天山乌鲁木齐河源降水观测误差分析及其改正

乌鲁木齐河源不同雨量计观测降水对比以及普通雨量计湿润损失和蒸发损失实验表明,普通雨量计观测降水中的动力损失(修正量/观测降水量)为13.9％,湿润损失为8.4％,蒸发损失为3.7％,三项之和为26.0％。修正以上观测偏差,得到乌鲁木齐河源1号冰川粒雪线处(4050m)年平均降水量645.8mm。     

日以下尺度降雨随机模拟研究进展

目前我国作物生长、土壤侵蚀等应用模式发展很快,利用这些模式进行气候变化影响评价的研究逐渐成为热点,但日以下尺度降雨观测资料却严重不足,迫切需要针对我国复杂的气候条件建立日以下尺度降雨模拟模型,为应用模式提供更为精细的降雨资料输入。重点从次降雨事件的划分方法、次降雨事件模型的模拟过程、Bartlett-Lewis和Neyman-Scott点过程模型的模拟过程、参数估计、参数敏感性分析以及模型改进等方面综合概述了日以下尺度降雨随机模拟的进展,同时给出这几种模型的对比研究结果,从而为人们根据不同目的和条件选择不同模型提供借鉴。最后指出,结合点过程和次降雨事件等方法优点的混合模型——基于天气分型的随机模拟模型以及将统计与动力方法相结合的模拟模型,可能是未来降雨模拟的重要发展方向。     

Multi-scale Characteristics and Comprehensive Evaluation of Precipitation Heterogeneity in Guangxi

Aiming at the uneven spatial and temporal distribution of precipitation and frequent occurrence of drought and waterlogging disasters in Guangxi, the multi-scale characteristics and comprehensive evaluation of precipitation heterogeneity can provide scientific support for regional response to drought and waterlogging disasters and intelligent management of water resources. Based on the daily precipitation data of 87 grid points from 1961 to 2017 in Guangxi, the Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) index were used to build day, pentad, ten days, month, season precipitation heterogeneity of multiple time scale level evaluation system. By using R/S analysis and geographical spatial analysis methods, the space-time evolution characteristics and climate division in Guangxi were discussed. The study showed that the spatial and temporal variation characteristics of PCD and PCP at the diurnal, synoptic and monthly scales were relatively consistent, and the heterogeneity of precipitation in Guangxi could be better expressed than that at the monthly and seasonal scales. The diachronic change of PCD in precipitation in Guangxi shows an increasing trend in northeast China and a decreasing trend in southwest China, and the trend of its future period is the same as the diachronic evolution. The spatial distribution of PCD in Guangxi has significant spatial autocorrelation and stratification heterogeneity, which are mainly reflected in the mean value, coefficient of variation and frequency of PCD. The comprehensive heterogeneity of precipitation in Guangxi is highly dispersed in the northeast, highly concentrated in the south, and slightly concentrated or dispersed in the northwest and central regions. The time-scale within a month is the best scale to express the non-uniformity of precipitation in Guangxi. If the advantages of more stable climatic and ten-day scales and more fine daily scales are taken into account, the use of climatic scale for daily sliding calculation and analysis will be the best way.     

国内外风蚀监测方法回顾与评述

为了准确认识风沙运动规律、建立风蚀模型,必须对风沙过程进行野外实地监测.鉴于风沙过程的复杂性,目前风蚀监测的方法多种多样.根据监测目的和原理的差异,将现有的主要风蚀监测方法分为风蚀量监测和输沙率监测两大类分别评述.风蚀量监测主要包括集沙盘法,降尘缸法,风蚀盘法,风蚀圈法,示踪法,遥感法,侵蚀针法等;输沙率的监测主要使用...     

