近159 年东亚夏季风年代际变化与中国东部旱涝分布

利用1850-2008 年我国东部地区90 个测站的旱涝等级和北半球夏季海平面气压格点等资料,使用BP 典型相关等方法,分析了近159 年旱涝等级与东亚夏季海平面气压的耦合相关关系。利用关键区域的海平面气压资料,定义出与我国东部旱涝分布有密切联系的东亚夏季风指数,在此基础上分析了东亚夏季风年代际变化对我国东部旱涝分布的影响。结果表明：(1) 近159 年中国东部旱涝具有4 种典型空间分布型,即华南与中国东部其他地区旱涝趋势相反型、黄淮地区与长江流域及其以南旱涝趋势相反型、江淮流域与中国东部其他地区旱涝趋势相反型和中国东部与西部旱涝趋势相反型。近159 年东亚夏季海平面气压场主要呈现亚洲大陆与西太平洋海平面气压强弱相反的分布特征;(2) 本文定义的夏季风指数的年代际变化与我国东部旱涝典型分布型的年代际变化有密切关系,但两者的相关关系并不是稳定不变的,存在显著的年代际位相差异,即20 世纪20 年代之前,当东亚夏季风偏强(弱) 时,长江流域以北容易偏旱(偏涝),长江流域及其以南容易偏涝(偏旱),20 世纪20 年代以后,当东亚夏季风偏强(弱) 时,长江流域以北容易偏涝(偏旱),长江流域及其以南容易偏旱(偏涝)。可见,使用较长年代资料进行考察,研究结论丰富了大多数使用近50-60 年资料的研究结果。东亚夏季风与我国东部旱涝分布之间关系的年代际位相差异,可能与东亚夏季风对太阳活动等外强迫的非线性反馈相联系     

东亚夏季风推进过程的气候特征及其年代际变化

利用1951~2001年NECP的逐日再分析资料及中国东部366站1957~2000年逐日降水资料,提出东亚夏季风推进过程的定量指标,分析东亚夏季风推进过程的年代际变化。结果表明：标准降水指数为1.5的等值线较好反映了中国东部夏季雨带的南北移动,以及雨带推进过程中呈现的阶段性与突变性特征。东亚夏季风的推进过程具有显著年代际变化,与夏季风前沿位置有关的指标在20世纪60年代中期前后发生显著变化,与夏季风推进强度有关的指标则在70年代末出现突变。60年代中期前,南海夏季风的建立时间较迟,但北推较快,夏季风前沿到达华北地区时间较早,在华北地区维持时间长,夏季风的北界位置偏北,华北雨季、淮河梅雨明显。70年代末以后南海夏季风的建立时间较早,夏季风前沿附近南风强度明显偏弱,降水主要集中在长江流域及其以南地区,华北雨季不明显。     

近159年东亚夏季风年代际变化与中国东部旱涝分布(英文)

Based on the drought/flood grades of 90 meterological stations over eastern China and summer average sea-level pressure (SLP) during 1850–2008 and BPCCA statistical methods, the coupling relationship between the drought/flood grades and the East Asian summer SLP is analyzed. The East Asian summer monsoon index which is closely related with interdecadal variation of drought/flood distribution over eastern China is defined by using the key areas of SLP. The impact of the interdecadal variation of the East Asian summer monsoon on the distribution of drought/flood over eastern China in the last 159 years is researched. The results show that there are four typical drought and flood spatial distribution patterns in eastern China, i.e. the distribution of drought/flood in southern China is contrary to the other regions, the distribution of drought/flood along the Huanghe River–Huaihe River Valley is contrary to the Yangtze River Valley and regions south of it, the distribution of drought/flood along the Yangtze River Valley and Huaihe River Valley is contrary to the other regions, the distribution of drought/flood in eastern China is contrary to the western. The main distribution pattern of SLP in summer is that the strength of SLP is opposite in Asian continent and West Pacific. It has close relationship between the interdecadal variation of drought/flood distribution patterns over eastern China and the interdecadal variation of the East Asian summer monsoon which was defined in this paper, but the correlation is not stable and it has a significant difference in changes of interdecadal phase. When the East Asian summer monsoon was stronger (weaker), regions north of the Yangtze River Valley was more susceptible to drought (flood), the Yangtze River Valley and regions south of it were more susceptible to flood (drought) before the 1920s; when the East Asian summer monsoon was stronger (weaker), the regions north of the Yangtze River Valley was prone to flood (drought), the Yangtze River Valley and regions south of it were prone to drought (flood) after the 1920s. It is indicated that by using the data of the longer period could get much richer results than by using the data of the last 50–60 years. The differences in the interdecadal phase between the East Asian summer monsoon and the drought/flood distributions in eastern China may be associated with the nonlinear feedback, which is the East Asian summer monsoon for the extrinsic forcing of solar activity.     

