新疆天山山区降雨的微物理结构特征

使用GBPP-100型雨滴谱仪,于2001年6月12日至7月31日在天山北坡的小渠子气象站和牧业气象试验站,对27次降雨过程进行了雨滴谱观测,共获取了4 719个雨滴谱样本。通过观测资料分析新疆中天山山区积状云、层状云、积状-层状混合云降雨的微物理结构特征。观测分析表明,天山山区降雨雨滴的平均直径0.41~0.55 mm,以积状云最大,混合云次之,层状云最小。最大平均直径0.88~1.12 mm、平均雨强1.18~2.78 mm·h^-1、平均含水量5.23~11.62 g·m^-3,混合云的这三个特征量均为最大。三类云的雨强与数密度呈正相关。积状云、层状云降雨的雨滴谱服从M-P分布,混合云服从Γ分布。由于山区地形的作用,使云中降雨粒子的生长时间受到限制,天山山区降雨小滴浓度高、尺度小,人工降雨潜力大。     

青藏高原唐古拉山区降水观测误差修正分析

青藏高原由于降水观测点分布等原因一直是水文和气候研究的薄弱环节。2005年5~10月在青藏高原唐古拉山中部冬克玛底河流域进行连续的人工气象观测。观测期间根据不同降水类型和气温之间的相关关系,采用气温2.7℃为临界值对降水类型进行了划分,利用已有的T-200B型自动雨雪量计和普通雨量计的修正公式,并在日尺度基础上对降水进行了修正对比。经过修正,中游T-200B型雨量站全年降水量662.1 mm;普通雨量计全年降水量为657.2 mm;2005年修正后的降水量相比1993年观测到的降水量472 mm增加了近200 mm。结果表明在高寒山区降水观测,依据同步观测的气温划分降水类型,可以根据相关修正公式修正T-200B型自动雨雪量计和普通雨量计降水观测值。从而能够在高寒山区恶劣的自然环境自动连续准确的观测高寒区域的降水。     

新疆阿尔泰山额尔齐斯河源区不同降水观测方法对比分析及1980-2015年降水变化研究

合理评估不同降水观测仪器的精度是评价区域降水变化的前提。基于阿尔泰山额尔齐斯河源区库威水文站ø20 cm标准雨量筒的人工降水观测和库威积雪站T-200b的自动降水观测,对比分析了T-200b和ø20 cm标准雨量筒的观测精度,在此基础上,基于1980-2015年库威水文站的降水观测,分析了阿尔泰山额尔齐斯河源区的降水变化。结果表明：两种方法观测的日降水、月降水和年降水量均具有良好的相关性;两种方法观测液态降水相关性要明显优于固态降水;随着降雨强度的增加,两种观测方法的相关性显著增强。总体上,T-200b观测的降水量较ø20 cm标准雨量筒偏高。1980-2015年间额尔齐斯河源区的年降水量以2005年为转折点呈现"先增加后减小"的变化趋势,且冷季（11月至次年3月）的降水增加显著,冷季的降水占年降水量的比例呈现逐渐增加的变化趋势。降水和融雪过程的变化已导致春季融雪水文过程发生改变,进一步合理评估地表可利用水资源的年内重分配是该地区水安全的重要保障。     

降水观测误差修正研究进展

获取准确的降水量是研究气候变化以及水文循环的基础,国内外学者针对雨量筒降水量捕捉率不足的问题做了大量工作。对近几十年来国内外降水量对比观测及雨量筒降水量修正方面的研究进行综述,认为目前对液态降水修正方案较为成熟,但是对固态降水尚未形成一个统一的修正标准。主要原因在于目前的降水量修正方案缺少对降水微过程的考虑。充分考虑降水微过程是给出包含物理意义降水量修正方案的关键。另外,更为细致的降水类型判定方案以及对微量降水事件的记录也是确定降水修正方案需要重点解决的问题。     

凡河流域降水特性及趋势分析

应用降水倾向率法和Mann-Kendall(非参数秩次相关检验)法对凡河流域1964～2008年雨量和雨日分布特征及其变化规律进行了分析.结果表明:流域多年平均降雨量为760.2 mm,多数年份降雨量在600～900,mm之间.降水主要集中在5～9月份,平均降水量为601.3 mm,占年平均降水量的79.1%,夏季降水...     

