南极长城站和中山站降水形态变化特征的研究

利用南极长城站1985—2015年和中山站1989—2015年的天气现象记录和日平均气温资料,分析两站降水、降雨和降雪日数的长期变化特征及其变化趋势,并讨论了长城站降水形态变化与当地气温和阿蒙森低压变化的联系。结果表明：长城站降水日数较多,年总降水日数为236~343 d,有增加的趋势,变化速率为4.51 d/10a;其中降雨日数为74~185 d,降雪日数为157~282 d,增加的速率分别为2.68 d/10a和1.25 d/10a。而中山站年降水日数较少,年总降水日数为104~173 d,有减小的趋势,变化速率为-1.30 d/10a,中山站全年气温几乎都在0℃以下,降雨稀少,降雪为主要的降水形态。长城站年平均气温和降雨日数与总降水日数的比值（雨日比）显著正相关,在增温速率较大的秋季（3—5月),雨日比也显著增加(4.36%/10a)。降水形态受气温的影响很大,随着气温升高,长城站年降水日数中降雨日数的比重增加。秋季阿蒙森低压经向中心的东移有利于暖湿气流吹向南极半岛,也促进了降雨的发生。     

张家口市崇礼的雪季与冬奥会赛期的降雪特征分析

利用张家口市崇礼1960-2014年逐日降水和天气现象资料,分析了雪季与冬奥会赛期(2月4-20日)的降雪特征。结果显示：崇礼最早降雪初日为10月13日,最迟降雪终日为4月30日,初、终雪日多年平均为11月2日和4月6日;雪季长度最长和最短分别为190 d和123 d,多年平均为156 d。雪季间最长连续无降雪时段多出现在12月末到1月下旬。冬奥会赛期前的11月上旬降雪日数少,但降雪量较大;此后各旬降雪日数、雪量差异不大。2月4-20日间平均4~5 d出现一次降雪,且主要为中小雪,出现大雪的概率极低。这些结果为冬奥会赛场充分利用降雪资源、制定赛事计划和赛事期间的气象条件预测及预报等保障提供参考依据。     

引发公路交通事故的气象条件分析

利用1999~2003年间发生在丽水市境内的交通事故,并结合该地的气候特点,分析了引发交通事故的气象条件。结果表明:交通事故的发生与日照、雨量、最高温度、温差、能见度、相对湿度、雪深以及风速等有一定的相关性。另外夏季高温、冬季低温、高湿、雨、雪天气以及转雨日都很容易引发交通事故;秋冬季节的雾、雨天、雪天会使能见度降低从而引发交通事故;雨日比无雨日容易发生交通事故;交通事故的发生还与降雨量级有系,特别是大雨天最容易发生交通事故。夏冬季的晴天比阴天容易发生交通事故,而秋季阴天比晴天容易发生交通事故;结冰、积雪等天气尽管发生的次数较少,但引发的交通事故损失却非常大。     

雨滴谱式降水现象仪与人工观测结果的一致性分析

为验证雨滴谱式降水现象仪的测量性能,利用南京市气象局在江宁布设的PARSIVEL型雨滴谱式降水现象仪2018年1—11月期间的天气现象观测资料,重点分析了雨滴谱式降水现象仪对不同类型降水的测量性能。结果表明:①总体而言,雨滴谱式降水现象仪与人工观测具有良好的一致性,但是在降水时间、降水类型方面存在一定差异。②白天,人工观测的总降水时间明显高于仪器观测结果,主要原因在于人工观测有时会忽略降水间隙,而仪器可能会漏掉极微量降雨;人工观测的降水现象分类较粗,有时会忽略降水的精细变化,而仪器能够灵敏检测到降雨的短时变化、毛毛雨和雨的转换、降雨和降雪的转换等。③夜间,人工观测有时会忽略个别时次的毛毛雨或雨,而仪器容易漏测微量降水,大雨强条件下有时会把降雨误判为霰或雪,降水现象的判别算法仍需改进。     

