台风麦莎登陆后粘性摩擦对正压特征波动的影响

本文推导出柱坐标系下含有粘性摩擦项的正压方程组。选取2005年台风麦莎登陆浙江过程中的8月6日15时的WRF(Weather Research and Forecasting)模式输出资料,利用数值差分方法对该正压方程组求特征波解,分析粘性摩擦对台风麦莎内部正压特征波动的影响。结果表明,重力惯性外波在粘性摩擦的影响下,最不稳定波的波数为45左右,波动在摩擦的影响下衰减,波动沿逆时针传播,在半径1000 km处,1波波速为47.43 m/s,在半径r>800 km的范围内,径向风分量扰动加大,辐合辐散运动增强;而摩擦影响下的涡旋Rossby波,2波最不稳定,波动增长率减小,在半径r=200 km处波动相速度为4.282~29.172 m/s,扰动涡度大值区范围减小,涡旋Rossby波的波动区域沿着径向向台风中心收缩。分析包含所有波动时,考虑摩擦后,最不稳定波数在45左右且波动衰减,1波波速在r=1000 km处(外螺旋雨带)为26.374 m/s;在半径r=200 km(内螺旋雨带)为5.275 m/s,考虑径向基本气流后,最不稳定波的波数保持不变,半径r=1000 km处的波速增加为30.324 m/s,r=200 km(内螺旋雨带)处波速为6.065 m/s,摩擦使得径向风分量扰动明显增大,辐合辐散运动加强。     

Ensemble data assimilation in a simple coupled climate model: The role of ocean-atmosphere interaction

A conceptual coupled ocean-atmosphere model was used to study coupled ensemble data assimilation schemes with a focus on the role of ocean-atmosphere interaction in the assimilation. The optimal scheme was the fully coupled data assimilation scheme that employs the coupled covariance matrix and assimilates observations in both the atmosphere and ocean. The assimilation of synoptic atmospheric variability that captures the temporal fluctuation of the weather noise was found to be critical for the estimation of not only the atmospheric, but also oceanic states. The synoptic atmosphere observation was especially important in the mid-latitude system, where oceanic variability is driven by weather noise. The assimilation of synoptic atmospheric variability in the coupled model improved the atmospheric variability in the analysis and the subsequent forecasts, reducing error in the surface forcing and, in turn, in the ocean state. Atmospheric observation was able to further improve the oceanic state estimation directly through the coupled covariance between the atmosphere and ocean states. Relative to the mid-latitude system, the tropical system was influenced more by ocean-atmosphere interaction and, thus, the assimilation of oceanic observation becomes more important for the estimation of the ocean and atmosphere.     

巴旦杏越冬冻害气象指标

低温冻害是危害新疆林果业持续健康高效发展的三大灾害之一,通过对越冬期间果树冻害历史灾情资料的调查及最低气温数据库的建立,研究冻害的发生时间、界限温度以及冻害发生年各项气象因子的变化特征,阐明果树越冬冻害与气象因子的关系.结果表明,可根据冬季平均气温、最低气温、降温天气及低温持续时间等确定该区巴旦杏越冬期发生冻害的气象指标.研究结果可为有效防范低温冻害提供理论依据,为林果业生产服务.     

A Study on the CO Isotopic Lines of the Star Forming Region AFGL 5157

By the mapping observations simultaneously at the ¹²CO (J=1-0), ¹³CO (J=1-0), and C¹⁸O (J=1-0) lines on the area of 24’×24’ (12 pc×12 pc) of the star forming region AFGL 5157, we have obtained the distribution and averaged physical parameters for the respective ¹³CO and C¹⁸O cores of this molecu- lar cloud. At the edge of the molecular cloud, the isotopic abundance ratio is X [(¹³CO)/(C¹⁸O)] ≈ 10, close to the ratio of a giant molecular cloud. The viral masses of the ¹³CO and C¹⁸O cores are less than the masses of the molecu-lar cloud cores, so the molecular cloud cores are gravitationally unstable, and the C¹⁸O molecular cloud core is more easy to collapse. The column density distributions of the C¹⁸O molecular cloud core in the northeast and southwest directions are, respectively, 1.1 × 10²³× z^−0.43 and 4.6 × 10²⁵× z^−0.58, where z is the distance from the center of the molecular cloud core. The high velocity molecular out?ow has been con?rmed from our ¹²CO spectra, the mass loss rate of the out?ow has been estimated, and the mass-velocity relation of the out?ow is ?tted by a power-law function of m ∝ v^−1.8. The star formation rate of the ¹³CO molecular cloud core is as high as 23%, probably, under the in?uence of     