基于多类型雨量计的降雨特性分析

为提高对降雨特性的认识,选择常用的6种测雨设备（翻斗式SL3-1、JDZ05、RG-3,称重式Pluvio2,雨滴谱仪Parsivel2和非计数式JQH-1）,成对布设在南京水利科学研究院滁州水文实验基地的同一个实验场地,同步观测了2019年4月1日至8月31日为期5个月的降雨过程。比测分析得到：在中大雨条件下（日雨量≥ 10 mm）,SL3-1和JDZ05测的降雨总量能够满足4%误差控制要求,RG-3、Pluvio2和Parsivel2测的降雨量比JQH-1测值小4%;在小雨条件下（日雨量<10 mm）,翻斗式和称重式雨量计的测量值小于JQH-1测值的4%;SL3-1、RG-3、Pluvio2、Parsivel2测得雨强≤ 0.1 mm/min的频率大于75%,雨强≤ 0.2 mm/min条件下的雨量累积比重大于50%;Pluvio2和Parsivel2监测的降雨开始时间比SL3-1分别早0.5 h和2 h以上,而结束时间分别晚0.5 h和2 h以上。比测结果有助于研究人员选择合适的测量设备获取所关注的降雨特性。     

地面雨滴谱观测技术及特征研究进展

雨滴谱是反映降水微观物理过程和宏观动力结构的主要指标之一.通过分析雨色斑滴谱,可以深入了解降水的发展和演变过程,揭示降水机制.传统雨滴谱测量包括动力学法、滤纸色斑法、面粉团法、快速摄影法和浸润法等,但是普遍存在精度低、工作量大、实时性差、成本高及无法自动完成测量分类等缺点.以雨滴谱仪为代表的新型雨滴谱测量技术包括冲击雨滴谱仪、光学雨滴谱仪和声学雨滴谱仪以及雷达技术等克服了这些缺点,在降水粒子观测和降水物理研究中发挥了重要的作用.综合概述了描述雨滴谱的主要分布模型及其适用条件.归纳分析了不同降水云系(对流云、层状云和层积云降水)、不同降水类型(大陆云和海洋云降水)及不同高度处观测的降水的雨滴谱特征.从学科发展趋势和社会需求的角度,概述了有关雨滴谱研究中存在的主要问题和发展趋势.     

基于多类型雨量计的降雨特性分析

为提高对降雨特性的认识,选择常用的6种测雨设备（翻斗式SL3-1、JDZ05、RG-3,称重式Pluvio2,雨滴谱仪Parsivel2和非计数式JQH-1）,成对布设在南京水利科学研究院滁州水文实验基地的同一个实验场地,同步观测了2019年4月1日至8月31日为期5个月的降雨过程。比测分析得到:在中大雨条件下（日雨量≥ 10 mm）,SL3-1和JDZ05测的降雨总量能够满足4%误差控制要求,RG-3、Pluvio2和Parsivel2测的降雨量比JQH-1测值小4%;在小雨条件下（日雨量 < 10 mm）,翻斗式和称重式雨量计的测量值小于JQH-1测值的4%;SL3-1、RG-3、Pluvio2、Parsivel2测得雨强≤ 0.1 mm/min的频率大于75%,雨强≤ 0.2 mm/min条件下的雨量累积比重大于50%;Pluvio2和Parsivel2监测的降雨开始时间比SL3-1分别早0.5 h和2 h以上,而结束时间分别晚0.5 h和2 h以上。比测结果有助于研究人员选择合适的测量设备获取所关注的降雨特性。     

典型表层岩溶泉域植被对降雨的再分配研究

本文在表层岩溶泉域植被结构特征分析的基础上,监测桂林丫吉试验场S31号泉域内香椿和云实两种主要植被的穿透雨和树干径流特征以及钻孔和表层岩溶水的变化。结果表明:香椿林的总穿透雨量1 861.83 mm,占总降雨总量的59.65%;云实灌丛总的穿透雨量为1 626.42 mm,占总降雨量的52.11%;穿透雨率随降雨量增加而减少。香椿林的树干径流总量为89.4 mm,占总降雨量的2.86%;云实灌丛的树干径流总量为27.79 mm,占总降雨量的0.89%;香椿林和云实灌丛的林冠截留总量分别为1 169.97 mm和1 466.99 mm,平均截留率为37.48%和47.01%;用水量平衡法计算得出以灌丛覆盖为主的S31号表层岩溶泉域年蒸散量为1 623.81 mm,占降水量的52.03 %,年径流深度为1 497.39 mm,占降水量的47.97%。植被冠层改变了降雨对表层岩溶带的补给形式和补给量。降雨经过植被冠层的截留后转化成穿透雨和树干径流进入表层岩溶带,穿透雨以连续波状的形式补给表层岩溶带,而树干径流则以快速集中的方式补给表层岩溶带。      

