Coronal heating by waves

Alfven waves or Alfvenic surface waves carry enough energy into the corona to provide the coronal energy requirements. Coronal loop resonances are an appealing means by which large energy fluxes enter active region loops. The wave dissipation mechanism still needs to be elucidated, but a Kolmogoroff turbulent cascade is fully consistent with the heating requirements in coronal holes and active region loops

Theoretical studies of the physics of the solar atmosphere

Significant advances in our theoretical basis for understanding several physical processes related to dynamical phenomena on the sun were achieved. We have advanced a new model for spicules and fibrils. We have provided a simple physical view of resonance absorption of MHD surface waves; this allowed an approximate mathematical procedure for obtaining a wealth of new analytical results which we applied to coronal heating and p-mode absorption at magnetic regions. We provided the first comprehensive models for the heating and acceleration of the transition region, corona, and solar wind. We provided a new view of viscosity under coronal conditions. We provided new insights into Alfven wave propagation in the solar atmosphere. And recently we have begun work in a new direction: parametric instabilities of Alfven waves

Measuring Regulatory Restrictions in Logistics Services

This study measures the extent of restrictions on trade in logistics services in the ASEAN+6 economies by constructing a logistics regulatory restrictiveness index for each economy that quantifies the extent of government regulations faced by logistics service providers. This is the first study of its kind to construct a regulatory index of the entire logistics sector, which includes the main modes of international transport and customs restrictions. The indices show that large differences exist in the logistics regulatory environment of ASEAN+6 economies. Many of these economies are open to trade in logistics services, while others are relatively restrictive. Malaysia, China, Indonesia, Lao PDR, the Philippines and Vietnam are the most restrictive economies of logistics services in this region. Relatively, Singapore and Australia are the most open economies for trade in logistics services, along with Japan and New Zealand. Preliminary investigations find evidence of negative relationships between logistics regulatory restrictiveness and logistics sector performance, as measured by the World Bank's Logistics Performance Index and its sub-components. These findings support that notion that a less restricted trade environment results in better performance for the logistics sector.Logistics, Transport, Government Regulation, Trade, East Asia

Wave instabilities of a collisionless plasma in fluid approximation

Wave properties and instabilities in a magnetized, anisotropic, collisionless, rarefied hot plasma in fluid approximation are studied, using the 16-moments set of the transport equations obtained from the Vlasov equations. These equations differ from the CGL-MHD fluid model (single fluid equations by Chew, Goldberger, and Low, 1956) by including two anisotropic heat flux evolution equations, where the fluxes invalidate the double polytropic CGL laws. We derived the general dispersion relation for linear compressible wave modes. Besides the classic incompressible fire hose modes there appear four types of compressible wave modes: two fast and slow mirror modes - strongly modified compared to the CGL model - and two thermal modes. In the presence of initial heat fluxes along the magnetic field the wave properties become different for the waves running forward and backward with respect to the magnetic field. The well known discrepancies between the results of the CGL-MHD fluid model and the kinetic theory are now removed: i) The mirror slow mode instability criterion is now the same as that in the kinetic theory. ii) Similarly, in kinetic studies there appear two kinds of fire hose instabilities - incompressible and compressible ones. These two instabilities can arise for the same plasma parameters, and the instability of the new compressible oblique fire hose modes can become dominant. The compressible fire hose instability is the result of the resonance coupling of three retrograde modes - two thermal modes and a fast mirror mode. The results can be applied to the theory of solar and stellar coronal and wind models.Comment: 18 pages, 11 figures, LaTeX, added explanations and references according to the referee's suggestions, fitted to the style of "Contributions to Plasma Physics" (now in press), corrections of some misprint

On the preferential acceleration and heating of solar wind heavy ions

The feasibility of producing the observed velocities and temperatures of solar wind heavy ions by the resonant cyclotron interaction with left-polarized hydromagnetic waves was investigated. A "most favorable case" scenario in which the waves are parallel-propagating and dispersionless and the energy for the wave acceleration and heating is taken from saturated low-frequency Alfven waves via a cascade to higher frequencies, is incorporated into a numerical solar wind code and agreement with observation is tested. The resonant cyclotron interaction is shown to fail on at least three points, even in this most favorable case

