超临界CO_(2)大展身手的时代

超临界二氧化碳(scCO_(2))是二氧化碳的一种物态(临界温度及临界压力以上),超临界流体技术在我国已经成为了重要的研究领域和新学科生长点。本文通过拟人化的手法,介绍了超临界二氧化碳的定义、优点、应用以及发展前景,同时也介绍了部分物理化学原理,帮助读者学习超临界二氧化碳的相关知识。

Three-Dimensional Wind Field Retrieved from Dual-Doppler Radar Based on a Variational Method:Refinement of Vertical Velocity Estimates

In this paper,a scheme of dual-Doppler radar wind analysis based on a three-dimensional variational method is proposed and performed in two steps.First,the horizontal wind field is simultaneously recovered through minimizing a cost function defined as a radial observation term with the standard conjugate gradient method,avoiding a weighting parameter specification step.Compared with conventional dual-Doppler wind synthesis approaches,this variational method minimizes errors caused by interpolation from radar observation to analysis grid in the iterative solution process,which is one of the main sources of errors.Then,through the accelerated Liebmann method,the vertical velocity is further reestimated as an extra step by solving the Poisson equation with impermeable conditions imposed at the ground and near the tropopause.The Poisson equation defined by the second derivative of the vertical velocity is derived from the mass continuity equation.Compared with the method proposed by O’Brien,this method is less sensitive to the uncertainty of the boundary conditions and has better stability and reliability.Furthermore,the method proposed in this paper is applied to Doppler radar observation of a squall line process.It is shown that the retrieved vertical wind profile agrees well with the vertical profile obtained with the velocity–azimuth display(VAD)method,and the retrieved radial velocity as well as the analyzed positive and negative velocity centers and horizontal wind shear of the squall line are in accord with radar observations.There is a good correspondence between the divergence field of the derived wind field and the vertical velocity.And,the horizontal and vertical circulations within and around the squall line,as well as strong updrafts,the associated downdrafts,and associated rear inflow of the bow echo,are analyzed well.It is worth mentioning that the variational method in this paper can be applied to simultaneously synthesize the three-dimensional wind field from multiple-Doppler radar observations.

The Seismic-Geological Comprehensive Prediction Method of the Low Permeability Calcareous Sandstone Reservoir

Currently in Niu-zhuang sub-sag, the seismic reflection amplitude of the newly discovered turbidite sandstone is stronger in the third Segment. The main reason is that Calcareous components accounts for a large part and physical properties is relatively poor, which results in no corresponding relation between reservoir and seismic attributes, and effective reservoir is difficult to predict and describe. Therefore, using the method of geological statistics, we firstly study the distribution of calcareous matters, secondly study the contribution to seismic reflection amplitude made by Calcareous high impedance component;thirdly analyze its influence on actual seismic reflection amplitude and determine the lithology thickness of Calcareous via replacement forward modeling. At last, we characterize the reservoir using the amplitude of calcareous matters. It proves that the method of seismic-geological comprehensive prediction is reliable. It has good guidance for exploration and development of the calcareous sand lithologic reservoir in similar areas.

Analysis of three echo-trainings of a rainstorm in the South China warm region

A rainstorm which occurred between May 22and 23, 2014 in Guangdong Province of the South Chinawarm region was simulated by using the ARW-WRFmodel. Three ＂echo-trainings＂ over the rainstorm centerwere analyzed and the results of both the simulation andobservational analysis showed that this rainstorm processwas composed of three stages. In the first stage, gravitywaves triggered the simultaneous but relatively indepen-dent formation of linearwhich moved toward theconvection and convective cells,northeast through the rain center,thus creating the echo-training. In the second stage, withthe formation of cold outflow, new convective cells werecontinuously created in the southwest and northwest of therain area and then gradually moved to merge into thenortheast rain area, thus forming a new echo-training. Inthe third stage, multiple rain bands above the rain areamoved southeastward and passed through the strongestprecipitation center, thus creating the third echo-training.The model simulation showed that a substantial warmingappeared at 900 hPa before the convective initiation,leading to the formation of a stable layer below 900 hPa,which was the primary cause for the gravity waves thattriggered the multiple convective cells. The multipleconvective cells formed the convective line, followingwhich new convection was formed from the cold outflowin its southwest and northwest directions. The newconvection in the southwest maintained the rain band;however, the new convection in the northwest, combinedwith the rain band of the north, formed a large radarreflectivity area and consequently, a larger MCS.

Relationship of tropical-cyclone-induced remote precipitation with tropical cyclones and the subtropical high

This study concerns the precipitation induced by a tropical cyclone （TC） before the TC arrives, which will be referred to as TC remote precipitation （TRP）. Based on the distribution characteristics of the non-rotational wind and the divergent-wind vertical circulation related to TC, the subtropical high, and TRP of 45 TRP events during June, July, and August of 2000-2009, the relationships among these three entities （TC, subtropical high, and TRP） can be categorized into four patterns. The first pattern accounts for the highest proportion of the TRP events （59%）, and a conceptual model is then provided for this pattern. The primary characteristics of this model are as follows： TC, the subtropical high, and TRP can interact with each other through the divergent-wind secondary circulation at both sides of the ridge line of the subtropical high （between the subtropical high and TC, and between the subtropical high and TRP）. At the upper level （150 or 200 hPa）, the northward non-rotational wind from the TC converged toward the subtropical high ridge line and subsided, and at 950 hPa the divergent wind from the ridge line of the subtropical high converged toward TC; these constructed the secondary circulation between TC and the subtropical high. In the meantime, the southward non- rotational wind at the upper level （150 or 200hPa） from TRP and the divergent wind at 950hPa from the subtropical high ridge line toward TRP constructed the secondary circulation between TRP and the subtropical high. As TC and TRP interacted with each other, the subtropical high ridge line was usually under the down- draft area of the whole atmosphere. The other three patterns are different from the first pattern mainly in terms of the intensity and position of the non-rotational-wind secondary circulation. The numerical simulation of the Beijing 7.21 rainstorm confirmed the relationship amongTC, the subtropical high, and TRP, indicating that when the interaction weakened, the TRP also weakened.