Modeling the East Asian climate during the last glacial maximum

Climatologists have been paying much attention to the global and regional climatic charac-teristics during the LGM. A lot of paleodata were obtained in East Asia during the LGM[1—5] and laid the firm foundation of reconstructing East Asian paleoclimate t…     

海洋的季节变化及风应力异常对海洋影响的数值试验

对一个6层5°×4°网格的全球海洋模式作了一些改进,建立了10层5°×4°网格的全球海洋模式,进行了季节变化数值模拟,积分250a,取得稳定的结果.除了高纬度海洋外,模拟的季节变化与实际观测十分接近.在此基础上,作了热带太平洋海温场对热带季风异常响应的3组敏感性实验,第1组为赤道西太平洋异常西风向东传播的试验;第2组为整个赤道太平洋风应力振荡异常试验;第3组为赤道西太平洋异常西风、东风交替向东传播的敏感性试验.模拟结果表明:(1)第1组风应力敏感性实验结果揭示出,西太平洋西风异常的向东传播的风应力异常可以产生类似厄尔尼诺的赤道东太平洋变暖;(2)第2组试验结果表明,热带太平洋风应力的局地振荡首先在中太平洋东西部激发出海温扰动,然后海温扰动分别向东太平洋和西太平洋传播,从而引起东、西太平洋海温的异常;(3)第3组试验验证风应力QBO可以产生海洋中类似的QBO振荡.     

评“1960年的Elsasser辐射图与山本辐射图”兼对“几个幅射图解的比较”一文的意见

大气长波辐射的图解法最早由Mugge和Moller(1932)研究。Elsasser(1942)则提出便于使用的Elsasser辐射图解。此后,大量作者提出了许多新的图解,其中比较成功的为山本图解。1960年,Elsasser等根据最新的吸收光谱实验资料重新给出了辐射图解。在山本与Elsasser(1960)的论文中,用了很多篇幅讨论了广义吸收系数随温度的变化,并指出广义吸收系数随温度的变化对大气长波辐射传输起着重要作用。他     

从气象卫星资料揭示的青藏高原夏季对流云系的日变化

文中利用日本静止气象卫星观测的1981～1994年1天8次的TBB观测值和1978～1994年NOAA卫星观测的1天2次OLR观测值研究了青藏高原地区夏季对流云系季节变化以及对流云的日变化及其东西向移动规律,并对1994年的资料进行了个例分析。结果表明,青藏高原夏季对流云有极为明显的日变化,以00～05SUTC为最弱,15～17UTC最强。在季风雨爆发后的7月中旬到8月上旬在高原中部（30～32°N,90°E）、东部（30°N,97°E）和西部（30°N,85～87°E）有3个TBB低值中心,多年月平均对流中心区云顶高度可达9．6km,而旬对流中心个别地区平均可达13km。对流云区开始发展于东部地区,随后对流云中心逐步向西移动,并于7月中下旬达到最西,此时西部地区从多年平均而言可以有短暂的强对流发展。     

EFFECTS OF THE ATMOSPHERIC COLD SOURCE OVER THE TIBETAN PLATEAU ON THE QUASI 4-YEAR OSCILLATION OF OCEAN-ATMOSPHERIC-LAND INTERACTION

Using correlation analyses, composite analyses, and singular value decomposition, the relationship between the atmospheric cold source over the eastern Tibetan Plateau and atmospheric/ocean circulation is discussed. In winter, the anomaly of the strong (weak) atmospheric cold source over the eastern plateau causes low-level anomalous north (south) winds to appear in eastern China and low-level anomaly zonal west (east) winds to prevail in the equatorial Pacific from spring to autumn. This contributes to the anomalous warm (cold) sea surface temperature the following autumn and winter. In addition, the anomalous variation of sea surface temperature over the equatorial middle and eastern Pacific in winter can influence the snow depth and intensity of the cold source over the plateau in the following winter due to variation of the summer west Pacific subtropical high.     

高空纬向风准3.5年振荡特征

本文利用1968—1985年NMC客观分析700和200 hPa月平均纬向风,对其准3.5年振荡（SO）作了研究。发现其主要活动于180°—150°W南北太平洋及25°—35°N纬带上。其传播特征为赤道上向东、副热带基本向西而中纬向东;50°—90°E间经向传播不明显,而太平洋上向北。CEOF分析表明,其方差主要集中于第1,2分量。对其演变及与东太平洋赤道海温的SO分量间关系也作了研究。     

STUDY ON THE QUASI-FOUR YEAR OSCILLATION OF AIR-SEA INTERACTION

Complex Singular Value Decomposition(CSVD)analysis technique was applied to study theQuasi Four year Oscillation(QFO)of air sea interaction and its coupled pattern evolution duringdifferent phases.Results show that:(1)CSVD method can better reveal phase relation betweentwo physical fields:(2)Not only northerly anomalies from Northern Hemisphere but alsosoutherly anomalies from Southern Hemisphere contribute to EI Nino.They converge in westernequatorial Pacific,leading to outburst of strong equatorial westerly anomalies,and result in strongEl Nino event onset:(3)An abnormal subtropical anticyclone circulation appears overnorthwestern Pacific while El Nino developing.It favors transitions from the warm SST(EINino)to the cold SST(La Nina),just as the tropical westerly anomalies produced by abnormalcyclone during a decaying La Nina.which encourage the development of El Nino:(4)Thewesterly anomalies in equatorial Pacific are mainly induced by eastward abnormal subtropicalcyclone pairs,which are located in north and south Pacific respectively,and are not the eastwardwesterly anomalies from equatorial Indian Ocean.     

