SST THERMAL FORCING – A DISCUSSION ON THE MECHANISM OF ATMOSPHERIC LOW-FREQUENCY OSCILLATION

Dynamic and numerical methods are used to discuss the atmospheric response to SST thermal forcing. The results show that for planetary scale systems, the standing SST thermal forcing can quickly excite a stable atmospheric equilibrium state response, which is characterized by obvious large-scale teleconnection oscillation in east-west and south-north directions. For synoptic scale systems, the SST thermal forcing mainly excites the atmospheric low-frequency oscillation. Some basic relation and dynamic processes between SST thermal forcing and atmospheric response pattern are revealed and some new viewpoints are presented.     

亚洲季风区ITCZ对华北雨季异常的可能影响

分析了冬、春季亚洲季风区ITCZ活动对华北夏季降水的影响。用OLR资料定义了ITCZ综合指数，分析表明该指数能比较清晰、客观地综合反映出亚洲季风区深对流活动的强度和位置。用该指数分析了华北多雨年和少雨年前期热带大范围对流活动的变化特征。印度和东亚季风区的ITCZ活动在多雨和少雨年显示出明显不同。华北夏季降水与2-4月ITCZ综合指数的时滞相关性最明显。这种时滞相关可能与球面Rossby波的频散相联系，并可以为华北夏季降水的长期预报提供新的参考依据。低频振荡分析表明，多雨年南北两个半球的低频振荡强度较强，范围较大，并不断由南向北传播，这种传播很可能与副热带高压的北跳有关。而少雨年低频振荡在南半球或热带地区呈准静止状态。     

皖23井记震特征及水井记震能力的定量分析

本文通过对皖23井记录到的59幅水震波图的主要参数的分析,发现该井记录水震波与地震发生的区域有关,存在明显分区记震特征。在分区对比分析的基础上,得到水位振荡幅度与震级、震中距的关系如下:Ⅰ区:logA=-5.0569+0.8906Ms-0.2730log△Ⅱ区:logA=-4.0201+0.8614Ms-0.5855log△Ⅲ区:logA=-3.5998+0.8290Ms-1.0162log△水位振荡持续时间与震级间的关系式如下:Ⅰ区:logT=-6.1248+1.0181MsⅡ区:logT=-4.0189+0.7556MsⅢ区:logT=-5.4129+0.9178Ms文章还对其记震能力作了定量分析,并提出了一种具有普遍意义的衡量水井记震能力的定量分析方法。     

气候的多平衡态及其转换

本文利用一个简单的气候模式,求得三个平衡态的全球半均温度值分别为:T_1=248.5K,T_2=271.9K和T_3=288.1K,其中对应于温暖时期和寒冷时期的T_3和T_1是稳定的.若要使现代温暖气候转变为寒冷气候,太阳常数约需比现代值减少3％:若从寒冷气候转变成温暖气候,太阳常数需增加约6.3％.这表明寒冷气候的状态要比温暖气候的状态相对稳定些.然后讨论了随机扰动对气候半衡态之间转换的作用.结果表明:仅通过天气随机扰动的涨落效应不可能使气候系统实现冰期-间冰期之间10~5年周期尺度的转换.     

准噶尔盆地中新生代湖水位升降曲线的建立与剖析

中新生代的准噶尔盆地为典型的内陆湖盆，四周为山系包围，是分析内陆湖泊水位升降的理想场所。本文参照全球海平面变化的计算方法，通过内陆湖盆沉积体系及其地貌特色的研究，建立准噶尔盆地中新生代湖水位升降曲线。中新生代的准噶尔盆地为一封闭型内陆盆地，湖水位升降主要受气候和构造因素的控制。笔者利用区域的气候和构造背景对湖水位的升降作了剖析，初步建立两种背景下的湖水位升降曲线。     

A temporary sampling technique for investigating groundwater quality near the ground surface

