应用红外云图亮温阈值法判断对流云团,统计分析2015-2019 年中国长三角地区盛夏副热带高压(副高)控制下的局地对流天气时空分布.结果表明:副高触发的对流天气频次日变化为午后单峰型,对流天气的高频区位于大城市附近、江南丘陵地区以及水陆交界处,而江河湖面、峡谷和盆地较少.副高偏南型的对流天气高频区位于山区和沿海地区,其低层处于有利于下垫面加热的偏西风场;副高偏北型高频区位于内陆,其低层的东风降低了沿海地区的下垫面温度,对流触发频率较小.不同对流参数的统计表明,对流有效位能对局地对流天气的触发有较明显参考.沿海地区的副高偏南型对流有效位能略高于副高偏北型,内陆地区相反.副高偏南型各站的抬升指数和抬升凝结高度均较低,表明该类型天气的不稳定性较强.

利用中国气象局上海台风所的WARMS高分辨率区域模式研究了上海地区三类主要的暴雨天气(准静止锋雨带型、副高边缘强对流型以及暖区雷暴型)对云微物理和边界层过程的敏感性.结果表明,不同云微物理和边界层参数化方案的组合对强降水中心的位置和强度影响较大,但是对主要雨带及走向影响不大.准静止锋雨带型采用Thompson方案模拟的整体降水量更多,WSM6方案模拟的强降水相关性更好,评分更高;副高边缘强对流型中WSM6-MYJ组合激发上海本地对流的效果更明显,但整个雨带来看Thompson方案更有优势;暖区雷暴型中WSM6-MYJ组合优势明显.总体上,Thompson-YSU组合能够模拟出准静止锋雨带型暴雨中丰富的液水含量和冰相粒子,以及较强的整层抬升作用;WSM6-MYJ组合则在副高边缘强对流型和暖区雷暴型这类型暴雨中刻画了较明显的强对流结构,使得地面降水更为强盛.

An application scheme of Poe based Ethernet technology in meteorological intelligent sensor system is designed. The working principle and implementation method of Ethernet power supply system (POE) based on IEEE802.3af Ethernet power supply industry standard are experimentally analyzed. The power supply part of the meteorological intelligent sensor makes full use of Poe technology to provide current on the network cable transmitting data, which greatly reduces the complexity of the power supply system and improves the reliability of the system power supply design. Through the test of the actual system, the function and performance of the meteorological intelligent transmission system have achieved the expected results.

利用欧洲中期天气预报中心和美国国家环境预报中心2017年5—8月逐日降水预报资料及同时段MICAPS降水观测资料,采用频率匹配技术对江淮流域夏季降水预报进行模式偏差订正及改进技术探讨.结果表明:(1)模式对小雨预报偏多,存在大量空报;对大雨及以上降水预报偏少,存在较大漏报.(2)偏差订正通过下调小量级降水、上调大量级降水,使各量级降水的强度和面积偏差均得到一定程度改善,降水量级两端订正效果明显,订正后小雨和暴雨准确率显著提升.(3)偏差订正对暴雨落区预报的改进效果与过程相关,个例分析表明:对于雨带位置预报较准确的大范围梅雨锋暴雨,偏差订正后暴雨TS评分明显提升;对于副高边缘的小范围暴雨以及雨带位置预报失误的梅雨锋暴雨或台风暴雨,偏差订正后暴雨TS评分改善不明显甚至降低.(4)针对上述问题,提出了系数动态调整和模式集成的改进思路,即对于平均雨量5 mm以下的小范围暴雨,适当上调订正系数;平均雨量在15 mm以上的大范围暴雨,适当下调订正系数.模式集成订正可有效提高暴雨TS评分.

