Sea level rise and tigers: predicted impacts to Bangladesh’s Sundarbans mangroves

The Sundarbans mangrove ecosystem, shared by India and Bangladesh, is recognized as a global priority for biodiversity conservation. Sea level rise, due to climate change, threatens the long term persistence of the Sundarbans forests and its biodiversity. Among the forests’ biota is the only tiger (Panthera tigris) population in the world adapted for life in mangrove forests. Prior predictions on the impacts of sea level rise on the Sundarbans have been hampered by coarse elevation data in this low-lying region, where every centimeter counts. Using high resolution elevation data, we estimate that with a 28 cm rise above 2000 sea levels, remaining tiger habitat in Bangladesh’s Sundarbans would decline by 96% and the number of breeding individuals would be reduced to less than 20. Assuming current sea level rise predictions and local conditions do not change, a 28 cm sea level rise is likely to occur in the next 50–90 years. If actions to both limit green house gas emissions and increase resilience of the Sundarbans are not initiated soon, the tigers of the Sundarbans may join the Arctic’s polar bears (Ursus maritimus) as early victims of climate change-induced habitat loss.     

The CQU Regional Seismic Network and applications to underground mining in Central Queensland,Australia

Digital seismograms continuously recorded from 1988 to 1992 by two stations of the RESNOM seismic network in northern Baja California, Mexico, were used to search for probable shear-wave anisotropic characteristics in the region of the Cerro Prieto fault. Shear-wave splitting was identified in many of the three-component records analyzed. We measured the polarization direction of the leadingS wave inside theS-wave window as well as the delay times between fast and slow phases on those records displaying shear-wave splitting. For station CPX, which is nearest the Imperial Valley region to the north, the preferred polarization direction found in this study (azimuth 180°±10°) coincides with the direction of the regional maximum compressive stress determined for the region. This polarization direction can be interpreted in terms of the “Extensive Dilatancy Anisotropy” model as the effect of vertical parallel aligned cracks. The preferred polarization direction measured at LMX, however, gives an azimuth of 45°±5°. Thus, it appears that faults and fractures aligned oblique to the main tectonic trend have a greater influence on the anisotropic characteristics of the crust south of Cerro Prieto volcano than that of the regional stress field. Time delays between slow and fastS waves observed at CPX appear constant from 1988 to 1992 while delays measured at LMX for the same interval indicate a small increase with time which cannot be attributed to azimuthal variations of paths.     

Retrogressive hydration of calc-silicate xenoliths in the eastern Bushveld complex: evidence for late magmatic fluid movement

Two calc-silicate xenoliths in the Upper Zone of the Bushveld complex contain mineral assemblages which permit delineation of the metamorphic path followed after incorporation of the xenoliths into the magma. Peak metamorphism in these xenoliths occurred at T=1100–1200°C and P <1.5 kbar. Retrograde metamorphism, probably coinciding with the late magmatic stage, is characterized by the breakdown of akermanite to monticellite and wollastonite at 700°C and the growth of vesuvianite from melilite. The latter implies that water-rich fluids (X_CO2 <0.2) were present and probably circulating through the cooling magmatic pile. In contrast, calc-silicate xenoliths within the lower zones of the Bushveld complex, namely in the Marginal and Critical Zones, also contain melilite, monticellite and additional periclase with only rare development of vesuvianite. This suggests that the Upper Zone cumulate pile was much ‘wetter’ in the late-magmatic stage than the earlier-formed Critical and Marginal Zone cumulate piles.     

Simulation of cyclones using synthetic data

A number of sensitivity experiments have been conducted to investigate the influence of using synthetic data on cyclone forecasts by a global spectral model. Some well known vortices have been used and the generated wind and pressure profiles are compared. It is found that the Rankine vortex and Holland’s vortex show the best representation of cyclonic circulation. Hence these two vortices are used in the sensitivity studies to simulate two cyclones, one of May 1979 and the other of August 1979. For this purpose the FGGE level-III b data set, produced at ECM WF, UK is used. Synthetic temperature and humidity data are also introduced to make the cyclones more realistic. With the use of Holland’s vortex the system is found to move faster than with the Rankine vortex. Also, the tracks of the cyclones simulated with Rankine vortex are found to be on the left side of the observed track while that of Holland’s vortex is on the right side of the observed track. However, substantial filling up of the systems are noticed with introduction of diabatic initialization of the mass and velocity fields and the forecasts of both the vortices behave differently. It is suggested that proper selection of synthetic vortex, initialization scheme and resolution of the model are very important for better forecast of cyclones.     

The nature of the sea surface as deduced from composite temperature analysis

Summary A technique is described for preparing detailed sea surface temperature analyses for large ocean areas utilizing injection temperature observations from commercial ships. The inadequacies of analyses based on averaged data are discussed, as well as some of the difficulties inherent in contouring scalar fields.Sea surface temperatures are interpreted according to some concepts derived from cross sectional profiles and surface current data. Isotach analyses of mean current drift are considered as flow patterns to aid temperature analysis in areas where data are sparse.