乌鞘岭高速公路路段多发交通事故的气象条件分析

利用2006年1月1日至2013年5月31日甘肃省乌鞘岭路段高速公路发生的一般、重大、特大公路交通事故个例和同期乌鞘岭气象站的气象观测资料,利用统计方法分析天气现象和气象要素与公路交通事故的关系。乌鞘岭路段的交通事故一年中3月、7月、9月发生的几率较大,这与季节交替时气象要素变化显著、雨带北移、降水日数增多有直接关系。乌鞘岭路段公路交通事故,由不良气象条件引发的占总事故数的81%。发生交通事故中不良天气的排序依次为结冰、降雨、降雪、积雪、大雾。普查气象要素与交通事故相关性,发现最低温度、地面最低温度、相对湿度、能见度、日降水量、极大风速与公路交通事故具有显著相关。     

近百年中国东部夏季降水年代际变化特征及其原因

本文利用测站降水观测资料分析过去一百多年中国东部华北、长江流域以及华南夏季降水的年代际变化特征发现,尽管这三个地区的夏季降水具有不同的年代际转折时期,但是均同时在1910年代初期、1920年代初期、1940年代中期、1960年代中期、1970年代末期以及1990年代初期发生了跃变。近一百年间不同年代际时期东部夏季降水的分布型主要以南正北负或者南负北正的偶极型为主,并且无论是偶极型分布还是三极型分布,两个相邻年代际时期中国东部降水分布型发生完全反向变化的概率较高（60%）。此外,夏季的PDO、冬季的AO以及春季的北极海冰也同时在1920年代末期、1940年代中期、1970年代末期以及1990年代中期左右发生了跃变,这几次跃变时期与中国东部三个不同地区夏季降水发生跃变的时期一致,表现出近百年来太平洋年代振荡（PDO）、北极涛动（AO）以及北极海冰这三个因子对中国东部夏季降水年代际变化的协同作用。在年代际时间尺度上,夏季的PDO与华北夏季降水显著负相关。PDO的年代际变化能够在500 hPa位势高度场中激发出太平洋—日本（PJ）型年代际遥相关波列;同时在850 hPa风场中激发出类似于影响华北夏季降水年代际变化的大气环流型,从而影响华北降水的年代际变化。冬半年的AO与长江流域夏季降水存在显著正相关关系。冬季到春季正位相的AO导致亚洲大陆南部处于湿冷状态,土壤湿度的记忆性可将这种状态延续到夏季。因此,夏季海陆热力对比减弱,东亚夏季风发生年代际减弱,相应地长江流域的降水年代际增多。春季北极海冰与华南夏季降水显著负相关,北极海冰的年代际异常能在500 hPa位势高度场中激发出与静止Rossby波异常传播相联系的欧亚—华南年代际遥相关波列,从而影响华南降水的年代际变化。     

乌鲁木齐市降水对大气污染的影响

根据2002—2003年乌鲁木齐市SO2、NO2、PM10的日平均浓度和日降水量分析了乌鲁木齐市降水对3种大气污染物的湿清除能力。分析表明大雨对SO2和PM10的湿清除能力大于小雨,而小雨大于中雨。中雪对SO2和PM10的湿清除能力大于大雪,而大雪大于小雪。小量以上降水(降雨和降雪)对NO2的湿清除能力基本相当。微雨对3种大气污染物具有湿清除能力,而微雪使3种大气污染物的浓度增加。     

Effects of summer precipitation on urban transportation

Potential shifts in summer precipitation due to an enhanced greenhouse effect indicate the possibility of more rain days and heavier rains in the Midwest, and this study assessed the effects of such changes on transportation in Chicago using a 3-year period of data. Traffic accidents in the metropolitan area doubled on rainy days, with 30% more accidents in more densely populated urban areas than in suburban-rural areas. During rain events accident severity (number of injuries) was 55% higher in suburban and rural areas where less dense but higher speed traffic flows exist than in the city, however. Rain days during dry months produced more accidents and injuries than during normal or wet months. Three times as many accidents occurred during heavy rain periods (> 12.8 mm) as during nonrain conditions. Rain had a negligible influence on weekday traffic volume on busy highways but there was a 9% decrease in traffic volume on rainy weekends. A 3–5% decrease in ridership of public transportation occurred on rainy days, with most decreases during midday. Nationally, 27% of all fatality-producing aircraft accidents occurred during rainy weather conditions, as did 57% of the 30-min flight delays at Chicago's O'Hare Airport. Results suggest that given continued transportation use patterns extend into the future, a future climate with more summer rain days, somewhat higher rain rates, and more storms would mean more total vehicular accidents, more total injuries in vehicular accidents, decreased ridership on public transportation systems, and more aircraft accidents and delays. A drier climate would likely experience fewer moderate to heavy rain events but results show that rain events during drier conditions produced a greater frequency of accidents and injuries per event than during wetter conditions.     

