Nonstationary analysis of the extreme temperatures in Turkey     

《Dynamics of Atmospheres and Oceans》2021

Record-breaking extreme temperatures have been measured in the last two decades all over Turkey, with recent studies detecting positive trends in extreme temperature time series. In this study, nonstationary extreme value analysis was performed on extreme temperature time series obtained from fifty stations scattered over the seven geographical regions of Turkey. Basic characterization of the data set was defined through outlier detection, homogeneity, trend detection, and stationarity tests. Trend-including non-stationary extreme temperature time series were analyzed with non-stationary Generalized Extreme Value distribution. Three main physical drivers were considered as the leading causes that trigger the observed trends in extreme temperatures over Turkey: time, teleconnection patterns of the Arctic Oscillations, and those of the North Atlantic Oscillations. The results showed that most of the absolute annual minimum and maximum temperature time series are inhomogeneous while the possible breakpoints date back to the1970s and 1990s, respectively. More than half of the absolute annual maximum time series (26/50 and many of the absolute annual minimum time series (21/50) showed a positive trend. No negative trend was detected in the extreme temperature time series. Based on the frequency analysis of the 21 annual maximum time series, the non-stationary estimations of 50-year return levels were detected to be higher than in the stationary model (between 0.44 °C and 3.73 °C). The return levels in 15 of the 20 minimum temperature time series increased from 0.11 °C up to 12.28 °C. Elevation increases the nonstationarity impact on absolute minimum temperatures and decreases it on absolute maximums. The findings in this study indicate that the consideration of non-stationarity in extreme temperature time series is a necessity during return level estimations over the study area.  相似文献   

冷空气对台风“海葵”(1211)倒槽特大暴雨作用分析   总被引：9，自引：1，他引：8  

吴海英  陈海山  曾明剑  刘安宁  王伟丽 《热带气象学报》2014,30(5):871-880

针对2012年8月10日发生在台风"海葵"(1211)减弱低压倒槽顶部的特大暴雨过程,利用加密自动气象站、卫星云图、NCEP再分析资料,结合中尺度数值模式的模拟结果,分析了这次特大暴雨期间的中尺度对流系统演变特征及形成机理。研究表明,东北冷涡后部南下的冷空气为特大暴雨的发生提供了有利的热动力条件,促进了降水的发展。冷空气主体偏北,仅从对流层中层侵入低压倒槽北部,而对流层低层并无明显冷空气影响,使暴雨区上空形成冷平流叠置于暖平流之上的温度平流垂直分布结构,促进这一地区对流不稳定层结的建立和发展。冷空气与低压倒槽内辐合上升的暖湿空气对峙于对流层中层,引起中层锋生,锋生效应使风场辐合加强,进一步促进锋生。两者相互作用促进暴雨区及附近的中小尺度对流系统发展,在暴雨区上空强迫出一支对流尺度的强上升气流,加强低层水汽向上输送,使暴雨区上空水汽辐合层迅速增厚,从而引发局地特大暴雨天气发生。  相似文献   

双钻具钻进回转供风排渣结构设计          下载免费PDF全文

夏志明  李贺岩  薛军 《探矿工程》2011,38(11):48-50

双钻具钻进回转供风、排渣机构是动力头的关键部分,其密封装置的运转质量又是钻机正常运转的重要保证。叙述了旁侧供风和中心供风的结构形式,着重介绍了排渣系统的密封件选择及结构特点。  相似文献   

中低纬海气相互作用的耦合型态及其年代际振荡特征研究   总被引：3，自引：0，他引：3  

朱艳峰  丁裕国  何金海 《热带气象学报》2002,18(2):139-147

采用北半球500hPa高度场和北太平洋海温场月平均资料（1951－1995），借助于SVD分析方法，对北太平洋地区海气相互作用的耦合型态的季节及其年代际变化特征作诊断分析。结果表明：（1）在大气－海洋相互作用过程中，与厄尔尼诺（或拉尼娜）事件有关的SST分布型起着重要作用，而与此耦合的大气则表现为类似于PNA型遥相关的变化。其中冬季（1月）海气相互作作用的耦合程度较高，具体为厄尔尼诺事件对应着高度场的PNA流型。而与拉尼娜相对应的夏季500hPa高度场类似于东亚－太平洋（PJ）流型，但在4个季节中，夏季的海气相关耦合程度相对较差。春秋季同属于过渡季节，秋季海气之间的相关耦合不及春季紧密。（2）1976年前后海气耦合分布型态发生明显变化，冬季500hPa高度场PNA流型加强，阿留申低压加深并向东南移动，1976年后的夏季500hPa高度场的PJ流型表现明显，而1976年前这个遥相关型并不显著。  相似文献   

前期ENSO事件对东北地区夏季气温的影响   总被引：12，自引：2，他引：12  

刘实  王宁 《热带气象学报》2001,17(3):314-319

利用太平洋海温、北半于500hPa高度和长春夏季气温资料，研究了前期Nino-C区海温与我国东北地区夏季气温的关系。结果表明：前一年5－7月Nino-C区海温与东北地区夏季气温有密切关系，特别是在ENSO事件出现之后。厄尔尼诺年的次年东北地区夏季多高温，而拉尼娜年的次年，东北地区夏季低温更明显，这种关系可用于进行东北地区夏季气温的预测。另外，通过对海－气相互作用、韵律关系等的分析，得出了前期海温对东北地区夏季气温的可能影响途径。  相似文献   

