A comparison of satellite-retrieved and simulated cloud coverage in the Baltic Sea area as part of the BALTIMOS project

A cloud-detection algorithm for METEOSAT first generation data has been developed. The algorithm utilizes solely infrared data from the METEOSAT thermal infrared window channel at around 11.5 μm. The developed algorithm estimates an assumed clear-sky brightness temperature from time series analysis on pixel bases. Land-/sea-depending dynamic thresholds are then utilized discriminating the infrared images in cloudy, undecided, and cloud free pixels. The cloud-detection algorithm has been validated against synoptic observations. The developed cloud-detection scheme has been applied to 10 years (1992–2001) of METEOSAT data, extracting cloud coverage statistics for the Baltic Sea catchment area. These have been compared to corresponding cloud coverage statistics derived from the BALTIMOS coupled model system. Building overall averaged values of the cloud coverage in the period from 1999 to 2001 gives results with very good agreement between simulation and observation: the total METEOSAT-derived cloud coverage amounts to 0.65 compared to 0.63 for BALTIMOS. In contrast, large discrepancies in the phase of the diurnal cycle of cloud coverage have been observed. A significant trend in total cloud amount was observed neither from the model nor from the satellite.     

Role of crustal fluids in triggering the West Bohemia/Vogtland earthquake swarms: Just what we know (a review)

We summarise the results of seismological studies related to triggering mechanisms, driving forces and source processes of the West Bohemia/Vogtland earthquake swarms with the aim to disclose the role of crustal fluids in the preparation, triggering and governing of the swarms. We present basic characteristics distinguishing earthquake swarms from tectonic mainshock-aftershock sequences and introduce existing earthquakes swarm models. From the statistical characteristics and time-space distribution of the foci we infer that self-organization is a peculiarity of West Bohemia/Vogtland swarms. We discuss possible causes of the foci migration in these swarms from the viewpoint of co-seismic and/or post-seismic stress changes and diffusion of the pressurized fluids, and we summarize hitherto published models of triggering the 2000-swarm. Attention is paid to the source mechanisms, particularly to their non-shear components. We consider possible causes of different source mechanisms of the 1997-and 2000-swarms and infer that pure shear processes controlled solely by the regional tectonic stress prevail in them, and that additional tensile forces may appear only at unfavourably oriented faults. On data from the fluid injection experiment at the HDR site Soultz (Alsace), we also show that earthquakes triggered by fluids can represent purely shear processes. Thus we conclude that increased pore pressure of crustal fluids in the region plays a key role in bringing the faults from the subcritical to critical state. The swarm activities are mainly driven by stress changes due to co-seismic and post-seismic slips, which considerably depend on the frictional conditions at the fault; crustal fluids keep the fault in a critical state. An open question still remains the cause of the repeatedly observed almost simultaneous occurrence of seismic activity in different focal zones in a wider area of West Bohemia/Vogtland. The analysis of the space-time relations of seismicity in the area between 1991 and 2007 revealed that during a significant part of this time span the seismicity was switching among distant focal zones. This indicates a common triggering force which might be the effect of an increase of crustal-fluid pore-pressure affecting a wider epicentral region.     

Occurrence and geochemistry of radium in water from principal drinking-water aquifer systems of the United States

A total of 1270 raw-water samples (before treatment) were collected from 15 principal and other major aquifer systems (PAs) used for drinking water in 45 states in all major physiographic provinces of the USA and analyzed for concentrations of the Ra isotopes ²²⁴Ra, ²²⁶Ra and ²²⁸Ra establishing the framework for evaluating Ra occurrence. The US Environmental Protection Agency Maximum Contaminant Level (MCL) of 0.185 Bq/L (5 pCi/L) for combined Ra (²²⁶Ra plus ²²⁸Ra) for drinking water was exceeded in 4.02% (39 of 971) of samples for which both ²²⁶Ra and ²²⁸Ra were determined, or in 3.15% (40 of 1266) of the samples in which at least one isotope concentration (²²⁶Ra or ²²⁸Ra) was determined. The maximum concentration of combined Ra was 0.755 Bq/L (20.4 pCi/L) in water from the North Atlantic Coastal Plain quartzose sand aquifer system. All the exceedences of the MCL for combined Ra occurred in water samples from the following 7 PAs (in order of decreasing relative frequency of occurrence): the Midcontinent and Ozark Plateau Cambro-Ordovician dolomites and sandstones, the North Atlantic Coastal Plain, the Floridan, the crystalline rocks (granitic, metamorphic) of New England, the Mesozoic basins of the Appalachian Piedmont, the Gulf Coastal Plain, and the glacial sands and gravels (highest concentrations in New England).     