Improved knowledge of processes determining groundwater quality is an important precondition for the solution of various ecological and water management problems. In areas with highly fluctuating groundwater levels, time-limited access, local pollution sources or temporary interactions between surface water and groundwater, a temporary groundwater sampling technique could be of advantage. Furthermore, depth-specific sampling is of high value for investigating groundwater pollution related to seepage or surface water infiltration. A stainless steel core probe has been developed to obtain groundwater samples and to measure the hydraulic head distribution at various defined depths. The sampling technique is applicable only for non-volatile water constituents. An advantage of the core probe is that it can be driven into soil or sediments using ordinary low cost percussion equipment. The probe enables hydraulic head measurements and water sampling over vertical intervals of 0.3 m. Results from field experiments using the stainless steel core probe were in good correspondence with results from groundwater sampling at nearby observation wells. In the upper layer of the aquifer, the intrinsic spatial change in concentrations of sulphate, chloride and other water constituents is a function of distance between observation points and groundwater surface. Results indicate strong effects of a fluctuating groundwater level on groundwater quality at certain depths.     

Anisotropy of the horizontal velocity fluctuation field in the large wavenumber region

Mesoscale atmospheric wind, temperature, and density fluctuations are described in terms of their power spectra. In the early 1980s, VanZandt[1] showed that the observed spectrum of the atmospheric fluctuations can result, as in the ocean, from an interna…     

Climatic fluctuation and disasters during recent 100 years in China’s tropics

China's tropics belongs to the humid tropical zone of Asian monsoon. The north boundary of China's tropics lies about 24oN but the eastern part of the boundary tends northwards and the western part tends southwards. The land area of China's tropics is 51.85×104 km2, accounting for 5.4% of the total land area of China and 28% of the total area of China's territory if the South China Sea is taken into account. During recent 100 years, based on the background of global changes, the climatic …     

西藏纳木错地区约120kaBP以来的古植被、古气候与湖面变化

西藏纳木错湖相沉积的U系和^11C测年结果表明，湖泊沿岸的6级湖岸阶地及拔湖约48～139．2m的高位湖相沉积形成于约120ka BP以来的晚第四纪。本文根据该套湖相层的发育和其中的孢粉组合特征对纳木错地区约120ka BP以来的湖面变化与古植被、古气候变迁进行了探讨。结果表明，纳木错地区晚更新世以来经历了频繁的湖面波动、气候的冷暖与干湿变化以及森林—草原与草原植被的交替演化。其总体特征是：约115．9ka BP时，纳木错湖面最高。在116～78ka BP期间，该区气候温和凉爽或温和偏湿，植被以疏林草原与森林草原或森林的交替出现为特征，湖面经历了较大幅度的波动，但基本保持在拔湖140～88m之间。在78～53ka BP期间，该区气候干冷，植被以疏林草原为主，湖面大幅度下降，并在拔湖约36～48m之间波动。约53～32ka BP期间，气候转为温暖偏湿或温暖湿润，湖面波动于拔湖约15～28m之间，波动较为频繁。与阶地的发育相对应，该时期内包含了3次明显的暖期和湖面波动过程，区域植被主要以松、蒿、桦为主，为含一定量的冷杉的森林。其中36ka BP左右气候最温暖湿润，区域内可能出现针叶林或针阔混交林。约32～12ka BP期间，该区气候最为干冷，古植被以草原和疏林草原为主，湖面再次发生较大幅度的下降，最低可至拔湖约8m处，但通常维持在拔湖约12～17m之间。约11．8～4．2ka BP期间，气候整体较为暖湿，其中在约8．4～4．2ka BP期间气候最温暖湿润，该区可能发育针叶林或针阔混交林，湖面波动于拔湖2～9m之间，整体波动幅度较小，但波动最为频繁。区域气候对比发现，纳木错地区的冷、暖气候变化过程与整个青藏高原乃至北半球的气候变化基本是一致的，特别是阶地下切所反映的湖面退缩过程与北大西洋的Henrich冷事件之间具有很好的对应关系。     

中国热带第四纪气候波动的海陆对比

古气候分析典型实例的对比．表明中国热带第四纪的气候波动，海域与陆域的差异主要出现在早、中更新世及末次盛冰期，而晚更新世以来直至历史时期，海陆的气候波动基本同步。中国热带万年尺度的气候变化．既受地球轨道参数的驱动，亦受季风环流的影响；千年和百年尺度的气候变化，与太阳常数本身的变化有关。