“频率匹配法”在集合降水预报中的应用研究   总被引：8，自引：1，他引：7  

李俊  杜钧  陈超君 《气象》2015,41(6):674-684

基于“频率匹配法”的思路,采用两种方法进行了集合降水预报的订正研究,一种方法是利用集合成员降水频率订正简单集合平均平滑效应的“概率匹配平均”法,另一种方法是利用实况降水频率订正集合成员降水预报系统偏差的“预报偏差订正”法,通过个例和批量试验,结果表明:(1)概率匹配平均法可以矫正简单集合平均的平滑作用所造成的小量级降水分布范围增大而强降水被削弱的负作用,这种改进对强降水区更显著,并且集合系统离散度越大这种改进也越大;但该方法对预报区域内总降水量的预报没有改进作用,不能改善预报的系统性偏差.(2)虽然预报偏差订正法对降水落区预报的改进有限,但可以订正模式降水预报的系统性误差,改进雨量预报以及集合预报系统的离散度特征和概率预报技巧;直接对集合平均预报进行偏差订正的效果优于单个成员偏差订正后的简单算术平均.(3)在对每个集合成员的降水预报进行偏差订正后,概率匹配平均仍可改善其简单平均的效果,因此在实际业务中,应该综合采用上述两种方法,以获得在消除系统性偏差的同时各量级降水分布又合理的集合平均降水预报.  相似文献   

2014年中国气候概况   总被引：6，自引：4，他引：2  

侯威  邹旭凯  王朋岭  叶殿秀  周兵  黄大鹏  李莹  赵琳  王有民  朱晓金  赵珊珊  王阳  钟海玲 《气象》2015,41(4):480-488

2014年,全国平均气温较常年偏高0.5℃,与1999年并列为1961年以来第六暖年;四季气温均偏高。全国平均降水量636.2 mm,接近常年,比2013年偏少3%;降水时空分布不均,辽宁、北京和河北偏少明显,冬、春、夏三季降水量均接近常年同期,秋季偏多。华南前汛期开始早、雨量多;西南雨季开始晚、结束早、雨量少;梅雨区降水量南多北少,江淮出现空梅;华北雨季不明显,出现空汛;华西秋雨开始早、结束晚、雨量多。夏季副热带高压脊线位置偏南,南海夏季风爆发晚,东亚夏季风强度略偏弱。2014年,我国气候属正常年景,极端天气气候事件少于2013年,暴雨洪涝、干旱等灾害偏轻,因灾造成死亡人数和受灾面积明显偏少,气象灾害属于偏轻年份。  相似文献   

孟加拉湾超级风暴费林对西藏强降水的影响分析     

德庆  徐珺  宗志平  赤曲  罗布坚参  代华光 《气象》2015,41(9):1086-1094

利用NCEP/NCAR(2.5°×2.5°)再分析资料和常规、非常规观测资料,通过环境场和中尺度特征较全面细致地分析了孟加拉湾风暴费林（Phailin）对西藏特大暴雪的影响。研究表明：“费林”对强降水的影响主要是登陆减弱为低压后,低压云系分两个阶段形成三个中尺度对流云团,对流云团在南支槽的作用下上高原。而强降水的发生和南风风速的大小有直接的对应关系,西南低空急流建立后西藏南部才出现强降水,而低空急流的建立是靠南支槽的贡献。南风风速和强降水的这一重要关系为此类天气提供了预报着眼点。  相似文献   

安徽滁州夏季一次飑线过程的雨滴谱特征   总被引：4，自引：3，他引：1       下载免费PDF全文

金祺  袁野  纪雷  鲁德金  冯静夷 《应用气象学报》2015,26(6):725-734

选取2014年7月31日安徽滁州一次飑线过程,使用地基雨滴谱仪资料分析此次过程的雨滴谱特征。根据雷达回波和地面降水强度将这次降水过程划分为对流降水、过渡性降水和层云降水,并以10 mm·h-1为临界值将对流降水进一步划分为对流前沿降水、对流中心降水、对流后沿降水。结果表明:对流中心降水、过渡性降水、层云降水的质量加权直径均比较稳定,平均值分别为1.8 mm, 1.0 mm, 1.7 mm。对流降水的标准化截距相比层云降水更大。对流中心降水各粒径段雨滴数浓度均较高;层云降水小雨滴浓度较低,且有少量大雨滴;过渡性降水由小雨滴组成。当雨水含量相同时,层云降水的质量加权直径相比对流降水更大。当雨强相同时,层云降水的反射率因子相比对流中心降水更大。更为精细的降水类型划分可有效改善Z-I关系。  相似文献   

