Regional Frequency Analysis of Observed Sub-Daily Rainfall Maxima over Eastern China     

Hemin SUN  Guojie WANG  Xiucang LI  Jing CHEN  Buda SU  Tong JIANG 《大气科学进展》2017,34(2):209-225

Based on hourly rainfall observational data from 442 stations during 1960–2014, a regional frequency analysis of the annual maxima(AM) sub-daily rainfall series(1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a moving window approach) for eastern China was conducted. Eastern China was divided into 13 homogeneous regions: Northeast(NE1, NE2), Central(C), Central North(CN1, CN2), Central East(CE1, CE2, CE3), Southeast(SE1, SE2, SE3, SE4), and Southwest(SW).The generalized extreme value performed best for the AM series in regions NE, C, CN2, CE1, CE2, SE2, and SW, and the generalized logistic distribution was appropriate in the other regions. Maximum return levels were in the SE4 region, with value ranges of 80–270 mm(1-h to 24-h rainfall) and 108–390 mm(1-h to 24-h rainfall) for 20- and 100 yr, respectively.Minimum return levels were in the CN1 and NE1 regions, with values of 37–104 mm and 53–140 mm for 20 and 100 yr,respectively. Comparing return levels using the optimal and commonly used Pearson-III distribution, the mean return-level differences in eastern China for 1–24-h rainfall varied from-3–4 mm to-23–11 mm(-10%–10%) for 20-yr events, reaching-6–26 mm(-10%–30%) and-10–133 mm(-10%–90%) for 100-yr events. In view of the large differences in estimated return levels, more attention should be given to frequency analysis of sub-daily rainfall over China, for improved water management and disaster reduction.  相似文献   

不同天气现象下毕节高温特征及预报回归检验分析          下载免费PDF全文

吴姗  姚浪  刘健平  帅龙  聂祥 《中低纬山地气象》2022,46(1):68-72

利用毕节2010-2019年观测资料,分析不同天气现象下日最高气温特征,建立高温模型,并对近5 a 24 h高温进行检验,得出如下结论:(1)毕节高温日变化在夏季最稳定,春季波动最大。气温日较差晴天最大,阴天最小,多云时略大于阴间多云。(2)毕节8~10成云出现频率高达65.7%,夏季晴天频率波动大,春、夏季多云频率较高,且按天气现象分类统计月平均高温时,其峰值均出现在7月。(3) 24 h高温预报准确率月、季变化特征明显,夏季准确率最高,较最低的冬季高出21.4%,在区别天气现象的情况下,阴雨天时预报准确率最高,多云时最低,其中12月多云时最低为25%。(4)回归模型分析发现不同季节同种天气现象24 h高温预报影响因子权重差异明显,日照时数和平均本站气压对模型影响程度较高。不同季节晴天影响因子差异最大,拟合效果最好时段在夏季,平均估计误差为1.2℃,估计误差最大在冬季,平均估计误差为1.7℃。  相似文献   

大珠母贝Pinctada　maxima(Jameson)亲贝人工促熟培育与诱导排放精卵的研究   总被引：3，自引：0，他引：3  

梁飞龙  许国领  邓防茂 《海洋湖沼通报》1998,(2)

用亚心形扁藻Platymonassubcoriformis,湛江等鞭藻Isochrysiszhanjiangensis及某些配合饲料培育大珠母贝pinctadamaxima(Jameson)亲贝,可以促进性腺发育成熟并保持易于诱导排放状态。在需要进行人工育苗时,给亲贝以一定的刺激,即可诱导产卵排精。采用这种方法进行大珠母贝人工育苗,受精率和活率都比剖贝取卵授精的方法高。而且不用杀死大珠母贝亲贝。  相似文献   

The Statistical Distribution of the Horizontal Velocities of Water Particles at Wave Surface Maxima     

GUAN Changlong Professor 《中国海洋工程》1998,(3)

On the basis of the linear model of random sea waves presented by Longuet-Higgins,the statis-tical distribution of the horizontal velocities of water particles at wave surface maxima is derivedtheoretically.The derived distribution is similar to that of wave surface maxima,and a new spectral widthε_u,which is defined as(1-(m_3~2/m_2m_4))~(1/2),is introduced in the distribution.When ε_u tends to zero,the distribu-tion is reduced to Rayleigh distribution and it is reduced to the normal distribution when ε_u tends to unity.For a narrow spectrum,it is proved that ε is equal to 1/2ε,where ε is(1-(m_2~2/m_0m_4))~(1/2)and is the commonlyused spectral width..  相似文献   

极大螺旋藻铁型超氧物歧化酶的纯化及性质   总被引：3，自引：0，他引：3  

陶明煊  吴国荣  陆长梅  程光宇  魏锦城 《湖泊科学》1999,(1)