提要:利用2018年4—8月格点降水分析资料和4个业务高分辨率区域模式降水预报资料,应用分位数频率匹配法对模式1h降水预报分别订正;基于上游关键区域的检验结果,采用动态权重多模式集成技术,探讨了多模式集成技术在短时强降水概率预报中的应用前景.结果表明:分位数频率匹配法对强降水预报改进具有正效果,可以减少模式的系统性偏差,提高模式降水预报的准确率.在短时临近时效内,上游关键区域降水信息对下游地区降水预报具有指示意义,基于上游关键区实况检验的动态权重多模式降水概率预报较简单集成概率具有更高的预报准确率,预报效果也更为稳定.个例分析也表明该技术对短时临近时效内的短时强降水预报预警有较好的指导作用.

β barrel outer membrane proteins (β-OMPs) play vital roles in mitochondria, chloroplasts, and Gram-negative bacteria. Evolutionarily conserved complexes such as the mitochondrial sorting and assembly machinery (SAM) mediate the assembly of β-OMPs. We investigated the SAM-mediated assembly of the translocase of the outer membrane (TOM) core complex. Cryo–electron microscopy structures of SAM–fully folded Tom40 and the SAM-Tom40/Tom5/Tom6 complexes at ~3-angstrom resolution reveal that Sam37 stabilizes the mature Tom40 mainly through electrostatic interactions, thus facilitating subsequent TOM assembly. These results support the β barrel switching model and provide structural insights into the assembly and release of β barrel complexes.

2020年7月18—19日,江淮地区出现一次特大暴雨过程,欧洲中期天气预报中心全球确定性预报模式(以下简称EC模式)、华东区域数值模式(以下简称华东模式)和国家气象中心Grapes高分辨区域模式(3 km分辨率,以下简称G3模式)预报的暴雨落区均明显偏北,且降水强度偏弱.通过对模式的风场及降水预报进行检验发现:模式天气形势预报的优劣,很多时候与模式的降水预报优劣是直接相关的,尤其是天气形势中的中低层风场,很容易受模式中降水潜热反馈过程的影响,导致错误的预报订正指引;比较而言,模式预报的高层流场,受潜热反馈过程影响较小,是值得在天气分析环节中加以重视的预报着眼点;此外,对于由中小尺度天气系统传播所致的大暴雨或特大暴雨,分辨率更高的区域模式预报结果可能具有更好的预报参考性,也是今后类似暴雨预报过程中应该重视的着眼点之一.

利用NCEP、ECMWF、日本数值、英国数值、上海台风模式和广州模式包含全球模式和区域在内的6家数值模式资料,利用近似SEAV方法,设计台风路径多模式集成预报方法(SHME),并用2014-2016年的台风客观预报数据进行多模式集成预报的效果检验,且与ECMWF模式进行比较,通过比较发现,SHME方法较ECMWF在12～48 h预报上有明显改进,在72～120 h预报2014年尤其突出,2015-2016年均与ECMWF预报效果相当.

首先利用上海77个区域站2011—2014年逐时气温和风资料,研究了地面风对上海城市热岛(urban heat island,UHI)的影响及UHI季节性空间分布特征的成因,并从海陆热力差异初步揭示了向岸风对热岛强度(urban heat island intensi-ty,IUHI)的影响.其次利用上海7个国家站1961—2014年逐月气温和风资料,研究了上海各季地面风速与IUHI的年际变化关系.结果表明:(1)UHI中心出现的位置与风向、风速有密切的关系,特别是夜间UHI中心有向城市下风方向漂移的特征,其平均漂移风速阈值为2 m·s-1,UHI区域随风速增大向城市下风方向延伸,IUHI随风速的增大而减小.(2)上海各季夜间UHI特征明显,尤以秋冬季最为明显,春季次之,夏季最弱.春夏季夜间UHI中心出现在城区西北侧,而秋冬季夜间UHI中心稳定在城区,表现为典型UHI.各季白天均表现为下风方大范围增暖现象.季节地面盛行风决定了UHI季节性空间分布特征.(3)白天向岸风具有抑制升温作用(春夏季最为明显),受其影响气温大值区易出现在内陆地区,春夏季城市偏东区IUHI小于偏西区;夜间向岸风具有抑制降温作用(秋冬季最为明显),受其影响秋冬季东部沿海地区出现明显增暖且城市偏东区IUHI大于偏西区.海陆热力差随季节不同和盛行风风速大小决定了向岸风这种作用的大小及影响范围.(4)各季年平均地面风速与IUHI均呈显著负相关,1961—2014年上海各季风速均表现为递减趋势(春冬季最明显),为IUHI增大提供有利条件.21世纪以来各季IUHI均呈现减缓特征(夏秋季最明显),风速并不是导致IUHI减缓的主要因素.

