热带低压影响下平潭海峡公铁两用大桥桥址处风雨特征分析

基于在平潭海峡公铁两用大桥桥址处建立的风雨监测系统,对2018-08某热带低压条件下的风雨特征进行研究。研究结果表明:在降雨过程中,1 min平均风速变化较强烈,降雨后,平均风速较低;湍流强度在降雨过程中比降雨前显著增强;湍流积分尺度在降雨过程中离散度较大,均值与降雨前差别不大;湍流强度和湍流积分尺度与降雨强度、平均粒子直径的相关性不明显,但在平均粒子直径1 mm附近,湍流强度和湍流积分尺度都出现极值;在降雨过程中,实测的各分量脉动风速功率谱与经验谱间在高频段存在一定差异,实测谱在高频段高于经验谱。

台风“威马逊”(1409)和“海鸥”(1415)影响广西风雨特征及预报偏差的比较分析

基于观测资料、数值模式产品及主观预报,对2014年超强台风“威马逊”和强台风“海鸥”影响广西的风雨特征及预报偏差进行对比分析。结果表明:(1)“威马逊”深入广西内陆,高层辐散更强,副高西脊点偏东,低层急流南北宽度更广且风速更大,台风强度更强,这是“威马逊”强降雨范围更广,小时雨强更强的可能原因。(2)主客观预报台风路径及强度随预报时效增加误差明显增大且差别较明显。ECMWF、广西遗传神经网络与中央台分别对台风路径、台风强度预报有很好的参考价值。(3)主客观均能报出强降水的形态但强度偏弱,预报误差随时效增加而增大且存在明显的空漏报。大暴雨量级预报评分ECMWF_HR明显高于广西主观,暴雨量级预报评分总体是广西主观优于ECMWF_HR。(4)ECMWF_HR没有准确预报副高西进南扩过程;副高预报的偏东偏北,是导致台风和急流中心偏南偏弱的可能原因。(5)ECMWF_HR预报850hPa水汽通量及其散度与实况在形态上基本一致,但位置偏西偏南,强度偏弱,这与预报副高偏东及台风偏西偏弱相关,应该引起今后业务预报关注。

ANALYSIS OF A TORNADO-LIKE SEVERE STORM IN THE OUTER REGION OF THE 2007 SUPER TYPHOON SEPAT

When super typhoon Sepat came close to the Fujian coastline on the night of 18 August 2007 (coded as 0709 in Chinese convention), an associated tornado-like severe storm developed at 2307–2320 Beijing Standard Time in Longgang, Cangnan County, Wenzhou Prefecture, Zhejiang Province approximately 300 km away in the forward direction of the typhoon. The storm caused heavy losses in lives and property. Studying the background of the formation of the storm, this paper identifies some of its typical characteristics after analyzing its retrieval of Doppler radar data, vertical wind shear and so on. Synoptic conditions, such as unstable weather processes and TBB, are also studied.

SIMULATION STUDY ON CAUSES OF TROPICAL STORM FITOW (0114) HEAVY RAIN

With PSU/NCAR nonhydrostatic mesoscale model MM5, the rainfall process of tropical storm Fitow(0114) is simulated for 00:00 UTC 31 Aug. – 00:00 UTC 2 Sept. 2001. Mesoscale separation is performed on the results with the filtering scheme. Analyses show that the MM5 model well reproduced the position and intensity of heavy rain. Mesoscale characteristics of heavy rain were well represented in rainfall time scale, rainfall area, stream field and divergence at lower and upper levels. The interaction between inverted typhoon troughs and the mesoscale systems lead to heavy rain occurrence. The distribution of divergence fields at lower and upper levels can have a kind of indication for the rainfall. Heavy rains are closely associated with topography and land-sea distribution in South China. Weak instability is favorable to the generation of heavy rain.

Climate as the Early Warning of Outbreaks of Leptospirosis in the District of Sampang Madura Island Indonesia

In Indonesia, most transmission of leptospirosis occurs through the rat under conditions of high rainfall or flooding. Sampang is endemic leptospirosis, during March-May 2013, there were 55 patients with 8 of them died. The purpose of this study was to analyze risk factors for outbreaks leptospirosis by climatic factors. Study is cross-sectional design of variable causes or risks that occur due to the object of research are measured simultaneously. The results showed that the distribution of events is based on epidemiological characteristics of leptospirosis in districts Sampang both rainy and dry season. Analysis of climatic factors show support to the continuation of leptospirosis whose temperatures ranged from 29.35 ~C-30.62 ~C, humidity range between 63.4%-80.5%. Rainfall ranges from 183-190 ram. Incidence of leptospirosis in Sampang shows the distribution of leptospirosis cases from 18 subdistricts, 14 subdistriets are at risk of the occurrence of leptospirosis. Results obtained rat trapping species caught in the neighborhood residential home patients were mice （Rattus tanezumi and Rattus novergicus） and the identification of the leptospira in rat urine sewers rat positive standing of the potential risk of leptospirosis in the community. The conclusions are climatic conditions, rainfall remarkable effecting on the incidence of leptospirosis.

Dynamics of local extreme rainfall of super Typhoon Soudelor (2015) in East China

The characteristics and dynamics associated with the distribution, intensity, and triggering factors of local severe precipitation in Zhejiang Province induced by Super Typhoon Soudelor(2015) were investigated using mesoscale surface observations, radar reflectivity, satellite nephograms, and the final(FNL) analyses of the Global Forecasting System(GFS) of the National Center for Environmental Prediction(NCEP). The rainfall processes during Soudelor's landfall and translation over East China could be separated into four stages based on rainfall characteristics such as distribution, intensity, and corresponding dynamics. The relatively less precipitation in the first stage resulted from interaction between the easterly wind to the north flank of this tropical cyclone(TC) and the coastal topography along the southeast of Zhejiang Province, China. With landfall of the TC in East China during the second stage, precipitation maxima occurred because of interaction between the TC's principal rainbands and the local topography from northeastern Fujian Province to southwestern Zhejiang Province. The distribution of precipitation presented significant asymmetric features in the third stage with maximal rainfall bands in the northeast quadrant of the TC when Soudelor's track turned from westward to northward as the TC decayed rapidly. Finally, during the northward to northeastward translation of the TC in the fourth stage, the interaction between a mid-latitude weather system and the northern part of the TC resulted in transfer of the maximum rainfall from the north of Zhejiang Province to the north of Jiangsu Province,which represented the end of rainfall in Zhejiang Province. Further quantitative calculations of the rainfall rate induced by the interaction between local topography and TC circulation(defined as "orographic effects") in the context of a one-dimensional simplified model showed that orographic effects were the primary factor determining the intensity of precipitation in this case,and accounted for over 50% of the total precipitation. The asymmetric distribution of the TC's rainbands was closely related to the asymmetric distribution of moisture resulted from changes of the TC's structure, and led to asymmetric distribution of local intense precipitation induced by Soudelor. Based on analysis of this TC, it could be concluded that local severe rainfall in the coastal regions of East China is closely related to changes of TC structure and intensity, as well as the outer rainbands. In addition, precipitation intensity and duration will increase correspondingly because of the complex interactions between the TC and local topography, and the particular TC track along large-scale steering flow. The results of this study may be useful for the understanding, prediction, and warning of disasters induced by local extreme rainfall caused by TCs, especially for facilitating forecasting and warning of flooding and mudslides associated with torrential rain caused by interactions between landfalling TCs and coastal topography.