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1.
基于逐小时地面常规观测资料、L波段探空资料、风廓线雷达风场资料和日本葵花气象卫星数据及ERA-Interim再分析资料,对2018年2月15—25日琼州海峡持续性海雾过程进行诊断分析。结果表明:此次持续性海雾过程分为4个阶段、3种类型,即15—17日辐射雾、18—20日和24—25日平流雾、22日锋面雾。辐射雾期间,琼州海峡为均压型环流控制,夜间气温降低,水汽处于饱和状态,1000 m以下存在双层逆温结构,雾顶出现在第一逆温层底部。两次平流雾期间,琼州海峡为入海变性高压脊后部偏强的东到东南风控制,气温(相对湿度)长时间维持不变(饱和),但18—20日的低空湿平流较24—25日强,水汽辐合层较厚,且比湿持续增大,致使平流雾持续时间较长;600 m以下较大的垂直风切变使雾层混合均匀,雾顶可发展至1000 m以上。锋面雾期间,徐闻站为4 m·s^(-1)以上的偏北风且伴有弱降水,琼州海峡附近低空为湿平流(水汽辐合)中心和冷暖平流交汇的锋区。海雾各阶段,气-海温差在-2~3℃之间,当气-海温差增大时,海雾消散。 相似文献
2.
利用NCEP/NCAR再分析资料和北部湾地区5站地面观测资料,对比分析了3次典型大雾过程的环流背景和气象要素特征。结果表明:(1)平流雾维持时间最长、强度最强,辐射雾发生范围最广,锋面雾发生范围最小、持续时间最短;(2)锋面雾和平流雾500hPa有较明显的南支槽,副高偏强,850hPa偏南风偏强,因冷空气入侵或冷空气减弱东移与暖湿气流相遇而成雾,辐射雾过程无冷空气直接影响,因夜间辐射冷却而成雾;(3)辐射雾过程气温与能见度呈同相变化特征,露点温度呈逐日上升趋势,锋面雾前期和后期气温、露点温度与能见度分别呈反相和同相变化特征,平流雾过程气温、露点温度呈逐日升高趋势,能见度具有较明显日变化特征;(4)辐射雾和锋面雾发生时相对湿度≥93%,偏南风和偏北风风速减小;平流雾期间相对湿度持续≥90%,风速由弱偏北风转偏南风。 相似文献
3.
沪宁高速公路大雾及气象要素特征分析 总被引：3，自引：0，他引：3
利用2006年6月-2009年5月沪宁高速公路AWM自动气象站资料,研究了不同类型大雾持续时间、能见度变化及其出现过程中风、湿度变化特征。结果表明,有超过50%的大雾会发展成浓雾;大雾持续时间以平流雾最长,辐射雾最短;67.6%的大雾在长时间低能见度之前会出现类似"象鼻"形的突变前兆,这可能与地理环境有关;大雾过程中风向以东风和西风为主,锋面雾有部分为偏南风;平流雾发生时风速较辐射雾和锋面雾大,锋面雾发生时风速较多为静风,结束时风速快速增大;平流雾发生时相对湿度多有突变,而辐射雾、锋面雾的相对湿度以渐变为主。 相似文献
4.
利用常规气象资料和NECP1°×1°再分析资料对2014年1月14—18日和1月30日—2月2日两次持续性大雾天气过程进行了诊断分析。结果表明:两次过程均存在平流雾、辐射雾以及平流-辐射雾,高空冷空气入侵南下是两次大雾天气结束的原因;大雾期间,高空环流形势较为稳定,地面气压梯度较小,大气层结存在不同程度的逆温,有上干下湿的特征;当有辐射雾出现时,地面受均压场控制,风速为1~3m/s,整层均为西北气流;有平流雾时,地面受单一气压场控制,风速为4~6 m/s,特别是低层存在暖湿气流的输送,近地面存在弱辐合上升,对流层中层存在弱辐散下沉;能见度与温度露点差基本存在同位相变化,与相对湿度存在显著的反位相变化。 相似文献
5.
山东中西部一次持续性大雾的形成及维持机制 总被引：2，自引：0，他引：2
利用常规气象观测资料和NCEP/NCAR提供的6 h再分析资料（分辨率为1°×1°）,对2013年1月12-16日发生在山东中西部地区的一次持续性大雾天气过程从环流背景、层结条件、动力和热力学机制等方面进行了诊断分析。结果表明：中高层偏西气流、对流层低层温度脊和地面冷高压的稳定维持为这次持续性大雾过程提供了有利的环流背景;大雾过程经历了辐射雾—平流辐射雾—平流雾的复杂演变阶段,不同阶段的大雾湿层厚度及逆温强度有所不同;适当的风速和低层弱的水汽辐合有利于大雾稳定维持和发展;近地层辐合上升、中高层辐散下沉,易在界面形成逆温层,有利于大雾的出现,而整层的辐合上升运动往往容易形成中高云,不利于近地层水汽的聚集,难以形成大雾。 相似文献
6.
7.