一种改进的数值预报降水偏差订正方法及应用   总被引：3，自引：3，他引：0       下载免费PDF全文

孙靖  程光光  张小玲 《应用气象学报》2015,26(2):173-184

对传统的消除偏差法进行改进,形成分等级消除偏差法,并使用混合训练期和60 d滑动训练期方案分别对2012年6—8月ECMWF (European Centre for Medium-Range Weather Forecasting) 模式夏季1~5 d的降水预报进行订正试验。为了尽可能符合中国东部夏季降水具有移动性及多种时间尺度变化的特点,混合训练期以预报期前30 d与预报期前一年同日的前后各15 d组成。结果表明:在使用分等级消除偏差法的基础上,相比ECMWF模式降水预报,两种训练期方案的订正结果几乎对各个阈值的ETS评分均有一定提高,特别是对25 mm以上降水预报评分的提高幅度,混合训练期方案的订正结果明显高于60 d滑动训练期方案;在区域性强降水预报的订正中,混合训练期方案优势更为明显。另外,通过分析两种训练期方案的预报偏差发现,分等级订正是此次消除偏差订正试验中提高强降水预报评分的关键,选择合适的训练期可以增加评分提高的幅度。由于上述试验使用的ECMWF模式预报和站点实况均是业务上常用数据,因此,该方法具有一定的业务应用价值。  相似文献   

IMPACT OF SSTA OF SOUTHERN HEMISPHERE ON FLOOD SEASON PRECIPITATION ANOMALIES IN YUNNAN     

杨竹云  杨素雨  严华生  张瑾文 《热带气象学报(英文版)》2015,21(3):255-264

Based on the reanalysis data of monthly mean global SST and wind from the NCEP/NCAR and the observation data of rain seasons in 124 stations of Yunnan province from 1961 to 2006, we applied the analytical methods of correlation analysis and composite analysis and a significance testing method to two sets of samples of average differences. The goal is to investigate into the influence of the Southern Hemispheric (SH) SST on the summer precipitation in Yunnan from January to May so as to identify the key time and marine regions. Physical mechanisms are obtained by analyzing the influence of sea level wind and the key marine regions on the precipitation during Yunnan’s rain season. Results show that there is indeed significant relationship between the SST in SH and summer precipitation in Yunnan. The key areas for influencing the summer precipitation are mainly distributed in a region called “West Wind Drift” in the SH, including the Southeast Indian, southern Australia, west coast of eastern Pacific off Chile, Peru and the southwest Atlantic Magellan. Besides, the most significant marine region is the west coast of Chile and Peru (cold-current areas of the eastern Pacific). Diagnostic analysis results also showed that monsoons in the Bay of Bengal, a cross-equatorial flow in the Indian Ocean near the equator and southwest monsoon in India weaken during the warm phase of the Peruvian cold current in the eastern Pacific. Otherwise, they strengthen.  相似文献   

IMPACT OF TROPICAL INTRASEASONAL OSCILLATIONS ON THE PRECIPITATION OF GUANGDONG IN JUNES     

林爱兰  李春晖  谷德军  郑彬 《热带气象学报(英文版)》2015,21(4):326-336

The impact of tropical intraseasonal oscillations on the precipitation of Guangdong in Junes and its physical mechanism are analyzed using 30-yr (1979 to 2008), 86-station observational daily precipitation of Guangdong and daily atmospheric data from NCEP-DOE Reanalysis. It is found that during the annually first rainy season (April to June), the modulating effect of the activity of intraseasonal oscillations propagating eastward along the equator (MJO) on the June precipitation in Guangdong is different from that in other months. The most indicative effect of MJO on positive (negative) anomalous precipitation over the whole or most of the province is phase 3 (phase 6) of strong MJO events in Junes. A Northwest Pacific subtropical high intensifies and extends westward during phase 3. Water vapor transporting along the edge of the subtropical high from Western Pacific enhances significantly the water vapor flux over Guangdong, resulting in the enhancement of the precipitation. The condition is reverse during phase 6. The mechanism for which the subtropical high intensifies and extends westward during phase 3 is related to the atmospheric response to the asymmetric heating over the eastern Indian Ocean. Analyses of two cases of sustained strong rainfall of Guangdong in June 2010 showed that both of them are closely linked with a MJO state which is both strong and in phase 3, besides the effect from a westerly trough. It is argued further that the MJO activity is indicative of strong rainfall of Guangdong in June. The results in the present work are helpful in developing strategies for forecasting severe rainfall in Guangdong and extending, combined with the outputs of dynamic forecast models, the period of forecasting validity.  相似文献   

COMPARISONS OF CIRCULATION ANOMALIES BETWEEN THE DAILY PRECIPITATION EXTREME AND NON-EXTREME EVENTS IN THE MIDDLE AND LOWER REACHES OF YANGTZE RIVER IN BOREAL SUMMER   总被引：1，自引：1，他引：0  

韩洁  管兆勇  李明刚 《热带气象学报(英文版)》2015,21(2):131-142

Based on the NCEP/NCAR reanalysis dataset and in situ meteorological observations of daily precipitation in boreal summer from 1979 to 2008, the features of circulation anomalies have been investigated using the composite analysis for the extreme events and non-extreme events of regional mean daily rainfall(RMDR) occurring over the midand lower- Yangtze valley(MLYV). The extreme RMDR(ERMDR) events are the events at and above the percentile99 in the rearranged time-series of the RMDR with ascending order of rainfall amount. The non-extreme RMDR events are those at the percentiles 90-85 and 80-75 separately. Our results suggest that the threshold value is 25 mm/day for the ERMDR at percentile 99. Precipitation at all the percentiles is found to occur more frequently in the Meiyu rainfall season in MLYV, and the ERMDR events have occurred with higher frequency since the 1990 s. For the percentiles-associated events, the MLYV is under the control of an anomalous cyclonic circulation in the mid- and lower- troposphere with vastly different anomalous circulation at higher levels. However, at both low and high levels, the ERMDR events-related anomalous circulation is stronger compared to that linked to the non-ERMDR events. The dominant sources of water vapor differ between the ERMDR and non-ERMDR events. During the ERMDR events plentiful water vapor is transported from the Bay of Bengal into the MLYV directly by divergence while there is distinctly increased water vapor from the South China Sea(SCS) in non-RMERMDR episodes. The diabatic heating rates < Q1>, < Q2> and< Q1>- < Q2> have their anomalous patterns and are consistent with each other for these percentiles but their strength decreases markedly with the drop of rainfall intensity. For the precipitation at percentiles 99 and 90-85, the sea surface temperature anomalies(SSTA) in the Pacific distribute positively(negatively) in the south(north), and are stronger when the ERMDR emerges, with little or no SSTA as the events at percentile 80-75 occur. Besides, these results suggest that the genesis of the ERMDR event is directly related to intense local circulation anomalies and the circulation anomalies over the Pacific and SCS in tropical to mid-latitudes, and probably linked with the Pacific SSTA closely while the non-ERMDR events are mainly associated with the anomalous circulation on a local basis. The findings here help understand and predict the happening of ERMDR events over the MLYV.  相似文献   

IMPACT OF ENSO ON THE PRECIPITATION OVER CHINA IN WINTER HALF-YEARS     

李天然  张人禾  温敏 《热带气象学报(英文版)》2015,21(2):161-170

In this paper, the impact of ENSO on the precipitation over China in the winter half-year is investigated diagnostically. The results show that positive precipitation anomalies with statistical significance appear over southern China in El Nio episodes, which are caused by the enhanced warm and humid southwesterlies along the East Asian coast in the lower troposphere. The enhanced southwesterlies transport more water vapor to southern China, and the convergence of water vapor over southern China increases the precipitable water and specific humidity. In La Nia episodes,although atmospheric elements change reversely, they are not statistically significant as those in El Nio periods. The possible physical mechanism of the different impact of ENSO cycle on the precipitation over southern China is investigated by analyzing the intraseasonal oscillations(ISOs) in El Nio and La Nia winter half-years, respectively. By comparing the characteristics of ISOs in El Nio and La Nia, a physical mechanism is proposed to explain the different responses of the precipitation over China to ENSO in the winter half-year. In El Nio episodes, over western North Pacific(WNP) and South China Sea(SCS) the ISOs are inactive and exert little effect on water vapor transport and convergence, inducing positive precipitation anomalies with statistical significance over southern China in El Nio episodes. In La Nia episodes, however, the ISOs are active, which weaken the interannual variation signals of ENSO over WNP and southern China and lead to the insignificance of the interannual signals related to ENSO. Therefore, the different responses of precipitation over China to ENSO in the winter half-year are possibly caused by the difference of intraseasonal oscillations over WNP and SCS between El Nio and La Nia.  相似文献   

海洋产脲酶细菌的筛选及诱导形成碳酸钙矿物的特征     

陈慧佳  张慧卿  冯莹  魏士平 《现代地质》2022,36(1):212-220

产脲酶细菌普遍存在于自然界,其对碳酸钙的矿化作用被广泛用于工程地质和环境等各项工程领域;本研究旨在从北戴河新河河口海洋沉积物中分离产脲酶细菌,探讨其诱导形成碳酸钙的特征,为地质与工程领域的应用提供良好的材料.从海洋沉积物样品中共分离出33株细菌,经筛选,其中有10株细菌具有产脲酶活性,16S rRNA基因序列分析表明:...  相似文献