重庆城市不同下垫面温度的多时间尺度变化特征     

姜平  刘晓冉  廖代强  柴闯闯  张甜  刘亮 《气象科技》2019,47(4):639-647

利用重庆市巴南区2014年1月1日至2017年12月31日逐小时草地、泥土、砾石、石板、水泥、沥青等6种不同下垫面的特种温度观测资料,通过扩展经验正交分解(EEOF)、概率密度分析(PDF)等气候统计方法,分析了不同下垫面温度的多时间尺度变化规律,进一步探讨了水泥和草地下垫面温度差异的变化特征。结果表明:不同下垫面的温度存在明显的多时间尺度变化特征。月平均变化上,石板、水泥和沥青的表面温度明显高于泥土、草地和砾石,且温度差异夏季大于冬季。日变化上,石板、水泥和沥青白天的表面温度高于泥土、草地和砾石,晚上不同下垫面温度差异较小;不同下垫面温度的日变化差异在春季和夏季明显强于冬季和秋季。石板、水泥和沥青表面出现45℃以上极端高温的概率多于其他下垫面,且出现这些高温的时间集中在14:00—15:00之间。水泥和草地的温度差异也表现出明显的多时间尺度变化(季节变化和日变化)特征。一天中,温度差异最大值出现的时间集中在14:00—16:00,其次是19:00—20:00。温度差异的日变化幅度也在夏季达到最大。  相似文献   

西北太平洋热带气旋移动方向变化异常的环流特征   总被引：3，自引：2，他引：1  

周宜卿  余锦华 《气象科学》2015,35(6):720-727

基于中国气象局和上海台风研究所整编的1972-2011年热带气旋(TC)best-track资料,采用极端天气气候事件定义的百分位法确定TC移动方向异常变化的阈值,利用Lanczos滤波法将大气环流分解成为季节内振荡(MJO)、准两周振荡(QBW)和天气3种尺度环流场,研究这3种尺度环流对热带气旋在南海地区异常北折的影响。结果表明:近40 a的资料统计显示,热带气旋12 h内移向逆时针方向偏转50°以及顺时针方向偏转47°为TC移动方向变化的95%分位数值,将12 h移动方向变化大于该数值的TC定义为移动方向变化异常。TC异常路径平均每年发生2.68次,9月份发生的概率最大,约为7%,最常发生在南海海域。分析3个发生在南海地区热带气旋异常北折的引导气流发现,在TC转向前,向西的引导气流纬向速度减慢,经向分量先向南加速,随后突然转为向北加速。天气尺度对应的引导气流对TC异常右偏影响最为明显,对流层中高层热带气旋中心东南侧强天气尺度西南气流引导TC异常右偏。  相似文献   

MS6.0以上强震临震前几小时震中区域天气特征     

陈涛  李磊  张效信  马启明  李文  提烁  吴晗  李仁康  罗静  苏建峰 《地震地磁观测与研究》2021,42(z1):8-10

1 研究背景 大气电场(Atmospheric electrical field)是描述空间电荷分布的一个重要物理量,受空间天气、气象活动、地质活动等因素的影响.20世纪即对地震前大气电场开展观测,异常结果与假说也被现代技术的最近测量所证实(Jin et al,2020;陈涛等,2021).但利用震前大气电场异常现象预测地震,需要克服的难题就是大气电场对天气条件的敏感性.目前,只有晴天气象条件下的大气电场异常才被认为是地震前兆信号.  相似文献   

热带大气季节内振荡对东亚季风区的影响及不同时间尺度变化研究进展     

林爱兰  梁建茵  谷德军 《热带气象》2008,24(1):11-19

在引证论述大气ISO对东亚季风区天气气候重要作用的基础上,概括性地回顾大气ISO基本特征及其形成机制的主要成果,重点针对热带大气ISO的季节变化、年际变化甚至年代际变化方面的研究工作进行总结评述。  相似文献   

Validation of ECMWF and NCEP–NCAR Reanalysis Data in Antarctica   总被引：3，自引：0，他引：3  

YU Lejiang  ZHANG Zhanhai  ZHOU Mingyu  Shiyuan ZHONG  Donald LENSCHOW  Hsiaoming HSU  WU Huiding  SUN Bo 《大气科学进展》2010,27(5):1151-1168

The European Center for Medium-Range Weather Forecast (ECMWF) Re-Analysis (ERA-40) and the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) ECMWF (ERA-40) and NCEP-NCAR reanalysis data were compared with Antarctic station observations, including surface-layer and upper-layer atmospheric observations, on intraseasonal and interannual timescales. At the interannual timescale, atmospheric pressure at different height levels in the ERA-40 data are in better agre...  相似文献   

On Multi-Timescale Variability of Temperature in China in Modulated Annual Cycle Reference Frame   总被引：2，自引：0，他引：2  