Collisional damping of surface waves in the solar corona

The damping of surface waves by viscosity and heat conduction is evaluated. For the solar corona, it is found that surface waves dissipate efficiently only if their periods are shorter than a few tens of seconds and only if the background magnetic field is less than about 10 Gauss. Heating of quiet coronal regions is possible if the coronal waves have short periods, but they cannot heat regions of strong magnetic field, such as coronal active region loops

Line-by-Line model for the calculation of infrared radiation fluxes and cooling rates in clear sky atmospheres

A line-by-line model for the purpose of proving the influence of the ab- sorption line parr.-eters and the performance of the spectral resoiution on evaluating radiative transfer has been developed for clear sky conditions in the infra¡ed. It has been found that for small spectral ranges a resolution scheme with grouping subintervals according to the distribution of lines in conjunction with numerical Gaussian quadrature of different orders which depend on the absorption line ranges, assures high accuracy. For la,rger spec- tral intervals a resolution scheme using constant subintervals with 0.01- cm-1 widths in conjunction with an eight point Gaussian quadrature gives sufrcient accuracy. The influence of overlapping of absorption bands has been examined and it has been found that for the demands of models using fast approximative algorithms only overlapping of simultaneously two bands in the IR has to be considered. However, the inclusion of the L4 p,m ozone band to the cor¡e- sponding overlapping bands of H2o and Coz improves the accu¡acy in the lower stratosphere considerably. The weak Co2 band at r0.4 p,m should be additionally included to the 9.6 pm ozorLe band and the water vapor continu- um range, ifdrastically enlarged carbon dioxide concentration are considered. Finali¡ the influence of the uncertainties of line para,meter values on radi- ation transfer has been considered. For the assumption of an elror of *. r0 % for a.ll line strenghts and hatfwidths an error margin of up to L0 To fot the cool- ing rates in the stratosphere and a maximum about 4 % in the troposphere has been found

Magnetohydrodynamic Slow Mode with Drifting He++^{++}: Implications for Coronal Seismology and the Solar Wind

The MHD slow mode wave has application to coronal seismology, MHD turbulence, and the solar wind where it can be produced by parametric instabilities. We consider analytically how a drifting ion species (e.g. He$^{++}$) affects the linear slow mode wave in a mainly electron-proton plasma, with potential consequences for the aforementioned applications. Our main conclusions are: 1. For wavevectors highly oblique to the magnetic field, we find solutions that are characterized by very small perturbations of total pressure. Thus, our results may help to distinguish the MHD slow mode from kinetic Alfv\'en waves and non-propagating pressure-balanced structures, which can also have very small total pressure perturbations. 2. For small ion concentrations, there are solutions that are similar to the usual slow mode in an electron-proton plasma, and solutions that are dominated by the drifting ions, but for small drifts the wave modes cannot be simply characterized. 3. Even with zero ion drift, the standard dispersion relation for the highly oblique slow mode cannot be used with the Alfv\'en speed computed using the summed proton and ion densities, and with the sound speed computed from the summed pressures and densities of all species. 4. The ions can drive a non-resonant instability under certain circumstances. For low plasma beta, the threshold drift can be less than that required to destabilize electromagnetic modes, but damping from the Landau resonance can eliminate this instability altogether, unless $T_{\mathrm e}/T_{\mathrm p}\gg1$.Comment: 35 pages, 5 figures, accepted for publication in Astrophys.

Wavelength dependence of the interplanetary scintillation index

Published observations of the interplanetary scintillation index m sub z are shown to vary with wavelength in a manner consistent with a smooth, power law spectrum of plasma fluctuations. This is in contrast to recent work arguing that the data require a spectrum with two separate regimes. It is concluded that published observations of m sub z are consistent with either type of density spectrum