SYNOPTIC CONTROL OF REGIONAL TEMPERATURE TRENDS IN THE COTERMINOUS UNITED STATES BETWEEN 1949 AND 1981

Regional patterns of January and mean annual temperature change between 1949 and 1981 are compared with regional changes in January precipitation totals and related to upper-level atmospheric circulation. During cold periods, cooling is concentrated in the eastern United States and is associated with a southward shift in the zone of maximum precipitation in the eastern United States (reflecting the mean position of the polar front jet), and with a strengthening of meridional flow aloft. During this same period, enhanced meridionality yields an increase in temperatures in the Pacific Northwest, associated with amplification of the mean long wave ridge over the Rocky Mountains. Warm periods in the eastern United States, conversely, correlate with a stronger zonal flow aloft (resulting in cooler, wetter conditions in the Pacific Northwest). Accordingly, temporal variation in regional temperature trends may be more readily interpreted as responses to synoptic controls which yield departures of opposite sign in locales influenced by ridges vs. troughs, rather than as a reflection of uniform, progressive hemispheric or global temperature change.     

Spike in phytoplankton biomass in Greenland Sea during 2009 and the correlations among chlorophyll-a,aerosol optical depth and ice cover

The distributions and correlations of chlorophyll-a(Chl-a),aerosol optical depth(AOD)and ice cover in the southeast Arctic Ocean-Greenland Sea(10°W–10°E,70°–80°N)between 2003 and 2009 were studied using satellite data and statistical analyses.Regression analysis showed correlations between Chl-a and AOD,Chl-a and ice cover,and AOD and ice cover with different time lags.The time lag of Chl-a and AOD indicated their long-term equilibrium relationship.Peaks in AOD and Chl-a and generally occurred in May and July,respectively.Despite the time lag,the correlation between Chl-a and AOD in the study region was as high as 0.7.The peak gap between Chl-a and AOD shifted for about 6 weeks during 2003–2009.In the summer and autumn of 2009,Chl-a and AOD levels were much higher than during the other years,especially in the northern band of the study region(75°–80°N).The driving forces for this localized increase in phytoplankton biomass could be mainly attributed to the very high rate of ice melting in spring and early summer and the high wind speed in autumn,together with the increased deposition of aerosol throughout the year.The unusually high AOD in the spring of 2003 was mainly due to a massive fi re in Russia,which occurred in the fi rst half of the year.Over the 7 years of the study,the sea surface temperature generally decreased.This may have been due to the release of dimethylsulfi de into the air,excreted in large amounts from abundant phytoplankton biomass,and its subsequent reaction,form large amounts of aerosol,and resulting in regional cooling.     

Hailstone trajectories determined from crystallography,deuterium content and radar backscattering

Time-resolved hailstone samples have been collected in the region of maximum radar echo (=10 cm) from four severe hailstorms in Central Switzerland. Thin sections of 1220 hailstones have been prepared and their embryos were classified according to their bubble structure and crystallography. From this embryo trajectories were deduced. Thick sections of seven hailstones were then prepared in order to measure the deuterium content of the different growth layers. This allows an independent check of the embryo and hailstone trajectories as well as an approximate calculation of the updraft velocities. The deuterium content of the vapor feeding the cloud (R ₀) has been determined from structural features of the stones as well as from the heightH _–10: in this latter, new method the lowest deuterium values are attributed to those isotherms at which the top of the region of high radar reflectivity (Z _m–10 dBZ) is observed. It is shown that both embryo and hailstone trajectories determined by the two methods are generally in good agreement and that deuterium measurements in conjunction with structural analyses and radar data result in realistic updraft velocities which are in substantial agreement with results from a numerical cloud model. In the temperature interval –10<T _c<–25C upward motion of the hailstones generally corresponds to accretion of clear layers and downward motion to accretion of opaque layers at the same temperature. This is thought to be due to higher liquid water contents in the stronger updrafts resulting in growth near the wet limit.Dedicated to Prof. H. U. Dütsch on the occasion of his 60th anniversary.     

A Depletion Protocol for Non-Renewable Natural Resources: Australia as an Example

This paper examines the implications of statements by Australia’s Minister of… Resources that Australia’s exports of coal are growing rapidly and that Australia’s coal will last “110 years at current rates of production.” If one assumes that coal production P(t), follows a Gaussian curve (similar to a Hubbert curve) one can construct a family of Gaussian curves showing possible future paths of P(t) which are consistent with the cited “110 years.” Each curve reaches a maximum after which P(t) declines toward zero. Knowledge of the present value of dP/dt allows one member of the family to be identified as the most probable future path of P(t). Families of curves and tabular data are presented for resource quantities that would last 50, 100 and 200 years “at current rates of production.” If, instead, Australia’s P(t) follows a declining exponential curve (exp(−kt)) with k = (1/110) per year, the stated quantity of coal will allow production to continue forever, with P(t) declining with a half life of 76 y. This and more rapidly declining exponential paths are the only paths that can be said to be sustainable. The envelope of the family of Gaussian curves divides the (P, t) plane into “allowed” and “forbidden” areas. The declining exponential curve divides the “allowed” area into an upper area that is “terminal” and a lower area that is “sustainable.” These facts, coupled with Australia’s expectations of rapid growth of its population, suggest that Australia’s present resource policies are “anti-sustainable” and that the people of Australia need to rethink their present policy of rapidly exporting their fossil fuels.     

