长期天气变化与地球自转速度的若干关系

本文应用1820—1983年的地球自转变化率资料,分析出地球自转变化存在准44个月、准11年、准24年和准49年的周期。南方涛动指数的变化,大气活动中心位置的移动,赤道东太平洋海温的异常等,都能从地球自转速度变化思期中找到关系。已经发现,在地转长期(准24年和准49年周期)加(减)速时,南方涛动指数减弱(增强),大气活动中心向西北(东南)移动,非洲干旱区降水偏多(偏少);同时发现:在地转短期(准44个月周期)加(减)速时,赤道东太平洋海温降低(升高)。本文讨论微机在地理学上的应用,介绍可以从英美市场获得的地理软件,并检讨微机在英美地理教学和研究上的一些限制,以促进其在国内地理学上的应用。现存的软件和硬件基本上可以满足地理教学和研究上的大部分需要。随着微机价格的降低,体积的缩小,计算速度、内外存储器容量以及可携带性的增加,其实际应用将会更广。微机已逐渐成为地理教学和研究中不可缺少的工具。     

东亚冬季风活动与厄·尼诺的关系

本文利用1951—1986年全球月平均海平面气压资料以及赤道东太平洋的海温资料,研究了东亚冬季风的年际变化与厄·尼诺的关系,主要结果有:(1)东亚冬季风盛行期(10—3)赤道东太平洋海温与海平面气压场的密切相关区,主要位于亚洲南部和西太平洋(正相关)、澳洲北部(正相关)以及阿留申群岛地区(负相关)。(2)海温的变化一般超前冬季风的变化1—2个季节,以11月的海温与之相关最密切。(3)厄·尼诺年冬季,东亚大陆冷空气南下路径偏东,我国南方多雨。反厄·尼诺年相反,冷空气南下路径偏西,我国南方少雨。     

中国夏季高温日数时空变化及其环流背景

本研究利用1955~2005年全国193个气象站点夏季(5~9月)逐日最高气温资料,分析了我国东部地区夏季高温日数变化的空间分布特征和时间变化规律。经验正交函数分析结果显示高温日数的变化有明显的区域特征,第一模态表现为区域整体一致的异常,中心区位于长江中下游地区,第二模态表现为江淮流域与华南反向变化的特点,第三模态表现为东南部地区与西南、华北的反向变化。这些模态与高层大气环流的变化有关。分析表明ENSO(厄尔尼诺-南方涛动)、赤道印度洋和西太平洋暖池海温,可以通过影响西太平洋和东亚地区大气环流而影响我国夏季高温日数频次,其中ENSO和西太平洋暖池区海温对高温日数变化第一模态的相关比较明显;而热带印度洋海温对第二模态有显著影响。与前期海温的关系分析可知,第一模态与前期夏季的西太平洋暖池和前期冬季赤道东太平洋海温相关关系最好,第二模态则受热带印度洋前期冬季海温影响最大,这对高温预测具有指示意义。     

四川西昌螺髻山全新世植被与环境变化

通过对沉积物进行孢粉、植物碎屑、硅藻和矿物等的研究和表土的孢粉分析,发现外来孢粉可以远远多于原地沉积的孢粉。并证明该地区在12400年B.P.时,雪线已经高于3660m,从12000年B.P.开始进入全新世。作者在文献[1]中探讨了我国大气透明度系数的空间分布及其主要影响因子。本文则探讨大气透明度系数的时间变化,特别是它的长期变化及其成因。结果发现:火山爆发可使大气透明度系数明显减小;由于人类活动影响,冬季大气透明度系数P_z、P_d有明显的减小趋势,P_2、F_d与用煤量等污染指标有很好的负相关。文中还对大气可降水含量的气候学推算方法进行了探讨。     

中国季风降水与赤道东太平洋海温的关系*

本文根据近38年(1951—1988年)海平面气压场与我国160个站降水的冬夏距平值,研究了季风降水与赤道东太平洋海温(SST)变化的关系,发现两者有联系的年占一定优势。季风降水与SST的关系虽非逐年对应,但SST异常对东亚季风气压场的年际变化及我国降水变化仍是一个不可忽视的影响因素。     