River channel evolution and tsunami impacts recorded in local sedimentary archives – the ‘Fiume Morto’ at Ostia Antica (Tiber River,Italy)

Ostia, the ancient port of Rome at the mouth of the river Tiber (Italy), flourished until the 2nd Century ad , although massive siltation had already caused the abandonment of its lagoonal harbour in the 1st Century bc . In search of an alternative harbour site, geomorphological and geoarchaeological research was carried out in the ‘Fiume Morto’, an abandoned Tiber meander to the immediate north of the town. To reconstruct its complex development and evaluate the suitability of the river channel as a fluvial harbour, a transect perpendicular to the former river channel's flow axis was systematically explored by a new methodological approach combining electrical resistivity tomography, direct push-electrical conductivity sensing and vibracores. Together with microfossil, mineralogical and geochemical analyses of sediment samples and 50 radiocarbon dates, in-depth stratigraphic data support a detailed reconstruction of different Tiber channel generations. Results reveal a meander development closely related to distinct ‘cut and fill’ dynamics. Inactive river channels were repeatedly filled with lagoonal sediments, abruptly followed by phases of intense incision. Yet, the overall Fiume Morto channel structure remained stable and almost in situ over centuries, showing nearly no lateral changes since the southward shift of the Tiber River mouth in the first millennium bc . In the 1st Century bc , channel conditions favoured navigation and transportation of goods with large ships. Open-water conditions, suitable for anchoring and landing activities, dominate from the 1st Century ad until 1557 ad , when the Fiume Morto meander was finally cut off and silted up within a short time. Within the fluvial deposits, sediments most likely related to tsunami inundations are preserved. These events occurred sometime before the 2nd Century bc , in the early 1st Century ad and in the 17th Century ad or later. Results are consistent with traces of tsunami influence found in Ostia's western lagoonal harbour.     

High-pressure synthesis,long-term stability of single crystals of diboron trioxide,B<Subscript>2</Subscript>O<Subscript>3</Subscript>, and an empirical electronic polarizability of <Superscript>[3]</Superscript>B<Superscript>3+</Superscript>

Single crystals of B₂O₃ are needed for the precise determination of the refractive indices used to calculate the electronic polarizability α of 3-coordinated boron. The α(B) values in turn are used to predict mean refractive indices of borate minerals. Since the contribution of boron to the total polarizability of a mineral is very low, the synthetic compound B₂O₃ represents an ideal model system because of its high molar content of boron. Millimeter-sized crystals were synthesized at 1 GPa in a piston-cylinder apparatus. The samples were heated above the liquidus (800 °C), subsequently cooled at 15 °C/h to 500 °C and finally quenched. The refractive indices were determined by the immersion method using a microrefractometer spindle stage. The refractive indices n _o = 1.653 (3) and n _e = 1.632 (3) correspond to a total polarizability for B₂O₃ of α = 4.877 Å³. These values were used to determine the electronic polarizability of boron of α(B) = 0.16 Å³. Although the surface of the B₂O₃ crystals was coated with a hydrous film immediately after being exposed to air, its bulk crystallinity is retained for a period of at least 2 months.     

Active regions and the large scale flow in the solar photosphere

Summary Statistics on sunspot leaders and followers in active regions are derived from the 50 years of Greenwich records 1905–1954. The results are combined with the probable structure of large scale solar eddies as synthesized from various relevant pieces of information. It is found that active regions tend to be located in anticyclonic ridges of the large disturbances. The statistical leader and follower populations are further subdivided, each into new and old spot classifications. The new leaders, especially, show motions different from those of other spots, suggesting the presence of a life cycle for the large disturbances. It is found that the divergence and vorticity are positive and anticyclonic, respectively, for the new active regions, the former quantity being numerically larger than the latter in this case. Various possible implications of the material are discussed.     

Sedimentology of a Late Quaternary lacustrine record from the south-eastern Carpathian Basin

The Upper Pleistocene geoarchives in the south-eastern Carpathian Basin are represented predominantly by loess–palaeosol records. In 2015, a 10 m sediment core composed of clay-rich lacustrine sediments was recovered by vibracoring a dry lake basin located between the Vršac Mountains (Serbia) and the Banat Sands in the south-eastern Carpathian Basin; a location relevant for placing regional archaeological results in a palaeoenvironmental context. Here, we present results from geoelectrical prospection and a lithostratigraphic interpretation of this sequence supported by a detailed granulometric study supplemented by ostracod analysis. An age model based on luminescence dating is discussed against sedimentological proxy data and its implication for palaeoenvironmental change. The cores show a stratigraphy of lighter ochre-coloured and darker greyish sediment, related to the deposition of clay and silt trapped in an aquatic environment. Geophysical measurements show ~20 m thick lacustrine sediments. The grain-size distributions including the variability in fine clay are indicative of a lacustrine environment. Fine particles were brought into the depositional environments by aquatic input and settled from suspension; also, direct dust input is constrained by grain-size results. Riverine input and aeolian dust input interplayed at the locality.     

