution is presented for linear force fields within a spherical shell, representing the solar corona. Allowing for a global magnetic helicity, we find magnetic fields over the entire corona with realistic inner boundary conditions obtained from transformation and extrapolation of photospheric magnetograms and considering alternative outer boundary conditions. Such fields are found for the well known coronal hole extension event of August 1996. This revised version was published online in June 2006 with corrections to the Cover Date.     

Hybrid modelling the Pioneer Venus Orbiter magnetic field observations

This study presents comparisons between the Pioneer Venus Orbiter (PVO) magnetometer (OMAG) observations and the HYB-Venus hybrid simulation code. The comparisons are made near periapsides of four PVO orbits using the full resolution PVO/OMAG data. Also, the statistics of the solar wind and interplanetary magnetic field (IMF) conditions at Venus are studied using the PVO interplanetary dataset. The statistics include the histograms and the probability density maps of the selected upstream parameters. The confidence intervals derived from the upstream statistics demonstrate the nominal simulation input parameter space. Moreover, the probability density maps give the dependencies between the upstream parameters. The comparisons between the simulation code and the data along the spacecraft trajectory show that the basic, large scale, trends seen in the magnetic field can be understood by the current simulation runs. The discrepancies between the simulation and the data were found to arise at low altitudes close to the planetary ionosphere in the region which cannot be resolved in detail by the grid size of the runs.     

Detection of regolith buried water stream channels on Mars with the help of synthetic aperture radar

A major theme in the study of Mars is the search for evidence that water was present in the past or is present today, either at or below the surface. Biological life is connected to water. Hence much research is focused on the detection of water stream channels, which in the past flowed on Mars. In these areas, the petrified remains of the former life on Mars may be found. These channels may be under the regolith layer; however, the radio wave penetrating ability allows for the detection of these channels under the regolith.     

Source investigation of impulsive He-rich particle events

We have investigated the source characteristic and coronal magnetic field structure of six impulsive solar energetic particle (SEP) events selected from Wang et al. [Wang, Y.-M., Pick, M., Mason, G.M. Coronal holes, jets, and the origin of ³He-rich particle events. ApJ 639, 495, 2006] and Pick et al. [Pick, M., Mason, G.M., Wang, Y.-M., Tan, C., Wang, L. Solar source regions for ³He-rich solar energetic particle events identified using imaging radio, optical, and energetic particle observations. ApJ 648, 1247, 2006]. Some results are obtained: first, 2 events are associated with wide (≈100°) CMEs (hereafter wide CME events), another 4 events are associated with narrow (?40°) CMEs (hereafter narrow CME events); second, the coronal magnetic field configuration of narrow CME events appear more simple than that of the wide CME events; third, the photospheric magnetic field evolutions of all these events show new emergence of fluxes, while one case also shows magnetic flux cancellation; fourth, the EUV jets usually occurred very close to the footpoint of the magnetic field loop, while meter type III bursts occurred near or at the top of the loop and higher than EUV jets. Furthermore, the heights of type III bursts are estimated from the result of the coronal magnetic field extrapolations.     

Active Region Dynamics

New methods of local helioseismology and uninterrupted time series of solar oscillation data from the Solar and Heliospheric Observatory (SOHO) have led to a major advance in our understanding of the structure and dynamics of active regions in the subsurface layers. The initial results show that large active regions are formed by repeated magnetic flux emergence from the deep interior, and that their roots are at least 50 Mm deep. The active regions change the temperature structure and flow dynamics of the upper convection zone, forming large circulation cells of converging flows. The helioseismic observations also indicate that the processes of magnetic energy release, flares and coronal mass ejections, might be associated with strong (1–2 km/s) shearing flows, 4–6 Mm below the surface.     

