The celestial mechanics approach: application to data of the GRACE mission

The celestial mechanics approach (CMA) has its roots in the Bernese GPS software and was extensively used for determining the orbits of high-orbiting satellites. The CMA was extended to determine the orbits of Low Earth Orbiting satellites (LEOs) equipped with GPS receivers and of constellations of LEOs equipped in addition with inter-satellite links. In recent years the CMA was further developed and used for gravity field determination. The CMA was developed by the Astronomical Institute of the University of Bern (AIUB). The CMA is presented from the theoretical perspective in (Beutler et al. 2010). The key elements of the CMA are illustrated here using data from 50 days of GPS, K-Band, and accelerometer observations gathered by the Gravity Recovery And Climate Experiment (GRACE) mission in 2007. We study in particular the impact of (1) analyzing different observables [Global Positioning System (GPS) observations only, inter-satellite measurements only], (2) analyzing a combination of observations of different types on the level of the normal equation systems (NEQs), (3) using accelerometer data, (4) different orbit parametrizations (short-arc, reduced-dynamic) by imposing different constraints on the stochastic orbit parameters, and (5) using either the inter-satellite ranges or their time derivatives. The so-called GRACE baseline, i.e., the achievable accuracy of the GRACE gravity field for a particular solution strategy, is established for the CMA.     

Control of paths of quaternary volcanic products in western Bohemian Massif by rejuvenated Variscan triple junction of ancient microplates

Our objective is to look for deep paths of Cenozoic volcanism and migration routes of active mantle volatiles through the lithosphere of the western Bohemian Massif. We show that the rejuvenated junction of three mantle domains, delimited by different orientation of seismic anisotropy and belonging to originally separated microplates — the Saxothuringian (ST), Moldanubian (MD) and Teplá-Barrandian (TB) — can provide the easiest upward routes of fluids through the deep lithosphere. Geographic distribution of mantle-fluid escapes at the surface suggests fluid migration through the ductile lower crust and through partly open faults in the rigid upper crust, which is locally detached and shifted from its lower part and from the mantle lithosphere. Present-day escapes of mantle-derived helium and CO₂ concentrate mainly in two tectonically different crust edifices — in the Cheb Basin (CHB) and in an allochtonous block called the Mariánské Lázně Complex (MLC). Crystalline basement of the CHB developed above the Variscan ‘triple junction’ of the mantle lithosphere domains. The basement was extended during the Cenozoic and dissected by systems of faults into small partly sunken blocks. Thanks to buoyancy the mantle fluids migrate upwards along the lithosphere junction into the faulted basement of the CHB. The highest CO₂ flow and the highest ³He/⁴He ratios are observed at intersections of major normal faults and along the southern boundary of the Smrčiny (Fichtelgebirge) granite Pluton. The fluid escapes are separated from the earthquake swarm epicentres. Routes of the fluids to the MLC are longer and more complicated. Surface escapes tap the mantle fluids mainly from the Mariánské Lázně Fault (MLF) and from the tectonic boundaries along which the MLC block of the TB lower crust was thrust over the ST complexes. Hypocentres of earthquake swarms of the two major focal areas at Novy Kostel and Lazy, located mainly at depths of 6–13 km, reside either in granite or in underlying gneiss, while the escapes of mantle fluids follow major faults or boundaries of crystalline units outside the Smrčiny and Karlovy Vary granite Plutons. We suggest that primarily those parts of faults in the upper crust, which is strengthened by granite magmatism and rigid enough to selectively accumulate stresses, are seismoactive. On the other hand, other parts of the faults tapping ascending mantle volatiles are ‘lubricated’ by the fluids and secondary mineralogical changes, and thus they cannot accumulate sufficient stresses to be released by earthquakes. A comparison of the most probable paths of the mantle fluids with the space-time distribution of the Novy Kostel hypocentres does not seem to support the model of the earthquake swarms triggered by pressurized fluids of mantle origin.     