多传感器联合反演高分辨率降水方法综述

精确测量具有强烈时空变异性的降水,是水文气象学颇具挑战的科学研究目标之一。基于多传感器联合反演降水(Multi-sensor Precipitation Estimation,MPE)的方法已成为卫星反演降水的主流趋势。首先介绍MPE方法的定义与分类,回顾MPE方法的历史发展阶段及研究现状;然后介绍主要的MPE算法,包括TRMM多卫星降水分析算法(TMPA)、气候预测中心算法(CMORPH)、全球卫星降水制图算法(GSMa P)、美国海军研究实验室联合算法(NRLB)和神经网络降水算法(PERSIANN);对比这5种主要算法的优缺点和反演精度(PERSIANN精度范围为-56%~200%,其他产品为-67%~10%),指出存在的主要问题,并且评价不同类型MPE算法的性能;最后结合目前存在的问题探讨MPE方法研究发展趋势。     

密闭取心饱和度校正数学模型

利用密闭取心井资料分析油、水饱和度是目前最直接有效的方法,但是由于岩心上提导致的孔隙体积变大、降压脱气和钻井液侵入等过程的影响,岩心测试油、水饱和度之和一般均只有75%~85%,油、水饱和度都有较大损失,因而需要对油、水饱和度进行校正,争取求准饱和度数据。本次研究进行了挥发过程及岩心上提过程的室内实验,发现密闭取心降压脱气过程是造成油水饱和度损失的主要因素,目前实验条件难以如实模拟这一过程,研究中以流体分流率原理为核心,建立了降压脱气的数学校正模型;降压还会导致孔隙增大,岩心的覆压孔渗实验能够准确反映这一变化,为油水饱和度校正提供依据。建立的密闭取心饱和度校正数学模型精度与保压密闭取心的测试结果相当,具有推广意义。钻井液浸入造成的油水饱和度损失数量比较小,但是疏松砂岩中强浸的岩心样品油水饱和度数据需要校正,校正量一般不大于2%。     

Impact of Different Intensity Tropical Cyclones on Precipitation Changes in China

Based on the daily precipitation data of more than 2 000 meteorological stations from 1960 to 2017 and the tropical cyclone (TC) best-track data of the China Meteorological Administration, the TC precipitation was identified by the Objective Synoptic Analysis Technique (OSAT). The research shows that the TC precipitation in China has a significant downward trend, which is slower than that of the research results 12 years ago. The TC precipitation in the peaking season (July to Sepember) accounted for 78.5% of the total TC precipitation. Both TC precipitation in peaking season and other months showed a significant downward trend. The TC precipitation climate trend is mainly characterized by reduction in spatial distribution, and shows obvious regional differences. From south to north, there is a distribution of “decreasing-increasing-decreasing”, and the decreasing trend centers are located in Guangdong and Hainan. According to the maximum intensity in the TC influence period, we classified TCs into three levels (weak TCs, medium intensity TCs and strong TCs) and studied the variations of TC precipitation in different intensities. The results show that the strong TC precipitation shows a significant decrease trend, which mainly determines the influence range and trend of TC total precipitation. Further analysis found that the frequency of affecting TC showed a significant reduction trend during the time period of 1960-2017 and an abrupt shift occurred in 1995. A comparative study of the two periods before and after 1995 showed that compared with the previous period (1960-1994), the frequency of TCs in the latter period (1995-2017) showed a significant decreasing trend in the south of 20°N. The maximum decreasing center was located in the northern part of the South China Sea, and this feature was mainly affected by the strong TC. It was decided that this trend of strong TC led to a decrease trend in the number of precipitation days in South China, especially in Guangdong and Hainan, which led to a decrease trend in TC precipitation.     

Simulation Study on Precipitation Recycling Ratio in the Tibetan Plateau from 1982 to 2005

A dynamical downscaling approach using a regional climate model WRF (Weather Research and Forecasting Model Vision 3.5) driven by a global climate model CCSM4 (The Community Climate System Model Version 4) was adopted, and the downscaling results for the historical period (1982-2005) were evaluated for annual mean precipitation rate and evaporation rate over the Tibetan Plateau (TP). Furthermore, the spatial distribution and seasonal variation characteristics of Precipitation Recycling Ratio (PRR) simulated by CCSM4 and WRF were analyzed with the QIBT (Quasi-isentropic Back-trajectory method). The results show that the historical spatial distributions of annual mean precipitation rate and evaporation rate over the TP were found to better reproduce in the dynamical downscaling modeling compared to its coarse-resolution forcing. The PRR of the TP is 32% simulated by WRF, with a higher PRR in the wet season and a lower PRR in the dry season for the river basins in the northern TP, but the opposite seasonal variation was found for the river basins in the southern TP. In addition, the different land covers over the TP are more precisely represented in the WRF model, the PRR of grassland, shrubland and sparsely vegetation is higher than that of other land cover types.     

