Chironomid‐inferred late‐glacial summer air temperatures from Lough Nadourcan,Co. Donegal,Ireland

Western Ireland, located adjacent to the North Atlantic, and with a strongly oceanic climate, is potentially sensitive to rapid and extreme climate change. We present the first high‐resolution chironomid‐inferred mean July temperature reconstruction for Ireland, spanning the late‐glacial and early Holocene (LGIT, 15–10 ka BP). The reconstruction suggests an initial rapid warming followed by a short cool phase early in the interstadial. During the interstadial there are oscillations in the inferred temperatures which may relate to Greenland Interstadial events GI‐1a–e. The temperature decrease into the stadial occurs in two stages. This two‐stage drop can also be seen in other late‐glacial chironomid‐inferred temperature records from the British Isles. A stepped rise in temperatures into the Holocene, consistent with present‐day temperatures in Donegal, is inferred. The results show strong similarities with previously published LGIT chironomid‐inferred temperature reconstructions, and with the NGRIP oxygen‐isotope curve, which indicates that the oscillations observed in the NGRIP record are of hemispherical significance. The results also highlight the influence of the North Atlantic on the Irish climate throughout the LGIT. Copyright © 2010 John Wiley & Sons, Ltd.     

Continuum model and analysis of wick-drained systems

An equivalent homogeneous continuum theory is developed for modelling discretely drained soil stratum. The model accounts for the local horizontal flow to discrete vertical drains such as wick or sand or stone columns as well as direct vertical drainage of the soil and global horizontal flow due to non-uniform horizontal conditions. Calibration curves for the model are presented for the case of no soil smear due to the drain installation and for the case when smear exists. The model is implemented in both analytical and finite element analyses for those cases where no well resistance is present and when it is of importance. The accuracy and applicability of the model is demonstrated for simple one- and two- layered problems including smear and well resistance.     

Petrography and geochemistry of granitoid and metamorphite pebbles from the early Archaean Moodies Group,Barberton Mountainland/South Africa

Pebbles of potassic granitoids and metamorphites constitute up to 5% of the basal conglomerate of the Moodies Group in a ratio of 2 : 1. The granitoid pebbles frequently show micrographic quartz–feldspar intergrowth, whereas the metamorphites—of a modal composition similar to that of the granitoids—are characterized by large quartz grains which could represent original quartz phenocrysts in felsic volcanic precursors.The granitoids show high K₂O, Sr, K₂O/Na₂O, and K/Rb, small enrichment of light REE, large negative Eu-anomalies, and slightly depleted and fractionated heavy REE. Compared to the granitoids the metamorphites show higher Fe₂O₃, TiO₂, and Cr concentrations, greater enrichment of light REE, and also large negative Eu-anomalies.There is little similarity between the Moodies pebbles and the majority of the rocks of the Ancient Gneiss Complex of Swaziland (AGC). There is only some similarity of the REE distribution patterns between the pebbles and the Mkhondo Metamorphic Suite, possibly an areally restricted phase of the AGC. The geochemical data, and especially the large negative Eu-anomalies suggest that the Moodies pebbles were derived from granites which represent residual magmas from which much plagioclase had been removed. The granites crystallized at depths of < 7 km from magmas with low H₂O-pressures in a rather thick sialic crust. It appears possible that the pre-Moodies granitoids originated through partial melting of low-Al₂O₃ siliceous gneisses of the AGC. A chronologic connection of the formation of the granitoids with the late Onverwacht Group volcanicity is possible.     

Astrodynamical Space Test of Relativity using Optical Devices I (ASTROD I)—a class-M fundamental physics mission proposal for cosmic vision 2015–2025: 2010 Update

