山东半岛冷流降雪过程的统计分析

对威海地区2001-2006年1、2、11、12月所有冷流过程的温压湿等气象要素进行分析,结果表明:地面偏西北风有利于冷流过程的发生;冷流降水量与海气温差有着较强的正对应关系,而与大气相对湿度没有明显的对应关系.相关系数进一步表明了850 hPa温度与海温之差直接决定了地面冷流降水量的大小.从探空指教和垂直湿位涡分布可以看出.,管大气近于弱的对流稳定,但仍不影响对称不稳定的产生.     

京津塘高速公路雾气候特征与气象条件分析

利用1954-2002年的北京、天津和塘沽3站的雾日、雾发生时间以及气象观测资料,对京津塘高速公路沿线雾的气候特征以及气象条件进行了分析.结果发现,京津塘沿线多年平均雾日在15～19天.北京、天津两站的雾日年际变化一致.但在多年雾日变化上北京雾日数略呈逐年下降趋势,而天津、塘沽则略呈上升趋势.京津塘公路沿线雾多在凌晨到日出前后生成,在日出后逐渐消失.雾持续时间随时间变化呈指数递减.地面温度、相对湿度、风速等气象要素对京津塘高速公路沿线雾的预报具有较好的指示意义.地面温度在-5～5℃范围内、风速在0～4m·s-1和相对湿度在90%～100%范围里,雾极易发生.     

重庆极端高温的变化特征及其对区域性增暖的响应

利用重庆1961-2006年31个站逐日最高温度资料,统计出年极端高温发生频次、年极端高温强度、年极端最高温度,分析了它们近46年来的变化情况.结果表明:近46年来重庆年极端高温发生频次呈西减东增的趋势,但增加/减少趋势并不显著.年极端高温的强度和年极端最高气温均在不断增强.年极端高温发生频次的增加对于重庆区域增暖的响应最显著,而年极端最高温度的升高比年极端高温频次的增加对重庆区域性增暖的响应偏弱,但又比年极端高温强度的增强对重庆区域性增暖的响应程度要偏强.     

Ocean Model Open Boundary Conditions with Volume,Heat and Salinity Conservation Constraints简

Open boundary conditions （OBCs） for a regional ocean model that can be integrated stably over a long timeframe, as well as satisfy the volume, heat and salinity conservation constraints, were developed. First, the idea that the inward and outward flux information can be treated separately in the OBCs was adopted. Second, in order to maintain the property that the volume, heat and salinity remains conserved in the simulation domain, conservation constraints were added to the OBCs, and an inverse method utilized to solve the constraint equations. Ideal experiments were designed to investigate the conservation property, and the OBCs were found to work efficiently to maintain the volume, heat and salinity conservation. It was found that simulations were comparable to observations when the OBCs were applied to a regional ocean model.     

Tropospheric Wet Refractivity Tomography Based on the BeiDou Satellite System简

This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS （BeiDou navigation satellite system） simulations only,GPS,and BDS＋GPS for the Shenzhen and Hongkong GNSS network.The simulations are carried out by adding artificial noise to a real observation dataset.Instead of using the δ and σ parameters computed from slant wet delay,as in previous studies,we employ the Bias and RMS parameters,computed from the tomography results of total voxels,in order to obtain a more direct and comprehensive evaluation of the precision of the refractivity field determination.The results show that：（1） the precision of tropospheric wet refractivity estimated using BDS alone （only 9 satellites used） is basically comparable to that of GPS; （2） BDS＋GPS （as of current operation） may not be able to significantly improve the data＇s spatial density for the application of refractivity tomography; and （3） any slight increase in the precision of refractivity tomography,particularly in the lower atmosphere,bears great significance for any applications dependent on the Chinese operational meteorological service.     