QIAN Cheng  Zhaohua WU  FU Congbin  ZHOU Tianjun 《大气科学进展》2010,27(5):1169-1182

The traditional anomaly (TA) reference frame and its corresponding anomaly for a given data span changes with the extension of data length. In this study, the modulated annual cycle (MAC), instead of the widely used climatological mean annual cycle, is used as an alternative reference frame for computing climate anomalies to study the multi-timescale variability of surface air temperature (SAT) in China based on homogenized daily data from 1952 to 2004. The Ensemble Empirical Mode Decomposition (EEMD) method is used to separate daily SAT into a high frequency component, a MAC component, an interannual component, and a decadal-to-trend component. The results show that the EEMD method can reflect historical events reasonably well, indicating its adaptive and temporally local characteristics. It is shown that MAC is a temporally local reference frame and will not be altered over a particular time span by an extension of data length, thereby making it easier for physical interpretation. In the MAC reference frame, the low frequency component is found more suitable for studying the interannual to longer timescale variability (ILV) than a 13-month window running mean, which does not exclude the annual cycle. It is also better than other traditional versions (annual or summer or winter mean) of ILV, which contains a portion of the annual cycle. The analysis reveals that the variability of the annual cycle could be as large as the magnitude of interannual variability. The possible physical causes of different timescale variability of SAT in China are further discussed.  相似文献   

Seasonality of Interannual Inter-hemispheric Oscillations over the Past Five Decades   总被引：2，自引：0，他引：2  

GUAN Zhaoyong  LU Chuhan  MEI Shilong  CONG Jing 《大气科学进展》2010,27(5):1043-1050

Air mass is inter-hemispherically redistributed, leading to an interesting phenomenon known as the Inter-Hemispheric Oscillation (IHO). In the present article, the seasonality of the interannual IHO has been examined by employing monthly mean reanalyses from NCEP/NCAR, EAR40, and JRA25 for the period of 1958-2006. It is found that the IHO indices as calculated from different reanalyses are generally consistent with each other. A distinct seesaw structure in all four seasons between the northern and southern...  相似文献   

How Well do Existing Indices Measure the Strength of the East Asian Winter Monsoon？   总被引：44，自引：7，他引：37  

WANG Lin  CHEN Wen 《大气科学进展》2010,27(4):855-870

Defining the intensity of the East Asian winter monsoon (EAWM) with a simple index has been a difficult task. This paper elaborates on the meanings of 18 existing EAWM strength indices and classifies them into four categories: low level wind indices, upper zonal wind shear indices, east-west pressure contrast indices, and East Asian trough indices. The temporal/spatial performance and prediction potential of these indices are then analyzed for the 1957--2001 period. It reveals that on the decadal timescale, most indices except the east--west pressure contrast indices can well capture the continuous weakening of the EAWM around 1986. On the interannual timescale, the low level wind indices and East Asian trough indices have the best predictability based on knowledge of the El Nino-Southern Oscillation and Arctic Oscillation, respectively. All the 18 existing indices can well describe the EAWM-related circulation, precipitation, and lower tropospheric air temperature anomalies. However, the variations of surface air temperature over large areas of central China cannot be well captured by most indices, which is possibly related to topographic effects. The results of this study may provide a possible reference for future studies of the EAWM.  相似文献   

Variations in the summer monsoon rainbands across eastern China over the past 300 years     

郝志新  郑景云  葛全胜 《大气科学进展》2009,26(4):614-620

Based on reconstructions of precipitation events from the rain and snowfall archives of the Qing Dynasty (1736–1911),the drought/flood index data mainly derived from Chinese local gazettes from 1736–2000, and the observational data gathered since 1951,the spatial patterns of monsoon rainbands are analyzed at different time scales.Findings indicate that monsoon rainfall in northern China and the middle-lower reaches of the Yangtze River have significant inter-annual(e.g.,5–7-yr and 2–4-yr)as well as inter-de...  相似文献   

夏季北大西洋涛动的过去、现在和未来     

尚华明  马雷凯 《沙漠与绿洲气象(新疆气象)》2009,3(6):58-60

北大西洋-欧洲的夏季气候年际变化与著名的冬季北大西洋涛动相似。本文定义夏季北大西洋涛动（SNAO）为夏季北大西洋温带平均海平面气压的经验正交函数（EOF）第一特征向量。与冬季北大西洋涛动相比,SNAO位置更北、空间尺度更小。SNAO也可用聚类分析来检测,它在日和月的时间尺度上具有近似等价的正压结构。尽管它比冬季北大西洋涛动的振幅要小,但因夏季北大西洋风暴路径的位置,SNAO对欧洲北部的降水、温度、多云天气形成强烈影响。因此,它是欧洲西北部发生夏季气候极端事件的重要影响因素,这些极端事件包括洪水、干旱、酷热。众所周知,厄尔尼诺一南方涛动（ENSO）影响夏季的欧洲气候,但SNAO的年际变化受ENSO的影响很小。在年代际时间尺度上,模拟和观测结果均表明SNAO一定程度上与大西洋多年代涛动（AMO）相关。SNAO变化可以追溯到很久以前,用树轮资料重建的1706年以来SNAO变化可以证实这一点。长期的器测资料,像英格兰中部的温度资料,可验证该重建的正确性。最后,有两种气候模式均能模拟SNAO的目前状况,并预测未来随全球温室气体浓度增加,SNAO指数正位相发展趋势更强,这意味着夏季的欧洲西北部将有长期干旱的可能性。  相似文献