ASTROD I is a planned interplanetary space mission with multiple goals. The primary aims are: to test General Relativity with an improvement in sensitivity of over 3 orders of magnitude, improving our understanding of gravity and aiding the development of a new quantum gravity theory; to measure key solar system parameters with increased accuracy, advancing solar physics and our knowledge of the solar system; and to measure the time rate of change of the gravitational constant with an order of magnitude improvement and the anomalous Pioneer acceleration, thereby probing dark matter and dark energy gravitationally. It is envisaged as the first in a series of ASTROD missions. ASTROD I will consist of one spacecraft carrying a telescope, four lasers, two event timers and a clock. Two-way, two-wavelength laser pulse ranging will be used between the spacecraft in a solar orbit and deep space laser stations on Earth, to achieve the ASTROD I goals.For this mission, accurate pulse timing with an ultra-stable clock, and a drag-free spacecraft with reliable inertial sensor are required. T2L2 has demonstrated the required accurate pulse timing; rubidium clock on board Galileo has mostly demonstrated the required clock stability; the accelerometer on board GOCE has paved the way for achieving the reliable inertial sensor; the demonstration of LISA Pathfinder will provide an excellent platform for the implementation of the ASTROD I drag-free spacecraft. These European activities comprise the pillars for building up the mission and make the technologies needed ready. A second mission, ASTROD or ASTROD-GW (depending on the results of ASTROD I), is envisaged as a three-spacecraft mission which, in the case of ASTROD, would test General Relativity to one part per billion, enable detection of solar g-modes, measure the solar Lense-Thirring effect to 10 parts per million, and probe gravitational waves at frequencies below the LISA bandwidth, or in the case of ASTROD-GW, would be dedicated to probe gravitational waves at frequencies below the LISA bandwidth to 100?nHz and to detect solar g-mode oscillations. In the third phase (Super-ASTROD), larger orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below the ASTROD bandwidth. This paper on ASTROD I is based on our 2010 proposal submitted for the ESA call for class-M mission proposals, and is a sequel and an update to our previous paper (Appouchaux et al., Exp Astron 23:491?C527, 2009; designated as Paper I) which was based on our last proposal submitted for the 2007 ESA call. In this paper, we present our orbit selection with one Venus swing-by together with orbit simulation. In Paper I, our orbit choice is with two Venus swing-bys. The present choice takes shorter time (about 250?days) to reach the opposite side of the Sun. We also present a preliminary design of the optical bench, and elaborate on the solar physics goals with the radiation monitor payload. We discuss telescope size, trade-offs of drag-free sensitivities, thermal issues and present an outlook.     

Noble gases and nitrogen in Martian meteorites Dar al Gani 476, Sayh al Uhaymir 005 and Lewis Cliff 88516: EFA and extra neon

Meteorite “finds” from the terrestrial hot deserts have become a major contributor to the inventory of Martian meteorites. In order to understand their nitrogen and noble gas components, we have carried out stepped heating experiments on samples from two Martian meteorites collected from hot deserts. We measured interior and surface bulk samples, glassy and non-glassy portions of Dar al Gani 476 and Sayh al Uhaymir 005. We have also analyzed noble gases released from the Antarctic shergottite Lewis Cliff 88516 by crushing and stepped heating. For the hot desert meteorites significant terrestrial Ar, Kr, Xe contamination is observed, with an elementally fractionated air (EFA) component dominating the low temperature releases. The extremely low Ar/Kr/Xe ratios of EFA may be the result of multiple episodes of trapping/loss during terrestrial alteration involving aqueous fluids. We suggest fractionation processes similar to those in hot deserts to have acted on Mars, with acidic weathering on the latter possibly even more effective in producing elementally fractionated components. Addition from fission xenon is apparent in DaG 476 and SaU 005. The Ar-Kr-Xe patterns for LEW 88516 show trends as typically observed in shergottites - including evidence for a crush-released component similar to that observed in EETA 79001. A trapped Ne component most prominent in the surface sample of DaG 476 may represent air contamination. It is accompanied by little trapped Ar (²⁰Ne/³⁶Ar > 50) and literature data suggest its presence also in some Antarctic finds. Data for LEW 88516 and literature data, on the other hand, suggest the presence of two trapped Ne components of Martian origin characterized by different ²⁰Ne/²²Ne, possibly related to the atmosphere and the interior. Caution is recommended in interpreting nitrogen and noble gas isotopic signatures of Martian meteorites from hot deserts in terms of extraterrestrial sources and processes. Nevertheless our results provide hope that vice-versa, via noble gases and nitrogen in meteorites and other relevant samples from terrestrial deserts, Martian secondary processes can be studied.     

Towards an operational aqueous phase chemistry mechanism for regional chemistry-transport models: CAPRAM-RED and its application to the COSMO-MUSCAT model