江南南部初夏雨季的降水和环流气候特征

基于1961～2010年气象台站逐日降水资料、同期美国NCEP/NCAR的逐日再分析格点资料,通过气候平均、REOF分析、聚类分析等方法,分析了江南地区初夏降水的地域性和时段性特征,及西太平洋副高和高、低空急流等大气环流的相应演变过程。结果发现:（1）江南南部27.5°～29.5°N存在一个独立于华南前汛期和江淮梅雨的初夏雨季,该雨季平均发生时间为6月11～30日,比江淮梅雨早约8天左右。（2）西太平洋副高的西伸东退是江南南部初夏雨季发生发展的重要环流背景,6月第2候副高发生突变性加速西伸之后雨季开始,雨季期间850 hPa副高西伸脊点基本稳定在最西位置即133°E附近,6月第6候副高东退北抬后雨季结束。（3）低层急流大风带的形成和位置是江南南部初夏雨季阶段的重要动力条件,印度洋和孟加拉湾向东北延伸的低层急流与西太平洋副高西北侧的气流连通形成低层急流大风带,并与北侧上空的高空急流耦合,降水集中区位于低层急流大风带左侧、高空急流入口区右侧。     

The North Atlantic oscillation simulated by versions 2 and 4 of IAP/ LASG GOALS Model

The capabilities of two versions of the Global-Ocean-Atmosphere-Land-System model (i.e. GOALS-2 and GOALS-4) developed at State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), are validated in terms of the simulations of the winter North Atlantic Oscillation (NAO), which is currently the subject of considerable scientific interest. The results show that both GOALS-2 and GOALS-4 exhibit a realistic NAO signal associated with relatively reasonable spatial pat-terns of sea level pressure, surface air temperature, and precipitation. Generally speaking, the associated pat-terns of precipitation in GOALSs match better with the observation in comparison with the case of surface temperature. For the imprint of NAO on the ocean, or perhaps a coupling between the two fluids, the asso-ciated tripole patterns of the North Atlantic SST anomaly are presented distinctly in GOALS-2, for GOALS-4 however, this is not the case. Spatially, the models’ main deficiencies appear to be that the simu-lated Icelandic lows shift northward apparently, which in turn result in the blemish of GOALSs in repro-ducing the accompanied surface wind anomalies. For the interannual and even longer time scale variations of DJF sea level pressure (SLP) over the North Atlantic region. GOALSs reproduce the center with the strongest variability rationally, but the intensities are far weaker than the observation.     

赤道东太平洋海表水温月异常的数值试验

本文利用中科院大气物理研究所的两层大气环流模式（ＩＡＰ－ＧＣＭ Ⅱ）作了冬季赤道东太平洋地区海表水温月异常增暖时对大气环流及我国气候影 响的数值试验。结果表明,该处海表水温的异常增暖能引起中太平洋信风带Ｗａｌｋｅｒ 环流的改变并激发出中高纬度３０－５０天的低频振荡;当该异常结束后,其后效仍 会对我国的气候产生影响。     

低空急流和非均匀层结条件下重力惯性波的传播与发展

本文从基流背景下线性化Boussinesq方程组出发,采用WKBJ方法,首先求得重力惯性波的广义波作用量变化方程及波参数随波包的变化方程,讨论了基流切变对重力惯性波传播和发展的影响;然后用Runge-Kutta方法讨论了不同层结(含降水影响)下重力惯性波的传播路径。得到了降水强度大、静力稳定度小的区域对重力惯性波有“吸引”作用,因而引起重力惯性波能量的集中,进而触发和强化对流天气的结论。      

A SPECTRUM OF LYAPUNOV EXPONENTS OBTAINED FROM A CHAOTIC TIME SERIES

A complete spectrum of Lyapunov exponents (LEs) is obtained from 1970— 1985 daily mean pressuremeasurements at Shanghai by means of a correlation matrix analysis technique and it is found that there exist LEs≥0,and <0. with their sum 0λ_i=K=0.110405 whereuponT=1 /K =9 is obtained as the predictable time scale, a result close to that acquired by the dynamic-statistical approachin early days and also in agreement with that present by the authors themselves(1991).