Geoidal Geopotential and World Height System

The geoidal geopotential value of W ₀ = 62 636 856.0 ± 0.5m ² s ^–2 , determined from the 1993 –1998 TOPEX/POSEIDON altimeter data, can be used to practically define and realize the World Height System. The W ₀ -value can also uniquely define the geoidal surface and is required for a number of applications, including General Relativity in precise time keeping and time definitions. Furthermore, the W ₀ -value provides a scale parameter for the Earth that is independent of the tidal reference system. All of the above qualities make the geoidal potential W ₀ ideally suited for official adoption as one of the fundamental constants, replacing the currently adopted semi-major axis a of the mean Earth ellipsoid. Vertical shifts of the Local Vertical Datum (LVD) origins can easily be determined with respect to the World Height System (defined by W ₀ ), in using the recent EGM96 gravity model and ellipsoidal height observations (e.g. GPS) at levelling points. Using this methodology the LVD vertical displacements for the NAVD88 (North American Vertical Datum 88), NAP (Normaal Amsterdams Peil), AMD (Australian Height Datum), KHD (Kronstadt Height Datum), and N60 (Finnish Height Datum) were determined with respect to the proposed World Height System as follows: –55.1 cm, –11.0 cm, +42.4 cm, –11.1 cm and +1.8 cm, respectively.     

Surface-sediment and epilithic diatom pH calibration sets for remote European mountain lakes (AL:PE Project) and their comparison with the Surface Waters Acidification Programme (SWAP) calibration set

A modern diatom-pH calibration data-set consisting of surface-sediment diatom assemblages from 118 lakes and 530 taxa is presented. The AL:PE data-set is from high-altitude or high-latitude lakes in the Alps, Norway, Svalbard, Kola Peninsula, UK, Slovenia, Slovakia, Poland, Portugal, and Spain (pH range = 4.5-8.0; DOC range = 0.2-3.2 mg l^-1). In addition, 92 epilithon samples from 22 high-altitude or high-latitude lakes comprise an AL:PE epilithon diatom-pH data-set. Weighted averaging partial least squares regression is used to develop pH-inference models. The AL:PE data-set has a root-mean-square-error of prediction (RMSEP) of 0.33 and a maximum bias of 0.36 pH units and r² of 0.82, as assessed by leave-one-out cross-validation. The epilithon data-set has, after data-screening and the deletion of one very obvious outlier, a RMSEP of 0.23 and a maximum bias of 0.18 pH units and r² of 0.88. The 167 sample SWAP diatom-pH data-set from lowland or upland lakes in the UK, Norway, and Sweden has a RMSEP of 0.29 and a maximum bias of 0.23 pH units and r² of 0.86.The pH optima, as estimated by weighted averaging and Gaussian regression, are compared for the three data-sets (AL:PE, SWAP, AL:PE epilithon). There is a good correspondence between the AL:PE and the AL:PE epilithon optima, but a consistent bias between the AL:PE and SWAP optima, with the SWAP optima being lower than the AL:PE estimates.The predictive performances of the AL:PE and SWAP calibration data-sets are compared using independent test samples and six core sequences, all from high-altitude lakes, one in south-east Siberia and five in eastern Scotland. The results show the importance of using the AL:PE data-set for inferring lake-water pH from diatom assemblages in high-altitude or high latitude lakes with low DOC concentrations.     

Temporary Array Data for Studying Seismic Anisotropy of Variscan Massifs – The Armorican Massif,French Massif Central And Bohemian Massif

We present the first results of a comparison of deep lithosphere structure of three Variscan massifs - the Armorican Massif, French Massif Central and Bohemian Massif, as revealed by recent tomographic studies of seismic anisotropy. The data originate from several field measurements made in temporary arrays of stations equipped with both short-period and broadband seismometers with digital recording. The study is based on teleseismic body waves and a joint inversion of anisotropic data (P-residual spheres, the fast shear-wave polarizations and split times) and demonstrates that the three Variscan massifs appear to consist of at least two parts with different orientation of large-scale fabric derived from seismic anisotropy. The boundaries of anisotropic lithospheric domains are related to prominent tectonic features recognised on the surface as sutures, shear zones or transfer fault zones, as well as grabens, thus indicating that some of them extend deep through the entire lithosphere.     

