2009年冬季至2010年春季黑龙江省气温持续偏低成因

利用常规观测温度资料和中国国家气候中心提供的环流特征量、NCEP／NCAR再分析资料及美国气候预测中心（CPC）提供的AO指数等,分析了2009年11月至2010年4月中高纬大气环流异常特征,探讨了AO与同期气温的关系。结果表明：黑龙江省冬春气候异常与500hPa大尺度环流背景有关。冬春持续偏冷,对应北半球欧亚中高纬地区呈“-＋-”的波列分布,90°-180°E呈现出“北正南负”的环流形势;北半球极涡面积偏大,冬季东亚大槽位置偏西,春季东亚大槽强度偏强,冬春AO指数持续异常偏强,显著负位相。     

西南地区冬季气温和降水的时空变化

In recent years,the socio-economic impacts of winter extreme climate events have underscored the importance of winter climate anomalies in Southwest China (SWC).The spatio-temporal variability of surface air temperature (SAT) and precipitation in SWC and their possible causes have been investigated in this paper based on observational data from 1961 to 2010.The results indicate that SAT anomalies in SWC have two dominate modes,one is homogenous,and the other a zonal dipole.The former is caused by the anomalies of East Asian winter monsoon;the latter arises from the anomalies of both subtropical west Pacific high and regional cold air in lower troposphere.The most dominant mode of precipitation anomalies in SWC is homogenous and it has a high correlation with northern hemisphere annular mode (NAM,AO).Neither NAM nor ENSO has significant impacts on SAT in SWC.The anomalies of NAM are associated with the anomalies of tropical circulations,and there-fore precipitation over the SWC.When NAM is in positive (negative) phase,the winter pre-cipitation is more (less) than normal in SWC.Winter precipitation increase over the whole SWC is associated with the El Nino.However,during La Nina winter,the pattern is not uni-form.There is an increase in precipitation over the central parts and a decrease in western and eastern parts of SWC.The severe drought in SWC in winter 2010 is more likely caused by anomalies of NAM,not El Nino.     

1959—2009年甘肃极端温度时空变化及其与AO相关分析

利用1959-2009年甘肃省24个台站的逐日最高和最低气温资料,运用百分位法定义了不同台站的逐年最高温度的极端高值、最低温度的极端低值.研究了甘肃省51 a来极端温度的时间变化特征;运用多元线性回归及空间插值法分析了其空间变化特征,并运用Pearson系数分析了极端温度与北极涛动(AO)相关关系.结果表明,甘肃省51 a最高温度的极端高值时间变化特征总体呈增加趋势,陇东及陇南地区增温显著;最低温度的极端低值显著增加的地区则为甘肃中部及西南部地区.最高温度的极端高值大值区地域集中在河西走廊西部地区,小值区在祁连山区及甘南高原;最低温度的极端低值大值区集中在陇东及陇南地区,小值区则在河西走廊的祁连山区.甘肃地区最低温度的极端低值与AO的相关关系要比最高温度的极端高值更为显著.     

东亚冬季风的时空变化及其与ENSO、AO相互关系的研究进展

作为亚洲季风系统中的一个重要组成部分, 东亚冬季风的变化对北半球甚至全球的天气气候都有重要的影响。本文回顾了近些年国内外关于东亚冬季风变化特征, 主要包括其时间和空间演变及其与ENSO、AO之间相互作用等研究的主要进展。目前已有的研究结果表明, 东亚冬季风系统是一个贯穿于整个大气对流层的深厚型环流系统, 其异常表现为东亚区域整层环流系统的异常;东亚冬季风具有2a, 5~7a的年际变化和10a以上的年代际变化, 有空间分布的不均匀性及爆发与撤退日期的突变性;强弱冬季风年的异常环流形势在对流层各层以及高纬度、中纬度和低纬度地区都有所表现;在年际尺度上, ENSO、AO与东亚冬季风有一定的相关性, 但是在年代际上, 东亚冬季风同两者之间有着更显著的联系, 通过大气动力和热力过程, 它们之间相互影响、相互作用, 共同影响我国、东亚甚至于全球天气气候的变化。      

Quantitative Comparison of a New Ab Initio Micrometeor Ablation Model with an Observationally Verifiable Standard Model

The Arecibo UHF radar is able to detect the head-echos of micron-sized meteoroids up to velocities of 75 km/s over a height range of 80–140 km. Because of their small size there are many uncertainties involved in calculating their above atmosphere properties as needed for orbit determination. An ab initio model of meteor ablation has been devised that should work over the mass range 10⁻¹⁶ kg to 10⁻⁷ kg, but the faint end of this range cannot be observed by any other method and so direct verification is not possible. On the other hand, the EISCAT UHF radar system detects micrometeors in the high mass part of this range and its observations can be fit to a “standard” ablation model and calibrated to optical observations (Szasz et al. 2007). In this paper, we present a preliminary comparison of the two models, one observationally confirmable. Among the features of the ab initio model that are different from the “standard” model are: (1) uses the experimentally based low pressure vaporization theory of O’Hanlon (A users’s guide to vacuum technology, 2003) for ablation, (2) uses velocity dependent functions fit from experimental data on heat transfer, luminosity and ionization efficiencies measured by Friichtenicht and Becker (NASA Special Publication 319: 53, 1973) for micron sized particles, (3) assumes a density and temperature dependence of the micrometeoroids and ablation product specific heats, (4) assumes a density and size dependent value for the thermal emissivity and (5) uses a unified synthesis of experimental data for the most important meteoroid elements and their oxides through least square fits (as functions of temperature, density, and/or melting point) of the tables of thermodynamic parameters given in Weast (CRC Handbook of Physics and Chemistry, 1984), Gray (American Institute of Physics Handbook, 1972), and Cox (Allen’s Astrophysical Quantities 2000). This utilization of mostly experimentally determined data is the main reason for calling this an ab initio model and is made necessary by the fact that individual average meteoroid mass densities are now derivable from Arecibo observations.     

Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter

This paper analyzes interannual variations of the blocking high over the Ural Mountains in the boreal winter and their association with the Arctic Oscillation/North Atlantic Oscillation (AO/NAO).In Jan...     

近51年500 hPa上北极涛动的时空变化特征分析

对1951-2001年北半球500hPa高度场月、季及年平均资料分别进行EOF分析．并对EOF分析得到的第一特征向量时间系数进行功率谱分析。结果发现：北极涛动是近51年北半球500hPa高度场异常的第一特征,方差贡献率在10％～20％之间;极区中心具有明显的偏心结构,范耐冬、春季大而向高纬伸展;夏、秋季小且向极区收缩。中高纬冬季中心区范围比夏季大且系统比较集中：极地到格陵兰岛附近、西南欧洲到地中海地区、贝加尔湖到日本海以及北美洲东南部地区是500hPa高度场上环流异常的主要发生地区;北极涛动正位相时期,冬季在20世纪90年代,春季在70年代中期以前,夏季在60,70年代,秋季在80年代中后期到90年代前期;北极涛动负位相时期,冬季在50年代．春季在70年代中期以后,夏季在50,90年代,秋季在90年代后半期。另外,只有1998年相对来说为全年各月北极涛动强年,说明1998年是近51年来气候最异常的一年。     

青藏高原东部冬季降水对北极涛动异常的响应

基于1979—2015年中国区域CN05.1格点降水以及全球降水气候中心(GPCC)降水等数据资料,采用回归、合成分析等方法,分析了青藏高原东部(简称高原)冬季降水的南、北区域性差异及其年际变化对北极涛动(AO)异常的响应.结果表明:(1)高原北部和南部冬季降水都与AO异常存在密切关系,但降水的年际变化并不一致,对AO...     

Ocean–atmosphere Teleconnections Play a Key Role in the Interannual Variability of Seasonal Gross Primary Production in China

Since the 1950s, the terrestrial carbon uptake has been characterized by interannual variations, which are mainly determined by interannual variations in gross primary production (GPP). Using an ensemble of seven-member TRENDY (Trends in Net Land–Atmosphere Carbon Exchanges) simulations during 1951–2010, the relationships of the interannual variability of seasonal GPP in China with the sea surface temperature (SST) and atmospheric circulations were investigated. The GPP signals that mostly relate to the climate forcing in terms of Residual Principal Component analysis (hereafter, R-PC) were identified by separating out the significant impact from the linear trend and the GPP memory. Results showed that the seasonal GPP over China associated with the first R-PC1 (the second R-PC2) during spring to autumn show a monopole (dipole or tripole) spatial structure, with a clear seasonal evolution for their maximum centers from springtime to summertime. The dominant two GPP R-PC are significantly related to Sea Surface Temperature (SST) variability in the eastern tropical Pacific Ocean and the North Pacific Ocean during spring to autumn, implying influences from the El Ni?o–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). The identified SST and circulation factors explain 13%, 23% and 19% of the total variance for seasonal GPP in spring, summer and autumn, respectively. A clearer understanding of the relationships of China’s GPP with ocean–atmosphere teleconnections over the Pacific and Atlantic Ocean should provide scientific support for achieving carbon neutrality targets.     

Interdecadal correlation of solar activity with Tibetan Plateau snow depth and winter atmospheric circulation in East Asia

Studies on the impact of solar activity on climate system are very important in understanding global climate change. Previous studies in this field were mostly focus on temperature, wind and geopotential height. In this paper, interdecadal correlations of solar activity with Winter Snow Depth Index (WSDI) over the Tibetan Plateau, Arctic Oscillation Index (AOI) and the East Asian Winter Monsoon Index (EAWMI) are detected respectively by using Solar Radio Flux (SRF), Total Solar Irradiance (TSI) and Solar Sunspot Number (SSN) data and statistical methods. Arctic Oscillation and East Asian winter monsoon are typical modes of the East Asian atmospheric circulation. Research results show that on interdecadal time scale over 11-year solar cycle, the sun modulated changes of winter snow depth over the Tibetan Plateau and East Asian atmospheric circulation. At the fourth lag year, the correlation coefficient of SRF and snow depth is 0.8013 at 0.05 significance level by Monte-Carlo test method. Our study also shows that winter snow depth over the Tibetan Plateau has significant lead and lag correlations with Arctic Oscillation and the East Asian winter monsoon on long time scale. With more snow in winter, the phase of Arctic Oscillation is positive, and East Asian winter monsoon is weak, while with less snow, the parameters are reversed. An example is the winter of 2012/2013, with decreased Tibetan Plateau snow, phase of Arctic Oscillation was negative, and East Asian winter monsoon was strong.