Lateglacial vegetation development in Denmark – New evidence based on macrofossils and pollen from Slotseng,a small-scale site in southern Jutland

This paper presents the first unambiguous terrestrial palaeoecological record for the late glacial “Bølling warming” in Denmark. Pollen and macrofossil stratigraphies from pre-Bølling to 10,800 cal yr BP are presented from a small kettle hole in Southwest Denmark, during which the lake basin developed from an immature stage after the deglaciation to complete infilling in the early Holocene. Results show that the recently deglaciated landscape bore a discontinuous vegetation of pioneer plants. After the Bølling warming, an open Dryas octopetala-Betula nana community developed with Helianthemum oelandicum. Subarctic species were dominant and local successions were probably delayed by relatively unstable and infertile soils. There is no indication of a climate cooling during the period corresponding to the Older Dryas, but the occurrence of several drought tolerant and steppe species indicates that the period was relatively dry. In the Allerød period the Dryas-B. nana vegetation was initially replaced by an open Salix and grass dominated vegetation and some 400 years later, the first tree birches were documented presumably occupying moist and sheltered soils while drier land remained open. In the Younger Dryas period trees disappeared and the vegetation became open again and dominated by subarctic species. Following climate warming at the Younger Dryas–Holocene transition a shrub community of Empetrum and Juniperus developed. After approximately 200 years it was replaced by birch forest. Overall, the late-glacial vegetation cover had a more open and patchy character than inferred from previous pollen studies as assessment of the vegetation succession based on macrofossil evidence is essential. The inferred general vegetation development corresponds well with results of other studies in the region. Canonical ordinations (RDA) indicate that vegetation changes at the landscape scale during the Lateglacial period were driven by changes in climate, soils and competition for light.     

Tracing tsunami signatures of the ad 551 and ad 1303 tsunamis at the Gulf of Kyparissia (Peloponnese,Greece) using direct push in situ sensing techniques combined with geophysical studies

The western Peloponnese was repeatedly hit by major tsunami impacts during historical times as reported by historical accounts and recorded in earthquake and tsunami catalogues. Geological signatures of past tsunami impacts have also been found in many coastal geological archives. During the past years, abundant geomorphological and sedimentary evidence of repeated Holocene tsunami landfall was found between Cape Katakolo and the city of Kyparissia. Moreover, neotectonic studies revealed strong crust uplift along regional faults with amounts of uplift between 13 m and 30 m since the mid-Holocene. This study focuses on the potential of direct push in situ sensing techniques to detect tsunami sediments along the Gulf of Kyparissia. Direct push measurements were conducted on the landward shores of the Kaiafa Lagoon and the former Mouria Lagoon from which sedimentary and microfaunal evidence for tsunami landfall are already known. Direct push methods helped to decipher in situ high-resolution stratigraphic records of allochthonous sand sheets that are used to document different kinds of sedimentological and geomorphological characteristics of high-energy inundation, such as abrupt increases in grain size, integration of muddy rip-up clasts and fining upward sequences which are representative of different tsunami inundation pulses. These investigations were completed by sediment coring as a base for local calibration of geophysical direct push parameters. Surface-based electrical resistivity tomography and seismic data with highly resolved vertical direct push datasets and sediment core data were all coupled in order to improve the quality of the geophysical models. Details of this methodological approach, new in palaeotsunami research, are presented and discussed, especially with respect to the question of how the obtained results may help to facilitate tracing tsunami signatures in the sedimentary record and deciphering geomorphological characteristics of past tsunami inundation. Using direct push techniques and based on sedimentary data, sedimentary signatures of two young tsunami impacts that hit the Kaiafa Lagoon were detected. Radiocarbon age control allowed the identification of these tsunami layers as candidates for the ad 551 and ad 1303 earthquake and tsunami events. For these events, there is reliable historical data on major damage on infrastructure in western Greece and on the Peloponnese. At the former Mouria Lagoon, corroborating tsunami traces were found; however, in this case it is difficult to decide whether these signatures were caused by the ad 551 or the ad 1303 event.     

It starts at home? Climate policies targeting household consumption and behavioral decisions are key to low-carbon futures

Through their consumption behavior, households are responsible for 72% of global greenhouse gas emissions. Thus, they are key actors in reaching the 1.5 °C goal under the Paris Agreement. However, the possible contribution and position of households in climate policies is neither well understood, nor do households receive sufficiently high priority in current climate policy strategies. This paper investigates how behavioral change can achieve a substantial reduction in greenhouse gas emissions in European high-income countries. It uses theoretical thinking and some core results from the HOPE research project, which investigated household preferences for reducing emissions in four European cities in France, Germany, Norway and Sweden. The paper makes five major points: First, car and plane mobility, meat and dairy consumption, as well as heating are the most dominant components of household footprints. Second, household living situations (demographics, size of home) greatly influence the household potential to reduce their footprint, even more than country or city location. Third, household decisions can be sequential and temporally dynamic, shifting through different phases such as childhood, adulthood, and illness. Fourth, short term voluntary efforts will not be sufficient by themselves to reach the drastic reductions needed to achieve the 1.5 °C goal; instead, households need a regulatory framework supporting their behavioral changes. Fifth, there is a mismatch between the roles and responsibilities conveyed by current climate policies and household perceptions of responsibility. We then conclude with further recommendations for research and policy.