Persistent Organic Pollutants (POPs) in Bottom Sediments of the Vistula River,Poland

The Vistula (Wisla) river, the biggest river in Poland, is 1038 km long and has a drainage area of 168 689 km². The river is strongly polluted by wastewaters. Big industrial plants are situated mainly in the upper part of the river, where it is slow‐flowing. This paper presents the results of the analysis of bottom sediment samples gathered from different locations along the Vistula river, from Kraków to Gdansk. The study was conducted in 2005. The following parameters were determined: chloroorganic pesticides, polychlorinated biphenyls (PCBs), chlorophenols, polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC). The sum of chloroorganic pesticides was in the range of 2.0 to 77.5 ng/g d.w. (dry wet) with the highest values in the upper part of the river. p,p′‐DDT was found in the highest concentration. The sum of PCBs was in the range of 0.9 to 64.2 ng/g d.w. The sum of chlorophenols varied from 0.48 to 14.3 ng/g d.w. 2,4‐Dichlorophenol and pentachlorophenol occurred in the highest concentration. The sum of PAHs was in the range of 1552 to 7832 ng/g d.w. Phenantren was found in the highest concentration and antracen in the lowest. TOC values varied from 4.3 to 43.9 g/kg d.w. The concentrations of pesticides and PCBs were the highest in the upper part of the river and decreased along the course of the river, but the other determined compounds did not show this trend. However, the highest values occurred always in the upper part of the river.     

Comparison of the anisotropic-ray-theory rays and anisotropic common S-wave rays with the SH and SV reference rays in a velocity model with a split intersection singularity

We describe the behaviour of the anisotropic–ray–theory S–wave rays in a velocity model with a split intersection singularity. The anisotropic–ray–theory S–wave rays crossing the split intersection singularity are smoothly but very sharply bent. While the initial–value rays can be safely traced by solving Hamilton’s equations of rays, it is often impossible to determine the coefficients of the equations of geodesic deviation (paraxial ray equations, dynamic ray tracing equations) and to solve them numerically. As a result, we often know neither the matrix of geometrical spreading, nor the phase shift due to caustics. We demonstrate the abrupt changes of the geometrical spreading and wavefront curvature of the fast anisotropic–ray–theory S wave. We also demonstrate the formation of caustics and wavefront triplication of the slow anisotropic–ray–theory S wave.Since the actual S waves propagate approximately along the SH and SV reference rays in this velocity model, we compare the anisotropic–ray–theory S–wave rays with the SH and SV reference rays. Since the coupling ray theory is usually calculated along the anisotropic common S–wave rays, we also compare the anisotropic common S–wave rays with the SH and SV reference rays.     

Extreme precipitation and long-term precipitation changes in a Central European sedge-grass marsh in the context of flood occurrence

This study offers a detailed analysis of the extreme precipitation and long-term precipitation changes in a sedge-grass marsh in the “Wet Meadows” area in the Czech Republic (Central Europe) in the context of flood occurrence. Namely, trends in annual maxima of daily precipitation and trends in the occurrence and amount of rainfall are investigated. The analysis is based on daily measurements of precipitation from 1977 to 2015. We found out that extreme precipitation has become significantly more frequent in recent years, and there are also other significant changes in the rainfall distribution. Possible negative effects on the wetland can be linked to a change of carbon exchange between the ecosystem and the atmosphere and a change of biodiversity. Awareness of these changes is necessary for possible positive human intervention when a desirable wetland functioning is threatened.