Auroral Plasma Acceleration Above Martian Magnetic Anomalies

Aurora is caused by the precipitation of energetic particles into a planetary atmosphere, the light intensity being roughly proportional to the precipitating particle energy flux. From auroral research in the terrestrial magnetosphere it is known that bright auroral displays, discrete aurora, result from an enhanced energy deposition caused by downward accelerated electrons. The process is commonly referred to as the auroral acceleration process. Discrete aurora is the visual manifestation of the structuring inherent in a highly magnetized plasma. A strong magnetic field limits the transverse (to the magnetic field) mobility of charged particles, effectively guiding the particle energy flux along magnetic field lines. The typical, slanted arc structure of the Earth’s discrete aurora not only visualizes the inclination of the Earth’s magnetic field, but also illustrates the confinement of the auroral acceleration process. The terrestrial magnetic field guides and confines the acceleration processes such that the preferred acceleration of particles is frequently along the magnetic field lines. Field-aligned plasma acceleration is therefore also the signature of strongly magnetized plasma. This paper discusses plasma acceleration characteristics in the night-side cavity of Mars. The acceleration is typical for strongly magnetized plasmas – field-aligned acceleration of ions and electrons. The observations map to regions at Mars of what appears to be sufficient magnetization to support magnetic field-aligned plasma acceleration – the localized crustal magnetizations at Mars (Acuña et al., 1999). Our findings are based on data from the ASPERA-3 experiment on ESA’s Mars Express, covering 57 orbits traversing the night-side/eclipse of Mars. There are indeed strong similarities between Mars and the Earth regarding the accelerated electron and ion distributions. Specifically acceleration above Mars near local midnight and acceleration above discrete aurora at the Earth – characterized by nearly monoenergetic downgoing electrons in conjunction with nearly monoenergetic upgoing ions. We describe a number of characteristic features in the accelerated plasma: The “inverted V” energy-time distribution, beam vs temperature distribution, altitude distribution, local time distribution and connection with magnetic anomalies. We also compute the electron energy flux and find that the energy flux is sufficient to cause weak to medium strong (up to several tens of kR 557.7 nm emissions) aurora at Mars. Monoenergetic counterstreaming accelerated ions and electrons is the signature of field-aligned electric currents and electric field acceleration. The topic is reasonably well understood in terrestrial magnetospheric physics, although some controversy still remains on details and the cause-effect relationships. We present a potential cause-effect relationship leading to auroral plasma acceleration in the nightside cavity of Mars – the downward acceleration of electrons supposedly manifesting itself as discrete aurora above Mars.     

Correlation between solar flare productivity and photospheric vector magnetic fields

Studying the statistical correlation between the solar flare productivity and photospheric magnetic fields is very important and necessary. It is helpful to set up a practical flare forecast model based on magnetic properties and improve the physical understanding of solar flare eruptions. In the previous study ([Cui, Y.M., Li, R., Zhang, L.Y., He, Y.L., Wang, H.N. Correlation between solar flare productivity and photospheric magnetic field properties 1. Maximum horizontal gradient, length of neutral line, number of singular points. Sol. Phys. 237, 45–59, 2006]; from now on we refer to this paper as ‘Paper I’), three measures of the maximum horizontal gradient, the length of the neutral line, and the number of singular points are computed from 23990 SOHO/MDI longitudinal magnetograms. The statistical relationship between the solar flare productivity and these three measures is well fitted with sigmoid functions. In the current work, the three measures of the length of strong-shear neutral line, total unsigned current, and total unsigned current helicity are computed from 1353 vector magnetograms observed at Huairou Solar Observing Station. The relationship between the solar flare productivity and the current three measures can also be well fitted with sigmoid functions. These results are expected to be beneficial to future operational flare forecasting models.     

夸克磁共振及磁共振治癌

主要提出了以下学术观点：①粒子世界中并不存在强相互作用，夸克休系是自由旋着的夸克在电磁－弱相互作用下产生的进动维系稳定的；②物质的质量源于夸克的质量，夸克的质量又源于它的自旋。自旋转速不同，能量不同，质量就不同；③用高能粒子碰撞分离出自由夸克很难，但用夸克磁共振（ＱＭＲ）分离出自由夸克却很容易；④利用纵向驰豫时间的差别，使ＱＭＲ仅在肿瘤组织内分离出自由夸克，就可在治癌的同时，不伤及正常组织，从而为     

NUMERICAL SIMULATION OF FREE MIXING LAYER WITH CROSS SHEAR

SupportedbytheNationalScienceFoundationofChinaSincethemiddleofthe7O'S,thestudyofevolutionofcoherentstructureinthenominallyplanemixinglayershasoccupiedtheeffortsofmanyresearchesinthefield-Alotofachieve-mentsaboutcounter-rotatingstreamwisevorticeshavebeenobtainedduringthelasttenyears.Mostnaturalshearflowsandmanyindustrialflowsinvolvecomplexities,suchas,withcrossshear.However,thescenarioofthecrossshearintroducedinitiallyisinherentlydifferentfromthatofthecrossshearintroducedinthemiddlestage,ass…