关于热带大气低频振荡的一个简单模式与数值模拟

本文首先从观测事实分析了热带大气的低频振荡现象，然后从理论上加以研究。为此，本文建立了一个包括触发热源和CISK机制的三维线性模式，用此模式讨论了热带大气低频振荡的性质、结构、传播和动力学机制。从模式的计算结果得到了周期为30d左右以大约9 m/s的速度向东传播的低频振荡现象，这种振荡为Kelvin波型的响应和向西传播的Rossby波型的响应的结合。计算还表明，这种振荡的周期与触发热源的周期关系不大，这说明了热带大气的低频振荡是大气自身的固有振荡，它是大尺度运动与对流凝结加热相互作用的结果。     

冬、夏季青藏高原地面加热场激发的500hPa遥相关型

本文用青藏高原地面加热场强度来表征高原的加热状况，并用统计的方法，分析了冬季（２月）和夏季（７月）青藏高原地面加热场强度与同期５００ｈＰａ位势高度的遥相关关系，得到如下结论：冬季高原地面加热场可激发北半球５００ｈＰａ产生遥相关型，这种遥相关型可看成是二维Ｒｏｓｓｂｙ波列由低纬向东北方向传播；夏季高原地面加热场可激发北半球５００ｈＰａ产生类似于ＥＵ型的遥相关，这种遥相关型可看成二维Ｒｏｓｓｂｙ波列由     

1966年云南东川6.5级地震的热异常时空结构分析

本文分析了１９６６年云南东川６．５级地震前后浅层地温异常的时空结构及降水异常的水平结构。分析表明，震前数月浅层地温稳定维持正异常，发震前一个月激剧增温，发震当月达最大，震后降低；震前震中区为负地温距平区，随发震时刻临近，负距平区迅速演变为正距平区，而且强度和面积都不断增大，至发震时达最大，震后不断减小；热异常是从深层传向地表的；震中区震前为旱区，震后为涝区。本文还讨论了震源处热信息传到地表的条件和可能机制，认为在水热活动异常的断裂带上，至少对于浅源地震，对流传热是一种较为可能的传热机制。     

An aerosol climatology of Samoa

An atmospheric monitoring station is operated at Cape Matatula, American Samoa, by the Geophysical Monitoring for Climatic Change program under the National Oceanic and Atmospheric Administration. A nearly continuous record of condensation nucleus (CN) concentration and multiwavelength aerosol scattering extinction coefficient (_sp) is available from mid-1977 to the present. This report presents the 1977–1983 data. The long-term mean of CN concentration is 274 cm^-3 the long-term mean of _sp (550 nm) is 1.54×10^-5, and no significant long-term, annual, or diurnal trend is apparent in either data record.     

对流和层状云系电活动,对流及降水特性的相关分析

通过对６次不同云系电特性、回波、对流及降水特性的综合分析，探讨了它们之间的相关性。结果表明：除不稳定能量外，－１０℃层和０℃层高度以及他们之间的高度差、０℃层与云顶的高度差也是表征雷暴动力和电特性的重要参量；雷暴云起电过程对冰相作用有较强的依赖性；雷暴中的电活动与对流活动成正相关，闪电多发生在３０ｄＢｚ强回波高度大于－１０℃层高度时段内，强烈的电活动与强降雨有很好的对应关系，而与一般性降雨对应关系较差；在雷暴消散期，闪电可能会影响雷暴的特性     

对流边界层中的一个双高斯型PDF扩散模式

对流边界层（ＣＢＬ）中的污染扩散是非高斯型的。本文在下列三个假设下建立了双高斯型几率分布函数（ＰＤＦ）模式：１．对流边界层任一确定高度铅直速度Ｗ的几率分布函数ｐｗ由两个高斯分布迭加而成；２．从污染源释放的粒子具有源高的铅直速度几率分布，且其轨迹是线性的；３．粒子在地面的反射为全反射，在混合层高度Ｚｉ为全反射或有部分吸收。然后分析了三个高度上铅直速度Ｗ的一些统计特征量，比较了由ＰＤＦ模式计算的横风向积分浓度和Ｌａｍｂ的数值模拟［１－３］，Ｄｅａｒｄｏｒｆｆ的水槽模拟［４－６］结果，并用美国ＣＯＮＤＯＲＳ计划的外场试验资料［７］对ＰＤＦ模式进行了验证，结果均相当一致。     

洋面冷锋的三维数值模拟──潜热释放对冷锋结构的影响

通过比较一次洋面冷锋过程的干、湿三维模拟结果，揭示潜热释放对冷锋结构的影响。结果表明：由于潜热释放的作用，冷锋区的温度梯度和风矢量的气旋性切变大大地加强了，冷锋附近的涡度场和垂直速度场呈现出更多的更加紧密的中尺度结构；锋面非地转直接环流在湿模拟中比在干模拟中发展得更加充分并且具有更高的组织性；潜热加热倾向于增加锋面环流的强度，尤其是其上升支的强度。研究表明，潜热释放过程是形成冷锋前沿上方低层大气中狭窄强上升气流区的关键因素之一。     

Growth Of The Summer Daytime Convective Boundary Layer At Anand

The heights of the daytime convective boundary layer (CBL), computed by a one-dimensional model for a bare soil surface at a semi-arid station,Anand, during the dry and hot summer month of May 1997, are presented. As input, the model requires surface heat flux, friction velocity and air temperature as functions of time. Temperature data at the one-metre level from a tower and sonic anemometer data at 9.5 m collected during the period 13–17 May 1997 in the Land Surface Processes Experiment (LASPEX-97) are used to compute hourly values of surface heat flux, friction velocity and Obukhov length following the operational method suggested by Holtslag and Van Ulden [J. Climate Appl. Meteorol. 22,517–529 (1983)]. The model has been tested with different values for the potential temperature gradient ( ) above the inversion. The model-estimated CBL heights comparefavourably with observed heights obtained from radiosonde ascents.     

A MASCOTTE-based characterization of MCSs over Spain, 2000–2002

A 3-year Mesoscale Convective Systems (MCSs) database, which extends from 2000 to 2002, has been built for the Iberian Peninsula and the Balearic Islands using the objective method MASCOTTE (MAximum Spatial COrrelation Technique). It was originally developed to track the evolution of convective systems over the Amazon region; after modifications, it is able to track MCS evolution even with an hour and a half of missed images and provides essential information of both dynamical and morphological characteristics of MCSs. MASCOTTE is tested against a visual and subjective method, and is found to offer advantages such as automation and a simple and efficient operation that make it very useful for building large MCS databases.Thirty-five MCSs were found between June and October, most of them originated along the Mediterranean coast and near the Pyrenees, showing an increasing occurrence from June to September, when the maximum is found. The regions most influenced by MCS occurrences are Balearic Islands, Valencia, Catalonia, Murcia and the Basque Country. The MCSs tend to be small, short-lived and linear, usually moving eastward or northeastward with low velocities.The MCSs-associated precipitation presents high variability, ranging from 80 to 0 mm h⁻¹ as maximum hourly records. Two different convective regions are identified based on MCS behavior in extreme precipitation events: Northern Spain (the Basque Country) with abundant and continuous precipitation regime but little MCS influence, and the Mediterranean coast, where precipitation is sporadic but much more intense.