东亚夏季风的年代际变率对中国气候的影响

利用NCEP的海平面气压 (SLP) 资料,按6月～8月10^oN～50^oN陆 (110^oE)、海 (160^oE) 气压差 ≤ -5 hPa的累计值代表夏季风强度。每年的值被1951～2000年50年平均值除作为夏季风指数 (SMI)。近50年的SMI序列表明有明显的年代际变化,1970年代中之前强夏季风年 (SMI > 1) 占优势,1976年开始均为弱夏季风年 (SMI < 1)。同时研究了SMI与中国夏季 (6月～8月) 降水量与平均气温的关系。发现夏季风强时中国东部华北多雨,长江少雨,同时长江到淮河气温高,但中国西部在夏季风强时南部多雨,北部少雨,气温为北高南低。夏季风弱时情况相反。同时指出,夏季风的年代际变化还影响到夏季风与中国气候的年际变化关系。     

夏季东亚地区水汽输送年代际变化特征及其对中国东部降水的影响

利用经验正交函数(EOF)分析方法和1951-2004年NCEP/NCAR月平均再分析资料及160个中国地面测站月降水资料,对夏季东亚地区水汽输送的年代际变化特征及其对中国东部降水的影响进行分析.研究结果表明:20世纪70年代中后期至90年代初期,中国东部夏季降水以"南北旱中间涝"分布型为主,90年代初期之后则以"南涝北旱"分布型为主,呈现出显著的年代际变化特征,即20世纪90年代后雨带南移的特征开始明显:夏季整层水汽输送通量主模态的空间结构及其时间系数可以较好地反映出近50年来东亚大陆东部经向水汽输送从1974年起由强变弱的"转折点"特征及其年代际减弱变化趋势:印度大陆和孟加拉湾北部、长江中下游地区、南海以及热带西太平洋地区纬向水汽输送从1973年起由弱变强的"转折点"特征及年代增强变化趋势.揭示了东亚夏季水汽输送年代际分量主模态的时空演变造成中国东部夏季降水从"南北旱中间涝"分布型转向"南涝北旱"分布型,即中国东部夏季雨带呈现出南移年代际变化特征的关键因素之一.     

东亚夏季风的年际变化及其对环流和降水的影响

Using NCEP/NCAR reanalysis geopotential height (GHT) and wind at 850 hPa, GHT at 500 hPa, precipitation rate, sea level pressure (SLP) and precipitation observations from more than 600 stations nationwide in June–August from 1951 to 2006, and focusing on the East Asia-West Pacific region (10°–80°N, 70°–180°E), interannual variation of East Asian summer monsoon (EASM) and its correlations with general circulation and precipitation patterns are studied by using statistical diagnostic methods such as 9-point high pass filtering, empirical orthogonal function (EOF) analysis, composite analysis and other statistical diagnosis, etc. It is concluded as follows: (1) EOF analysis of SLP in the East Asia-West Pacific region shows the existence of the zonal dipole oscillation mode (APD) between the Mongolia depression and the West Pacific high, and APD index can be used as an intensity index of EASM. (2) EOF analysis of GHT anomalies at 500 hPa in the East Asia-West Pacific region shows that the first EOF mode is characterized with an obvious meridional East Asian pattern (EAP), and EAP index can also be used as an EASM intensity index. (3) The composite analysis of high/low APD index years reveals the close correlation of APD index with EAP at 500 hPa (or 850 hPa). The study shows an obvious opposite correlation exists between APD index and EAP index with a correlation coefficient of −0.23, which passes the confidence test at 0.10 level. (4) Both APD and EAP indexes are closely correlated with precipitation during flood-prone season in China and precipitation rate over the East Asia-West Pacific region. The significant correlation area at 5% confidence level is mainly located from the southern area of the Yangtze River valley to the ocean around southern Japan, and the former is a positive correlation and the latter is a negative one. Foundation: Cooperative Project funded by the Ministry of Science and Technology of the People’s Republic of China, No.2007DFB20210; National Natural Science Foundation of China, No.90502003; JICA China-Japan Technical Cooperative Project “China-Japanese Cooperative Research Center on Meteorological Disasters”. Author: Yu Shuqiu, Associate Professor, specialized in climate and climate change.     