Mechanism reductions of the detailed aqueous phase chemistry mechanism CAPRAM 3.0i are performed. Manual methods and automatic techniques are both applied in order to provide a less computationally intensive mechanism which is operational in regional chemistry transport models (CTMs). The finally reduced mechanism contains less than 200 reactions (4 times smaller than the detailed CAPRAM 3.0i) and describes the main characteristics of inorganic and organic aqueous phase processes occurring in tropospheric warm clouds. Most of the chemical reduction potential is realized in the CAPRAM 3.0i organic chemistry. The number of aqueous phase species decreases from 380 in the full mechanism to 130 in the final reduced version. The calculated percentage deviations between the full and reduced mechanism are on average below 5% for the most important organic and inorganic target compounds such as oxidants, inorganic and organic acids, carbonyls and alcohols. Comparisons of the required CPU times between the full and reduced mechanisms show reductions of approximately 40%. 2-D test simulations with the CTM MUSCAT were performed using prescribed meteorological conditions in order to examine the applicability of the reduced mechanism at regional scale. Simulations with the reduced CAPRAM 3.0i mechanism and a much less complex mechanism with only limited inorganic chemistry (INORG) were compared to evaluate the effects of more detailed chemistry. The model results show large differences in the level of oxidants and the inorganic and organic mass processing. Prospectively, the reduced mechanism represents the basis for studying aerosol cloud processing effects at regional scale with future CTMs and will allow more adequate interpretation of field data.     

Seasonal characteristics of tropical marine boundary layer air measured at the Cape Verde Atmospheric Observatory

Observations of the tropical atmosphere are fundamental to the understanding of global changes in air quality, atmospheric oxidation capacity and climate, yet the tropics are under-populated with long-term measurements. The first three years (October 2006–September 2009) of meteorological, trace gas and particulate data from the global WMO/Global Atmospheric Watch (GAW) Cape Verde Atmospheric Observatory Humberto Duarte Fonseca (CVAO; 16° 51′ N, 24° 52′ W) are presented, along with a characterisation of the origin and pathways of air masses arriving at the station using the NAME dispersion model and simulations of dust deposition using the COSMO-MUSCAT dust model. The observations show a strong influence from Saharan dust in winter with a maximum in super-micron aerosol and particulate iron and aluminium. The dust model results match the magnitude and daily variations of dust events, but in the region of the CVAO underestimate the measured aerosol optical thickness (AOT) because of contributions from other aerosol. The NAME model also captured the dust events, giving confidence in its ability to correctly identify air mass origins and pathways in this region. Dissolution experiments on collected dust samples showed a strong correlation between soluble Fe and Al and measured solubilities were lower at high atmospheric dust concentrations. Fine mode aerosol at the CVAO contains a significant fraction of non-sea salt components including dicarboxylic acids, methanesulfonic acid and aliphatic amines, all believed to be of oceanic origin. A marine influence is also apparent in the year-round presence of iodine and bromine monoxide (IO and BrO), with IO suggested to be confined mainly to the surface few hundred metres but BrO well mixed in the boundary layer. Enhanced CO₂ and CH₄ and depleted oxygen concentrations are markers for air-sea exchange over the nearby northwest African coastal upwelling area. Long-range transport results in generally higher levels of O₃ and anthropogenic non-methane hydrocarbons (NMHC) in air originating from North America. Ozone/CO ratios were highest (up to 0.42) in relatively fresh European air masses. In air heavily influenced by Saharan dust the O₃/CO ratio was as low as 0.13, possibly indicating O₃ uptake to dust. Nitrogen oxides (NO_x and NO_y) show generally higher concentrations in winter when air mass origins are predominantly from Africa. High photochemical activity at the site is shown by maximum spring/summer concentrations of OH and HO₂ of 9?×?10⁶ molecule cm^?3 and 6?×?10⁸ molecule cm^?3, respectively. After the primary photolysis source, the most important controls on the HO_x budget in this region are IO and BrO chemistry, the abundance of HCHO, and uptake of HO_x to aerosol.     

An atmosphere–ocean regional climate model for the Mediterranean area: assessment of a present climate simulation

We present an atmosphere–ocean regional climate model for the Mediterranean basin, called the PROTHEUS system, composed by the regional climate model RegCM3 as the atmospheric component and by a regional configuration of the MITgcm model as the oceanic component. The model is applied to an area encompassing the Mediterranean Sea and compared to a stand-alone version of its atmospheric component. An assessment of the model performances is done by using available observational datasets. Despite a persistent bias, the PROTHEUS system is able to capture the inter-annual variability of seasonal sea surface temperature (SST) and also the fine scale spatio-temporal evolution of observed SST anomalies, with spatial correlation as high as 0.7 during summer. The close inspection of a 10-day strong wind event during the summer of 2000 proves the capability of the PROTHEUS system to correctly describe the daily evolution of SST under strong air–sea interaction conditions. As a consequence of the model’s skill in reproducing observed SST and wind fields, we expect a reliable estimation of air–sea fluxes. The model skill in reproducing climatological land surface fields is in line with that of state of the art regional climate models.