吉林一次降水层状云的结构和物理过程研究

利用机载粒子测量系统的探测结果,配合雷达及地面降水资料,结合一维层状云模式,通过对吉林2004年7月1日的一例降水性层状云系的宏微观物理结构和降水机制的定量化分析,对顾震潮三层模型有了进一步的认识.观测资料表明,该降水过程为典型的层状云降水,地面降水存在不均匀性,云系结构符合顾震潮三层概念模型,其中第1层为尺度很小的冰...     

梅雨期一个伴有前导层状降水对流线的结构特征

采用美国ERSL实验室LAPS系统融合NCEP 1°×1°逐日再分析资料、业务观测和雷达资料,分析了2007年6月18日发生在湖北中部的一个伴有前导层状降水对流线发生、发展及消亡的结构特征。结果表明,该系统在雷达回波上主要分为两部分：后方回波强而窄的对流带和前方回波相对弱的宽层状降水区,在对流带和层状降水区之间有一条回...     

Modeling Arctic Boundary Layer Cloud Streets at Grey-zone Resolutions

To better understand how model resolution affects the formation of Arctic boundary layer clouds,we investigated the influence of grid spacing on simulating cloud streets that occurred near Utqiaġvik(formerly Barrow),Alaska,on 2 May 2013 and were observed by MODIS(the Moderate Resolution Imaging Spectroradiometer).The Weather Research and Forecasting model was used to simulate the clouds using nested domains with increasingly fine resolution ranging from a horizontal grid spacing of 27 km in the boundary-layer-parameterized mesoscale domain to a grid spacing of 0.111 km in the large-eddy-permitting domain.We investigated the model-simulated mesoscale environment,horizontal and vertical cloud structures,boundary layer stability,and cloud properties,all of which were subsequently used to interpret the observed roll-cloud case.Increasing model resolution led to a transition from a more buoyant boundary layer to a more shear-driven turbulent boundary layer.The clouds were stratiform-like in the mesoscale domain,but as the model resolution increased,roll-like structures,aligned along the wind field,appeared with ever smaller wavelengths.A stronger vertical water vapor gradient occurred above the cloud layers with decreasing grid spacing.With fixed model grid spacing at 0.333 km,changing the model configuration from a boundary layer parameterization to a large-eddy-permitting scheme produced a more shear-driven and less unstable environment,a stronger vertical water vapor gradient below the cloud layers,and the wavelengths of the rolls decreased slightly.In this study,only the large-eddy-permitting simulation with gird spacing of 0.111 km was sufficient to model the observed roll clouds.     

冰云光学特性与等效球Mie理论的误差分析

用改进的射线光学理论和等效球Ｍｉｅ理论，计算了若干冰晶和冰晶尺度分布在太阳光谱区中一系列波长上的光学特性和散射特性，详细分析了Ｍｉｅ散射计算的误差，并假定冰云光学特性有１０％误差的情况下，用Ｄｅｌｔａ－Ｅｄｄｉｎｇｔｏｎ近似对所引起的冰云辐射特性的误差进行了数值试验。结果表明，沿用已久的等效球Ｍｉｅ理论因计算冰云光学特性在波长小于２．６μｍ波段误差过大，将引起冰云辐射特性有显著误差，最后提出了计算冰云光学特性的新方案。     

Heavy Element Enrichment in the Intergalactic Medium for Large Red Shifts

A simple model for heavy element enrichment in the intergalactic medium is examined. The dependence of the heavy element abundance in the intergalactic medium on star formation processes in primary galaxies is studied. The results are in agreement with observational data on the abundance of heavy elements in L _a-clouds.     

The Rôle Of Astrochemistry In Low Mass Star Formation

Molecular processes play both active and passive/diagnostic rôles in the process of star formation. Various molecular behaviours can be identified in star-forming regions with the result that different molecular species can be used to constain different aspects of the infall process, such as the density structures, the kinematics and the evolutionary history of star-forming cores. The main limitations in the chemical analysis of infall sources arise from poorly constrained boundary conditions; in particular the chemical and physical initial conditions are usually very uncertain. The most promising application of astrochemical modelling is probably in the analysis of the infall dynamics through combined chemical/radiative transfer modelling of molecular emission line profiles.     

Observations of the infrared source in s 140 and the heating of the associated gas

Near infrared observation of the infrared source in S140 was made using the 1.26 m infrared telescope of Beijing Observatory, yielding fluxes in the J, H and K bands. Combining with data from satellite and ground-based IR and submillimetre observations, we found the spectral gradient, IR luminosity and the shell structure of the IR source.

We also combined observations of CO and NH₃ in an analysis of the heating of the gas associated with the source. Besides through dust, the central source may also input energy into the gas through shock waves. External sources of heat and heating by photoelectric process and cosmic rays are also discussed.