Experimental Seasonal Forecast of Monsoon 2005 Using T170L42 AGCM on PARAM Padma

As a part of the Experimental Extended Range Monsoon Prediction Experiment, ensemble mode seasonal runs for the monsoon season of 2005 were made using the National Centre for Environmental Prediction (NCEP), T170L42 AGCM. The seasonal runs were made using six initial atmospheric conditions based on the NCEP operational analysis and with forecast monthly sea-surface temperature (SST) of the NCEP Coupled forecast system (CFS). These simulations were carried out on the PARAM Padma supercomputer of Centre for Development of Advanced Computing (C-DAC), India. The model climatology was prepared by integrating the model for ten years using climatological SST as the lower boundary. The climatology of the model compares well with the observed, in terms of the spatial distribution of rainfall over the Indian land mass. The model-simulated rainfall compares well with the Tropical Rainfall Measuring Mission (TRMM) estimates for the 2005 monsoon season. Compared to the model climatology (7.81 mm/day), the model had simulated a normal rainfall (7.75 mm/day) for the year 2005 which is in agreement with the observations (99% of long-term mean). However, the model could not capture the observed increase in September rainfall from that of a low value in August 2005. The circulation patterns simulated by the model are also comparable to the observed patterns. The ensemble mean onset is found to be nearer to the observed onset date within one pentad.     

南海夏季风爆发日期和强度的短期气候预测方法研究

利用合成及相关统计方法，研究冬季南海季风指数与850hPa风场、500hPa高度、海表温度、OLR等环境场的相互关系及其影响南海夏季风活动的可能机制。指出冬季南海季风指数及环境场的异常特征可以作为预测南海夏季风活动的前兆信号。在此基础上建立了预测南海夏季风爆发日期和强度的概念模型，1998－2001年的预测试验取得了较好成绩。     

西北地区一次斜压槽引发的强沙尘暴研究

利用T10 6数值预报及常规气象资料 ,对 1998年 4月 15日西北地区强沙尘暴进行分析 ,分析结果表明 ,这是一次由斜压槽及冷锋锋生触发的沙尘暴 ,高空急流及其下部的Ferrel环流对沙尘暴发生起到重要作用 ;强沙尘暴发生在高空急流出口区右侧、5 0 0hPa正涡度中心下风方和次级反环流的上升运动区内。     

高空急流入口区次级环流在一次突发性强降水过程中的作用

通过对 1999年秋季一次突发性降水过程高空急流的分析 ,发现急流入口区南侧辐散 ,其低层辐合上升 ,当低层有印缅槽活动的时候 ,对流加强 ,印缅槽发展 ;急流入口区北侧辐合 ,其低层辐散下沉 ,有向南的非地转风     

1998年青藏高原东部及其邻近地区大气热源与南海夏季风的关系

利用 1998年 5 8月南海季风试验期间的站点观测资料及NCEP再分析资料 ,计算了大气热源和水汽汇 ,并分析了南海季风爆发前后季风区对流层温度演变及其热力机制。结果表明 :南海夏季风的爆发与季风区对流层中高层南北温度梯度的逆转密切相关。南北温度梯度最先在孟加拉湾以东季风区发生逆转 ,半个月后在印度半岛及其以西地区逆转。季风爆发前中南半岛北部对流层中高层的迅速增温是由感热和潜热共同造成的 ,而华南及南海北部地区的增温则是由暖平流所致。 5、6月高原东部对流层中高层由非绝热加热造成的显著增温对东亚夏季风的北进和维持是非常重要的。 5、6月高原地区热源以感热为主 ;7、8月感热和潜热共同起作用     

Forecasting Monsoon Precipitation Using Artificial Neural Networks

This paper explores the application of Artificial Intelligent (AI) techniques for climate forecast. It pres ents a study on modelling the monsoon precipitation forecast by means of Artificial Neural Networks (ANNs). Using the historical data of the total amount of summer rainfall over the Delta Area of Yangtze River in China, three ANNs models have been developed to forecast the monsoon precipitation in the corre sponding area one year, five-year, and ten-year forward respectively. Performances of the models have been validated using a ＇new＇ data set that has not been exposed to the models during the processes of model development and test. The experiment results are promising, indicating that the proposed ANNs models have good quality in terms of the accuracy, stability and generalisation ability.     

南海海平面高度年循环的特征

根据 ＴＯＰＥＸ／ ＰＯＳＥＩＤＯＮ－ＥＲＳ高度计提供的海平面高度异常资料和并行海洋气候模式（ＰＯＣＭ）模拟海平面高度资料，分析了南海海平面高度年循环特征。结果表明：ｌ月，３月和５月海平面高度的异常值分别与７月，９月，１１月的异常值相反。ｌ月（７月），深水海区与吕宋海峡的海平面高度为负（正）异常，在大部分陆架区和南海的西和南部，海平面高度为正（负）异常。在３月（９月），除海平面高度异常的量级已减少，且较小的ＳＳＨ正异常（负异常）出现在南海的中部以外，海平面高度异常的分布型与 １月（７月）类似； ＳＳＨ的年循环的最大振幅出现在吕宋岛的西北海域；风的季节变化是南海ＳＳＨ季节变化的主要原因。     

河南省汛期气候预测概念模型

在河南省6种雨型的基础上，分析了物理要素海温、季风、西太平洋副高及气候因子和河南省汛期降水的关系，给出了河南省汛期降水的气候预测概念模型。通过逻辑推理，可以具体预测雨型。     

Quantitative measurements on the paleo-weathering intensity of the loess-soil sequences and implication on paleomonsoon

The loess-soil sequences in northern China provide a near continuous record of Quaternary paleoclimate. The pedogenetic intensity of the sequences is closely linked with the variations of the East Asian summer monsoon. In this study, 2181 samples from the Changwu and Xifeng loess sections are analyzed and two high-resolution paleo-weathering timeseries of the last 1.2 Ma are generated, using the ratio of CBD extractable free Fe₂O₃ (FeD) versus the total iron (FeT). This new index is compared with micromorphological features, low-frequency magnetic susceptibility, frequency-dependent magnetic susceptibility, and the Rb/Sr ratio^[5,6]. The results suggest that the FeD/FeT ratio is able to better reflect the degree of soil development. Since the chemical weathering of loess in the Loess Plateau region mainly depends upon the summer precipitation and temperature under modern climate condition, which are closely associated with strength of summer monsoon, and the chemical weathering intensity of loess primarily reflects the variations of the summer monsoon circulation.     

圆梁山隧道毛坝向斜段典型岩溶现象及发育分布特征

圆梁山隧道毛坝向斜段核部及两翼的可溶地层中发衣分布有大量的典型岩溶现象，本文详尽讨论了岩溶洼地，槽谷，巨型组合槽谷和地下溶洞等大型岩溶形态的基本特征，形成机制，受控因素，并进一步认识到其发育分布主要受控于岩性和构造因素。