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1.
一次大暴雨过程的多普勒雷达资料同化的敏感性试验   总被引:3,自引:1,他引:2  
利用WRF中尺度模式及WRF-3DVAR变分同化系统和LAPS雷达资料前处理模块建立试验平台,直接同化S波段多普勒雷达反射率和径向速度资料,通过对2008年8月15-16日发生在我国长江中游的一次大暴雨过程的各项预报对比试验研究,初步检验和评估不同种类多普勒雷达观测数据同化对改进数值模式初始场及其数值预报能力的影响及作用.初步结果表明:多普勒雷达资料同化对提高暴雨数值预报能力有重要作用.无论在24 h累计降水还是在逐时降水预报方面,同化多普勒雷达资料均可使降水雨带分布和强降水中心预报的准确性得到较大改善;多普勒雷达反射率资料同化对初始水汽场的改变显著,对初始风场影响较小,而同化径向速度对初始水汽场的改变较小,但可增加初始风场的中小尺度信息,使初始风场产生较大变化.总体上看,虽然雷达反射率和径向速度资料同化均可改进强暴雨的数值预报,但雷达反射率资料同化对降水雨带和中心预报的改进更为显著和重要.  相似文献   

2.
多普勒天气雷达资料对中尺度模式短时预报的影响   总被引:22,自引:8,他引:22  
利用中尺度模式ARPS(The Advanced Regional Prediction System)及其资料分析系统ADAS(ARPS Data Analysis System),将国内新一代多普勒雷达(CINRAD)反射率及径向风资料直接用于中尺度数值模拟,通过一次华北地区暴雨过程的模拟对比试验,分析了雷达资料对初始场的改进效果及其对模拟结果的影响,结果表明:(1)利用雷达径向风资料对初始风场进行调整后,自近地面到对流层顶的u,v,w都发生了变化,调整后的初始风场在对流层中层变化最大.(2)利用雷达反射率进行微物理调整和云分析能调整初始场中的云水信息,使得雷达回波附近3 km以下的水汽混合比(qv)增加,4 km以下的雨水混合比(qr)增加,对流层(约10 km以下)的云水混合比(qc)增加,4~9 km的对流层上部云冰混合比(qi)和雪混合比(qs)增加.ADAS通过非绝热初始化调整温度场,从而得到了一个动力和热力上平衡的初始场.(3)模拟的1 h雨量与实况的对比表明,同时利用雷达反射率和径向风改进过的初始场能明显增强3 h内的降水强度和落区预报,改善中尺度数值模式短时定量降水预报.模拟的1 h流场对比分析表明,经雷达径向风调整后,能够在初始场中增加气旋性涡旋等中小尺度风信息,明显减少模式的spin-up时间.(4)通过对雷达径向风和反射率对模式初始场和模拟结果影响的对比分析发现,雷达径向风主要是改进初始风场,而雷达反射率主要是改进初始场中的湿度参数,增加初始场中云水等的含量,调整温度场.通过模拟的6 h降水对比发现,利用雷达径向风调整初始场后,对降水模拟有一定的改进,但效果不甚明显,而雷达反射率资料对定量降水预报改进效果明显,同时使用雷达径向风和反射率资料改进初始场后对降水的模拟效果最明显.  相似文献   

3.
利用ARPS模式(Advanced Regional Prediction System)的资料分析系统ADAS(ARPS Data Analysis Sys-tem),以NCEP GFS资料为背景场对我国西北地区CINRAD-CB\CC型雷达反射率资料进行同化试验研究,并借助于WRF(Weather Research and Forecasting Model)模式,对发生在黄河河套及河北地区的一次天气过程进行个例模拟试验。不同模拟方案模拟结果的对比分析和短时预报检验表明:①C波段雷达反射率资料的引入与S波段雷达反射率资料在空间覆盖上构成互补,与卫星、地面等资料的云综合分析能够分析出与实况更为接近的降水场和垂直结构信息;②同化了C波段雷达反射率资料的试验方案在模拟回波系统演变上优于未同化的,但由于模拟低层暖湿条件不足,系统逐渐衰弱与实况不符;③对比实况降水发现,区域C波段雷达反射率资料的同化对短时降水预报效果有一定改善。  相似文献   

