Optimal selection of representative climate models and statistical downscaling for climate change impact studies: a case study of Rhode Island,USA

Theoretical and Applied Climatology - The future climate impact studies rely on future projections obtained from downscaling of Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models....     

Assessment of Metals Concentration and Ecotoxicology of the Sediment Core of Rehri Creek, Karachi Coast, Pakistan

Trace metal concentrations were investigated in a recent sediment core collected from the Rehri Creek area of the Karachi coast,Sindh-Pakistan.The core was sliced horizontally at 2.5-cm intervals to determine grain size,sediment composition,pH,organic matter,and acid-leachable trace metals:cadmium,chromium,copper,lead,and zinc.The trace metals were analyzed by ICP.To separate anthropogenic from geogenic input,several approaches were made,including comparison with sediment quality guidelines—ecotoxicological sense of heavy metal contamination and classification by quantitative indexes.Grain-size analysis and sediment composition of core sample show a sandy nature with neutral pH.Elemental sequence(ES)of the trace metals is in the order of Zn(19.2-109.56 ppm)>Si(66.46-101.71 ppm)>Ba(12.05-26.86 ppm)>As(8.18-17.36 ppm)>Ni(4.2-14.69 ppm)>Cr(3.02-9.62 ppm)>Pb(2.79-6.83 ppm)>Cu(2.2-5.29 ppm)>Co(0.9-2.05 ppm).Thus it is likely that the area may face a serious threat of metal pollution with the present deposition rates unless stringent pollution control norms are adopted.The Sediment Geo-accumulation Index shows that there is no Cr,Cu,Ni,Pb,Zn,or Fe pollution;however,the former index and the Pollution Load Index indicate arsenic pollution in the sediments.     

Lessons for New Zealand from Britain's Foot and Mouth Epidemic

This paper explores some implications for New Zealand's rural community of Britain's foot and mouth epidemic in the light of growing international trade and travel, and changes in New Zealand's rural society. The paper includes ecological mapping with a projected/likely spatial distribution of an epidemic in New Zealand, and an assessment of the possible institutional and social responses in the wake of a disease outbreak. It notes the course of the epidemic in Britain, and possible differences and similarities in institutional response frameworks between Britain and New Zealand.     

Errors in response calculations for non-classically damped structures

The classical normal mode method of determining response is extremely useful for practical calculations, but depends upon the damping matrix being orthogonal with respect to the modal vectors. Approximations that allow the method to be used when this condition is not satisfied have been suggested; the simplest approach is to neglect off-diagonal terms in the triple matrix product formed from the damping and modal matrices. In this paper the errors in response caused by this approximation are determined for several simple structures for a wide range of damping parameters and different types of excitation. Based on these results a criterion, relating modal damping and natural frequencies, is formulated; if this is satisfied, the errors in response caused by this diagonalization procedure are within acceptable limits.     

On the marine atmospheric boundary layer characteristics over Bay of Bengal and Arabian Sea during the Integrated Campaign for Aerosols,gases and Radiation Budget (ICARB)

Detailed measurements were carried out in the Marine Atmospheric Boundary Layer (MABL) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) which covered both Arabian Sea and Bay of Bengal during March to May 2006. In this paper, we present the meteorological observations made during this campaign. The latitudinal variation of the surface layer turbulent fluxes is also described in detail.     

Comment on ‘Shang S. 2012. Calculating actual crop evapotranspiration under soil water stress conditions with appropriate numerical methods and time step. Hydrological Processes 26: 3338–3343. DOI: 10.1002/hyp.8405’

A previous study analyzed errors in the numerical calculation of actual crop evapotranspiration (ET_a) under soil water stress. Assuming no irrigation or precipitation, it constructed equations for ET_a over limited soil‐water ranges in a root zone drying out due to evapotranspiration. It then used a single crop‐soil composite to provide recommendations about the appropriate usage of numerical methods under different values of the time step and the maximum crop evapotranspiration (ET_c). This comment reformulates those ET_a equations for applicability over the full range of soil water values, revealing a dependence of the relative error in numerical ET_a on the initial soil water that was not seen in the previous study. It is shown that the recommendations based on a single crop‐soil composite can be invalid for other crop‐soil composites. Finally, a consideration of the numerical error in the time‐cumulative value of ET_a is discussed besides the existing consideration of that error over individual time steps as done in the previous study. This cumulative ET_a is more relevant to the final crop yield. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

Stellar nucleosynthetic contribution of extinct short‐lived nuclei in the early solar system and the associated isotopic effects