中国降水量变化的空间分布特征与东亚夏季风

利用NCEP/NCAR海平面气压场和中国站点月降水量资料,研究了中国近47 a来的降水量变化空间分布特征及东亚夏季风与中国夏、秋季降水的关系.1961-2007年中国年降水量减少的区域主要在东北、华北、西北东部、西南东部和华南西部,形成一个东北一西南向的带状区域,其余大部为增加趋势,其中陕西北部和四川中南部减少趋势显著...     

东亚夏季风的年际变化及其与环流和降水的关系

利用1951-2006 年6-8 月NCEP/NCAR 的500 hPa 高度场、850 hPa 高度场和风场、降 水率和海平面气压以及全国600 多站的降水量资料, 选择东亚-西太平洋地区(10^o-80^oN, 70^o-180^oE) 经9 点高通滤波、EOF 分析、合成分析和其它统计诊断手段, 研究了东亚夏季风的年际变化及其与环流和降水的关系, 得到如下的结论: 1. 东亚-西太平洋地区海平面气压 存在着蒙古低压和西太平洋高压之间纬向的偶极子振荡型(APD), APD 指数可以作为东亚夏季风强度指数; 2. 东亚-西太平洋地区500 hPa 高度距平EOF 的第一模态具有明显经向东亚遥相关型特征(EAP)。EAP 指数也可以作为东亚夏季风强度指数。3. APD 指数与500 hPa (或 850 hPa) 的东亚遥相关型关系密切。APD 指数和EAP 指数存在明显的反相关关系, 它们之间的相关系数为-0.23, 已超过了10%显著检验; 4. APD 指数和EAP 指数都和我国汛期降水、东亚-西太平洋降水率关系密切, 超过5%显著性的相关区主要在长江流域以南地区至日本南部海面一带, 前者为正相关, 后者为负相关。     

广东雾霾天气能见度时空特征分析——年际年代际变化

利用1980-2003年广东省22个地面气象观测站24 a的气象观测资料,采用经验正交函数分解(EOF)和连续功率谱分析方法,分析广东省雾霾天气下能见度的时空分布特征.结果发现,广东地区雾霾天气能见度的年际年代际变化主要表现在EOF的前2个主模态,方差贡献分别占17.4%和11.8%.其中第1主模态的空间场与广东省自然地理区划基本对应,其时间序列反映的主要是雾霾天气下能见度的年代际变化.在1992年前后由正向负的逐渐减小可能与上世纪90年代以后广东地区经济活动的明显增强有关;第2主模态的空间场反映出广东地区能见度时空变化一致性的特点,其时间序列具有显著的准2 a、4 a和8 a振荡周期,所反映的主要是雾霾天气能见度的年际变化,可能与大尺度季风区对ENSO年际变化信号的响应有关.     

中国年代际暴雨时空变化格局

采用1951~2010年中国659个气象站点的日值降水数据,以中国气象局颁布的降水强度等级划分标准为依据,分别计算1951~1960、1961~1970、1971~1980、1981~1990、1991~2000、2001~2010年的年代际暴雨雨量、雨日和雨强,并统计了其相应的站点数目变化。结果表明,在时间上,中国年代际暴雨雨量和雨日显著增加,暴雨雨强也呈现增加趋势;在空间上,中国年代际暴雨雨量和雨日呈现出从东南沿海地区向华中和西南及环渤海地区逐渐扩张的梯度增加趋势,年代际暴雨雨强远不如暴雨雨量和暴雨雨日梯变明显。中国暴雨1951~2010年年代际时空变化格局很可能是在全球变暖大背景下中国地势与城市化共同作用的结果。     