极大螺旋藻 Ｓｐｉｒｕｌｉｎａｍａｘｉｍａ藻体ＳＯＤ聚丙烯酰胺梯度凝胶电泳呈现４条同工 酶带, Ｈ_ ２Ｏ_２明显抑制该酶活性, ＫＣＮ对酶活性无影响,确认为 Ｆｅ－ＳＯＤ经硫酸铵分部盐析、离子交 换柱层析及凝胶过滤,纯化到电泳单斑点均－程度．纯化的Ｆｅ－ＳＯＤ分子量为３９．３ＫＤ,亚基分子 量为２０ＫＤ金属元素分析表明,每个亚基含０ ５５个Ｆｅ原子,该酶在紫外区最大吸收峰值为 ２７５．８nｍ、该酶氨基酸组成与蓝、绿藻和高等植物的Ｆｅ－ＳＯＤ相似,但它含有较高的丙氨酸,酸性氨 基酸和碱性氨基酸比值与低等植物及原核生物相近而明显高于高等植物．  相似文献   

Spatio-temporal downscaling of projected precipitation in the 21st century: indication of a wetter monsoon over the Upper Mahanadi Basin,India     

Subbarao Pichuka 《水文科学杂志》2017,62(3):467-482

An attempt is made to assess the future trend of spatio-temporal variation of precipitation over a medium-sized river basin. The Statistical Downscaling Model (SDSM, version 4.2) is used to downscale the outputs from two general circulation models (GCMs) for three future epochs: epoch-1 (2011–2040), epoch-2 (2041–2070) and epoch-3 (2071–2100). Considering the Upper Mahanadi Basin as a test bed, the study results indicate a “wetter” monsoon (June–September) and the annual increase in precipitation is 12% during epoch-3, which is consistent for both GCMs. Monthly analyses indicate that the precipitation totals are likely to increase and the magnitude of increase is greater during monsoon months than non-monsoon months. The number of month-wise daily extremes increases in most months in the year. However, the maximum percentage increase (with respect to baseline period, 1971–2000) in the number of extreme events is found in the non-monsoon months (specifically before and after the monsoon).  相似文献   

Water temperature modelling: comparison between the generalized additive model,logistic, residuals regression and linear regression models     

Fatima Laanaya  André St-Hilaire  Erwan Gloaguen 《水文科学杂志》2017,62(7):1078-1093

Water temperature has a significant influence on aquatic organisms, including stenotherm fish such as salmonids. It is thus of prime importance to build reliable tools to forecast water temperature. This study evaluated a statistical scheme to model average water temperature based on daily average air temperature and average discharge at the Sainte-Marguerite River, Northern Canada. The aim was to test a non-parametric water temperature generalized additive model (GAM) and to compare its performance to three previously developed approaches: the logistic, residuals regression and linear regression models. Due to its flexibility, the GAM was able to capture some of the nonlinear response between water temperature and the two explanatory variables (air temperature and flow). The shape of these effects was determined by the trends shown in the collected data. The four models were evaluated annually using a cross-validation technique. Three comparison criteria were calculated: the root mean square error (RMSE), the bias error and the Nash-Sutcliffe coefficient of efficiency (NSC). The goodness of fit of the four models was also compared graphically. The GAM was the best among the four models (RMSE = 1.44°C, bias = ?0.04 and NSC = 0.94).  相似文献   

CIC-200型离子色谱仪常见故障解析     

常姣  杨静  李颖  李晓锐  姚林鹏 《地震地磁观测与研究》2018,39(4):164-168

结合夏县中心地震台CIC-200型离子色谱仪实际观测,从仪器输液系统、分离系统、基线、管路等方面详细阐述色谱仪常见故障,逐一分析原因,并给出相应故障排除方法,为同类仪器维护提供参考,并为获得准确观测数据,延长仪器使用寿命,提出日常维护方法及建议。  相似文献   

2012年江苏扬州M 4.9地震前地磁垂直分量日变双低点异常     

郭明瑞  胡久常  吴佳林  王桂丹  王锡娇  崔泽岩 《地震地磁观测与研究》2018,39(3):89-93

2012年6月13日和7月10日华东地区部分地磁台垂直分量日变形态出现双低点异常,首次异常出现后37天,于7月20日发生江苏扬州M 4.9地震,震中位于低点位移分界线附近。分析认为,在强震前由于应力变化,引起孕震体环境中介质电导率等电磁性质发生改变,区域地磁场垂直分量日变曲线出现相位和幅度变化,说明地磁垂直分量日变双低点异常与地震的孕育和发生相关。  相似文献   

大地电场台站日变幅年度变化趋势分析     

赵文舟  马钦忠  陈婧  李伟  周江南  杨彦明 《地震地磁观测与研究》2018,39(6):165-172

为了直观展示大地电场日变幅年度变化趋势,获取多年尺度下数据变化形态及特征,选取2012-2015年,4个地电台网8个存在潮汐地电场变化的地电台站观测数据,进行去除台阶、异常数据及滤波处理,计算地电场日变幅。结果显示：①2012-2013年大多数台站存在春冬低、夏秋高的日变幅趋势性特征;②2014-2015年存在几种不同日变幅年度变化趋势,同时同一台站不同测道间日变幅变化趋势存在差异性,该变化趋势和差异性的存在可能与地下介质结构变化和介质的非均匀性有一定关系。  相似文献