Abstract— A wide range of stellar nucleosynthetic sources has been analyzed to derive their contributions of short‐lived and stable nuclei to the presolar cloud. This detailed study is required to infer the most plausible source(s) of short‐lived nuclei through a critical comparison among the various stellar sources that include AGB stars, novae, supernovae II, Ia, and Wolf‐Rayet stars that evolved to supernovae Ib/c. In order to produce the canonical value of ²⁶Al/²⁷Al in the early solar system, almost all stellar sources except low‐mass AGB stars imply large isotopic anomalies in Ca‐Al‐rich inclusions (CAIs). This is contrary to the observed isotopic compositions of CAIs. The discrepancy could impose stringent constraints on the formation and thermal evolution of CAIs from different chondrites. Among the various stellar scenarios, the injection of short‐lived nuclei into the previously formed solar protoplanetary disc by a massive star of an ad hoc chosen high‐injection mass cut is a possible scenario. There is a possibility of the contribution of short‐lived nuclides by a 1.5–3 M_⊙ AGB star as it implies the smallest shift in stable isotopes. A low‐mass AGB star of relatively low metallicity would be even a better source of short‐lived nuclei. However, this scenario would require independent gravitational collapse of the presolar cloud coupled with ambipolar diffusion of magnetic flux. Alternatively, numerous scenarios can be postulated that involve distant (≥10 pc) massive stars can contribute ⁶⁰Fe to the presolar cloud and can trigger its gravitational collapse. These scenarios would require production of ²⁶Al and ⁴¹Ca by irradiation in the early solar system. Significant production of ²⁶Al and ⁶⁰Fe can be explained if massive, rotating Wolf‐Rayet stars that evolved to supernovae Ib/c were involved.     

Numerical simulations of the differentiation of accreting planetesimals with 26Al and 60Fe as the heat sources

Abstract— Numerical simulations have been performed for the differentiation of planetesimals undergoing linear accretion growth with ²⁶Al and ⁶⁰Fe as the heat sources. Planetesimal accretion was started at chosen times up to 3 Ma after Ca‐Al‐rich inclusions (CAIs) were formed, and was continued for periods of 0.001–1 Ma. The planetesimals were initially porous, unconsolidated bodies at 250 K, but became sintered at around 700 K, ending up as compact bodies whose final radii were 20, 50, 100, or 270 km. With further heating, the planetesimals underwent melting and igneous differentiation. Two approaches to core segregation were tried. In the first, labelled A, the core grew gradually before silicate began to melt, and in the second, labelled B, the core segregated once the silicate had become 40% molten. In A, when the silicate had become 20% molten, the basaltic melt fraction began migrating upward to the surface, carrying ²⁶Al with it. The ⁶⁰Fe partitioned between core and mantle. The results show that the rate and timing of core and crust formation depend mainly on the time after CAIs when planetesimal accretion started. They imply significant melting where accretion was complete before 2 Ma, and a little melting in the deep interiors of planetesimals that accreted as late as 3 Ma. The latest melting would have occurred at <10 Ma. The effect on core and crust formation of the planetesimal's final size, the duration of accretion, and the choice of (⁶⁰Fe/⁵⁶Fe)_initial were also found to be important, particularly where accretion was late. The results are consistent with the isotopic ages of differentiated meteorites, and they suggest that the accretion of chondritic parent bodies began more than 2 or 3 Ma after CAIs.     

Seismic analysis of a rotor-bearing system

The seismic analysis of a rotor-bearing system is presented in the time domain. The governing equations of motion for the rotor are derived including the effects of rotatory inertia, shear deformation, gyroscopic effects, axial force, axial torque, stiffness and damping provided by the lubricants in the bearings, base translation and base rotation. A simple and efficient finite rotor element based on a Galerkin formulation is proposed to model the rotor. The effects of disks and flywheels mounted on the rotor are also included in the analysis. An example problem for a rotor-bearing system is solved using El Centro earthquake data. Four cases are investigated that will permit one to study the influence of spin, base rotation, comparison between rigid body model and beam model and the influence of axial force and axial torque. The results of the above study show that the gyroscopic effects amplify the response of the rotor-bearing system. The base rotations of the rotor-bearing system under seismic excitation contribute significantly to the response.     

Modeling landslide susceptibility over large regions with fuzzy overlay

Landslide susceptibility mapping is most effective if detailed surface and subsurface information can be combined with authoritative landslide catalogs or a deep understanding of local conditions. However, these types of homogeneous input data and catalogs are frequently not available over large areas. In this study, we model landslide susceptibility in Central America and the Caribbean islands by combining three globally available datasets and one regional dataset with fuzzy overlay. This primarily heuristic model provides the flexibility to test a range of different contributing variables and the capability to compare landslide inventories within the model framework that vary greatly in their size, spatiotemporal scope, and collection methods. We create a regional susceptibility map and evaluate its performance using receiver operating characteristics for both continuous and binned susceptibility values. This susceptibility map forms the basis for a near-real-time landslide hazard assessment system that couples susceptibility with rainfall and soil moisture triggers to estimate potential landslide activity at a regional scale. The application of this susceptibility model at the regional scale provides a foundation for transferring the methodology to other geographic areas.