末次冰期冰盛期中国地区水循环因子变化的模拟研究

ISCCP卫星资料（1983-2006年)的结果显示：青藏高原地区是高云的高值中心;而以四川为中心直到同纬度的中国东南沿海地区是中云的高值区,同时,青藏高原地区是中云的低值中心。利用全球气候模式CCM3嵌套区域模式MM5模拟了现代和LGM时的气候。通过MM5模拟的结果与ISCCP的卫星资料对比表明：模拟结果再现了中国地区高云和中云分布的主要特征。这暗示云分布的气候特征可能主要由相对湿度决定。同时,通过MM5的结果与NCEP资料的对比也说明,模式结果可以较好地模拟水汽和温度的垂直分布。在此基础上,研究了LGM时水循环因子的变化。模式结果显示：LGM时夏季对流层的温度降低,在对流层中上层存在温度降低的中心;而在冬季在南方的对流层中层存在减温中心,在北方的对流层的中上层温度增加。大气中水汽含量与温度变化有很好的正相关,除了冬季北方对流层中上层水汽增加外,水汽含量一般减少,而且在近地层减少的最多,随高度增高水汽变化逐渐变小。但是,水汽的相对变化在对流层上层存在减少的高值中心。相对湿度存在变化,最大的变化超过15%,而且有增加,也有减少。在区域尺度相对湿度不是保守的。相对湿度变化与中云和低云的变化一致。在LGM,中国地区高云量减少,除中国西南地区外,中云和低云量减少,低云量减少的最多。降水的变化与中云和低云的变化相对应,云量增加降水增加,云量减少降水也减少。从相对湿度和有效降水可以看到在西南地区在LGM时变得潮湿,在夏季西北地区也变得潮湿。     

NUMERICAL EXPERIMENT ON THE SEASONAL VARIATION OF GLOBAL OCEAN AND THE EL NINO PROCESS:PARTI:CONTROL EXPERIMENT ON THE SEASONAL VARIATION OF GLOBAL OCEAN

A 6-layer,4°×5° horizontal resolution global ocean model has been designed and improved.After a 100-year in-tegration,an equilibrium state has been reached from the upper to lower layers.By taking the mean state of last l0 mod-el years as climatic state,we analyzed the characteristics of the seasonal variation in our model integration.The resultsshow that the simulated seasonal variation is similar to the observed.So the design of our model is successful.Then,us-ing the simulated climatic state of the seasonal variation as the initial state,and the observed stress and thermal state asthe atmospheric forcing,we simulated the process of El Nino in 1972—1973 successfully.The simulated results of sea-sonal variation using our model will be presented in part I.     

MM5 Simulations of the China Regional Climate During the LGM. Ⅱ： Influence of Change of Land Area,Vegetation, and Large-scale Circulation Background

Using a regional climate model MM5 nested to an atmospheric global climate model CCM3, a series of simulations and sensitivity experiments have been performed to investigate the relative LGM climate response to changes of land-sea distribution, vegetation, and large-scale circulation background over China. Model results show that compared with the present climate, the fluctuations of sea-land distribution in eastern Asia during the LGM result in the temperature decrease in winter and increase in summer. It has significant impact on the temperature and precipitation in the east coastal region of China. The impact on precipitation in the east coastal region of China is the most significant one, with 25%-50% decrease in the total precipitation change during the LGM. On the other hand, the changes in sea-land distribution have less influence on the climate of inland and western part of China. During the LGM, significant changes in vegetation result in temperature alternating with winter increase and summer decrease, but differences in the annual mean temperature are minor. During the LGM, the global climate, i.e., the large-scale circulation background has changed significantly. These changes have significant influences on temperature and precipitation over China. They result in considerable temperature decreases in this area, and direct the primary patterns and characteristics of temperature changes. Results display that, northeastern China has the greatest temperature decrease, and the temperature decrease in the Tibetan Plateau is larger than in the eastern part of China located at the same latitude. Moreover, the change of large-scale circulation background also controls the pattern of precipitation change. Results also show that, most of the changes in precipitation over western and northeastern parts of China are the consequences of changing large-scale circulation background, of which 50%-75% of precipitation changes over northern and eastern China are the results of changes in large-scale circulation backgrou