张家口地区一次长时间降雪过程的滴谱特征分析

本文利用OTT Parsivel2激光雨滴谱仪和站点加密观测资料，对2019年11月29日张家口地区一次长时间降雪天气过程的滴谱演变特征进行了初步分析，本次降雪先后经历开始阶段、雪花阶段、稳定强降雪阶段、结束阶段。结果表明：（1）总体上，降雪天气过程中微物理参量（降雨强度R、数浓度Nt、雨水含量W、雷达反射率因子Z、质量加权平均直径Dm）演变趋势基本相同，其中开始阶段、稳定强降雪阶段、结束阶段的降水强度、雨水含量、雷达反射率因子受粒子数浓度影响较大，而雪花阶段降水强度、雨水含量、雷达反射率因子受粒子直径影响较大。（2）稳定强降雪阶段，粒子数浓度Nt量级为103至104，而Dm小于1 mm，这是由于大雪片在温度较低的情况下，下落过程中破碎形成大量小雪片。降雪过程中，雪滴下落速度小于2 m/s的粒子数占总粒子数的90%，强降雪阶段的雪滴下落速度集中于1~1.5 m/s。（3）分别使用二、三、四阶矩和最小二乘法对不同降雪阶段粒子谱进行Gamma分布拟合，在降雪过程中，最小二乘法拟合效果优于二、三、四阶矩方法。     

Long-term variability of occurrence of precipitation forms in winter in Kraków, Poland

The paper discusses long-term change in snowfall, rainfall and mixed precipitation viewed in conjunction with air temperature and North Atlantic Oscillation (NAO) in winter (December–February). In the study of contemporary climate change and its effect on the hydrological cycle it is useful to focus on winter precipitation forms. A 146-year secular observation series from Kraków, spanning the period 1863–2008, was used to extract data on the number of days with precipitation and on precipitation amount broken down by form. Statistically significant trends were found in total and mixed precipitation, but not in snowfall and rainfall. The climate warming effect has contributed to a material decrease in the snowfall to total winter precipitation ratio during the second half of the 20th c. The highest impact of air temperature was found in the wintertime variation in number of days with snowfall while the NAO had a significant influence on the frequency and amount of both rainfall and snowfall.     

融雪性降水量资料实时处理技术

介绍区域自动站冬季融雪产生的雨量记录的识别和自动处理的方法。将融雪性降水量的识别分为降雪和融雪两个过程。在满足降雪的前提条件下,测站有雨量记录,且当时符合融雪条件,则该雨量记录作为融雪产生的记录处理。据实际使用自动识别的准确率可达90%以上。降雪和融雪的条件以区域自动站的气温作为主要依据,结合临近的国家气象观测站资料进行综合判别。为提高对天气状况和降水性质的识别还加入了雷达估测降水和冬季降水相态判别等产品,弥补用单一参考站降水资料的缺陷,对融雪雨量记录识别效果有显著作用。     

Towards More Snow Days in Summer since 2001 at the Great Wall Station,Antarctic Peninsula:The Role of the Amundsen Sea Low

The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability.We studied the precipitation phase at the Great Wall Station and Antarctic Peninsula(AP)region,based on daily precipitation,synoptic records and ERA-Interim data during the austral summers of 1985?2014.Overall,there was no trend in the total precipitation amount or days,but the phase of summer precipitation(rainfall days versus snowfall days)showed opposite trends before and after 2001 at the AP.The total summer rain days/snow days increased/decreased during 1985?2001 and significantly decreased at a rate of?14.13 d(10 yr)?1/increased at a rate of 14.31 d(10 yr)?1 during 2001?2014,agreeing well with corresponding variations in the surface air temperature.Further,we found that the longitudinal location of the Amundsen Sea low(ASL)should account for the change in the precipitation phase since 2001,as it has shown a westward drift after 2001[?41.1°(10 yr)?1],leading to stronger cold southerly winds,colder water vapor flux,and more snow over the AP region during summertime.This study points out a supplementary factor for the climate variation on the AP.     