陕北黄土高原区极端降水时空变化特征及其影响因素

基于1970—2017年逐日降水数据,辅以趋势分析、空间分析和小波相干等气候诊断方法,对陕北黄土高原区极端降水时空变化特征进行分析,探讨不同海区海温异常与降水变化的响应关系。结果表明：① 1970—2017年,陕北地区气温波动上升,降水增加,半干旱界线明显向西北方向移动;② 1970—2017年,陕北地区降水呈现极端化。具体表现为,弱降水日数减少,强降水日数增加,降水持续时间呈现破碎化,1日最大降水量、5日最大降水量和降水强度均表现出显著的上升趋势;③ 在影响因素上,陕北地区极端降水变化受赤道太平洋中西部海温影响明显于东部,受赤道太平洋北侧影响明显于南侧,受海温年代周期变化影响（14~16a）明显于中长期周期（4~8a）。同时,NINO W区可作为区域极端降水响应的关键海区。当NINO W区海温异常偏高时,陕北地区降水普遍偏高,降水强度和持续时间增加,易发生雨涝灾害。     

山西降水与ENSO的相关性研究

基于山西38个测站1958-2013年的逐月降水资料、CPC南方涛动指数、NOAA逐月太平洋海温等资料,应用趋势分析和相关分析等统计方法分析了近56年山西年及四季降水对ENSO事件的响应。结果表明:1 La Nina年,山西年降水、秋、冬季降水易偏多,春、夏季易偏少;El Nino年,春季降水易偏多,年降水、夏、秋和冬季易减少。La Nina次年,冬季降水易偏多,年降水、春、夏和秋季易偏少;El Nino次年,年降水、春、夏季降水易偏多,秋、冬季易偏少。2山西年降水与上年太平洋海温在Nino 3,4区存在小区域的正相关,上年对应海域海温偏高(低),年降水易偏多(少),与同期太平洋海温在Nino 3区存在负相关,对应海域海温偏高(低),年降水易偏少(多);春季降水与前期冬季(同期)太平洋海温在Nino 3,4(Nino C)区存在正相关;夏季降水与前期春季(同期)太平洋海温在Nino 3区存在负相关;秋季降水与前期夏季(同期)太平洋海温在Nino C(Nino 3和Nino C)区存在负相关区;冬季降水与前期秋季(同期)太平洋海温在Nino 3,4(Nino C)区存在大面积负相关。3 SOI与山西大部分地区的降水趋势指数为显著负相关,中西部、东北部局部地区相关系数达-0.5以上,SOI为正(负)值时,上述地区月降水易偏少(多);SOI与东北部滞后1个月的降水趋势指数有相关系数达-0.45以上的负相关区域;SOI与滞后2(3)个月的降水趋势指数的相关分析表明,不同区域对SOI变化的响应不同,相关系数分别为-0.38~0.29和-0.43~0.22。     

江南春季降水的准2a振荡及其与热带海温异常的关系

基于中国160站的逐月降水观测资料及NOAA扩展重建的海表温度资料,从1951~2012年逐月的历史时间序列中提取出准2 a振荡(TBO)分量,对中国江南地区春季(3~5月)降水的TBO特征及其与热带海温的关系进行了分析。结果发现:①TBO为江南春季降水最主要的年际周期,TBO分量的方差贡献占到原始序列的52.2%。②江南春季降水与热带海温异常存在明显的时滞关系,其TBO分量与前期Nino3.4区和印度洋海表面温度距平(SSTa)的相关较原始序列更为显著,且持续时间更长,说明热带海温异常对江南春季降水TBO分量的影响是非常显著的。③江南春季降水TBO与Nino3.4指数的时滞关系还呈现出显著的年代际转折,20世纪80年代中期之前,江南春季降水TBO分量与Nino3.4指数在滞后1~11个月内都表现出明显的正相关关系,但从80年代中期至90年代末期这种时滞关系减弱,直至21世纪以来,江南春季降水TBO与Nino3.4指数的时滞关系又重新建立。④通过对比分析年代际转折前后与江南春季降水TBO循环所对应的热带海温演变特征,发现在20世纪80年代中期之前,TBO分量与超前1个季节的赤道中东太平洋海温异常演变具有同步性,使得两者之间的正相关关系稳定;而1986~1999年期间,无论是赤道中东太平洋地区或者印度洋地区海温的演变,都没有表现出像之前类似的TBO循环特征,从而导致两者的相关关系减弱。也就是说,江南春季降水的TBO与中东太平洋海温时滞关系的年代际转折与赤道中东太平洋海温是否具有显著的TBO周期密切相关。     

