河北一次暴雨过程中不同时段强降水的成因

利用NECP再分析资料和常规观测资料,对2010年8月21日河北的一次暴雨过程进行了分析。结果发现:本次暴雨过程降水主要集中在3个时段内发生,并且成因各不相同。20日午夜前后,东北部地区暴雨主要是冷平流和干侵入,在副高外围产生对流不稳定,引发短时强降水;21日08点前后,保定、廊坊地区暴雨的主要成因是低层切变附近强烈的上升运动;而晴空区近地层辐射增温和低压倒槽幅合抬升是21日傍晚东北部地区再次出现短时强降水的触发条件。可见,随着系统的不断演变,暴雨过程的降水成因也在变化。利用最新时次的卫星、雷达、逐小时自动站等观测资料,对天气系统进行跟踪分析,是此类暴雨预报的有效手段。     

Aerodynamic Parameters of a UK City Derived from Morphological Data

Detailed three-dimensional building data and a morphometric model are used to estimate the aerodynamic roughness length z ₀ and displacement height d over a major UK city (Leeds). Firstly, using an adaptive grid, the city is divided into neighbourhood regions that are each of a relatively consistent geometry throughout. Secondly, for each neighbourhood, a number of geometric parameters are calculated. Finally, these are used as input into a morphometric model that considers the influence of height variability to predict aerodynamic roughness length and displacement height. Predictions are compared with estimations made using standard tables of aerodynamic parameters. The comparison suggests that the accuracy of plan-area-density based tables is likely to be limited, and that height-based tables of aerodynamic parameters may be more accurate for UK cities. The displacement heights in the standard tables are shown to be lower than the current predictions. The importance of geometric details in determining z ₀ and d is then explored. Height variability is observed to greatly increase the predicted values. However, building footprint shape only has a significant influence upon the predictions when height variability is not considered. Finally, we develop simple relations to quantify the influence of height variation upon predicted z ₀ and d via the standard deviation of building heights. The difference in these predictions compared to the more complex approach highlights the importance of considering the specific shape of the building-height distributions. Collectively, these results suggest that to accurately predict aerodynamic parameters of real urban areas, height variability must be considered in detail, but it may be acceptable to make simple assumptions about building layout and footprint shape.     

Changes in pick beginning date and frost damage risk of tea tree in Longjing tea-producing area

We analyze the pick beginning date and frost damage risk trends of Jiukeng, Longjing-43, and Wuniuzao tea trees with time, using meteorological data from 12 station pairs over the period 1971–2010 in the Longjing tea-producing area. The pick beginning date of Jiukeng, Longjing-43, and Wuniuzao varieties had no statistically significant trends before 1990. The pick beginning date of Jiukeng variety had statistically significant decreasing trends after 1990, and there were no statistically significant trends in the start date after 1990 for Longjing-43 and Wuniuzao varieties. The average pick beginning dates of Longjing-43 and Wuniuzao varieties before 1990 are later than those after 1990 by 3.8–4.8 and 2.0–3.1 days, respectively. We used the trend of difference between beginning date of tea plucking (BDTP) and 0 °C terminal date to analyze frost damage risk trends. Eleven counties had no statistically significant frost damage risk trends for Jiukeng, Longjing-43, and Wuniuzao varieties, leaving only one county with statistically significant trends.     

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.     

The equal area law of asymptotically AdS black holes in extended phase space

According to Maxwell’s equal area law we study the “real” phase diagram of the charged AdS black hole and the Kerr-AdS black hole. In the extended phase space constructed by treating the cosmological constant as pressure, the two kinds of AdS black hole display themselves like van der Waals system. Under the critical temperature T _c , there exists a regime where the condition of stable equilibrium will be violated. We employ the equal area law to find an isobar which is the real two phase coexistence line. As a byproduct we find a simple method to derive the critical value of the thermodynamic quantities.     

Double-detonation model of type Ia supernovae with a variable helium layer ignition mass

Although Type Ia supernovae(SNe Ia) play an important role in the study of cosmology, their progenitors are still poorly understood. Thermonuclear explosions from the helium double-detonation sub-Chandrasekhar mass model have been considered as an alternative method for producing SNe Ia. By adopting the assumption that a double detonation occurs when a He layer with a critical ignition mass accumulates on the surface of a carbon–oxygen white dwarf(CO WD), we perform detailed binary evolution calculations for the He double-detonation model, in which a He layer from a He star accumulates on a CO WD. According to these calculations, we obtain the initial parameter spaces for SNe Ia in the orbital period and secondary mass plane for various initial WD masses. We implement these results into a detailed binary population synthesis approach to calculate SN Ia birthrates and delay times. From this model,the SN Ia birthrate in our Galaxy is ～0.4- 1.6 × 10-3yr-1. This indicates that the double-detonation model only produces part of the SNe Ia. The delay times from this model are ～ 70- 710 Myr, which contribute to the young population of SNe Ia in the observations. We found that the CO WD + sdB star system CD-30 11223 could produce an SN Ia via the double-detonation model in its future evolution.     