2019年12月大气环流和天气分析   总被引：2，自引：1，他引：2  

徐冉  桂海林  江琪  张天航 《气象》2020,46(3):441-448

2019年12月大气环流主要特征为:北半球极涡为偶极型分布,环流呈三波型,东亚槽略偏弱,南支槽偏强,且副热带高压位置偏西。12月,全国平均降水量为11.2 mm,较常年同期(10.5 mm)偏多6.7%;全国平均气温为-2.7℃,较常年同期(-3.2℃)偏高0.5℃。月内共出现3次较强降水过程和3次中等强度冷空气过程。另外,7—10日、20—26日我国中东部地区发生了两次持续性大范围雾-霾天气过程。  相似文献   

多种方法分析城市化对保定气温变化的贡献   总被引：1，自引：0，他引：1  

王蓉蓉  周顺武  彭旭东  马悦  王传辉  顾东艳 《内蒙古气象》2014,(2):23-26,43

文章通过三种方法构造不同的背景气温序列,分析近33a(1979—2011年)城市化对保定气温变化的影响。结果表明:(1)对比保定站与郊区背景站气温资料得到城市热岛效应导致的增暖幅度为0.15℃/10a,城市化贡献率为30.3%。(2)用NCEP/DOE的2m气温再分析资料为背景得到的城市化增温幅度为0.238℃/10a,分离出的城市化贡献率为48.08%。(3)比较城市站与山区背景站资料得出年均气温的城市化增暖幅度为0.216℃/10a,贡献率为43.64%。(4)三种方法计算得出的城市化增温幅度及贡献率各不相同,却一致表明城市化对保定年气温的增暖贡献较为显著。  相似文献   

高分五号大气痕量气体差分吸收光谱仪甲醛反演可行性分析及初步结果     

王雅鹏  陶金花  程良晓  余超  范萌  张莹  陈元琳  朱莉莉  顾坚斌  陈良富 《遥感学报》2021,25(10):2040-2052

大气痕量气体差分吸收光谱仪EMI（ Environmental trace gases Monitoring Instrument）是搭载在“高分五号”（GF-5）卫星上的覆盖紫外—可见光波段的光谱仪,用于测量240—710 nm波长范围内的地球后向散射和太阳辐射,旨在量化全球对流层和平流层痕量气体的分布,如臭氧、二氧化氮等。本文关注EMI载荷对大气弱痕量气体甲醛（HCHO）的探测能力,并基于实测数据初步评估EMI HCHO产品的探测能力与精度。研究结果表明EMI的辐照度波长校准精度高,但在不同行之间存在较大的不均匀性,其波长校正的精度与仪器的狭缝函数高度依赖行位置的变化。基于EMI的HCHO反演的结果表明,EMI UV2频段的标称信噪比较低,使得利用差分吸收光谱技术（DOAS）得到的HCHO斜柱浓度SCD（Slant Column Density）存在较大的随机误差和拟合残差。现阶段,评估得到的EMI HCHO斜柱浓度的不确定性为1.2×10¹⁶ molec./cm²。与国际同类载荷TROPOMI（TROPospheric Ozone Monitoring Instrument）、OMI（Ozone Monitoring Instrument）的交叉对比验证结果表明,EMI可以捕捉到中国地区夏季HCHO的空间分布特征。EMI & TROPOMI与EMI & OMI的相关系数均大于0.8。但是在华东地区EMI HCHO普遍高于OMI和TROPOMI,其原因需要进一步研究。本文的研究证明了EMI对夏季HCHO的探测潜力及不足,可为后续类似载荷的指标设计和算法研发提供参考。  相似文献   

AN ANALYSIS OF THE ATMOSPHERIC WATER BALANCE OVER THE SOUTHERN HEMISPHERE     

David A. Howarth  John N. Rayner 《自然地理学》2013,34(6):513-535

An analysis of the atmospheric water balance over the Southern Hemisphere is conducted for the time period June 1980 through May 1984 that includes the 1982–1983 El Niño event. Notable spatial and temporal variations are evident in the moisture flux divergence fields, in the mean meridional transport of water vapor, and in the moisture content of portions of the tropical atmosphere that are attributable to the 1982–1983 ENSO event. Estimates of the net gain/loss of atmospheric water are provided for 10° latitude belts; although the magnitudes of the differences between evaporation and precipitation fall within the range of previous estimates, they are most probably underestimated. [Key words: atmospheric water balance, El Niño, hydrologic cycle, southern hemisphere, water vapor flux.]  相似文献   

The August 2007 Heat Wave in North Carolina: Meteorological Factors and Local Variability     

《自然地理学》2013,34(3):217-240

August 2007 was an exceptionally warm month across North Carolina. Hundreds of daily maximum and daily high minimum temperature records, as well as numerous all-time temperature records, were either tied or broken during the month. At the same time, a drought of historic proportions overspread much of the Southeast United States. A critical aspect of the August 2007 heat wave was the observed variability in heat and humidity across the different geographic regions of North Carolina. The highest maximum temperatures occurred most frequently in the Piedmont and Sandhills regions, while minimum temperatures were exceptionally high along the coast. The broad-scale pattern of heat can be tied to adiabatic warming associated with subsidence downstream of a persistent upper-level ridge centered over the Mississippi River Valley. Regional to local variations in the heat and humidity across North Carolina are linked to upwind sensible heat fluxes associated with major soil moisture deficits, adiabatic warming connected with downsloping winds off the Appalachian Mountains, and the depth of the mixing layer. Along the coast, the pattern of heat and humidity was tied to the positioning of a mesoscale thermal trough and the presence and strength of the sea-breeze circulation.  相似文献