立体雷达方法在星载测雨雷达上的应用

星载测雨雷达的应用,必须满足一些主要条件：高的空间分辨率、宽阔的覆盖范围、大的动态降雨测量范围以及精确的点测量等。由于技术条件的限制,满足这些条件的雷达工作在被雨衰减的频率段,因此必须修正由于衰减所导致的误差。立体雷达方法利用雷达从两个不同角度对雨团的观测来进行衰减效应的订正并实现整个观察区域的雷达反射率因子和比衰减因子场的反演。通过数值实验研究了星载特性的引入造成的不均匀性束内填充效应对立体雷达方法的影响     

近59年德江县暴雨特征分析

摘要：利用贵州省德江县国家一般气象站1959—2017年每日降雨量资料、乡镇区域自动站2011—2017年每日降雨量资料,对德江县暴雨特征开展研究,结果表明:1、德江县暴雨日出现在春、夏和秋季,主要集中在5月到7月,6月暴雨日数最多;暴雨日数年变化呈现一定的波动,但总体是上升趋势;2、德江暴雨主要出现在夜间,占77.7%;3、暴雨主要分布在德江县的南部,北部出现的暴雨次数相对较少。 关键词：暴雨、暴雨日、时空分布     

一次影响山东强暴雨过程的中尺度分析

利用１９９０年华北区域中尺度暴雨监测联防业务试验期间的获得的较为稠密的地面观测资料,卫星云图及常规天气图资料,对１９９０年８月中旬的一次影响山东强暴雨天气过程作了初步的天气学分析和中尺度分析,指出了直接造成这场大暴雨的中尺度系统和有利于它们发展的环境条件,文中重点讨论了中尺度天气系统及云团与雨团的关系。     

近36年遵义市暴雨洪涝灾害变化特征及成因分析

暴雨、大暴雨等自然因素和防洪、除涝工程等社会因数是影响暴雨洪涝灾害发生、发展的重要因素。基于1984-2019年遵义市13个国家气象观测站逐日降水量资料、遵义市第一次自然灾害风险普查暴雨洪涝灾害数据,采用常规统计、突变检验、线性倾向估计、相关分析、对比分析等方法,得出遵义市暴雨、大暴雨以及受灾面积的年际、年代际以及长期变化变化特征,同时揭示农作物受灾面积的变化成因。结果表明：近36年遵义市暴雨日数及其累计降水量呈波动式微弱增加趋势,大暴雨日数及其累计降水量呈显著减少趋势,暴雨、大暴雨均具有不同的阶段性变化特征。1984-1999年农作物受灾面积呈显著上升趋势,2000-2019年农作物受灾面积呈显著下降趋势。大暴雨日数及其累计降水量与受灾面积呈显著正相关,并且具有明显的阶段性差异。暴雨洪涝灾害发生、发展既受暴雨、大暴雨等气象自然因子影响,也受气象灾害防御工程和灾害性天气预报预警水平等社会因素影响。     

A review of the Study of Hydrogen Peroxide in Seawater

Hydrogen peroxide can oxidize or reduce a number of biological important trance metals in seawater. Therefore, it can indirectly affect the marine ecosystem by causing the changes in the speciation of these metals. The results of researches about hydrogen peroxide in seawater in the last more than thirty years were reviewed and the direction of study in the further was proposed in this paper. Hydrogen peroxide can be found rather ubiquitously in the upper water at concentration of 0~102 nmol/L. In water column the maximum of the concentrations of hydrogen peroxide presents in surface water and the concentrations decrease with the increase of depth. In general, the concentrations in costal seawater are higher than these in the oligotrophic ocean. Diel variation of hydrogen peroxide occurs in seawater: the concentrations increase since sunup until the mixmum of afternoon and decrease until the minimum at drawn. The sources of hydrogen peroxide in marine environment include photochemical production, atmospheric deposition and biological production, and the photochemical production is primary among them. The sinks of hydrogen peroxide in the ocean consist of biological and chemical and photochemical decomposition and the main one is biological decomposition. The biogeochemistry of hydrogen peroxide in the continental shelf influenced by river water and factors affecting photochemical production and detail of decomposition should be studied in the future.     

降温降水对池塘水环境影响及诱发鳜鱼疾病的研究

探讨气候变化（降水、降温）与养殖鳜鱼（Ｓｉｎｉｐｅｒｃａ ｃｈｕａｓｔｓｉ）池溏主要水生态因子关系问题。结果表明，降水、降温会引起藻类种群的改变，进而溶氧变化，最终影响鱼的健康，低溶氧是诱发鳜鱼疾病的首要水化因子。所以，气侯变化是生态因子变化继而诱发鳜鱼疾病的催化剂。水中营养盐浓度影响藻类生长。     

Partitioning of rainfall in a eucalypt forest and pine plantation in southeastern australia: II stemflow and factors affecting stemflow in a dry sclerophyll eucalypt forest and a pinus radiata plantation

Stemflow of a dry sclerophyll eucalypt forest and a nearby Pinus radiata plantation was studied on a rainfall event basis. The stemflow yields of the forests are quantified, compared, and presented on an annual basis for four years. Yields of the individual eucalypt species are compared and the tree characteristics responsible for the yield differences are discussed. The influence of event size, type, and season on stemflow are also shown. Rainfall angle is shown to have a significant effect on stemflow yield.     

城市化进程对北京地区降水的影响分析

用北京20个基本气象站1978—2009年的日降水观测资料以及北京地区水文总站遍布全市的82个雨量站资料,讨论了北京地区降水分布的特征及其城市效应的影响。得到如下结论：（1）北京地区降水量的贡献以中雨以上降水为主。30多年来各级降水除了中雨趋势不明显以外,其他都呈现减小趋势。北京地区降雨量的减少,主要是由于大雨以上量级雨量减少所造成的。（2）近30 a来整个区域降水日数呈减少趋势：西部、西北部及北部山区降水日数较多,越靠近城区降水日数越少。（3）当大尺度降水系统较弱或者局地性强降水系统时,城市效应明显,即相对于区域平均而言,城区及下风方局地降雨增加;而大尺度天气系统较强时,城市效应基本被掩盖。（4）从强降水分布看,1980s以后随着城市化进城加快,短时强降雨局地性特征明显,降雨分布不均,降雨中心的面积和强度明显缩小。这种分布可以在城市热岛分布特征上得到一些合理的解释。     

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.     

伊宁市1991-2011年降雨特征分析

利用1991～2011年5～9月伊宁市气象站逐小时降水资料,分析了伊宁近21a降雨特征。结果表明,21a来伊宁雨日年际变化较为明显,后10a和前10a相比,中雨、大雨和暴雨日数均出现增加,但小雨日数明显减少导致总雨日出现了减少。小雨过程发生最多的时段是7月中旬,中雨和大雨过程最多时段同在5月下旬。前半夜为中雨、大雨、暴雨过程最易发生时段,后半夜为小雨过程最易发生时段。逐小时降水量和降水频次呈现较为一致的日变化特征,夜雨多且雨量集中。伊宁的降水主要以短时性降水（1～4h）为主,多发生在前半夜至后半夜,1h降水频次最多的是量级≤1mm的降水,但1.1～3mm量级的降水贡献率最高。