A coupled air-sea model for tropical cyclones （TCs） is constructed by coupling the Pennsylvania State University/National Center for Atmospheric Research mesoscale model （MM5） with the Princeton Ocean Model.Four numerical simulations of tropical cyclone development have been conducted using different configurations of the coupled model on the f-plane.When coupled processes are excluded,a weak initial vortex spins up into a mature symmetric TC that strongly resembles those observed and simulated in prior research.The coupled model reproduces the reduction in sea temperature induced by the TC reasonably well,as well as changes in the minimum central pressure of the TC that result from negative atmosphere-ocean feedbacks.Asymmetric structures are successfully simulated under conditions of uniform environmental flow.The coupled ocean-atmosphere model is suitable for simulating air-sea interactions under TC conditions.The effects of the ocean on the track of the TC and changes in its intensity under uniform environmental flow are also investigated.TC intensity responds nonlinearly to sea surface temperature （SST）.The TC intensification rate becomes smaller once the SST exceeds a certain threshold.Oceanic stratification also influences TC intensity,with stronger stratification responsible for a larger decrease in intensity.The value of oceanic enthalpy is small when the ocean is weakly stratified and large when the ocean is strongly stratified,demonstrating that the oceanic influence on TC intensity results not only from SST distributions but also from stratification.Air-sea interaction has only a slight influence on TC movement in this model. 相似文献
Oil from the Oligocene oil sands of the Lower Ganchaigou Formation in the Northern Qaidam Basin and the related asphaltenes was analyzed using bulk and organic geochemical methods to assess the organic matter source input, thermal maturity, paleo-environmental conditions, kerogen type, hydrocarbon quality, and the correlation between this oil and its potential source rock in the basin. The extracted oil samples are characterized by very high contents of saturated hydrocarbons (average 62.76%), low contents of aromatic hydrocarbons (average 16.11%), and moderate amounts of nitrogen–sulfur–oxygen or resin compounds (average 21.57%), suggesting that the fluid petroleum extracted from the Oligocene oil sands is of high quality. However, a variety of biomarker parameters obtained from the hydrocarbon fractions (saturated and aromatic) indicate that the extracted oil was generated from source rocks with a wide range of thermal maturity conditions, ranging from the early to peak oil window stages, which are generally consistent with the biomarker maturity parameters, vitrinite reflectance (approximately 0.6%), and Tmax values of the Middle Jurassic carbonaceous mudstones and organic-rich mudstone source rocks of the Dameigou Formation, as reported in the literature. These findings suggest that the studied oil is derived from Dameigou Formation source rocks. Furthermore, the source- and environment-related biomarker parameters of the studied oil are characterized by relatively high pristane/phytane ratios, the presence of tricyclic terpanes, low abundances of C27 regular steranes, low C27/C29 regular sterane ratios, and very low sterane/hopane ratios. These data suggest that the oil was generated from source rocks containing plankton/land plant matter that was mainly deposited in a lacustrine environment and preserved under sub-oxic to oxic conditions, and the data also indicate a potential relationship between the studied oil and the associated potential source rocks. The distribution of pristane, phytane, tricyclic terpanes, regular steranes and hopane shows an affinity with the studied Oligocene Lower Ganchaigou Formation oil to previously published Dameigou Formation source rocks. In support of this finding, the pyrolysis–gas chromatography results of the analyzed oil asphaltene indicate that the oil was primarily derived from type II organic matter, which is also consistent with the organic matter of the Middle Jurassic source rocks. Thus, the Middle Jurassic carbonaceous mudstones and organic rock mudstones of the Dameigou Formation could be significantly contributing source rocks to the Oligocene Lower Ganchaigou Formation oil sand and other oil reservoirs in the Northern Qaidam Basin.
1. Introduction The relationship between frontogenesis and convec- ?tion has been studied intensively by many researchers ? ? ?(Orlanski and Ross, 1977 Ross and Orlansk… 相似文献
The development of symmetric disturbance superposed on the background field of Hoskins-Bretherton (1972) frontogenesis model is investigated by means of WKBJ approach,It is found thatthe forcing of large-scale deformation,the frontal circulation and the spatial-temporal variations ofstability parameters (F~2,N~2,M~2) can bring about the development of symmetric disturbance,even though the frontal baroclinic flow is symmetric stable (F~2N~2-M~2=q>0),Thefrontogenetical process of deformation confluence zone and the ascending branch of frontalcirculation are in favor of the development of symmetric disturbance,The actions of ageostrophicshear in frontal zone and the variation of stability parameters are dependent on the structure ofdisturbance. 相似文献
The Dahongshan Group is divided into five formations from the bottom to the top: the Laochanghe Formation; the Manganghe Formation;
the Hongshan Formation, the Feiweihe Formation and the Potou Formation. As can be seen from the U-Pb concordia plot for zircon
fractions collected from the metamorphic sodic lava of the Hongshan Formation, the upper intersect age with the concordia
is 1665.55
-10.86+13.56
Ma. Sm-Nd dating of four whole-rock samples and one hornblende from the Manganghe and Hongshan formations yielded an isochron
age of 1657 ± 82 Ma. This result is in good agreement with the zircon U-Pb age and thus can represent the formation age of
the Dahongshan Group. The initial143Nd/144Nd ratio is estimated at 0.510646. with ENd (T) = + 3.1 ± 1.8. In addition the Dahongshan Group rocks are characterized by
low REE contents, with δEu>1. All this goes to show that the original rocks of the Dahongshan Group were derived from a depleted
mantle. The calculated Sm-Nd model ages range from ∼ 1900 to ∼ 2000 Ma. representing the time of crust/ mantle differentiation
in the area studied.
From the above results, in conjunction with the time-scale scheme for China, the Dahongshan Group should be assigned to the
Middle Proterozoic. 相似文献