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Die Schwankungen der Oberflächentemperatur des Meeres nach der zusammengesetzten Temperaturanalyse

Zusammenfassung Es wird eine Methode beschrieben, die geeignet ist, mittels Temperaturbeobachtungen von Handelsschiffen aus die Vorarbeiten zu detaillierten Analysen von Oberflächentemperaturen in großräumigen Meeresgebieten durchzuführen. Die Unzulänglichkeit von Analysen gemittelter Werte sowie einige Schwierigkeiten bei der graphischen Darstellung von Skalarfeldern werden besprochen.Gemäß den Vorstellungen, die von Querschnittsprofilen und Oberflächenstromwerten abgeleitet wurden, werden Oberflächentemperaturen gedeutet. Um die Temperaturanalyse in Gebieten mit geringen Beobachtungen zu erleichtern, werden Isotachen-Analysen mittlerer Strömungswerte als Strömungsvorbilder benutzt.

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La nature de la température superficielle de la mer suivant l'analyse composée de la température

Résumé L'article actuel décrit une méthode propre à préparer, au moyen des observations de la température faites au bord des navires marchands, des analyses détaillées de la température superficielle dans de grandes étendues océaniques. L'impropriété de l'analyse des valeurs moyennes ainsi que plusieurs difficultés que l'on rencontre en représentant des champs scalaires sont exposées.Suivant les conceptions déduites des coupes transversales et des courants de surface, on interprète les températures superficielles des courants de l'océan. Dans le but de faciliter l'analyse des températures dans de grandes zones océaniques où des observations sont rares, on se serve comme modèle de courant des analyses des isotaches des valeurs moyennes de courants.

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Submitted October 1961 for publication in Deutsche Hydrographische Zeitschrift.     

Dyke magnetization, magnetostratigraphy and upper-crustal structure in the Reydarfjordur area of eastern Iceland

A dyke swarm approximately 12 m.y. old and comprising 103 basaltic dykes was sampled during a palaeomagnetic investigation of the Reydarfjördur area, eastern Iceland. Of 100 dykes yielding statistically significant palaeomagnetic directions 36 are normal, 43 reversed and 21 are intermediate; 5% of the dykes are olivine-phyric. The magnetic stratigraphy of the lava pile in this area is partially known from earlier palaeomagnetic studies, and six additional sections measured by field magnetometer and a palaeomagnetic section of 40 flows (20 reversed, 16 normal, and 4 intermediate) are reported here. These sections can be correlated by means of petrologic horizons (silicic tuffs, olivine basalts and porphyritic units) and exhibit stratigraphic thickening towards the centre of the Reydarfjördur dyke swarm. The portion of the basalt pile cut by the dyke swarm can be related both petrologically and palaeomagnetically to the dykes, and the number of exposed dykes is found to be of the same order, but smaller than, the number of lava flows in that comparable portion of the lava pile. This implies that in general the exposed dyke swarm is related to the exposed lava pile which is unlikely to extend much further downdip than the known extension updip. The lava pile in Iceland evolves as large lenticular units formed at eruptive axes, and distributed en échelon along the length of the axial zone with spacings comparable to the thickness of the lithosphere.     

Rare earth abundances in Deccan trap basalts

Twenty one basaltic flows of known mineralogical and chemical composition from the Deccan of western India have been analyzed for nine rare-earth elements (REE), together with Hf, Ta and Th by instrumental neutron activation methods. The flows, which are tholeiites and transitional alkali basalts, are relatively enriched in the Light REE and have total REE abundances systematically related to their bulk petrochemistry. The results are compared with REE abundances of basalts from other provinces.     

Thermal metamorphism of primitive meteorites—VIII. Noble gases,carbon and sulfur in Allende (C3) meteorite heated at 400–1000°C

Noble gases, C and S are lost from Allende samples heated for 1 week at temperatures of 400–1000°C in a low pressure environment. In the extreme, losses of ³He and ⁴He are ~ 100 × while for C. S and Ne, Ar and Kr isotopes and ¹³²Xe. these are ≤10 ×. Except for He, these losses are less severe than those of Bi or Tl from samples heated in the same runs. Significant He. Ne and Ar isotopic fractionation during heating indicates preferential outgassing of specific reservoirs. Apparent activation energies for all species generally indicate loss controlled by a diffusive process. Next to He, ⁴⁰Ar is the most labile of those species considered here but still less so than Bi or Tl. L-group (but not H- or LL-group) chondrites may have lost mobile elements like Tl while being outgassed after late impact-associated heating. A less likely alternative possibility involving a collateral relation between condensation conditions and depth in a parent object may also explain the L-group trend.     

Surface settlement of a finite elastic layer whose modulus increases linearly with depth

An examination has been made of the behaviour of a finite layer of elastic material of constant Poisson's ratio, whose Young's modulus increases linearly with depth, and which rests on a rough rigid base. Values of surface settlement at the corner of a rectangular area of uniform loading are presented for values of Poisson's ratio of \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{2} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{3} $\end{document} and 0, and for wide ranges of degree of inhomogeneity and loading breadth to depth ratio.