Conditions and timing of high-pressure Variscan metamorphism in the South Carpathians, Romania

High-pressure (HP) metamorphic rocks, including garnet peridotite, eclogite, HP granulite, and HP amphibolite, are important constituents of several tectonostratigraphic units in the pre-Alpine nappe stack of the Getic–Supragetic (GS) basement in the South Carpathians. A Variscan age for HP metamorphism is firmly established by Sm–Nd mineral–whole-rock isochrons for garnet amphibolite, 358±10 Ma, two samples of eclogite, 341±8 and 344±7 Ma, and garnet peridotite, 316±4 Ma.

A prograde history for many HP metamorphic rocks is documented by the presence of lower pressure mineral inclusions and compositional zoning in garnet. Application of commonly accepted thermobarometers to eclogite (grt+cpx±ky±phn±pg±zo) yields a range in “peak” pressures and temperatures of 10.8–22.3 kbar and 545–745 °C, depending on tectonostratigraphic unit and locality. Zoisite equilibria indicate that activity of H₂O in some samples was substantially reduced, ca. 0.1–0.4. HP granulite (grt+cpx+hb+pl) and HP amphibolite (grt+hbl+pl) may have formed by retrogression of eclogites during high-temperature decompression. Two types of garnet peridotite have been recognized, one forming from spinel peridotite at ca. 1150–1300 °C, 25.8–29.0 kbar, and another from plagioclase peridotite at 560 °C, 16.1 kbar.

The Variscan evolution of the pre-Mesozoic basement in the South Carpathians is similar to that in other segments of the European Variscides, including widespread HP metamorphism, in which P–T–t characteristics are specific to individual tectonostratigraphic units, the presence of diverse types of garnet peridotite, diachronous subduction and accretion, nappe assembly in pre-Westphalian time due to collision of Laurussia, Gondwana, and amalgamated terranes, and finally, rapid exhumation, cooling, and deposition of eroded debris in Westphalian to Permian sedimentary basins.     

A mechanism for Atlantic multidecadal variability in the Kiel Climate Model

Atlantic Multidecadal Variability (AMV) is investigated in a millennial control simulation with the Kiel Climate Model (KCM), a coupled atmosphere–ocean–sea ice model. An oscillatory mode with approximately 60 years period and characteristics similar to observations is identified with the aid of three-dimensional temperature and salinity joint empirical orthogonal function analysis. The mode explains 30 % of variability on centennial and shorter timescales in the upper 2,000 m of the North Atlantic. It is associated with changes in the Atlantic Meridional Overturning Circulation (AMOC) of ±1–2 Sv and Atlantic Sea Surface Temperature (SST) of ±0.2 °C. AMV in KCM results from an out-of-phase interaction between horizontal and vertical ocean circulation, coupled through Irminger Sea convection. Wintertime convection in this region is mainly controlled by salinity anomalies transported by the Subpolar Gyre (SPG). Increased (decreased) dense water formation in this region leads to a stronger (weaker) AMOC after 15 years, and this in turn leads to a weaker (stronger) SPG after another 15 years. The key role of salinity variations in the subpolar North Atlantic for AMV is confirmed in a 1,000 year long simulation with salinity restored to model climatology: No low frequency variations in convection are simulated, and the 60 year mode of variability is absent.     

Laser ablation ICP-MS screening of corals for diagenetically affected areas applied to Tahiti corals from the last deglaciation

Fossil corals are unique archives of past seasonal climate variability, providing vital information about seasonal climate phenomena such as ENSO and monsoons. However, submarine diagenetic processes can potentially obscure the original climate signals and lead to false interpretations. Here we demonstrate the potential of laser ablation ICP-MS to rapidly detect secondary aragonite precipitates in fossil Porites colonies recovered by Integrated Ocean Drilling Program (IODP) Expedition 310 from submerged deglacial reefs off Tahiti. High resolution (100 μm) measurements of coralline B/Ca, Mg/Ca, S/Ca, and U/Ca ratios are used to distinguish areas of pristine skeleton from those afflicted with secondary aragonite. Measurements of coralline Sr/Ca, U/Ca and oxygen isotope ratios, from areas identified as pristine, reveal that the seasonal range of sea surface temperature in the tropical south Pacific during the last deglaciation (14.7 and 11 ka) was similar to that of today.     