Using real-time correction technology for typhoons, this paper discusses real-time correction for forecasting the track of four typhoons during 2009 and 2010 in Japan, Beijing, Guangzhou, and Shanghai. It was determined that the short-time forecast effect was better than the original objective mode. By selecting four types of integration schemes after multiple mode path integration for those four objective modes, the forecast effect of the multi-mode path integration is better, on average, than any single model. Moreover, multi-mode ensemble forecasting has obvious advantages during the initial 36h.

2016年3月8日起,欧洲中期天气预报中心全球模式(以下简称ECMWF模式)进行了全面升级.利用常规气象资料和相关ECMWF模式预报资料,对ECMWF模式改进后的春雨期(3—5月)降水预报进行检验和分析,同时总结不同天气背景下,ECMWF模式降水预报的误差分布特征及原因.结果表明:2016年ECMWF模式对流性降水的落区预报偏差成为我国南方春雨期降水落区预报误差的主要来源;当环流背景表现为北方无明显冷空气南下,江南和华南地区受南支槽前西南暖湿气流控制时,模式容易在西南地区预报过多的对流性降水,而其下游地区则存在少报或漏报.

In this paper, 1416 conventional ground-based meteorological observation stations on the mainland of China were subdivided into groups of differing spatial density. Data from each subgroup were then used to analyze variations in the tropical cyclone (TC) precipitation statistics derived from each subgroup across the mainland of China (excluding Taiwan, Hong Kong, and Macao), as well as in two regions (east China and south China) and three provinces (Guangdong, Hainan, and Jiangxi) between 1981 and 2010. The results showed that for the mainland of China, total precipitation, mean annual precipitation, mean daily precipitation, and its spatial distribution were the same regardless of the spatial density of the stations. However, some minor differences were evident with respect to precipitation extremes and their spatial distribution. Overall, there were no significant variations in the TC precipitation statistics calculated from different station density schemes for the mainland of China. The regional and provincial results showed no significant differences in mean daily precipitation, but this was not the case for the maximum daily precipitation and torrential rain frequency. The maximum daily precipitation calculated from the lower-density station data was slightly less than that based on the higher-density station schemes, and this effect should be taken into consideration when interpreting regional climate statistics. The impact of station density on TC precipitation characteristics was more obvious for Hainan than for Guangdong or Jiangxi provinces. In addition, the effects were greater for south China (including Guangxi Zhuang Autonomous region, Guangdong, and Hainan provinces) than east China (including Shandong, Jiangsu, Zhejiang, Shanghai, Fujian, Anhui, and Jiangxi provinces). Furthermore, the analysis proved that the statistical climatic characteristics began to change significantly when the station spacing was between 40 and 50 km, which are close to the mean spacing for all stations across the mainland of China. Moreover, TC areal precipitation parameters, including mean total areal precipitation and mean daily areal precipitation, also began to change significantly when the spacing was between 40 and 50 km, and were completely different when it was between 100 and 200 km.

Combined with observation data and numerical model products,meteorological conditions in "20160227" marine accident of Qingdao and its forecast are analyzed and reflected.The results show that (1)Foggy area near the accident point originates from south part of Qingdao coastal water.It spreads towards north and east then,and only extends to 50～60 km from the coastal line characterized as local offshore fog.(2)Both advection and radiation factors favor to the development of this fog event.The fact that all operational numerical model products haven't provided useful guidance during the event reflects our poor forecast skill for offshore fog.(3) All official meteorological units fail to forecast this offshore fog in advance.There exists a big disparity between our current ability in marine meteorological service and needs from relevant sectors.In respect of CMA's marine meteorological operations,inexperienced staff,manpower shortage,products without pertinence and lag-behind dissemination in provincial or prefectural meteorological offices have seriously restrained the advances of related services.An operational marine fog ensemble forecast system would be a crucial support for the future operations.Currently,combination synoptic situation with latest observation could facilitate a better forecast or waming.

