如皋观测场搬迁前后气温对比分析

针对如皋观测场搬迁后气温偏低的现象,本文对产生这种现象的原因从环境条件、天气过程、土壤土质做了专题分析,结果表明:这种现象是多种因素共同作用的结果,其中最主要的是:(1)观测场环境变化是形成气温偏低的重要原因.(2)观测场所在地的土壤母质等地质背景是形成气温差异的条件之一.(3)冷空气的直接影响为气温差异提供了有利的背景.经分析揭示出:如皋观测场搬迁后的气温偏低现象是更自然地反映了大气自然状况.     

Single-Doppler Radar Observations of a High Precipitation Supercell Accompanying the 12 April 2003 Severe Squall Line in Fujian Province

In this study,single Doppler radar data were used to examine the structure and evolution of a high precipitation(HP) supercell embedded in a cold front near Jianyang,Fujian Province on 12 April 2003.The synoptic environment was characterized by high humidity at low levels,moderate CAPE(convective available potential energy;1601 J kg~(-1)),moderate wind shear(22 m s~(-1) in 0-5 km),and veering of the horizontal winds with height,similar to those HP supercells previously observed in midlatitudes.In additio...     

从地质特征分析成都主城区在地震中的安合性

汶川MS 8.0大地震发生后,关于成都市主城区安全性的讨论一度十分激烈。本文从成都市及周边的基本地质构造和沉积特征入手,讨论成都市主城区在地震中的安全性问题。经过分析认为：川西坳陷刚性稳定的岩石圈结构决定了成都平原不会发生破坏性的大地震; 成都平原沉积盖层厚度大、质量佳、分布适宜决定了龙门山发生的地震不会对成都主城区造成巨大破坏。因此,面对天然地震,成都市主城区是安全的。     

Significance of polycyclic aromatic hydrocarbons (PAHs) in Permian/Triassic boundary sections

In this study the abundances of several polycyclic aromatic hydrocarbons (PAHs Table 1, I–XXI) have been measured throughout three Permian/Triassic (P/Tr) sections from Meishan (South China), Kap Stosch area (East Greenland) and Peace River Basin (Western Canada). Dibenzothiophene (I) and dibenzofuran (II) were found to decrease in abundance just before or shortly after the P/Tr transition in all three sections while perylene (III) was observed to increase in abundance at the onset of the main extinction horizon (bed 25) in Meishan. Perylene has been attributed to a wood degrading fungal source and, therefore, it seems possible these phenomena are related to the demise of land plants. Further, distinct patterns of various combustion-derived PAHs occurring in each section imply that forest fire events occurred within the Late Permian and Early Triassic. In the Meishan section high amounts of combustion-derived PAHs [pyrene (IV), fluoranthene (V), benzo[a]anthracene (VI), benzofluoranthenes (sum, i.e. VII), benzo[a]pyrene (VIII), benzo[e]pyrene (IX) and coronene (X)] occur within bed 25, also containing ash attributed to the fallout from massive volcanic eruptions in Siberia and/or China.     

Key techniques for the emergency disposal of Quake lakes

The Wenchuan Earthquake of May 12, 2008 formed a large number of Quake lakes; 104 of them had a dam taller than 10 m, a water storage capacity larger than 1.0 × 10⁵ m³, and a catchment area greater than 20 km². If these Quake lakes are not thoroughly assessed and properly disposed, the losses caused by the burst of these lakes may be even larger than those caused by this earthquake itself. The Quake lakes with high risks have been properly disposed with the schemes proposed by the authors. This article presents a case study on the emergency disposal of the Tangjiashan, Laohuzui, Jiadanwan, and other Quake lakes. The key techniques applied in the emergency disposal of Quake lakes, including site exploration, risk assessment, design of discharge chutes, selection of construction method and equipment as well as post-emergency disposal evaluation, are discussed.     

On the DB gap of white dwarf evolution:effects of hydrogen mass fraction and convective overshooting

We investigate the spectral evolution of white dwarfs by considering the effects of hydrogen mass in the atmosphere and convective overshooting above the convection zone.Our numerical results show that white dwarfs with MH～10-16M⊙ show the DA spectral type between 46000■Teff■26000K and the DO or DB spectral type may appear on either side of this temperature range.White dwarfs with10-15M⊙ appear as DA stars until they cool to Teff～31000K;from then on they will evolve into DB white dwarfs as a result of conve...     

Magnetic activity of the spotted dwarf AP149 in the α Persei open cluster

The simultaneous photometric and spectroscopic observations of the spotted G dwarf AP149 in the young open cluster α Persei are analyzed here.We reconstruct the observed light curves with a two-starspot model by means of a light curve modeling technique,and find that the active regions shift oppositely along longitude on a time scale of one day.Combining with the observational data obtained by other groups,we discuss the evolution of spotted regions in the photosphere,and find that its starspots evolve not ...     

WD+RG systems as the progenitors of type Ia supernovae

Type Ia supernovae(SNe Ia)play an important role in the study of cosmic evolution,especially in cosmology.There are several progenitor models for SNe Ia proposed in the past years.By considering the effect of accretion disk instability on the evolution of white dwarf(WD)binaries,we performed detailed binary evolution calculations for the WD+red-giant(RG)channel of SNe Ia,in which a carbon-oxygen WD accretes material from a RG star to increase its mass to the Chandrasekhar mass limit.According to these calcu...     

Characteristics of infrared point sources associated with OH masers

We collect 3249 OH maser sources from the literature published up to April 2007, and compile a new catalog of OH masers. We look for the exciting sources of these masers and their infrared properties from IRAS and MSX data, and make a statistical study. MSX sources associated with stellar 1612 MHz OH masers are located mainly above the blackbody line; this is caused by the dust absorption of stellar envelopes, especially in the MSX A band. The mid-IR sources associated with stellar OH masers are concentrate...     

Modeling the WMAP large-angle anomalies as an effect of a local density inhomogeneity

We investigate large-angle scale temperature anisotropy in the Cosmic Microwave Background (CMB) with the Wilkinson Microwave Anisotropy Probe (WMAP) data and model the large-angle anomalies as the effect of the CMB quadrupole anisotropies caused by the local density inhomogeneities. The quadrupole caused by the local density inhomogeneities is different from the special relativity kinematic quadrupole. If the observer inhabits a strong inhomogeneous region, the local quadrupole should not be neglected. We ...