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.     

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.     

卫星遥感反演降水研究综述

降水是地球水循环的基本组成部分,具有重要的气象、气候和水文学意义.精准地测量降水及其区域和全球分布,长期以来一直是一个颇具挑战性的科学研究目标。经过近50年的发展,基于可见光、红外和微波等各类卫星传感器的降水反演算法也逐渐发展成熟起来。简要回顾可见光／红外、被动微波、雷达和多传感器联合反演等卫星遥感降水反演的基本原理、...     

冰核对云物理属性和降水影响的研究

系统回顾了冰核对云和降水影响的研究进展,详细分析了冰核对云的宏微观特征、对流系统结构和强度、辐射、雷电、降水量和降水强度的影响途径,并从云微物理过程的角度解释了其影响机制。得到如下结论:1通常情况下,冰核浓度增加,冰晶浓度增大,云滴浓度减小,云的生命史延长;2对于发展阶段的对流云,冰核在温度较高的过冷区活化使潜热在中低层提早释放,增加了对流系统中层不稳定能量,促进了对流系统的发展;3卷云中冰核浓度的增加,改变了冰相水物质与液相水物质的比例;削弱或抑制了卷云中同质核化,增大了卷云中冰晶粒子的平均半径;4冰核浓度的增加,能够使到达地气系统的净辐射增加;5冰核浓度的变化能够引起雷电活动发生频次和强度的变化;6冰核浓度增加,引起降水量的变化不确定,即降水量增加、减少或者变化不显著的情况都可能存在。这些结果为改进数值模式中冰核活化参数化方法提供指导,从而提高数值模式对云和降水的预报能力;同时为人工影响天气选择合适的人工催化剂和撒播时机提供参考。     

Research on Accuracy Validation and Calibration Methods of TRMM Remote Sensing Precipitation Data in Irrawaddy Basin

TRMM daily precipitation data were validated compared to thirteen precipitation observation station data in Irrawaddy basin, and a calibration method of TRMM 3B42 data based on water balance concept was developed. SWAT model was used to calculate water balance, and then the TRMM data calibration ratio was inferred based on it. Average slope of sub-basin was the independent variable, and calibration ration was the dependent variable for the regression analysis. The calibration ratio of sub-basins without hydrological observation stations were calculated according to the average slope, and then the TRMM precipitation were calibrated according to the ratio in the whole basin. Results showed that TRMM annual and monthly precipitation had a highly correlation with observed data, but had a bad bias. Annual precipitation of TRMM precipitation after calibration were nearly the same as observed; monthly precipitation curve were similar with observed. Daily precipitation forecast rank was improved from medium to well, and there were 2 station forecast bad, 7 forecast well and 4 forecast medium before calibration, but 6 forecast well, 2 forecast medium and 5 forecast excellent after calibration. The results proved that TRMM data precision were highly improved over different temporal scales in Irrawaddy basin through this method, data for hydrological and water resources analysis were also provided.     

山西省降水规律特性研究

以降水的成因和来源为基础出发点,对山西省的降水发生发展和分布特点进行全面研究,分析其在时间和空间上的变化趋势和特点,对水资源根本基础进行深入探讨,为整个地区的水资源分析评价和水资源发展战略规划及水生态和水环境保护提供科学参考依据.     