Disappearance of a coronal hole induced by a filament activation

We present a rare observation of direct magnetic interaction between an activating filament and a coronal hole(CH). The filament was a quiescent one located at the northwest of the CH. It underwent a nonradial activation, during which filament material constantly fell and intruded into the CH. As a result, the CH was clearly destroyed by the intrusion. Brightenings appeared at the boundaries and in the interior of the CH, meanwhile, its west boundaries began to retreat and the area gradually shrank. It is noted that the CH went on shrinking after the end of the intrusion and finally disappeared entirely. Following the filament activation, three coronal dimmings(D1–D3) were formed, among which D1 and D2 persisted throughout the complete disappearance of the CH. The derived coronal magnetic configuration shows that the filament was located below an extended loop system, which obviously linked D1 to D2. By extrapolating this result, our observations imply that the interaction between the filament and the CH involved direct intrusion of the filament material to the CH and the disappearance of the CH might be due to interchange reconnection between the expanding loop system and the CH's open field.     

SUSTAINABLE RURAL LIVELIHOOD AND ECOLOGICAL SHELTER CONSTRUCTION IN UPPER REACHES OF CHANGJIANG RIVER ——Case Study of Zhaotong of Yunnan Province

1INTRODUCTION Ecological shelter construction (ESC) in the upper reaches of the Changjiang (Yangtze) River has been an important component of Development Program of West- ern China. In recent years, most of the literatures dis- cussing the meanings and goals of ESC have been fo- cused on the macro-level, and the scholars have concep- tualized it as a comprehensive strategy to promote the sustainable development of regional economy, society and environment, in which forestry's construc…     

中国淡水和近海鱼类的生态对策研究

通过渐近体长（Ｌ∞），渐近体重（Ｗ∞）、生长系数（Ｋ）、初次性成熟年龄（Ｔｍ）、最大年龄（Ｔｍａｘ）、瞬时自然死亡率（Ｍ）和种群繁殖力（ＰＦ）等七个生态学参数的比较，研究１９种淡水鱼类和１５种近海鱼类的生态对策。根据ｒ—选择和ｋ—选择的典型特征以及各参数间相互关系的显著性，３种鲟鱼类属ｋ—选择；牙鲆等５种近海鱼类偏向ｋ—选择；青鱼、勒氏笛鲷等９种鱼类偏向ｒ—选择；鲤、黄鲫等１７种鱼类为ｒ—选择。对ｒ－ｋ选择的资源特征及其对捕捞的反应做了分析，只有合理控制捕捞强度和起捕年龄，才能保护资源，获得较好的经济效益。     

胶南造山带及邻近地区的重磁场特征及地质解释

胶南造山带的重磁场特征为一条醒目的重力低、磁力高值带，走向北东－南西，陆上部分长约450km，宽40～70km。其重磁场值一般为0×10－5m／S2～20×10－5m／S2、0～300nT，反映胶南造山带的轮廓及带内低密度的早元古代晋宁期花岗岩基和中强磁性的中生代燕山晚期岩浆岩的分布。根据重力场降低、磁异常升高程度和规模大小（宽窄），该重磁场带又可分为日照－青岛、乳山－威海、即墨－海阳三段，前者重力低、磁力高的程度较强，范围较大。造山带内重磁异常值具负相关关系，域值呈正相关性，即重力值越低的地区磁异常值越高，二者的范围大体相当。这一特征反映了造山带内部早元古代晋宁期花岗片麻岩的发育程度和中生代岩浆岩侵入的规模。胶南造山带的重力低、磁力高值带与连云港－苏山岛重力高、磁力低值带恰成对照。后者重磁场值一般为10×10－5m／S2～30×10-5m／S2、一50～-100nT，反映连云港－苏山岛块体的结晶基底由高密度、低磁性的原东海群、荆山群包体和无古宙侵入岩组成。该造山带南东侧西低东高的重力梯度带（Vzz＝1．2×10－5m·S－2／km～1．75×10－5m·S－2／km）反映了赣榆一荣成断裂（倾向NW）的存在；北西侧正磁异常带表明该断裂为控岩断裂，其南段的正负重力梯度带（Vzz＝1．0×10-5m·S-