4.
珠江流域4~9月降水空间分布特征和类型   总被引:2,自引:1,他引:1       下载免费PDF全文
利用美国CAPS的非静力高分辨率区域预报模式ARPS(先进区域预报系统)对0414号台风"云娜"进行数值模拟,模拟结果表明ARPS较好地模拟台风"云娜"的移动路径及台风大暴雨.并着重讨论新一代天气雷达资料对台风"云娜"数值模拟的影响,通过对雷达资料同化进模式与没有雷达资料同化进模式对比模拟的试验结果分析表明:雷达资料进模式,对中高层的风场调整,改进对台风细微结构特征描述,加大近台风中心南侧的西风分量和近台风中心西侧的北风分量,从而改进云娜台风登陆后西行移动路径预报;对扰动温度、雨水混合率、云水混合率及水汽混合率场等调整,改善模式初始场台风中高层成雨条件,对台风降水预报,尤其暴雨的落区、降水分布及其随时间变化的预报有较大改进.  相似文献   

5.
利用美国CAPS的非静力高分辨率区域预报模式ARPS(先进区域预报系统)对0414号台风“云娜”进行数值模拟,模拟结果表明ARPS较好地模拟台风“云娜”的移动路径及台风大暴雨。并着重讨论新—代天气雷达资料对台风“云娜”数值模拟的影响,通过对雷达资料同化进模式与没有雷达资料同化进模式对比模拟的试验结果分析表明:雷达资料进模式,对中高层的风场调整,改进对台风细微结构特征描述,加大近台风中心南侧的西风分量和近台风中心西侧的北风分量,从而改进云娜台风登陆后西行移动路径预报;对扰动温度、雨水混合率、云水混合率及水汽混合率场等调整,改善模式初始场台风中高层成雨条件,对台风降水预报,尤其暴雨的落区、降水分布及其随时间变化的预报有较大改进。  相似文献   

6.
一次大气波导过程的数值模拟   总被引:4,自引:2,他引:2       下载免费PDF全文
胡晓华  费建芳  张翔  韩锐 《气象科学》2008,28(3):294-300
利用ARPS模式对南京周围地区的一次大气波导过程进行了数值模拟,通过对南京站初始时刻、 6 h和14 h的模拟结果分析表明:同化探空资料的初始场较NCEP资料更接近实况,初始场对预报结果的影响具有一定的持续性,且同化了探空资料的初始场的模拟结果比未同化探空资料的初始场的模拟结果较接近于真实大气状况;同化多个测站探空资料的数值模拟表明ARPS模式对大气波导具有一定的预报能力.  相似文献   

7.
《气象》2021,(8)
为了更好地应用闪电观测资料,在华中区域快速更新循环同化系统中引入适用于本地的闪电定位资料与代理回波特征的转换关系,并开展了相应的同化应用研究。针对2015年6月1日发生在湖北监利的一次强降水过程,开展了利用新、旧闪电-代理回波的对比同化试验,重点分析了引入新的闪电-代理回波转换关系对模式计算的雷达反射率、云微物理变量和降水预报的影响,并与直接同化雷达反射率进行对比。数值试验结果表明:新的闪电-代理回波关系较好地捕捉到强降水信号,通过调整初始时刻云水、雨水、云冰、云雪、霰等微物理量,尤其是提高了初始时刻雨水、云水的含量,达到调整降水预报的目的;对比降水结果可以得到在使用新的闪电-雷达回波关系后,能够有效降低漏报率,并且模式在短时间尺度可以响应出与实况更为接近的降水预报,提高短时临近预报准确率,取得了与直接同化雷达反射率相似的结果。  相似文献   