评估分析了欧洲中期天气预报中心(European Centre for Medium-range Weather Forecasts,ECMWF)细网格模式(以下简称EC-thin)在长三角地区汛期(5—9月)的暴雨预报评分及ECMWF降水极端天气预报指数(EFI)对暴雨预警的指示作用.研究发现:(1)EC-thin降水和降水EFI对暴雨预报的ETS评分随着预报时效的延长而明显降低,在短时效内,细网格模式降水预报占优,超过60 h后,降水EFI的评分相对更好.(2)对EC-thin降水而言,在不同的预报时效采用不同的降水阈值来预报暴雨,可望达到最佳的评分效果.短期时效内该阈值随着预报时效的延长,大致从55 mm逐渐下降到35 mm.(3)对于降水EFI而言,12—36 h内EFI为0.65～0.7时,暴雨预报ETS评分最高.随着预报时效的延长逐渐下降,60—84 h内EFI为0.55～0.6时,暴雨预报ETS评分最高.(4)在不同预报时效内,采用合理的方式和阈值综合考虑EC-thin降水和降水EFI,可望得到更高的暴雨预报评分.

After a careful rethink on short-range forecast of the northern Henan severe rainstorm on 9 July 2016,we found that there existed obvious alternate growing and merging of convective clouds during this rainstorm event involving interaction of meso-small scale systems.As important guidance,all global models,including deterministic and ensemble ones,failed to provide effective forecasts or hints in advance for this event.High resolution regional models and rapid refresh systems performed better and could help forecasters to predict heavy or very heavy rainfall events in northern Henan 12 h or 6 h earlier.Reasons for the forecast failure of this severe rainstorm process are that forecasters relied too much on global models and were lack of experience on high resolution model application or confidence in products from high resolution models.Only more comprehensive trainings on high resolution model for forecasters before putting them into use could forecasters maximize their operational potential.Applying more probabilistic products gradually in QPF decision process would meet the trend of technological advance and could provide more effective supports for heavy or extreme rainfall forecasting.

In preparation for the Fourth International Workshop on Tropical Cyclone Landfall Processes (IWTCLP-IV), a summary of recent research studies and the forecasting challenges of tropical cyclone (TC) rainfall has been prepared. The extreme rainfall accumulations in Hurricane Harvey (2017) near Houston, Texas and Typhoon Damrey (2017) in southern Vietnam are examples of the TC rainfall forecasting challenges. Some progress is being made in understanding the internal rainfall dynamics via case studies. Environmental effects such as vertical wind shear and terrain-induced rainfall have been studied, as well as the rainfall relationships with TC intensity and structure. Numerical model predictions of TC-related rainfall have been improved via data assimilation, microphysics representation, improved resolution, and ensemble quantitative precipitation forecast techniques. Some attempts have been made to improve the verification techniques as well. A basic forecast challenge for TC-related rainfall is monitoring the existing rainfall distribution via satellite or coastal radars, or from over-land rain gauges. Forecasters also need assistance in understanding how seemingly similar landfall locations relative to the TC experience different rainfall distributions. In addition, forecasters must cope with anomalous TC activity and landfall distributions in response to various environmental effects.