湖南极端干旱气候时段人影作业潜力分析

利用湖南97个气象观测站逐日综合气象干旱指数、逐日降水量和湖南天气气候分区,研究湖南极端干旱特征和极端干旱时段内人工影响天气增雨潜力,结果表明:①湖南极端干旱期有相当的增雨潜力,各个分区的极端干旱频次和大气可降水量年代际变化除70年代外均呈现为北少南多的特点。②极端干旱时段内各分区年均可增雨日数主要表现为月际差异,可增雨日数主要集中在8—10月,各分区区域差异较小,各分区在伏旱期的可增雨日数大约占伏旱期的16%～20%。③湖南极端干旱按照出现的季节分类有11种,频次最高的是夏秋连旱,同时夏秋连旱的可增雨日数最多。     

Assessment of the Pacific decadal oscillation’s contribution to the occurrence of local torrential rainfall in north China

On 21–22 July 2012, torrential rains hit North China, with the daily precipitation record at Beijing station reaching 160.6 mm; this event is named the Beijing 7–21 case. This paper assesses the likelihood of the occurrence of local torrential rains, such as the Beijing 7–21 case, from the perspective of climate variability. In particular, the influence of the Pacific Decadal Oscillation (PDO) is assessed. There were five extreme events, with daily precipitation records equal to or larger than 160.6 mm, at Beijing station during the period 1951–2012; all of these events happened during negative phases of the PDO. The present analysis indicates that precipitation events more extreme than the Beijing 7–21 case should happen more than once per decade during negative phases of the PDO, but only about once every four decades during positive PDO phases. The negative phase of the PDO is found to be associated with a much greater probability of daily records of southerly winds in North China during summer. Strong southerly summer monsoons are deemed favorable for increasing the occurrence of local extreme rainfall over North China.     

Comparison of weather station snowfall with winter snow accumulation in high arctic basins

Abstract

Most water balance studies in the High Arctic indicate that the weather stations underestimate annual precipitation, but the magnitude of such error is unknown. Based on up to seven years of field measurements, this study provides a comparison of snowfall at weather stations with the winter snow accumulation in their nearby drainage basins.

Snowfall is the major form of precipitation in the polar region for nine months every year. Without vegetation, snowdrift is controlled by the local terrain. By establishing the snow characteristics for different terrain types, total basin snow storage can be obtained by areally weighting the snow cover for various terrain units in the basin. Such a method was successfully employed to compute total winter snowfall in the drainage basins near Resolute, Eureka and Mould Bay. Results show that the basins had 130 to 300per cent more snow than the weather stations recorded. Using revised snowfall values that are reinforced by Koerner's snow core measurements from ice‐caps, it is hoped that a more realistic precipitation map can be provided for the High Arctic.     

伊犁河谷初冬降水条件下风廓线雷达评估分析

对伊犁河谷地区初冬降水条件下风廓线雷达资料评估其数据获取率并与探空资料进行对比分析,定义两者风向偏差在10°以内或风速偏差在1 m/s范围的样本为有效样本,分别用E_v和E_d表示风速有效样本比率(风速有效样本数/总样本数)和风向有效样本比率(风向有效样本数/总样本数)。结果显示:超过80%数据获取率的高度,降雨时为3000 m,降雪时达到预设2000 m;降雪时E_v和E_d均比无降水时高,且降雪量大小与风廓线的探测高度呈正相关,降雪量大小对E_d有明显影响,对E_v无明显影响;比较不同高度数据,降雪时0～3 km范围的E_v和E_d值均比无降水时高30%左右,无降水时3～5 km范围的E_d接近100%。     