应用常规气象观测、加密自动站、能见度观测等资料和NCEP FNL再分析资料,对2014年辽宁地区一次罕见的长时间大范围强浓雾天气的成因进行诊断。结果表明：2014年11月20-22日辽宁地区大雾过程分为两个阶段,其中21日14-16时大雾爆发性发展后,特强浓雾持续12 h,此种情况在辽宁近20 a比较罕见。大雾第一阶段为辐射雾,雾前低层弱暖平流利于升温,大雾期间中层弱冷平流利于出现晴空辐射条件,夜间在辐射降温作用下,975 hPa高度以下形成逆温;气温下降、温度露点差减小、相对湿度增大;近地面微风利于降温,同时水汽不易流出,逆温作用使得水汽不易向高层扩散,近地面层水汽浓度增大,导致第一阶段大雾快速发展。大雾第二阶段为锋面雾,大雾快速发展期间无逆温、有弱冷锋过境,锋面附近辐合导致水汽上升冷却凝结,同时锋面附近低云降下雨滴在干冷空气中蒸发,利于近地面附近水汽饱和、冷凝,是大雾快速发展的原因。 相似文献
8.
一次罕见冬季强浓雾天气成因分析 总被引：6，自引：1，他引：5
利用加密观测资料和NCEP/NCAR 1°×1°的6 h再分析资料,对2006年12月25~27日发生在我国中东部地区的一次罕见强浓雾天气过程从大尺度背景、动力和热力机制等方面进行了诊断分析。结果表明:①本次过程大雾发生阶段近地面风速很小,在0.3~2.9 m/s之间变化;浓雾发生阶段风速在0.3~2.4 m/s之间变化;15 m能见度维持阶段风速在0.8~1.1 m/s之间变化;②虽然浓雾发生前的很长一段时间内水汽条件差,而且后期西风槽影响时也无降水,但是槽前西南气流的持续水汽输送使得强浓雾形成所必须的水汽条件得到满足;③在大雾发生前,稳定层结逐渐建立并在大雾期间稳定维持,稳定层结的建立和维持对浓雾的形成、持续有重要作用;日出后首先在较高层出现不稳定层结,继而下传到底层,稳定层结被破坏,大雾减轻或消散;④第1阶段(25日夜里至26日上午)强浓雾出现前,能见度出现多次急速大幅振荡,在第2阶段(26日傍晚至27日上午)则未出现类似现象。 相似文献
9.
河北平原一次持续大雾天气分析 总被引：2，自引：1，他引：1
利用气象观测资料和NCEP 1°×1°资料,从天气背景、温湿特征、层结条件、动力热力学特征等方面分析了2007年11月7～13日河北平原1次持续大雾的成因.结果表明:这次大雾是在较为稳定的大气环流背景下产生的,中高层以纬向环流为主,冷空气以扩散形势影响华北地区;地面夜间风速在0～2 m/s,充足的水汽及地面辐射冷却作用有利于大雾的形成和维持;大气层结是对流稳定的,同时近地面层为逆温结构;近地面层的弱辐合及持续微弱的暖平流十分有利于逆温层的维持,对于大雾长时间维持具有重要作用.大雾多发生在地面辐合线偏向冷空气一侧.本次大雾性质复杂,持续大雾由平流辐射雾-辐射雾-平流雾3个阶段构成,不同阶段大雾逆温强度及湿层厚度有所不同. 相似文献
10.
通过2014年11月下旬连续两次大雾过程的对比分析发现:22日半夜至23日上午的大雾具有平流雾的特征,处于稳定的2~4 m/s的东北偏东气流中,实况探空逆温层结不明显,弱冷空气从偏北偏东路径扩散影响,高压底部偏东气流从东海带来的暖湿水汽成为起雾的主因;而24日上午的大雾具有辐射雾的特征,基本处于准静风和低于2 m/s风向不定的情况之下,逆温层结明显,倒槽北拱东伸,地面气压场弱,天空晴朗,前期水汽条件充沛。23日大雾过程具有突发性、维持时间长的特点,预报难度大。从22—23日的数值模拟来看,除前期浙北空气中颗粒物较多、浙江西高东低及钱塘江口的地形作用等影响因子以外,高压底部的偏东气流与倒槽发展带来的东南气流的辐合对水汽输送和堆积起到关键作用,是形成23日这次长时间突发性大雾过程的主因,并且在模式的探空曲线中300 m高度以下也存在明显的逆温层,但由于高度过低以至于在常规探空图中不易被察觉。 相似文献
11.
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 Nio3.4 index in summer and autumn but negatively correlated in spring and winter. 相似文献
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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
13.
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(Stl), 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
14.
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
15.
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
16.
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
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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
18.
Fei LIU Chen XING Jinbao LI Bin WANG Jing CHAI Chaochao GAO Gang HUANG Jian LIU Deliang CHEN 《大气科学进展》2020,37(7):663-670
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
19.
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
20.
Yuepeng PAN Mengna GU Yuexin HE Dianming WU Chunyan LIU Linlin SONG Shili TIAN Xuemei Lü Yang SUN Tao SONG Wendell W. WALTERS Xuejun LIU Nicholas A. MARTIN Qianqian ZHANG Yunting FANG Valerio FERRACCI Yuesi WANG 《大气科学进展》2020,37(9):933-938
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