共线SPDC下剩余脉冲泵浦光滤光特性研究

从宽带脉冲泵浦光的光谱及滤光片的滤光特性参数出发,分析了自发参量下转换（SPDC）产生纠缠光源的系统中各类滤光片对剩余脉冲泵浦光的滤除效率。分析结果表明,适当组合不同类型的滤光片可以有效地滤除剩余脉冲泵浦光,并从实验上验证了分析结果的正确性。该研究为脉冲泵浦光条件下SPDC过程产生的纠缠光源的有效测量提供了理论指导和实验验证。     

走向Internet网际

从１９９５年３月１３日开始，我们开始与中国科学院网络中心和昆明电信局通信处联系，准备建立云南天文台Ｅｍａｉｌ系统。到３月２１日本系统技术上已基本调试完成。本文介绍了这一系统的建立过程和通过这一系统可以得到的网络资源。     

用MapInfo软件实现地震震中县乡一级地名的快速检索

在大震地震速报时 ,通常不仅需要迅速确定地震的三要素 ,各级政府和有关部门还需要尽快知道震中的地名 ,以迅速采取相应的措施。另外 ,各省地震局上报中国地震局的快报和月报也要求给出乡 (镇 )一级的地名。目前 ,多数省的地震部门在确定地震震中地名时 ,采用的是根据所定位地震的经纬度在地图上查找地名的方法 ,既繁琐费时 ,又容易出错。本文介绍的是利用目前最流行的地理信息系统 ( GIS)软件 Map Info及开发工具 Map Basic,快速精确的确定出地震震中到县和乡 (镇 )一级地名的方法。1　GIS软件 Map Info及开发工具 Map BasicMap Inf…     

IRAS 20231+3440区外流激发源的性质研究

给出红外点源IRAS 20231 3440附近恒星形成区近红外．JHK’和H2成像观测结果，以及与该IRAS点源成协的近红外点源IRS1的K波段分光观测结果．．JHK’观测显示该区域存在嵌埋的年轻星天体，H2窄波段观测揭示了若干个氢分子发射结点，其中有几个结点排列成线形，暗示分子氢喷流的存在．喷流的北部与已知观测的分子外流成协，表明二者之间存在联系．喷流的走向提示IRS1可能是其激发源，对IRS1的K波段分光观测给出了进一步的证据．从近红外、MSX及IRAS资料估计出IRS1的能谱分布，表明它是一个处于ClassI状态的中等质量的年轻星天体．     

A Remark on Using Gravitational Lensing Probability as a Probe of the Central Regions of CDM Halos

We calculate the gravitational lensing probabilities by cold dark matter (CDM) halos with different density profiles, and compare them with current observations from the Cosmic Lens All-Sky Survey (CLASS) and the Jodrell-Bank VLA Astrometric Survey (JVAS). We find that the lensing probability is dramatically sensitive to the clumping of the dark matter, or quantitatively, the concentration parameter. We also find that our predicted lensing probabilities in most cases show inconsistency with the observations. It is argued that high lensing probability may not be an effective tool for probing the statistical properties of inner structures of dark matter halos.     

REDUCED GROWTH IN HYBRID TILAPIA (OREOCHROMIS MOSSAMBICUS×O. NILOTICUS) AT INTERMEDIATE STOCKING DENSITY

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