Improved Analyses and Forecasts With AIRS Temperature Retrievals Using the Local Ensemble Transform Kalman Filter

In this paper we investigate the impact of the Atmospheric Infra-Red Sounder (AIRS) temperature retrievals on data assimilation and the resulting forecasts using the four-dimensional Local Ensemble Transform Kalman Filter (LETKF) data assimilation scheme and a reduced resolution version of the NCEP Global Forecast System (GFS). Our results indicate that the AIRS temperature retrievals have a significant and consistent positive impact in the Southern Hemispheric extratropics on both analyses and forecasts, which is found not only in the temperature field but also in other variables. In tropics and the Northern Hemispheric extratropics these impacts are smaller, but are still generally positive or neutral.     

Low-Mass Young Stars in Cep OB2: Ages, Distribution and Accretion Disks

We are studying the young clusters Tr37 and NGC7160 in the Cep OB2 region as part of a program to understand the evolution of accretion disks at the ages of disk dissipation and planet formation. Here, we present the first identifications of low mass (spectral types K-M) members of the clusters and study the presence and characteristics of their accretion disks, finding evidences of disk evolution. Using optical photometry and spectroscopy, we have identified ～70 members in Tr37 and ～20 in NGC7160, confirming age estimates of 3 and 10 Myr respectively. Accretion rates are ～10^?8 M _⊙yr^?1 in Tr37. We have not found any accreting members in NGC7160, suggesting that disk accretion generally ends before the age of 10 Myr, which is consistent with the results from other populations.     

Bred vectors of the Lorenz63 system

The breeding method has been widely used in studies of data assimilation, predictability and instabilities. The bred vectors(BVs), which are the nonlinear difference between the control and perturbed runs, represent the time-evolving rapidly growing errors in dynamic systems. The Lorenz(1963) model(hereafter Lorenz63 model) has chaotic dynamics similar to weather and climate. This study investigates the features of BVs of the Lorenz63 model and its impact on regime prediction of the Lorenz63 model. The results show that the Lorenz63 model has two different BVs for each breeding cycle, and the two BVs approach being identical when growth rate is high. The duration of the current and next regime is associated with the relative directions between the BV with high growth rate and the model trajectory.     

Fish farming enhances biomass and nutrient loss in Posidonia oceanica (L.) Delile

Fish farming impact on the seasonal biomass, carbon and nutrient (nitrogen and phosphorus) balance of the endemic Mediterranean seagrass Posidonia oceanica was assessed in the Aegean Sea (Greece) in order to detect changes in magnitude and fate of seagrass production and nutrient incorporation with organic loading of the meadows. Phosphorus concentration in the leaves, rhizomes and roots was enhanced under the cages throughout the study. Standing biomass was diminished by 64% and carbon, nitrogen and phosphorus standing stock by 64%, 61% and 48%, respectively, under the cages in relation to those at the control. Seagrass production decreased by 68% and element (C, N, P) incorporation by 67%, 58% and 58%, respectively, under the cages. Leaf shedding was reduced by 81% and loss of elements (C, N, and P) through shedding by 82%, 74% and 72%, respectively, under the cages. Leaf and element (C, N, P) residual loss rate, accounting for grazing and mechanical breakage of leaves, was decreased by 79%, 85%, 100% and 96%, respectively, at the control station. At the control station, 13.98 g C m^?2 yr^?1, 1.91 g N m^?2 yr^?1 and 0.05 g P m^?2 yr^?1 were produced in excess of export and loss. In contrast, under the cages 12.69 g C m^?2 yr^?1, 0.31 g N m^?2 yr^?1 and 0.04 g P m^?2 yr^?1 were released from the meadow. Organic loading due to fish farm discharges transformed the seagrass meadow under the cages from a typical sink to a source of organic carbon and nutrients.     

Nonporphyritic chondrules from equilibrated Rumuruti and ordinary chondrites: Chemical evidence of secondary processing

Abstract– Nineteen nonporphyritic pyroxene and pyroxene/olivine chondrules, chondrule fragments, and irregular objects were studied from two equilibrated chondrites, the ordinary (L/LL5) Knyahinya chondrite and the Rumuruti type (R4) Ouzina chondrite. Major element contents for almost all objects in the chondrites are disturbed from their chondritic ratios, most probably during metamorphic re‐equilibration. However, the volatile elements (Na₂O + K₂O) in Ouzina scatter around the CI line, probably the result of being generated and/or processed in different environments as compared with those for Knyahinya. All studied objects from Knyahinya and Ouzina possess systematically fractionated trace element abundances. Depletion of LREE with respect to HREE and ultra‐refractory HFSE documents variable degrees of LREE transport into an external mineral sink and restricted mobility of most of the HREE and HFSE. Moderately volatile elements preserve volatility‐controlled abundances. Strongly fractionated Rb/Cs ratios (up to 10× CI) in all studied objects suggest restricted mobility of the large Cs ion. All studied objects sampled and preserved Y and Ho in solar proportions, a feature that they share with the nonporphyritic chondrules of unequilibrated ordinary chondrites.     