Upholding labour productivity under climate change: an assessment of adaptation options

Changes in labour productivity feed through directly to national income. An external shock, like climate change, which may substantially reduce the productivity of workers is therefore a macroeconomic concern. The biophysical impact of higher temperatures on human performance is well documented. Less well understood are the wider effects of higher temperatures on the aggregate productivity of modern, diversified economies, where economic output is produced in contexts ranging from outdoor agriculture to work in air-conditioned buildings. Working conditions are at least to some extent the result of societal choices, which means that the labour productivity effects of heat can be alleviated through careful adaptation. A range of technical, regulatory/infrastructural and behavioural options are available to individuals, businesses and governments. The importance of local contexts prevents a general ranking of the available measures, but many appear cost-effective. Promising options include the optimization of working hours and passive cooling mechanisms. Climate-smart urban planning and adjustments to building design are most suitable to respond to high base temperature, while air conditioning can respond flexibly to short temperature peaks if there is sufficient cheap, reliable and clean electricity.

Key policy insights

• The effect of heat stress on labour productivity is a key economic impact of climate change, which could affect national output and workers’ income.

• Effective adaptation options exist, such as shifting working hours and cool roofs, but they require policy intervention and forward planning.

• Strategic interventions, such as climate-smart municipal design, are as important as reactive or project-level adaptations.

• Adaptation solutions to heat stress are highly context specific and need to be assessed accordingly. For example, shifting working hours could be an effective way of reducing the effect of peak temperatures, but only if there is sufficient flexibility in working patterns.

     

Atmospheric correction of AMSR-E brightness temperatures for dry snow cover mapping

Differences between the brightness temperatures (spectral gradient) collected by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) at 18.7 and 36.5 GHz are used to map the snow-covered area (SCA) over a region including the western U.S. The brightness temperatures are corrected to take into account for atmospheric effects by means of a simplified radiative transfer equation whose parameters are stratified using rawinsonde data collected from a few stations. The surface emissivity is estimated from the model, and the brightness temperatures at the surface are computed as the product of the surface temperature and the computed emissivity. The SCA derived from microwave data is compared with that obtained from the Moderate Resolution Imaging Spectroradiometer for both cases of corrected and noncorrected brightness temperatures. The improvement to the SCA retrievals based on the corrected brightness temperatures shows an average value around 7%.     

Antioxidant efficiency and detoxification enzymes in spotted dogfish Scyliorhinus canicula

Although elasmobranchs are widely distributed species, commonly found on sandy, gravely or muddy bottoms, several biological aspects of their metabolism still remain poorly investigated. In this work the efficiency of antioxidant system and detoxification enzymes were investigated in the coastal spotted dogfish Scyliorhinus canicula and in the red mullet Mullus barbatus for comparison with a teleost species.Organisms were sampled during a bottom trawl survey and analyzed for the biotransformation activity (EROD), levels of metallothioneins, catalase, glutathione S-transferases and total oxyradical scavenging capacity (TOSC) toward peroxyl radicals and hydroxyl radicals.EROD activity in the elasmobranchs was more than one order of magnitude lower than in the red mullets, while similar levels of metallothioneins were measured in these species. S. canicula showed significantly lower antioxidant enzymes and a more reduced efficiency in neutralizing ^√OH; on the other hand the scavenging capability toward ROO^√ was comparable in S. canicula and M. barbatus.     

The Tucson revised index of asteroid data

Attention is called to the availability of the TRIAD computer file, a compilation of all reliable physical parameters for minor planets.     

Challenges and lessons from a wetland LiDAR project: a case study of the Okefenokee Swamp,Georgia, USA

Airborne LiDAR (Light Detection and Ranging) provides opportunities to generate high-quality digital elevation models (DEMs) even in wetland environments. Our project, performed over the Okefenokee Swamp in Georgia during the spring of 2010, shows that several, distinctive factors must be considered to ensure successful wetland LiDAR projects. Some of the challenges include selecting optimal flight times in accordance with weather variability and water levels, having effective and quality control protocols, applying and developing filtering and interpolation algorithms, breaklines in swamps and accounting for data striping and noise. While some of these issues are faced in any airborne LiDAR acquisition, many of these require special consideration in a low-slope wetland environment with water saturated soils, widespread shallow water, and sediments and extensive vegetation. An examination of these issues and how they were handled will help in ensuring the success of future LiDAR acquisitions and, in particular, will advance knowledge of producing quality DEMs in wetland environments.     

Solar Scintillometry: Calibration of Signals and its Use for Seeing Measurements

Since 1993 it is known that there is a good correlation between the scintillation in the solar irradiance and solar image quality (Seykora, 1993). This effect is now being used in a number of experiments to evaluate solar image quality and to measure site seeing. In this paper we explore further the calibration of this scintillation (_I) in terms of the Fried parameter (_r0) taking into account variations in the refractive index structure constant C _N ² with height (h), zenith distance () dependence and the effects of wind velocities. A variant in the scintillometer setup is proposed which decreases sharply the dependance on C _N ² , , and the wind velocities. It uses an array of scintillometers. The same array can be used to measure theC _N ² profile with height. Some preliminary results of the calibration of current NSO site survey measurements are presented.