Das erdmagnetische Feld im Jahr 1992 nach Messungen des Erdmagnetischen Observatoriums Wingst

Ohne Zusammenfassung     

Mean wind-direction shear through a forest canopy

The equations of motion applying to the wind field in a forest canopy are simplified to a balance between the shearing stress gradient and either the form-drag of the leaves in the upper dense canopy, or the overall horizontal pressure gradient in the more open space beneath. The equations imply that, in descending through the forest, the stress and wind vectors turn through an angle which depends on the forest characteristics and on the stability and the speed of the airflow above the forest. The turning is roughly confirmed by an overall average measured on a very flat site near Thetford, Norfolk, covered by an extensive uniform pine forest.     

Unterwasserbeobachtungen im sublitoralen Solfatarenfeld von Vulcano (Äolische Inseln,Italien)

Zusammenfassung Unterwasserbeobachtungen im sublitoralen Solfatarenfeld von Vulcano brachten Einzelheiten über die verschiedene Gestaltung des Meeresbodenreliefs im Bereich der Gasaustritte und über die Anlagerung von kolloidalem Schwefel. Die Befunde werden anhand mehrerer Unterwasserphotographien erläutert und es wird auf die Ähnlichkeit der rezenten Bodengestaltung mit gewissen aus triadischen Pb-Zn-Erzlagerstätten bekannten Gefügen hingewiesen. Hinweise auf Flora und Fauna im Bereich der submarinen Vulkanexhalationen ergänzen die Untersuchungen.

---

Underwater studies in the sublitoral field of solfataras of Vulcano revealed details on the relief of the sea bottom in areas with volcanic exhalations and on the deposition of colloidal sulphur. The observations made are illustrated by several underwater photographs. The similarity between the recent shape of the ground and certain fabrics known from Triassic Pb-Zn- ore deposits is pointed out. These studies are supplemented by short data on the abundant flora and fauna in the area of the submarine volcanic exhalations.

     

Quasi-exospheric heat flux of solar-wind electrons

Density, bulk-velocity, and heat-flow moments are calculated for truncated maxwellian distributions representing the cool and hot populations of solar-wind electrons, as realized at the base of a hypothetical exosphere. The electrostatic potential is thus calculated by requiring charge quasineutrality and the absence of electrical current. Plasma-kinetic coupling of the cool-electron and proton bulk velocities leads to an increase in the electrostatic potential and a decrease in the heat-flow moment. If the velocities differ by the Alfvén speed along the magnetic field, for example, the potential rises to 72.6 V and the heat flux falls to 2.72×10^–2 erg cm^–2 s^–1. In each case the heat flux is carried mainly by the quasi-exospherichot electrons.     

In-flight performance analysis of the CHAMP BlackJack GPS Receiver

JPL's BlackJack receiver currently represents the most widely used geodetic grade GPS receiver for space applications. Using data from the CHAMP science mission, the in-flight performance of the BlackJack receiver has been assessed and the impact of various software updates performed during the 2.5 years since launch is described. Key aspects of the study comprise the channel allocation, anomalous data points, and the noise level of the code and carrier data. In addition, it has been demonstrated that the code measurements collected onboard the CHAMP satellite are notably affected by multipath errors in the aft-looking hemisphere, which can be attributed to cross-talk between the occultation antenna string and the primary precise orbit determination antenna. For carrier smoothed 10 s normal points, the code noise itself varies between a minimum of 5 cm at high elevations and 0.5 m (C/A) to 1.0 m (P₁, P₂) at 10° elevation. Carrier-phase data exhibit representative errors of 0.2 to 2.5 mm. The results of the CHAMP GPS data analysis contribute to a better understanding and possible improvement of the BlackJack receiver and support the design of optimal data editing and weighting strategies in precise orbit determination applications.     

GIOVE-A initial signal analysis

In late December 2005 the GIOVE-A test satellite was launched by the European Space Agency (ESA) to secure the frequencies for the Galileo system and to provide a platform for testing the new navigation signals. We performed an initial assessment of these signals using the 30 m deep space antenna of the DLR ground station in Weilheim (Germany). The antenna gain raised the signals above the noise level, thus allowing a detailed analysis even without knowledge of the ranging codes. The present paper covers the analysis of the L1/E1 signals, which includes a discussion of the spectrum, the time domain signal and a decoding of the spreading codes for the Open Service.     

Alternative Validation of a LC-MS/MS-Multi-Method for Pesticides in Drinking Water

The development of instrumental analytics such as the LC-MS/MS has made it possible to quickly determine many component concentrations in a single chromatogram. However, the validation of such multi-methods needs new strategies for robustness and optimization. Statistical execution of analytical tests is one tool that can be utilized to meet this requirement. A Central Composite Design (CCD) was utilized for the validation of an LC-MS/MS multi-method for 84 analytes. The experimental design includes six design variables and two non-design variables (response variables). Concentration, ionization temperature, dwell time, gradient, flow (of eluent), and spraying/curtain gas (continuous design variables) were varied on five different levels; the whole design encompassed 91 runs. To investigate the robustness of a LC-MS/MS method both peak sensitivity and chromatographic separation had to be verified. Therefore, two non-design variables were necessary. The distribution of the peaks over analysis time was applied to describe the quality of the chromatographic separation. The sensitivity was described with the signal to noise ratio (S/N). The evaluation of the measured data was accomplished with the Analysis of Variance (ANOVA) and the Response Surface Methodology (RSM). Three main effects (concentration, ionization temperature, dwell time) and no significant interaction effect were found for the response variable “S/N”. The variables of concentration, ionization temperature, and dwell time had no significant effects for the response variable “S/N”. The ANOVA of the response variable chromatographic separation abandoned no significant effects as well. Therefore, robustness of the method can be guaranteed for all non significant design variables.     

Calculation of the Inverse of the Covariance

In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix.     

New equipment and processing for magnetotelluric remote reference observations

Robust estimates of magnetotelluric and geomagnetic response functions are determined using the coherency and expected uniformity of the magnetic source field as quality criteria. The method is applied on data sets of three simultaneously recording sites. For the data acquisition we used a new generation of geophysical equipment (S.P.A.M. MkIII), which comprises novel concepts of parallel computing and networked, digital data transmission. The data-processing results show that the amount of noise on the horizontal components of the magnetic field varies considerably in time, between sites and over the frequency range. The removal of such contaminated data beforehand is essential for most data-processing schemes, as the magnetic channels are usually assumed to be free of noise. The standard remote reference method is aimed at reducing bias in response function estimates. However, this does not necessarily improve their precision as our results clearly show. With our method, on the other hand, we can filter out source field irregularities, thereby providing suitable working conditions for the robust algorithm, and eventually obtain considerably improved results. Contrary to previous concepts, we suggest rejecting as much data as feasible in order to concentrate on the remaining parts of high-quality observations.