甘肃河西走廊沙尘暴与赤道中,东太平洋海温之间的遥相关分析

春、夏季甘肃河西走廊沙尘暴发生次数与赤道中、东太平洋海温之间遥相关分析结果表明：春、夏季河西走廊沙尘暴发生次数与前二年赤道中、东太平洋海温的负相关最好,时间过远或过近,相关性反而较差。利用前期的赤道中、东太平洋海温可以较好地预报出河西走廊春季沙尘暴发生的多寡。     

火山爆发与ENSO事件的联系

ENSO(EI Nino/Southern Oscillation)现象是海洋与大气相互作用的一个突出表现。ENSO 事件发生时,赤道东太平洋海表温度异常增高,南方涛动指数迅速下降,同时带来全球气候和海洋环境的异常。由于这一事件的出现常常带来严重的气候灾害和世界经济的巨大损失,所以越来越受到气象学家和海洋学家的重视。现在以 ENSO 为中心的海气相互作用的研究已成为当前地球科学中发展最快的领域之一。     

西北西风区与东部季风区年气温变化特征对比分析

利用我国西北西风区138站、东部季风区375站1964\_2006年43 a的年平均气温资料,对其时空变化特征及气温变化倾向率进行了对比分析。结果表明,西风区与季风区的时间变化规律基本一致,总体是在波动中呈一致的上升趋势,上升的趋势均是随着时间的推移而增加的,但西风区的年际变化更为剧烈,年际变化幅度大;除西风区1站和季风区4站具有负温度变率外,其余各站均为正温度变率,西风区≥0.4 ℃/10a变率区位于新疆西北部、新疆东部至青海西部的带状分布区及内蒙中部地区,而季风区≥0.4 ℃/10a位于受季风影响相对弱的北部地区,主要是西安-天津以西、以北的华北、东北地区。     

Reconstruction of the starting time series of rainy season in Yunnan and the evolvement of summer monsoon during 1711–1982

According to the textual research into the historical documents dominated by ar-chives yearly, as well as the verification with several other kinds of data, the later or earlier starting time of the rainy seasons in Yunnan during 1711–1982 has been reconstructed. The analysis indicates that there are obvious fluctuations in the starting date of the rainy seasons in Yunnan in a year or years, and long fluctuation on the decadal scale. The rainy season comes earlier in the early 18th century, later in the 19th century and earlier again in the 20th century. This reflects to a certain degree the gradual change of the summer monsoon in Yunnan. There exists an obvious quasi-3 years cycle, which is related to El-Nino’s quasi-3 years cycle, and a 11.3-year cycle which is notably related to the 11-year cycle of the solar activity of starting date of the rainy seasons in Yunnan. Meanwhile, the dissertation finds that the El-Nino is very important to the starting date of the rainy seasons in Yunnan. The starting date of the rainy seasons in Yunnan often comes later or normally in the year of El-Nino. However, there is an obvious imperfect period in such influence, which in turn may mean that there is a certain fluctuation in the effect of ENSO on Asian summer monsoon.     

1960-2016年秦岭—淮河地区热浪时空变化特征及其影响因素

基于134个气象站点1960-2016年逐日最高温和相对湿度数据,辅以趋势分析、空间分析和相关分析等方法,对秦岭—淮河地区热浪时空变化特征进行分析,探讨了赤道东太平洋海温异常与热浪变化的相关关系。结果表明：①近57年秦岭—淮河地区热浪呈现“非线性、非平稳和阶段性”的变化过程,年代变化可分为3个阶段：1960-1972年热浪呈现东西分异,分界线大致位于112°E,以东地区热浪异常偏多,以西地区则“高低交替”波动;1973-1993年热浪维持“低位波动”,并在20世纪80年代中期呈现快速增加;1994-2016年,关中平原、秦巴山区、巫山山区和四川盆地热浪维持“高位波动”,黄河下游、淮河平原和长江下游热浪则经历从“相对偏多”向“相对偏少”的转变;②在影响因素方面,最高温波动变化是秦岭—淮河地区热浪频次年代变化的主导因素,相对湿度变化的影响相对较弱;③近57年来关中平原热浪年代变化与赤道太平洋西部海温异常关系更为密切,长江流域与东部海温异常关系更为密切;对于黄河下游和秦巴山区的热浪变化与不同分区赤道太平洋海温异常关系均较弱。     