A major change in magma sources in late Mesozoic active margin of the circum-Sea of Japan domain: Geochemical constraints from late Paleozoic to Paleogene mafic dykes in the Sergeevka belt,southern Primorye,Russia

More than 30 mafic dykes crop out in the Sergeevka belt in the coastal South Primorye, Far East Russia, of which geologic settings have been unclear for years. This study conducted major- and trace elements characterization, Sr–Nd isotope analyses, and Ar–Ar amphibole and U–Pb zircon datings for these rocks in order to identify their origin. The results demonstrated that all dykes are characterized by high Ba/Yb and low Nb/Y, Zr/Y, and Th/Yb ratios, which suggest their origin from arc melts derived from thin wedge mantle and shallow-dipping slab. These dykes are clearly separated into two distinct age/geochemistry suites; that is, the Paleogene and Early Cretaceous one with dolerites/basalts and adakitic rocks, and the Permian–Triassic one with high-Mg and high-Al gabbro-dolerite varieties. Their geochemistry suggests that the older suite was sourced from a primitive depleted MORB mantle (DMM)-type mantle, whereas the younger suite from an enriched mantle II (EM2)-type mantle domain. The transition in source type from DMM to EM2 occurred during the Jurassic-earliest Cretaceous time, probably by a strong influence of a mantle plume onto the long-continuing subduction-related magmatism. The plume influence reached the maximum when the unique meimechite-picrite complex formed in the region.     

Glasses in the D'Orbigny angrite

The angrites are a small and heterogeneous group of achondritic meteorites with highly unusual chemical and mineralogical features. The abundant presence of glasses in D'Orbigny makes this rock a unique member of the angrite group. Glasses fill open spaces, form pockets, and occur as inclusions in olivines. Their physical settings exclude an incorporation from an external source. Major and trace element (rare earth elements [REE], Li, B, Be, transition elements, N and C) contents of these glasses and host olivines were measured combining laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), secondary-ion mass spectrometry (SIMS), Nuclear Reaction Analysis (NRA), and EMP techniques. Based on the major element composition, glasses filling voids could represent either a melt formed by melting an angritic rock or a melt from which angrites could have crystallized. Trace element contents of these glasses strongly indicate a direct link to the D'Orbigny bulk meteorite. They are incompatible with the formation of the glasses by partial melting of a chondritic source rock or by shock melting. The refractory elements (e.g., Al, Ti, Ca) have about 10 × CI abundances with CaO/TiO₂ and FeO/MnO ratios being approximately chondritic. Trace element abundances in the glasses appear to be governed by volatility and suggest that the refractory elements in the source had chondritic relative abundances. Although the glasses (and the whole rock) lack volatile elements such as Na and K, they are rich in some moderately volatile elements such as B, V, Mn, Fe (all with close to CI abundances), and Li (about 3-5 × CI). These elements likely were added to the glass in a sub-solidus metasomatic elemental exchange event. We have identified a novel mechanism for alteration of glass and rock compositions based on an exchange of Al and Sc for Fe and other moderately volatile elements in addition to the well-known metasomatic exchange reactions (e.g., Ca-Na and Mg-Fe).Because glass inclusions in olivine were partly shielded from the metasomatic events by the host crystal, their chemical composition is believed to be closer to the original composition than that of any other glasses. The relative trace element abundances in glasses of glass inclusions in olivine and glass pockets are also unfractionated and at the 10 to 20 × CI level. These glasses are chemically similar to the common void-filling glasses but show a much wider compositional variation. Inclusion glasses demonstrate that at least olivine grew with the help of a liquid. In analogy to olivines in carbonaceous chondrites, initial formation could also have been a vapor-liquid-solid condensation process. At that time, the glass had a purely refractory composition. This composition, however, was severely altered by the metasomatic addition of large amounts of FeO and other moderately volatile elements. The presence of volatile elements such as carbon and nitrogen in glasses of glass inclusions is another feature that appears to give these glasses a link with those hosted by olivines of carbonaceous chondrites. All these features point to an origin from a vapor with relative abundances of condensable elements similar to those in the solar nebula.     

Adding Human Health Risk Analysis Tools to Geographic Information Systems

The development of a module for performing human health risk analysis is presented. This risk module differs from other tools in that it is integrated into a geographic information system (GIS) in a plug–in fashion. The main challenge in the development of the risk module was handling the many different spatial data structures in an open GIS environment. Selection of programming language and other development issues are discussed. The application of the risk module to two mining activities in Bolivia is described.     

Heating experiments on glass inclusions in Allende (CV3) olivines: Clues to the formation conditions of chondrules?

Several pieces of the Allende CV3 chondrite were heated up to different final temperatures (1100, 1250, 1450 °C) with the aim to study glassy and glass-bearing inclusions in olivines as well as the glass mesostasis of chondrules and aggregates. The experiments were performed in a Pt-Pt90Rh10 heating stage at 1 bar pressure. The oxygen fugacity is estimated to have been between 10⁻⁹ and 10⁻¹⁰ atm at 1200 °C. The variation of the chemical composition of the heated glasses gives information concerning the behavior of the incompatible elements (with respect to the host) Al, Ca and Na. The chemical variation in the heated mesostasis glass shows that Ca exchange between the gas and condensed phases at sub-solidus temperatures can occur in a short time. Laboratory heating experiments show that glass inclusions will behave as closed systems and therefore preserved the alkalis they acquired. On the other hand, the mesostasis glass can loose them when heated to temperatures higher than 1100 °C. Evidently, the presence of Na-rich glasses, in chondrules and aggregates available to us, indicate that if there was a thermal process that did affect them, it must have been a low temperature one.