多种东亚冬季风指数及其与中国东部气候关系的比较

利用NCEP/NCAR再分析资料及气温和降水观测资料,对比分析了12种不同定义的东亚冬季风(EAWM)指数及其与中国东部冬季温度和降水的关系。结果显示:多数EAWM指数具有较好的一致性,同时也存在差异,体现了不同定义的指数反映东亚冬季风整体性和局部性特征的侧重点有所不同。有10个EAWM指数均反映出近60年东亚冬季风呈减弱趋势,尤其是近30年最为明显,平均减弱速率达-0.25σ/10a,各指数均有强烈的年际变率和年代际波动。有10个(8个)EAWM指数与我国东部冬季温度(降水)第1模态呈显著负相关;其中西伯利亚高压指数对冬季温度年际变率方差解释率最高(53.3%),而对降水年际变率方差解释率最高的是对流层中高层东亚经向风指数(50.4%)。此外,不同EAWM指数与温度和降水的对应关系在El Niňo状态、La Niňa状态有不同的变化,表明在利用单个EAWM指数监测冬季气候时,要考虑到各个指数在ENSO不同状态下具有的差异性参考意义。     

Interannual variation of East Asian summer monsoon and its impacts on general circulation and precipitation

Using NCEP/NCAR reanalysis geopotential height (GHT) and wind at 850 hPa, GHT at 500 hPa, precipitation rate, sea level pressure (SLP) and precipitation observations from more than 600 stations nationwide in June–August from 1951 to 2006, and focusing on the East Asia–West Pacific region (10o–80oN, 70o–180oE), interannual variation of East Asian summer monsoon (EASM) and its correlations with general circulation and precipitation patterns are studied by using statistical diagnostic methods such as 9-point high pass filtering, empirical orthogonal function (EOF) analysis, composite analysis and other statistical diagnosis, etc. It is concluded as follows: (1) EOF analysis of SLP in the East Asia–West Pacific region shows the existence of the zonal dipole oscillation mode (APD) between the Mongolia depression and the West Pacific high, and APD index can be used as an intensity index of EASM. (2) EOF analysis of GHT anomalies at 500 hPa in the East Asia–West Pacific region shows that the first EOF mode is characterized with an obvious meridional East Asian pattern (EAP), and EAP index can also be used as an EASM intensity index. (3) The composite analysis of high/low APD index years reveals the close correlation of APD index with EAP at 500 hPa (or 850 hPa). The study shows an obvious opposite correlation exists between APD index and EAP index with a correlation coefficient of –0.23, which passes the confidence test at 0.10 level. (4) Both APD and EAP indexes are closely correlated with precipitation during flood-prone season in China and precipitation rate over the East Asia–West Pacific region. The significant correlation area at 5% confidence level is mainly located from the southern area of the Yangtze River valley to the ocean around southern Japan, and the former is a positive correlation and the latter is a negative one.     

Interdecadal change of snow depth in winter over the Tibetan Plateau and its effect on summer precipitation in China

This paper obtained a set of consecutive and long-recorded observational snow depth data from 51 observation stations by choosing, removing and interpolating original observation data over the Tibetan Plateau for 1961–2006. We used monthly precipitation and temperature data from 160 stations in China for 1951–2006, which was collected by the National Climate Center. Through calculating and analyzing the correlation coefficient, significance test, polynomial trend fitting, composite analysis and abrupt change test, this paper studied the interdecadal change of winter snow over the Tibetan Plateau and its relationship to summer precipitation and temperature in China, and to tropospheric atmospheric temperature. This paper also studied general circulation and East Asian summer monsoon under the background of global warming.     

过去千年太阳活动异常期的中国东部旱涝格局

根据过去千年中国东部旱涝等级资料,采用各级旱涝发生几率的比率差指标,参照新近重建的5条过去千年太阳活动序列,重建了其间11个太阳活动异常期的中国东部旱涝格局。结果发现：在11个太阳活动异常期,中国东部旱涝格局各不相同。其中在5个太阳活动极小期（1010-1050年、1280-1350年、1460-1550年、1645-1715年、1795-1823年）,中国东部旱涝格局虽不一致,但长江中下游地区（华北地区）出现偏旱（涝）的几率更高;而在2个太阳活动极大期和4个太阳辐射高值期,中世纪极大（1100-1250年）整个东部多偏旱,1845-1873年的太阳辐射高值期,整个东部多偏涝;其余4个时段（1351-1387年、1593-1612年、1756-1787年、1920-2000年）则旱涝相间出现。集合平均表明：在太阳活动极小期,中国东部呈自南向北的“涝—旱—涝”分布：长江流域偏旱,南北两侧的华南沿海和华北平原偏涝,且西北东部及西南偏旱;而在太阳活动极大期和太阳辐射高值期,长江流域及西北东部多偏涝,华南和华北多偏旱。