Cross-dependence of finite-frequency compressional waveforms to shear seismic wave speeds

Seismic tomography has been one of the primary tools to image the interior of the earth and other elastic structures. To date the inversions of compressional ( P ) and shear ( S ) wave speeds have been carried out separately under the assumption that P traveltimes are affected only by the P wave speed of the elastic media and S traveltimes by the S wave speed. Using numerical and analytical solutions, we show that for finite-frequency seismic waves, S wave speed perturbations may have significant effects on P waveforms. This suggests that when waveform-derived traveltime and amplitude anomalies are used in tomographic inversions, the P -wave measurements should be related to not only P wave speed perturbations but also S wave speed perturbations.     

清代云南雨季早晚序列的重建与夏季风变迁

根据以档案为主的历史文献资料逐年进行考订,复原了云南1711~1911年间的雨季早晚序列,并利用多种资料进行了检验。分析表明,云南雨季开始期年际和年代际的波动都较剧烈,还存在年代际尺度以上的长时间尺度波动。雨季开始期从18世纪初逐步转向偏早,19世纪又转向偏迟,到20世纪又偏早,这在一定程度上反映了夏季风的长期变迁。云南雨季开始期存在明显的准3年和11.3年周期,准3年周期可能和El Nino事件的准3年周期有关,11.3年周期明显和太阳活动的11年周期有关。同时发现,El Nino事件对云南雨季的开始期有重要的影响,在El Nino年云南雨季开始期主要为偏迟或正常,但这种影响存在明显减弱的时期,可能意味着ENSO事件对亚洲夏季风的影响存在某种震荡。     

1711-1982年云南雨季早晚序列的重建与夏季风变迁

According to the textual research into the historical documents dominated by archives yearly, as well as the verification with several other kinds of data, the later or earlier starting time of the rainy seasons in Yunnan during 1711-1982 has been reconstructed. The analysis indicates that there are obvious fluctuations in the starting date of the rainy seasons in Yunnan in a year or years, and long fluctuation on the decadal scale. The rainy season comes earlier in the early 18th century, later in the 19th century and earlier again in the 20th century. This reflects to a certain degree the gradual change of the summer monsoon in Yunnan. There exists an obvious quasi-3 years cycle, which is related to EI-Nino＇s quasi-3 years cycle, and a 11.3-year cycle which is notably related to the 11-year cycle of the solar activity of starting date of the rainy seasons in Yunnan. Meanwhile, the dissertation finds that the EI-Nino is very important to the starting date of the rainy seasons in Yunnan. The starting date of the rainy seasons in Yunnan often comes later or normally in the year of EI-Nino. However, there is an obvious imperfect period in such influence, which in turn may mean that there is a certain fluctuation in the effect of ENSO on Asian summer monsoon.     