雷达雨量計

雷达雨量計是把电波射向天空的雨云来了解降雨量的测雨設备。它是通过从天线发射电波(一般是长約3厘米的电磁波),并接收碰撞于雨滴后反射回来的回波,来算出雨滴的量和两者之間的距离。观測方法有两种:(1)平面位置显示法(PPI),使天线     

Characteristics of the top ten snowstorms at First-Order Stations in the U.S.

Snowstorms can produce varying degrees of damage depending on the amount and intensity of the snowfall over a given amount of time. Concurrent weather conditions such as freezing rain and high winds often exacerbate the amount of damage received. In order to assess the frequency of potentially damaging conditions during climatologically significant snowstorms, the top ten snowstorms (TTS) at individual First-Order Stations in the eastern two-thirds of the conterminous U.S. were determined, and the hourly weather conditions during each event were analyzed. The results show that TTS have occurred as early as September and as late as June, with January being the peak month of occurrence. Hourly precipitation totals during TTS were 2.3 mm or less 88% of the time. Seven percent of TTS were classified as a blizzard with over half of the blizzards occurring in the West North Central region. The most common concurrent weather condition during a TTS was fog followed by blowing snow. Regionally, heavy snow events in the Northeast had relatively higher precipitation amounts, colder temperatures, higher winds, and more fog and blowing snow than any other region.     

Extreme rainfall events: evaluation with different instruments and measurement reliability

With regard to extreme events, it is well documented that an intensity of about 1 mm/min already represents an extreme intensity. Under alpine conditions, a precipitation event with an intensity of 3 mm/min has occurred. Therefore, the rain gauges in this region have to be able to measure in this and even in higher intensity ranges. This study deals with basic automated tipping-bucket rain (TBR) gauge and Bulk precipitation samplers, which are able to hold more than 95 % of the cumulative rainfall, that are verified within the space of the week without losses during the extreme events and with minimal evaporation loss. Bulk samplers collected more rainfall than TBR gauges in 110 of 221 extreme events analysed over the past 10 years. In 17 extreme events, an underestimation greater than 10 % was evaluated. The objective was to single out the counting errors associated with TBR gauge, during extreme events, so as to help the understanding of the measured differences between instruments in the field. We want to determine whether the automated precipitation gauge can provide a reliable and precise measurement of precipitation with particular interest regarding heavy and extreme events.     

Analysis of the 1 November 2015 heavy rainfall episode in Algarve by using weather radar and rain gauge data

The trigger for the study presented in this paper was the extreme rain event of 1 November 2015 in Algarve region. The main objective was the analysis and improvement of the precipitation field using a radar–rain gauge merging method. Ordinary kriging with radar-based error correction has been applied to hourly values of precipitation from both sensors. The merging technique allowed keeping the better radar spatial pattern, being the respective estimates corrected by the rain gauges observations. The procedure led to a reduction in the errors of the precipitation estimates, evaluated by cross-validation, when compared to univariate interpolation of rain gauge observation or radar rain product. Finally, some discussion is also added on the problematic of flooding in urban areas, especially those with absent or deficient urban planning.     

Analysis of the 1 November 2015 heavy rainfall episode in Algarve by using weather radar and rain gauge data

The trigger for the study presented in this paper was the extreme rain event of 1 November 2015 in Algarve region. The main objective was the analysis and improvement of the precipitation field using a radar–rain gauge merging method. Ordinary kriging with radar-based error correction has been applied to hourly values of precipitation from both sensors. The merging technique allowed keeping the better radar spatial pattern, being the respective estimates corrected by the rain gauges observations. The procedure led to a reduction in the errors of the precipitation estimates, evaluated by cross-validation, when compared to univariate interpolation of rain gauge observation or radar rain product. Finally, some discussion is also added on the problematic of flooding in urban areas, especially those with absent or deficient urban planning.