8.
卫星资料在模式初值中的初步应用研究   总被引:1,自引:0,他引:1       下载免费PDF全文
运用物理初值化方法,将气象卫星资料引入模式初始场,使初始场向观测场逼近,试图改进由于初始资料不完善而造成的模式积分前期降水量偏少的现象。应用ARPS中尺度模式对天津地区的一次强降水天气过程进行了数值模拟对比试验,结果表明,加入卫星观测资料后,部分卫星观测为对流云区,水汽和云水物质的水平和垂直分布进行了较为明显的调整,模式的临近短时降水预报也有明显增强的趋势。可判断出模式的初始状况更接近观测实际,对提高中小尺度天气系统的短期和临近预报的准确率有积极作用。  相似文献   

9.
李华宏  曹杰  王曼  胡娟  闵颖 《气象科技》2014,42(5):823-831
为了改善低纬高原地区天气预报水平,利用WRF(Weather Research and Forecasting)模式及其变分同化系统进行雷达VAD(Velocity Azimuth Display)反演风场资料同化试验。通过设计不同的试验方案,对2009年6月30日00:00至7月1日00:00发生在云南的一次强降水过程进行数值模拟和对比分析,结果表明:同化VAD反演风场资料后对区域模式的风矢量初始场有明显影响。同化系统能把雷达反演风场信息有效地引入模式初始场,改善强降水区域的水汽输送和风场辐合强度;同化VAD反演风场资料后对区域模式累计降水预报有一定改进作用。从长时间累计降水量定量检验结果看,具体表现为25mm以上量级的降水准确率明显提高、漏报率下降,预报偏差更趋合理。不同的同化试验方案之间的模拟结果差异较大。同化频率越高、同化持续时间越长,对区域模式初始场和预报场的影响越明显。但同化持续时间不宜过长,否则可能导致系统移速过快、降水强度偏大、空报率增加等异常。  相似文献   

10.
李新峰  赵坤  王明筠  明杰 《气象科学》2013,33(3):255-263
高分辨率的中尺度预报模式ARPS及其3DVAR/云分析系统,针对2010年登陆福建的超强台风“鲇鱼”,研究对流可分辨尺度下,每1h循环同化沿海新一代多普勒雷达网资料分析、研究对台风初始场和预报场的改进作用.结果表明:单独同化雷达资料可显著改善初始场中的台风内核区动力和热力结构,以及台风强度和位置,进而提高18h台风强度、路径和降水预报,但预报路径和降水分布与实况仍存在差异.在雷达资料同化基础上加入常规观测资料,对初始场中台风内核区结构改进不大.但在显著调整大尺度背景场,从而进一步减少台风路径预报误差,能准确预报出福建沿海两个强降水区域的位置和强度.总体而言,雷达资料同化主要提高台风结构分析,而常规观测资料同化主要改善环境场分析,两者有效结合使得预报结果和实况最为接近.  相似文献   

11.
The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.  相似文献   

12.
Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter.  相似文献   

13.
The moving-window correlation analysis was applied to investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the synchronous autumn precipitation in Huaxi region, based on the daily precipitation, sea surface temperature (SST) and atmospheric circulation data from 1960 to 2012. The correlation curves of IOD and the early modulation of Huaxi region’s autumn precipitation indicated a mutational site appeared in the 1970s. During 1960 to 1979, when the IOD was in positive phase in autumn, the circulations changed from a “W” shape to an ”M” shape at 500 hPa in Asia middle-high latitude region. Cold flux got into the Sichuan province with Northwest flow, the positive anomaly of the water vapor flux transported from Western Pacific to Huaxi region strengthened, caused precipitation increase in east Huaxi region. During 1980 to 1999, when the IOD in autumn was positive phase, the atmospheric circulation presented a “W” shape at 500 hPa, the positive anomaly of the water vapor flux transported from Bay of Bengal to Huaxi region strengthened, caused precipitation ascend in west Huaxi region. In summary, the Indian Ocean changed from cold phase to warm phase since the 1970s, caused the instability of the inter-annual relationship between the IOD and the autumn rainfall in Huaxi region.  相似文献   

14.
正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment.  相似文献   

15.
Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.  相似文献   

16.
Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.  相似文献   

17.
Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.  相似文献   

18.
正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on  相似文献   

19.
Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.  相似文献   

20.
The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o.  相似文献   

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