晴雨(雪) 和气温预报评分方法的初步研究

利用全国逐日天气预报产品和对应实况数据, 分析了目前普遍使用的晴雨(雪) 和气温预报评分方法存在的问题, 并进行了改进尝试和研究。结果表明:由于没有考虑降水概率的影响, 在降水概率全国差异较大的多数月份, 晴雨(雪) 预报正确率与单站无降水频率表现为正相关, 具有无降水频率越大评分越高的趋势; 采用绝对标准值(1 ℃或2 ℃) 作为阈值进行气温预报准确率评分, 评分结果与气温日际变化呈明显负相关, 气温日际变化偏小则评分值偏高的趋势比较明显。该文提出的晴雨(雪) 和气温预报改进评分方法能有效减少降水概率和气温日际变化对晴雨(雪) 和气温预报评分的影响, 提高不同气候背景地区天气预报评分结果的可比性, 在天气预报质量检验和评估业务中具有一定的应用和推广价值。     

降水现象对大气消光系数和能见度的影响

大气中各种粒子对大气消光系数和能见度有不同程度影响,除气溶胶粒子外,降水粒子对能见度影响也不可忽视。为了解降水粒子对能见度的影响,确定能见度变化与降水现象之间的关系,该文在分析降水粒子的大小、速度、形状、谱分布、光学特性等特征的基础上,忽略气溶胶粒子的影响,建立基于实测谱分布的降水与能见度的理论模型,讨论不同类型降雨、降雪对大气消光系数和能见度的影响。同时选取Parsivel降水粒子谱仪在南京地区的降雨和降雪观测记录,利用实测数据来对比验证本文所建立的降水-能见度理论模型。结果表明:能见度随着降水强度的增大呈指数降低;受降水粒子特性和天气条件等多种因素影响,能见度与降水强度之间的关系并不是唯一对应的;降雨和降雪对能见度的影响各不相同,相比而言,降雨对能见度的影响比较容易确定,而降雪对能见度的影响比较复杂,主要因为雪花或冰晶的类型复杂多变,对大气消光系数有不同程度的影响。结合理论分析和实测数据对比验证,降水现象对能见度的影响得到了证实。     

Spatial and interannual variations of spring rainfall over eastern China in association with PDO–ENSO events

The spatio-temporal variations of eastern China spring rainfall are identified via empirical orthogonal function (EOF) analysis of rain-gauge (gridded) precipitation datasets for the period 1958–2013 (1920–2013). The interannual variations of the first two leading EOF modes are linked with the El Niño–Southern Oscillation (ENSO), with this linkage being modulated by the Pacific Decadal Oscillation (PDO). The EOF1 mode, characterized by predominant rainfall anomalies from the Yangtze River to North China (YNC), is more likely associated with out-of-phase PDO–ENSO events [i.e., El Niño during cold PDO (EN_CPDO) and La Niña during warm PDO (LN_WPDO)]. The sea surface temperature anomaly (SSTA) distributions of EN_CPDO (LN_WPDO) events induce a significant anomalous anticyclone (cyclone) over the western North Pacific stretching northward to the Korean Peninsula and southern Japan, resulting in anomalous southwesterlies (northeasterlies) prevailing over eastern China and above-normal (below-normal) rainfall over YNC. In contrast, EOF2 exhibits a dipole pattern with predominantly positive rainfall anomalies over southern China along with negative anomalies over YNC, which is more likely connected to in-phase PDO–ENSO events [i.e., El Niño during warm PDO (EN_WPDO) and La Niña during cold PDO (LN_CPDO)]. EN_WPDO (LN_CPDO) events force a southwest–northeast oriented dipole-like circulation pattern leading to significant anomalous southwesterlies (northeasterlies) and above-normal (below-normal) rainfall over southern China. Numerical experiments with the CAM5 model forced by the SSTA patterns of EN_WPDO and EN_CPDO events reproduce reasonably well the corresponding anomalous atmospheric circulation patterns and spring rainfall modes over eastern China, validating the related mechanisms.     

张家港市天气与道路交通安全的关系

对张家港市2010—2012年每日气象要素和交通事故数据进行了统计和分析。结果表明,在张家港市这个中国东部沿海发达地区典型的县级市里,交通事故的发生与节气、大风、降雨、积雪、能见度和温度等气象现象和要素都有着一定的内在关系。天气对道路交通安全的影响,不仅表现在对道面客观通行状况的影响,也表现在天气变化对驾驶员心理的间接影响。如果充分利用气象预报为交通服务,就能在很大程度上减少交通事故的发生概率。