     

长江流域降水稳定同位素的云下二次蒸发效应

对长江流域443个GNIP的降水样品同位素原始资料,分降雪和降雨进行δ2H和δ18O线性回归,得到降雪样品的相关方程为δ2H=7.965δ18O+17.114,有最大的斜率和截距;而降雨样品根据降水量大小从<10mm至>300mm分为4组后,得到的相关方程随着降水量的减小,斜率和截距均减小,斜率从7.701减小为5.705,截距从7.812×10-3减小为-5.479×10-3。δ2H~δ18O相关方程的斜率及截距与气温、水汽压之间的关系表明,在降水从云层底部降落到地面的过程中,仅较小降雨事件有明显的二次蒸发现象,并伴随着同位素的分馏。长江流域较小降雨事件占有比例很小,仅为所有降水事件的6.32%,所以二次蒸发效应仅引起地区大气降水方程斜率和截距的微弱减小。研究表明,单个降水原始资料的同位素分析,能产生长期加权平均降水同位素分析得不到的宝贵信息。     

Advances in Measurement Techniques and Statistics Features

Rain Drop Size Distribution (DSD) is one of the key parameters to micro physical process and macro dynamical structure of precipitation. It provides useful information for understanding the mechanisms of precipitation formation and development. Conventional measurement techniques include momentum method, flour method, filtering paper, raindrop camera and immersion method. In general, the techniques havelarge measurement error, heavy workload, and low efficiency. Innovation of disdrometer is a remarkable progress in DSD observation. To date, the major techniques are classified into impacting, optical and acoustic disdrometers, which are automated and more convenient and accurate. The impacting disdrometer transforms the momentum of raindrops into electric impulse, which are easy to operate and quality assured but with large errors for extremely large or small raindrops. The optical disdrometer measures rainfall diameter and its velocity in the same time, but cannot distinguish the particles passing through sampling area simultaneously. The acoustic disdrometer determines DSD from the raindrop impacts on water body with a high temporal resolution but easily affected by wind. In addition, the Doppler can provide DSD with polarimetric techniques for large area while it is affected by updrafts, downdrafts and horizontal winds.DSD has meteorological features, which can be described with the Marshall Palmer (M-P), the Gamma, the lognormal or the normalized models. The M P model is suitable for steady rainfall, usually used for weak and moderate rainfall. The gamma model is proposed for DSD at high rain rate. The lognormal model is widely applied for cloud droplet analysis, but not appropriate for DSD with a broad spectrum. The normalized model is free of assumptions about the shape of the DSD. For practical application, statistical comparison is necessary for selection of a most suitable model. Meteorologically, convective rain has a relatively narrow and smooth DSD spectrum usually described by the M P model. Stratiform rain has a broad DSD spectrum described with the Gamma model. Stratocumulus mixed rain has relatively large drop diameter but small mean size usually described by the Gamma model. The continent rainfall is altitude dependent and it differs from the maritime cloud rainfalls in terms of rain rate and drop diameter. Overall, the meteorological features are useful to improve our understanding of precipitation formation but also important to development of precipitation retrieval techniques with a high accuracy.     

祁连山东段宁张公路达坂山垭口段的冻土分布

据观测资料表明，达坂山地区是青海省境内降水最多的地区，公路垭口段降水量大、冷季降雪多、雪层较厚，稳定积雪时间长达１８０－２００天。雪盖的保温作用占主导地位，加之局部小气候影响，使区内多年冻土下界海拔比邻近地区高约２００ｍ，年平均地温偏高，多年冻土层较薄，而且处在极不稳定的状态下。     

TRMM3B42降雨数据在渭河流域的应用分析

运用渭河流域24个气象站点日降雨数据对2001~2012年热带测雨卫星(TRMM)3B42数据在不同子流域、不同降雨强度以及不同时间尺度的精度进行了对比验证,并对比分析了基于TRMM和站点数据的渭河流域降雨时空分布特征。结果显示:在不同子流域的日TRMM数据比站点观测数据对低值降雨更为敏感,而在极大值降雨数据观测上两者差距较大,月尺度TRMM站点观测数据确定性系数在0.89到0.96之间;两种数据在流域降雨的时空分布上表现一致性,在年内6月中旬~10月初为湿润多雨期,其余月份降雨较少,空间分布呈东南部大,西北部小的格局。