Paleolimnology of McNearney lake: an acidic lake in northern Michigan

McNearney Lake is an acidic (pH=4.4) lake in the Upper Peninsula of Michigan with low acid neutralizing capacity (ANC=-38 eq L^-1) and high SO _inf4 ^sup2- and aluminium concentrations. Oligotrophy is indicated by high Secchi transparency and by low chlorophyll a, total phosphorus, and total nitrogen concentrations. The lake water is currently acidic because base cations are supplied to the lake water at a low rate and because SO _inf4 ^sup2- from atmospheric deposition was not appreciably retained by the lake sediments or watershed and was present in the water column.This interdisciplinary paleolimnological study indicates that McNearney Lake is naturally acidic and has been so since at least 4000 years B.P., as determined from inferred-pH techniques based on contemporary diatom-pH relationships. Predicted pH values ranged from 4.7 to 5.0 over the 4000-year stratigraphy. Considerable shifts in species composition and abundance were observed in diatom stratigraphy, but present-day distributions indicate that all abundant taxa most frequently occur under acidic conditions, suggesting that factors other than pH are responsible for the shifts. The diatom-inferred pH technique as applied to McNearney Lake has too large an uncertainly and is not sensitive enough to determine the subtle recent changes in lakewater pH expected from changes in atmospheric deposition because: (1) McNearney Lake has the lowest pH in the contemporary diatom data set in the region and confidence intervals for pH predictions increase at the extremes of regressions; (2) other factors in addition to pH may be responsible for the diatom species distribution in the lake and in the entire northern Great Lakes region; (3) McNearney Lake has a well-buffered pH as a consequence of its low pH and high aluminium concentrations and is not expected to exhibit a large pH change as a result of changes in atmospheric deposition; and (4) atmospheric deposition in the region is modest and would not cause a pH shift large enough to be discernable in McNearney Lake.Elevated atmospheric deposition is indicated in recent sediments by Pb, V, and polycyclic aromatic hydrocarbon accumulation rates and to a lesser extent by those of Cu and Zn; however, these accumulation rates are substantially lower than those observed for acidified lakes in the northeastern United States. Although atmospheric loadings of materials associated with fossil fuel combustion have recently increased to McNearney Lake and apparently are continuing, the present study of the diatom subfossil record does not indicate a distinct, recent acidification (pH decrease).Order of the first two authors is alphabetical     

辨析“气候变暖”

近年来人们对＂气候变暖＂及其机制的争论达到了前所未有的程度,这可能是因为气候变化不再是单纯研究大气变化规律的科学,而变成一门与＂减排方案＂和＂征收碳税＂有关的政治与经济问题相联系,与国家经济利益有关的崭新课题.＂气候变暖＂既与利益有关,就会难免偏离公正,偏离纯理论科学.本研究对国内外＂气候变暖＂最新动态进行回顾分析,得出以下认识和结论.1）过去百年城市发展,极大地影响了器测温度数据,如果没有对＂热岛效应＂进行矫正,无疑高估了过去百年全球升温的幅度;2）过去百年全球有所变暖是事实,但不同学者增温估算不一致.不仅升温幅度不确定,而且人类和自然因素对升温贡献各占多少也不确定;如果考虑到城市发展对增温估算的影响,过去百年增温应当比0.4℃更低,远没有达到历史上次级波动的变化范围.3）尽管过去百年地球有所变暖,但在万年轨道尺度上,现在地球处于变冷的大趋势过程中.对现在气候变暖更合理解释,是属于变冷大趋势中的次级变暖波动;4）不论过去还是现在,大气CO2浓度变化总是落后于温度变化,即总是温度驱动着CO2变化,而不是CO2浓度驱动地球增温.     

Is there an observable lack of reciprocity in PKP(DF) traveltimes?

On average, traveltimes of PKP_DF for equatorial ray paths through the quasieastern hemisphere of the inner core are around 0.5 s faster than equivalent ray paths through its quasiwestern hemisphere. In these observations, the eastern hemisphere is sampled primarily by westward and the western hemisphere by eastwardpropagating waves. Noting that westward propagation is faster than eastward propagation inside a rotating earth, I estimate the expected traveltime difference from Coriolis splitting of the displacement eigenfunctions of the PKP_DF equivalent modes. It turns out that Coriolis effects are too small to give rise to residuals of the required magnitude. Thus, the observations must be primarily due to velocity heterogeneities.     

Tropospheric and stratospheric wind contributions to Earth's variable rotation from NCEP/NCAR reanalyses (2000–2005)

The individual tropospheric and stratospheric wind contributions to the Earth's variable rotation during the period 2000–2005 are investigated to further our understanding of the role of wind in exciting polar motion and the variation of the Earth's rotational rate (or the length of day, LOD, change). Instead of the previous empirical approach, which simply assumed the tropopause as an equal-pressure level, the present study employs a tropopause, which is space- and time-dependent and is from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP/NCAR) reanalyses. For the axial component, the tropospheric and stratospheric wind effects are essentially additive. For the equatorial components, however, a significant cancellation is found between the tropospheric and stratospheric wind terms, based on the NCEP/NCAR reanalysis model.