Based on the conventional observational data at the surface and upper levels,satellite cloud images and numerical modelling products,the evolution characteristics and causes of a radiation heavy fog event from November 29 to December 1,2015 in Shanghai and the coastal region are investigated.The heavy fog process was predicted using the WRF (Weather Research and Forecasting) model and ECMWF (European Center for Medium-range Weather Forecasting) models.The results show that the heavy fog event is mainly caused by the radiation cooling effect and is characterized by strong intensity and long duration of near-sea fog.The heavy fog event can be divided into three periods:the formation of radiation fog on land and coastal region at the nighttime on November 29,the disappearance of fog on land at day on November 30,and the advection and enhancement of fog from near sea to coastal region in the evening on November 30 till the end of this fog event in the morning on December 1.This heavy fog event forms earlier than normal radiation fog events,mainly because of the continuous descending of low cloud ceiling and radiation cooling.Poor radiation heating and increasing humidity maintain the fog over the near sea surface for a long time period.When the fog over the near sea area moves towards the coastal land at night,the fog advection and radiation cooling effects result in the heavy fog again.Both the WRF model and the high-resolution EC model were not very successful to predict this heavy fog event,probably due to the poor simulation of humidity at lower levels.Thus,synthesis analysis using cloud images and AWS (Automatic Weather Station) data at the coastal region is still an important mean for the short-time forecast of coastal fog,before the numerical weather prediction models are accurate enough to meet the operational requirements.

By means of combining NWP outputs and historical observation data,a precipitation probability forecast method based on relative humidity is established.Fine-grid forecasting results of relative humidity from EC model during the year 2012 and 2013 in eastern China are classified into different vertical layers and different moisture grads.The historical precipitation probability corresponding to these layers and grads are analyzed to find out a relationship between the forecast humility and precipitation probability.The relative humidity predicted by the current forecast model is then used to estimate the future precipitation probability.Different methods such as ETS score,Brier score,reliability map and case study are used to verify the forecasting effects of precipitation from July 2013 to May 2014.The results show that the method can produce fairly good distribution of future precipitation.The effects of synoptic-scale rain band appear to be better than those of convective precipitation.The false forecasting rate is effectively reduced compared with EC model results.The precipitation production can be used to specify the location and probability of the precipitation and provides a better reference value.

2016年超强台风"尼伯特"和"莫兰蒂"的路径极为相似,登陆福建北上途经太湖流域后入海的路径也几乎重合,但太湖流域出现的降水却迥然不同,前者仅造成了太湖流域个别测站的暴雨-大暴雨,后者则出现大范围暴雨-大暴雨.利用常规气象观测资料、多普勒雷达资料、中国气象局的台风最佳数据集及美国国家环境预报中心(NCEP)提供的再分析资料等,对两个台风登陆后的环流背景、台风结构特征等进行了对比分析.结果发现:"莫兰蒂"登陆后的低压环流结构保持良好,北上过程中与外围浅层冷空气的相互作用明显,海上水汽输送通道畅通,台风倒槽导致太湖流域大范围暴雨-大暴雨;"尼伯特"登陆后迅速减弱,环流结构出现"空心化",水汽输送弱,高层弱冷空气与台风残余低涡的叠加触发局地短时强降水,未能导致太湖流域大范围暴雨.从预报回顾看,模式对登陆台风北上过程中强度预报过强是导致"尼伯特"在太湖流域风雨预报过度的主要原因.3d以上的中期台风降水预报中,经验概念模型与模式集合预报结果的相互印证,有利于得出比模式确定性降水预报更合理的预报结论.

Timely and relatively accurate detection of the center position of a near-landfalling typhoon is essential for weather forecasts, warning, disaster preparedness and data assimilation. Due to the vortex like nature of the flow near the typhoon center, the Zero Radial Velocity Line (ZRVL) of a Doppler radar extends through the typhoon center and the radar site. This paper proposes a method to detect the typhoon center by intersecting the ZRVLs of a dual-Doppler radar system. Simulation with Rankine Vortex model shows the validity of this method. This paper also evaluated the method by locating the centers of Typhoon FUNG-WONG (No. 201416) which impacted the east coastal regions of China from the afternoon of 22 September to the morning of 23 September, 2014 BST (Beijing Standard Time). During this period, the centers of the coastal typhoon were precisely positioned by intersecting the ZRVLs of two Doppler radars. The positioning accuracy of this method is comparable to that from Automatic Weather Stations (AWS) wind data. This method is suitable for areas where AWS data are unavailable, supposing radars are apart 100 km with a maximum unambiguous distance of 148km, this technique can cover most regions effectively.