加拿大阿尔伯达省西部上泥盆统凯恩组白云岩的成因

加拿大阿尔伯达省西部上泥盆统凯恩组主要由粉晶白云岩和细晶白云岩组成，另外还常见一种充填溶蚀孔洞的亮晶白云石。粉晶白云岩纹理、泥裂和鸟眼等构造发育，其δ＾１３Ｃ为＋１．０‰－＋３．０‰，δ＾１８Ｏ为－６．０‰－－４．３‰，为潮坪上混合水白云化形成。细晶白云岩分布于假整合面之下，其δ＾１３Ｃ为＋０．２‰－＋２．９‰，δ＾１８Ｏ为－６．９‰－－４．６‰，也是混合水白云化的产物。亮晶白云石洁净明亮、晶粒粗     

A universal nutrient application strategy for the bioremediation of oil-polluted beaches

Biostimulation by nutrient application is a viable technology for restoring oil-contaminated beaches. Maximizing the nutrient residence time is key for achieving a rapid cost-effective cleanup. We considered the nutrient injection strategy through a perforated pipe at the high tide line and we simulated numerically beach hydraulics, which allowed us to estimate the optimal injection flow rate of nutrient solution. Our results indicate that the optimal application is one that starts following the falling high tide and lasts for half tidal cycle. The saturated wet-front of the nutrient solution on the beach surface would move seaward with the same speed of the falling tide keeping a constant distance with the tide line. The numerical results were generalized to beaches of wide ranges of hydraulic and tidal properties using a novel dimensionless formulation for water flow and solute transport in porous media. Nomographs were presented to provide the flow rate based on four parameters: The beach slope and hydraulic conductivity, and tidal amplitude and period.     

A multidimensional streamline-based method to simulate reactive solute transport in heterogeneous porous media

We present a new streamline-based numerical method for simulating reactive solute transport in porous media. The key innovation of the method is that both longitudinal and transverse dispersion are incorporated accurately without numerical dispersion. Dispersion is approximated in a flow-oriented grid using a combination of a one-dimensional finite difference scheme and a meshless approximation. In contrast to previous hybrid alternatives to incorporate dispersion in streamline-based simulations, the proposed scheme does not require a grid and, hence, it does not introduce numerical dispersion. In addition, the proposed scheme eliminates numerical oscillations and negative concentration values even when the dispersion tensor includes the off-diagonal coefficients and the flow field is non-uniform. We demonstrate that for a set of two- and three-dimensional benchmark problems, the new proposed streamline-based formulation compares favorably to two state of the art finite volume and hybrid Eulerian–Lagrangian solvers.     

COMPOSITIONAL GRADIENTS IN MESOPHYTIC FORESTS OF EASTERN NORTH AMERICA

Numerical classification and ordination techniques are used to examine compositional variability in 112 stands of mesophytic upland forest in the eastern United States from data published by Braun (1950). Five forest types are identified and used to interpret ordination results. Two prominent environmental gradients account for much of the compositional variability in the data set: along the first ordination axis a microclimate gradient reflects increasing soil moisture availability and cold stress from dry uplands to northern hardwood sites; along the second ordination axis, a soil fertility gradient segregates hemlock coves and dry uplands, both of which are characteristically found on shallow, nutrient-poor soils, from the other forest types. The efficacy of combining numerical classification and ordination techniques for analyzing and interpreting patterns in ecological data is underscored by these results.     

Significance of the clay mineral distribution in fluvial sediments of the Neogene to Recent Himalayan Foreland Basin (west‐central Nepal)

Clay mineral assemblages of the Neogene Himalayan foreland basin are studied to decipher their significance with respect to tectonic and climate processes. Fluvial deposits of the Siwalik Group (west‐central Nepal), and sediment of the Ganga River drainage system were analysed for clay mineralogy. The observed clay mineral assemblages are mainly composed of illite (dominant), chlorite, smectite and kaolinite. Illite and chlorite are chiefly of detrital origin, derived from Himalayan sources. Kaolinite and smectite are authigenic, and mainly developed within pore space and as coating of detrital particles. With increasing burial, diagenetic processes affected the original clay mineral signature. Illitisation of smectite and kaolinite occurred below 2500 and 3500 m depth, respectively. Therefore, illite in the lower parts of the Siwalik Group consists of a mixture of inherited illite and illitised smectite and kaolinite, as suggested by illite crystallinity. Detrital grains that make up the framework of the Siwalik Group sandstones mainly consist of quartz, feldspar and lithic fragments, which are principally of sedimentary and metamorphic origin. Lithoclast content increases over time at the expense of quartz and K‐feldspar in response to uplift and erosion of the Lesser Himalaya Series since about 11–10 Ma. Despite mainly felsic source rocks, dominantly physical erosion processes in the Himalayan belt, and high‐energy fluvial depositional systems, smectite is abundant in the <7 Ma Siwalik Group deposits. Analyses of the Siwalik deposits and comparison with the clay mineralogy of the modern drainage system suggest that smectite preferentially formed in floodplains and intermontane valleys during early diagenesis because of downward percolating fluids rich in cations from weathering and soil development. In general, increasing seasonality and aridity linked to variability of the Asian monsoon from about 8 Ma enhanced clay mineral formation and development of authigenic smectite in paleo‐plains on the southern side of the Himalaya.