Diagnostic Analysis of the Quasi-Balanced Flow of a Mesoscale Vortex During the 12 June 2008 Guangxi Rainstorm

By using the high-resolution observation data and MM5 model simulation data, the analysis on the 12 June 2008 Guangxi flash-flood rainstorm shows that the associated major mesoscale weather system of this event is a quasi-stationary mesoscale vortex, which resulted from the interaction between the midlatitude synoptic-scale waves in the westerly belt and the low-latitude warm-moist flow under the terrain effect. The genesis, development, and movement of the mesoscale vortex have significant impacts on the intensity and persistence of the severe precipitation from the Guangxi flash-flood rainstorm. This vortex is characterized by the coexistence of strong vorticity and divergence with the same order of magnitude. Well organized, deep, and moist convection was observed for a long period of time, and was produced by the interaction between the mesoscale vortex and the gravity waves. The latter was generated by the terrain effect and the ageostrophic effect of high winds in the low-level jet. According to the quasi-balanced dynamical theory, quasi-balanced flow must have existed in the mesoscale motions with both divergent and rotational winds. Thus, based on the diagnosis of the quasi-balanced flow, the PV-ωinversion method is employed to analyze the organized moist convection. The results show that 50%-70% of the vertical circulation in the rainstorm areas was quasi-balanced, so the quasi-balanced flow could well reflect features of the strong vertical motions associated with the coexistence of vorticity and divergence during this event.     

A 35-GHz Polarimetric Doppler Radar and Its Application for Observing Clouds Associated with Typhoon Nuri

Millimeter-wavelength radar has proved to be an effective instrument for cloud observation and research. In this study, 8-mm-wavelength cloud radar (MMCR) with Doppler and polarization capabilities was used to investigate cloud dynamics in China for the first time. Its design, system specifications, calibration, and application in measuring clouds associated with typhoon are discussed in this article. The cloud radar measurements of radar reflectivity (Z), Doppler velocity (Vr), velocity spectrum width (Sw) and the depolar-ization ratio (LDR) at vertical incidence were used to analyze the microphysical and dynamic processes of the cloud system and precipitation associated with Typhoon Nuri, which occurred in southern China in August 2008. The results show the reflectivity observed using MMCR to be consistent with the echo height and the melting-layer location data obtained by the nearby China S-band new-generation weather radar (SA), but the Ka-band MMCR provided more detailed structural information about clouds and weak precipitation data than did the SA radar. The variation of radar reflectivity and LDR in vertical structure reveals the transformation of particle phase from ice to water. The vertical velocity and velocity spectrum width of MMCR observations indicate an updraft and strong turbulence in the stratiform cloud layer. MMCR provides a valuable new technology for meteorological research in China.     

THREE-DIMENSIONAL CALCULATION OF PARTICLE-LIQUID TWO-PHASE TURBULENT FLOW IN A HYDRAULIC TURBINE RUNNER

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New dating indicates intermittent human occupation of the Nwya Devu Paleolithic site on the high-altitude central Tibetan Plateau during the past 45,000 years

The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great interest. Here, we report on our reinvestigations and dating of the Nwya Devu site, located nearly 4600 meters above sea level on the central Tibetan Plateau. A new microblade techno-complex was identified on a lower lake shore at this site,distinct from the previously reported blade tool assemblage. These two lithic assemblages were dated to 45.6±2.6 and10.3±0.5 ka using opt...     

Regulation of different light conditions for efficient biomass production and protein accumulation of Spirulina platensis

Light plays an important role in the photosynthesis and metabolic process of microalgae.However, how different light conditions regulate the biomass production and protein accumulation of microalgae is mostly unknown. In this study, the influence of different light conditions, including light colors, densities, and light:dark cycles on the cell growth and biochemical composition of Spirulina platensis was symmetrically characterized. Under different colored lights, S. platensis all shows an incr...     

A Method for Reducing Ocean Wave-Induced Magnetic Noises in Shallow-Water MT Data Using a Complex Adaptive Filter

In shallow-water areas, the marine magnetotelluric(MT) method faces a challenge in the investigation of seabed conductivity structures due to electrical and magnetic noises induced by ocean waves, which seriously contaminate MT data. Ocean waves can affect electric and magnetic fields to different extents. In general, their influence on magnetic fields is considerably greater than that on electric fields. In this paper, a complex adaptive filter is adopted to reduce wave-induced magnetic noises ...     

Urban Impact on Landfalling Tropical Cyclone Precipitation: A Numerical Study of Typhoon Rumbia (2018)

Coastal urban areas are prone to serious disasters caused by landfalling tropical cyclones(TCs). Despite the crucial role of urban forcing in precipitation, how fine-scale urban features impact landfalling TC precipitation remains poorly understood. In this study, high-resolution ensemble simulations of Typhoon Rumbia(2018), which crossed the Yangtze River Delta urban agglomeration, were conducted to analyze the potential urban impact on TC precipitation. Results show that the inner-core rainfal...     

对气液包体压碎台的评价

在加拿大瓦比贡(Wabigoon)和乌奇(Uchi)太古代绿岩带进行的实例研究证明,利用压碎台分析可以准确和重复地测定含CO_2的气液包体。这些包体可作为中温热液金-石英-碳酸盐-硫化物矿床的判断特征。单独利用该法不能区别勘查区中不同品位的矿脉,但在利用压碎分析初步确定局部变质流体的成分后,在野外可廉价、准确地鉴定采自可能含金的中温热液矿床的样品。压碎台最适用于沉积物的地球化学测量,其石英中的特征气液包体可提供比与金有关的异常宽得多的勘查靶区。在中温热液矿脉的围岩中,可迅速无误地测出含CO_2的气液包体晕。晕的延伸范围与蚀变矿物组合一致,所以,在野外露头稀少或强烈风化的地区,压碎分析可圈定供进一步详查的靶区。