Objective Analysis on Large-scale Circulation Type and Its Links to Precipitation over China

Atmospheric circulation anomaly is a direct cause of weather and climate change. In the past, most researches for the relationship between Weather Type (WT) and precipitation have mainly focused on the subjective classification and diagnosis. Compared to the subjective analysis, objective classification uses more consistent index and standard unification, thus, we can get more WTs, and it has been widely used in many areas. By using daily 12UTC Sea Level Pressure (SLP), Precipitable Water (PW), and 700 hPa wind speed (UV700) data from ECMWF’s Interim Reanalysis, the classification of WTs over China was performed with the method of obliquely rotated T-mode principle component analysis. WT and its link to precipitation over China were further analyzed. The results show that the influence of different WTs on precipitation is not uniform over China, and also show distinctly difference in different seasons. A common feature is that WTs great impact on the regions and months with large precipitation, while less impact on regions and months have with less precipitation. In addition, precipitation trends originating from WT intensity changes are much more deterministic, significant, and predictable than trends from WT frequency changes.     

黄土高原降水量空间插值方法研究

为了研究黄土高原降水量的空间分布特征,利用ARCGIS软件分别采用多种空间内插方法对黄土高原108个气象站点1980-2009年30年间的平均年降水量进行空降插值。经过正交检验以及内插检验得到最优的插值方法为普通克里金法,最终对利用该方法获得的黄土高原降水量内插图进行分析,得出近30年来黄土高原区降水量分布呈现出明显的由东南向西北递减的态势。     

斑岩铜矿床研究进展

斑岩铜矿不但形成于环太平洋成矿域,还形成于特提斯成矿域和中亚成矿域（古亚洲洋成矿域）。成矿物质来源于深部,经过“洋壳一地幔熔岩流”、“原始岩浆”、“浅部富矿岩浆”和“岩浆结晶一成矿”4个阶段,其中在“原始弧岩浆”阶段,通过MASH过程,有大量成矿物质和能量的聚集。成矿流体为富H2O、高温、高压、高盐度、强氧化性、高氧逸度的富矿气液相流体,这些特点有利于成矿物质在岩浆一热液分离过程中向流体富集,并以氯络合物的形式运移。随着成矿流体的上侵,温度和压力的降低是成矿物质沉淀的主要影响因素。磁铁矿的结晶为成矿流体提供了大量的S2-离子,也是导致成矿物质沉淀的主要因素。斑岩型蚀变带从里向外为石英内核、钾化带、SCC带和泥化带,铜矿化主要发育在矿化带外围以及SCC带。目前,斑岩铜矿成矿模型主要有经典模型、系统模型和多阶段叠加模型。     

统计相关条件下降水及洪水预报误差相关分析

以三峡水库上游寸滩至万县区间降水预报误差和入库洪水预报误差相应数据为例,在探讨两者统计相关性的基础上,采用Frank、Gumbel、Clayton三种二元Copula连接函数分析了两预报误差的相关结构,以离差平方和最小为准则进行了Copula函数的选择,并与两预报误差独立情况下联合频率分布进行比较和分析。研究结果表明,降水预报误差和洪水预报误差的相关性对其二元联合分布有一定影响,同时,在两预报误差负相关条件下,其联合分布可做简化处理。本文研究结果可为水库预报调度风险管理提供决策参考。     

在厚靶分析中外标法的表面形状校正

在厚靶的非破坏性x射线荧光分析中，以钇做外标元素，研究了不同样品形状及与源、探测器距离不同时，引起接收到元素荧光强度差异的校正方法。给出了对不同形状瓷片中元素特征峰计数校正前后的比较。探讨了此种方法带入的测量误差。     

微型堆中子活化分析中铁对镓测定干扰的修正

在微堆中子活化分析中利用~(71)Ga(n,γ)~(7Z)Ga反应产生的834keV能峰测Ga时,由于快中子~(54)Fe(n,p)~(54)Mn反应所产生的~(54)Mn 834keV能峰会对Ga的测定产生明显的干扰,有必要用理论或实验的方法加以修正。文章分别用理论和实验的方法对Fe在Ga测定中所带来的干扰进行了扣除,取得较满意的结果。该方法也适用于其它元素同类型干扰的扣除。