甘肃罕见冰雹天气过程个例分析

针对2005年5月30日甘肃区域性罕见冰雹天气过程,结合天气实况、环流形势以及环境场特征,利用卫星云图和新一代天气雷达产品资料,分析了这次强冰雹天气过程的影响系统、云图和雷达回波演变过程,得到了冰雹云在雷达强度回波、速度回波和卫星云图中的特征,揭示了这次强冰雹不是带状冰雹云系移到本地产生的,而是发展成中口尺度（MβCS）的中尺度对流系统造成的。同时,得出了一些做好冰雹预报预警量化指标。     

冰雹过程雷达回波综合分析

利用哈尔滨雷达站新一代天气雷达资料,对2002年7月2日出现的冰雹天气进行了详细分析,重点讨论了冰雹云回波特征、结构和演变过程。得到了本次天气过程中冰雹回波的特征及其在预报中的相关特征指标,对冰雹强对流天气的预报具有很好的指示作用。     

2008年6月10日濮阳冰雹过程的多普勒雷达资料分析

利用2008年6月10日濮阳冰雹天气过程的新一代天气雷达观测资料,运用基本反射率、风暴相对径向速度、垂直积分液态含水量等产品对冰雹过程进行了分析,结果表明:本次冰雹过程由局地对流单体发展而成,雷达回波尺度不大,但回波强度很大,强中心最大达60-65 dBz.风暴相对径向速度产品图上,大风区、逆风区和正负速度对等出现、发展,预示强风暴的出现.速度场的强弱变化早于回波强度变化,可更早得到风暴的发展信息,从而提前预报出短时强对流等灾害性天气.垂直积分液态含水量在降雹过程中有明显跳跃现象,大值区与冰雹落区有一定的对应关系.     

SWAN雷达产品在甘肃河东地区冰雹短临预报中的应用

选取2011年7月发生在甘肃省河东地区的7次冰雹个例,综合分析SWAN系统输出的雷达产品资料的主要特征,提取冰雹天气的雷达产品资料的指标,根据这些指标利用SWAN系统外推算法资料生成冰雹临近预报产品。通过2012年甘肃河东地区的2次冰雹天气过程对与其同时的临近预报产品检验结果表明,预报效果良好,具有较高的业务应用价值。     

一次典型超级单体风暴过程分析

利用赤峰多普勒天气雷达观测资料,对2005年6月19日一次典型超级单体风暴造成的雷雨大风和冰雹天气过程进行分析,揭示出强对流天气雷达回波强度场和多普勒速度场的典型特征,为强对流天气的监测、识别和临近预报、人工消雹提供参考.     

2012年夏季西宁地区两次冰雹天气的对比分析

针对2012年夏季发生在西宁地区的两次冰雹天气过程,从天气形势、物理量场和雷达回波特征、闪电定位特征等几方面进行了综合分析。结果表明:这两次冰雹天气均发生在典型的高空槽型环流背景下,较好的对流不稳定条件、水汽和较强的垂直风切变条件下。6月5日冰雹天气在整层湿度较大的环境下,受地形和局地热力作用,产生能量分布差异,由地面冷锋抬升触发产生。7月13日的冰雹天气在上干下湿的环境下,是暖区切变触发的局地强对流。应用雷达资料能很好地监测中尺度天气系统的发展演变过程,回波强度、回波顶高的变化和速度对的出现及雷达产品的应用对冰雹天气的出现具有指示意义,对今后的防雹减灾工作有较好的应用价值。     

一次人工防雹作业的双偏振雷达特征分析

利用红河C波段双偏振雷达资料，分析了2020年3月17日红河州冰雹天气过程中双偏振雷达产品特征及在人工防雹中的应用。分析结果表明：本次冰雹天气过程主要影响天气系统是冷锋切变，蒙自探空站T-lnP图及V-3θ图上表现出明显的对流潜势特征；雷达常规产品表现出典型的冰雹结构特征；双偏振特征量中，差分反射率低值区对应反射率因子的高值区，且为大冰雹中心，对应的ZDR在-0.39～0.10 dB之间，中高层出现了明显的ZDR 异常大值区，幅相相关系数较低在0.87～0.93之间，KDP在-0.10～-0.01 o/㎞之间，表明冰雹表面较干；防雹作业后对比分析，作业区各项雷达产品指标均下降且未出现冰雹，而非作业区冰雹特征依然明显且出现冰雹。     

石河子地区三次冰雹天气过程的综合分析

选取春季发生在新疆石河子地区沙漠边缘的3次冰雹天气过程,应用常规观测资料并结合雷达回波资料,从天气形势、物理量场和雷达回波演变特征等几方面进行了综合分析。结果表明:3次降雹过程都发生在典型的高空槽型的冰雹环流背景形势下,较好的对流不稳定条件、水汽条件和较强的垂直风切变促使冰雹等强对流天气过程发生发展。多普勒雷达能很好地监测中尺度天气系统的发展演变过程,回波强度和回波顶高度的变化、速度对和逆风区的出现、垂直累积液态含水量(VIL)增加以及风暴跟踪信息(STI)预警等都对冰雹天气的出现具有指示意义,对今后的防雹减灾工作有较好的应用价值。     

风廓线雷达产品在冰雹天气过程中的应用研究

本文利用威宁县2022年6月2日一次冰雹天气过程风廓线雷达资料和威宁国家基准气候站降水资料,采用数理统计等方法对本次天气过程的风廓线雷达特征进行分析结果表明：冰雹、短时强降水开始前,低空急流的建立和垂直风切变的加强,急流造成的辐合加上近地层风向的切变作用为冰雹和强降水的产生提供了很好的动力条件;冰雹和短时强降水开始发生时,2000米高度以上有很大的正速度,可以作为一个指标判断对流发展的强弱情况;冰雹发生时折射结构常数（Cn2）值在-128~-110dB之间,也能很好的反映冰雹等强对流天气的开始,增强和结束过程。     

河南省人工消雹作业判据研究

使用河南省气象台站１９８２－１９９７年４－８月地面报表和同时期雷达回波资料统计分析了４０次区域性冰雹过程的天气特征,回波参数特征,找出了相关性较好的各种预报判据和多普勒天气雷达强度场,速度场上的图像特征,为制作 冰雹的短时预报,雷达监测及人工消荼提供科学的依据。     

CHARACTERISTICS AND TRENDS OF CLIMATIC EXTREMES IN CHINA DURING 1959–2014

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.     

LOW-FREQUENCY CIRCULATION AND EXTENDED-RANGE FORECAST IN CONNECTION WITH AUTUMN EXTREME HEAVY RAINFALL PROCESS IN HAINAN

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.     

AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING–TIANJIN–HEBEI REGION UNDER CLIMATE CHANGE

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.     

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

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.     

Revisiting the Concentration Observations and Source Apportionment of Atmospheric Ammonia

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     

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正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted     

A Brief Introduction to Marine Meteorological Science Experiment Base at Bohe Town,Maoming City,Guangdong Province

<正>With the support of specialized funds for national science institutions,the Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration set up in October 2008 an experiment base for marine meteorology and a number of observation systems for the coastal boundary layer,air-sea flux,marine environmental elements,and basic meteorological elements at Bohe town,Maoming city,Guangdong province,in the northern part of the South China Sea.     

Information for Authors

AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.     

Information for Authors

AIMS AND SCOPE Atmospheric and Oceanic Science Letters （AOSL） pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome.