In this paper,a strong cold air gale process in March 2010 was analyzed.The results showed that the strong cold air gale appeared in the typical synoptic situation of the horizontal trough before the ridge of Lake Baikal.The cold air breaked out from lower levels to higher levels because the upper lever trough changed from the horizontal direction to vertical direction.The main reason of this strong gale was the pressure gradient caused by the interaction of the cold air and the intense development of depression in the East China Sea,and the strong cold temperature advection in low and middle layer.In addition,the coupling of divergence with a negative(positive) value at upper(low) level and intense momentum transportation downward,caused by the dynamic forcing descending due to the upper frontal zone passage,further increased the ground wind speed.

The climatic characteristics of typhoon influenced Zhoushan over the past 50 years are analyzed.It is found that the typhoons show distinct annual and monthly variations.The typhoon impact is closely related to its moving track,intensity at landfall and duration time after landfall.Analysis also shows that heayy rain driven by typhoon occurred at the north/east of Zhoushan is less than that at the south/west,while the situation of disastrous gale is opposite to the heavy rain.Typhoons shifting to the offshore sea,landing on Zhejiang and Fujiang prov-ince are the main tracks which have correspondence with strong rainfall and disastrous gales.Finally,the serious impact of four typhoon storms and two wind circulation features of typhoon are concluded.

海雾是近年来造成舟山海上交通和海上作业发生灾害性事件最为突出的危险天气现象,本文通过天气形势、大气稳定度、相对湿度、温度、风向风速及海温等资料分析,对舟山海雾的发生与消散及持续问题进行了探讨,得出了一些规律。

对舟山海域一次猛烈的低压大风过程进行了诊断分析。结果表明:地面气旋的强烈发展是由于其与高空疏散槽前的正涡度平流中心、辐散中心和暖平流中心在垂直方向紧密耦合的结果,高空急流的活动和加强进一步促进了地面气旋的发展,地面气旋发生发展在青藏高原上空西北急流出口区的左侧和日本海上空西南急流入口区的右侧。地面气旋的发展和冷空气共同作用造成的强气压梯度是引起海上强风的主要原因;高空西南急流轴附近激发出的次级环流下沉支中往南的非地转风,加大了地面风速;对流层中下层垂直环流由上升运动转为一致的下沉运动,引起动量下传进一步加大了地面风速。

In this paper two strong wind processes caused by cold air and depression are analyzed.It reveals that the rapidly growing of the surface pressure gradient because of the depression axis suddenly turning toward northwest is one of the important reason which occurs the strong wind along the coast of North Zhejiang Province.Meanwhile,the distribution features of the vertical descending velocity caused by the difference of divergence between the lower lever and the upple lever of two wind processes are pointed out.It indicates that the lower(not the middle) level momentum descending directly strengths the surface wind velocity.This may be the reason of different surface wind velocity of these two wind processes when the surface pressure gradient is nearly same.

In this paper a strong cold air gale process occurred at the end of December in 2004 is analyzed.It reveals that the main reason of this strong gale is the pressure gradient caused by cold air and the depression in East China Sea,the strong cold temperature advection in upper and lower layer and the middle momentum transportation downward because of the dynamic forcing descending caused by the divergence at the lower lever and the convergence at the middle lever.The occurring area and time of the maximal ground gale are just in the area and at the time of the divergence and descending center at the lower level below 700 hPa and the convergence center at the 700hPa lever.

对两次强对流天气过程的影响系统、物理量场和雷达回波特征等进行了对比分析.分析表明:两次强对流过程有许多相似之处,高、低空西南急流适宜配置而引起的高低层动力场的耦合是强对流发生的动力条件,强对流发生在低层露点锋区及低层水汽通量和散度辐合、高层则相应辐散的大值区域.高低层相对散度正值越大,其所产生的雨量也就越大.多普勒雷达反射率因子图上弓状回波的后侧出现下沉入流急流,相应速度图上的速度值越大,回波移动速度越快,预示着所造成的地面风力也就越大.

利用海岛自动测风站网的风力资料分析了舟山海域风力的分布特征,在此基础上有针对性地把舟山海域划分为5个海区,针对目前舟山沿海海面风力预报(公众预报)范围偏大,不能正确反映舟山海域风力局地特征的重大缺陷,提出了以分海区大风预报代替舟山沿海海面风力预报的设想和预报技术思路.预报实践表明:与目前的舟山沿海海面风力预报相比,分海区大风预报不仅更加客观合理和具有针对性,而且能够有效地解决海上安全与效益之间的矛盾,适合在海岛地区推广应用.

In this paper the synoptic situation and physical element fields of heavy rain which occurred in winter in zhoushan are analyzed,It reveals that the relationship between the heavy rain in Winter and EI Nino events is close.In addition,the change of local meteorological factors is analyzed.All of these could be taken for factors of the reference to forecast the heavy rain in winter.