Venus observations from ENVISAT–SCIAMACHY: Measurements and modeling

This work shows the capability of observing Venus with a sensor originally designed for Earth remote sensing. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY), onboard ENVISAT, successfully observed visible and near-infrared spectra from the Venusian atmosphere. The Venus spectra were simulated using a line-by-line radiative transfer model. The single scattering approximation was applied in order to consider the effects of an approximately 20 km-thick haze layer above the main cloud deck, which was considered as a reflecting cloud located in the upper atmosphere of the planet. CO₂ absorption lines could be distinguished in both observed and simulated spectra and a good agreement between them was also found.     

Hyperspectral imaging—An advanced instrument concept for the EnMAP mission (Environmental Mapping and Analysis Programme)

In the upcoming generation of satellite sensors, hyperspectral instruments will play a significant role. This payload type is considered world-wide within different future planning.Our team has now successfully finalized the Phase B study for the advanced hyperspectral mission EnMAP (Environmental Mapping and Analysis Programme), Germans next optical satellite being scheduled for launch in 2012. GFZ in Potsdam has the scientific lead on EnMAP, Kayser-Threde in Munich is the industrial prime.The EnMAP instrument provides over 240 continuous spectral bands in the wavelength range between 420 and 2450 nm with a ground resolution of 30 m×30 m. Thus, the broad science and application community can draw from an extensive and highly resolved pool of information supporting the modeling and optimization process on their results. The performance of the hyperspectral instrument allows for a detailed monitoring, characterization and parameter extraction of rock/soil targets, vegetation, and inland and coastal waters on a global scale supporting a wide variety of applications in agriculture, forestry, water management and geology. The operation of an airborne system (ARES) as an element in the HGF hyperspectral network and the ongoing evolution concerning data handling and extraction procedures, will support the later inclusion process of EnMAP into the growing scientist and user communities.     

Ion Acceleration at the Earth’s Bow Shock

The Earth’s bow shock is the most studied example of a collisionless shock in the solar system. It is also widely used to model or predict the behaviour at other astrophysical shock systems. Spacecraft observations, theoretical modelling and numerical simulations have led to a detailed understanding of the bow shock structure, the spatial organization of the components making up the shock interaction system, as well as fundamental shock processes such as particle heating and acceleration. In this paper we review the observations of accelerated ions at and upstream of the terrestrial bow shock and discuss the models and theories used to explain them. We describe the global morphology of the quasi-perpendicular and quasi-parallel shock regions and the foreshock. The acceleration processes for field-aligned beams and diffuse ion distribution types are discussed with connection to foreshock morphology and shock structure. The different possible mechanisms for extracting solar wind ions into the acceleration processes are also described. Despite several decades of study, there still remain some unsolved problems concerning ion acceleration at the bow shock, and we summarize these challenges.     

Properties of the interstellar gas inside the heliosphere

Methods and results of investigations of the interstellar gas inside the heliosphere are summarized and discussed. Flow parameters of H and He and the relative abundances of H, He, N, O, and Ne in the distant heliosphere are given. Charge exchange processes in front of the heliosphere affect the flow of hydrogen and oxygen through the heliopause. The speed of hydrogen is reduced by 6 km/s, and screening leads to a reduction of the O/He and H/He ratios in the neutral gas entering the heliosphere. When the screening effect and the acceleration processes leading to the anomalous cosmic rays (ACR) are sufficiently understood, abundances in the LIC can be derived from measurements inside the heliosphere. Since isotopic ratios are virtually not changed by screening or by EUV and solar wind ionisation, relative abundances of isotopes in the gaseous phase of the LIC can be determined with no or minor correction from investigations of the neutral gas, pickup ions and ACR particles.     

Compressive and Rarefactive Electron-Acoustic Solitons and Double Layers in Space Plasmas

Space observations in several near-Earth environments have revealed the presence of positive-potential, large-amplitude electrostatic structures, associated with high-frequency disturbances, and indicative of electron dynamics. Earlier models proposed in terms of electron-acoustic solitary waves in a two-electron-temperature plasma were inadequate, because only negative potential structures could thus be obtained, whereas the observations point to positive potential structures. In this paper, it is shown that the theoretical restriction to negative potential solitons is due to the neglect of the inertia of the hot electrons, implicitly or explicitly assumed in previous papers. If hot electron inertia is retained, however, there exists a parameter range where positive potential solitary waves are formed, which can have important consequences for the re-interpretation of several astrophysical phenomena involving two-electron-temperature plasmas. PACS: 52.35.Mw, 52.35.Sb, 96.50.Ry     

氧化铝的直接电镀

讨论了在氧化铝基板上的厚膜应用领域中采取直接电镀的方法。研究了建立在钯涂层、碳涂层和导电聚合物基础上的三种直接电镀的方法，测定和比较了它们与传统电镀／ 化学镀技术的操作步序、电镀速度和膜层结合力等技术指标。     

Effects of Superthermal Particles on Waves in Magnetized Space Plasmas

Distributions with excess numbers of superthermal particles are common in space environments. They are well modelled by the isotropic kappa distribution, or, where magnetic effects are important, the kappa-Maxwellian. This paper presents a review of some studies of electrostatic and electromagnetic waves in such plasmas, based on the associated generalized plasma dispersion functions, Z _κ and Z _κM. In particular, the effects of low values of κ are considered, i.e. strongly accelerated distribution functions. Recently the full susceptibility tensor for oblique propagation of electromagnetic waves in a kappa-Maxwellian magnetoplasma has been established and has been applied to the study of whistler waves.     

On compositional variations of heavy ions during solar particle events

Intensity-time profiles of protons, alpha particles, and heavy ions (C, O, Fe) in the MeV/nucleon energy range have been analyzed for one solar particle event following the solar flare on September 23, 1978. The data have been obtained with the wide angle double dE/dx-E sensor of the Max-Planck-Institut/University of Maryland experiment onboard ISEE-3. We found time variations in the iron to helium ratio of up to 2 orders of magnitude and a significant variation of the O/He ratio during this event, whereas the C/O-ratio at the same energy/nucleon appears to be time independent. We investigated the influence of a rigidity dependent mean free path in interplanetary space and of rigidity dependent coronal propagation on heavy ion ratios during solar particle events. We found that both the magnitude and time scale of the ratio changes during the September 23 event cannot be explained by rigidity dependent interplanetary or coronal propagation alone. These ratio changes are probably caused by multiple injection at the sun.