高低层纬向风切变的年际变率及气候学意义

用1959～1998共40年全球格点风场资料计算了200 hPa与850 hPa的纬向风速差, 即对流层纬向风切变(简称TZWS),并在此基础上得到其距平值。为了全面考察对流层中环流异常的年际变率特征, 根据TZWS的标准差分布, 文中选出了7个TZWS标准差数值大于5 m/s的代表性区域。这7个区域分别位于赤道中太平洋、赤道东太平洋、北太平洋亚热带地区、南太平洋亚热带地区、赤道大西洋、亚洲西南部以及东北部。前5个分别位于赤道、亚热带太平洋和大西洋的区域TZWS指数, 其年际变率与ENSO循环有密切联系, 反映了热带海洋温度异常对低纬度地区对流层环流的影响; 后2个区域的TZWS指数反映的是亚洲西南部和东北部的气候统变率, 在年际时间尺度上与ENSO循环有着明显的区别。通过对全球陆地降水和温度场的分析, 比较了热带、副热带的TZWS指数以及北极涛动指数的异同, 发现后2个区域TZWS指数能很好且能独立反映出北半球中高纬度地区陆地降水及陆地温度的异常模态。     

CLIMATE CHANGE: LONG-TERM TRENDS AND SHORT-TERM OSCILLATIONS

Identifying the Northern Hemisphere (NH) temperature reconstruction and instrumental data for the past 1000 years shows that climate change in the last millennium includes long-term trends and various oscillations. Two long-term trends and the quasi-70-year oscillation were detected in the global temperature series for the last 140 years and the NH millennium series. One important feature was emphasized that temperature decreases slowly but it increases rapidly based on the analysis of different series. Benefits can be obtained of climate change from understanding various long-term trends and oscillations. Millennial temperature proxies from the natural climate system and time series of nonlinear model system are used in understanding the natural climate change and recognizing potential benefits by using the method of wavelet transform analysis. The results from numerical modeling show that major oscillations contained in numerical solutions on the interdecadal timescale are consistent with that of natural proxies. It seems that these oscillations in the climate change are not directly linked with the solar radiation as an external forcing. This investigation may conclude that the climate variability at the interdecadal timescale strongly depends on the internal nonlinear effects in the climate system.     

非平衡热力学在短期灾害性天气预报中的应用

综述了非平衡热力学应用于天气预报的若干进程以及在短期灾害性天气预报应用中的明显效果。     

未来的天气气候预测体系

天气气候预测中的不确定性是不可避免的。它一方面给用户或有关决策者带来很大的困难,同时也给科学工作者提出了新的研究课题。文章较为系统地评述了近几年出现的关于如何发展未来气象预测体系的若干观点,根据风险经济学和决策理论,构建了一个未来天气气候预测体系的概念模型。其主要思想是将气象预测过程同用户决策过程有机地结合起来,充分利用来自用户的知识和风险管理经验,形成一个相互作用协同发展的预测体系。     

过山气流二维定常模式的实际应用

本文对气流流经三种不同水平宽度的地形所产生的动力学效应进行了研究。应用定常的二维模式作数值模拟,结果表明:大尺度地形可影响到山脊上游的大气运动,山脊上游出现下沉气流,造成干燥气候;中尺度山脉促使下游大气产生波状扰动,可影响飞机飞行;小尺度山丘(或建筑群)对气流中的气溶胶扩散会产生影响。充分孓解小尺度地形气流的特点,可给山区城镇工厂烟囱的合理布局以及作物育苗阶段的秧田选地提供依据。     

多时空尺度海气相互作用与ZEBIAK-CANE模式的改进

实际气候系统中包含了行星尺度、洋盆尺度和局地海气相互作用的过程.一层大气的Zebiak-Cane(ZC)模式仅仅描写了局地海气相互作用.于是,行星尺度的Hadely环流异常和洋盆尺度的Walker环流异常需要引进到ZC模式中.通过在ZC模式中引进Hadley异常的改进,结果表明改进的模式不仅能对1970～1990年,而且也能对1991～1995年的赤道东太平洋海温异常作出提前9～10个月的预报.     

AN ATMOSPHERIC MOTION EQUATION BUILT ON THE CONSERVATIVE RELATIONSHIP OF THE ANGULAR MOMENTUM EXCHANGE BETWEEN THE SOLID EARTH AND THE ATMOSPHERE ON SEASONAL-ANNUAL TIMESCALE

Within the seasonal-annual timeseale,there exists an angular momentum conservative exchange relationship be-tween the solid earth and the atmosphere,and their angular momentum exchange not only can cause variations inlength-of-day(LOD)but also can express anomalies in atmospheric general circulation.Therefore,their angular mo-mentum exchange mechanism should be introduced into the general circulation model.Considering the angular momentum anomalous exchange caused by the air-earth interface friction effect,awhole-layer atmospheric motion equation is derived in this paper including the earth spin anomalous friction forceparameterized by using the change in the earth rotation rate.Through analysing the equation,it shows that the magni-tude of the earth spin anomalous friction force is the same as that of Coriolis force on seasonal-annual timescale.     

地球自转变速可能对大气和海洋运动的影响

本文从一个理想的地球大气和地球海洋出发,研究了固体地球自转角速度变化引起的大气和海洋的附加运动。结果论出,地球自转减慢时,附加的经向气流和经向海流向赤道辐合,纬向气流和海流有向东的分量,地球自转加快时则情形相反。分析认为地球自转速度在几年内的起伏可引起大气和海洋的异常运动并可激发出埃尔-尼诺形成时的海洋波动。     

Spatial Interpolation of Daily Precipitation in China:1951-2005

Climate research relies heavily on good quality instrumental data; for modeling efforts gridded data are needed. So far, relatively little effort has been made to create gridded climate data for China. This is especially true for high-resolution daily data. This work, focuses on identifying an accurate method to produce gridded daily precipitation in China based on the observed data at 753 stations for the period 1951-2005. Five interpolation methods, including ordinary nearest neighbor, local polynomial, r...     

Seasonal and Interannual Variations of Upper Tropospheric Water Vapor Band Brightness Temperature over the Global Monsoon Regions

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