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1.
Identifying Global Monsoon Troughs and Global Atmospheric Centers of Action on a Pentad Scale 总被引：7，自引：0，他引：7 
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下载免费PDF全文 Using two datasets of global pentad grid precipitation and global 850 hPa geopotential height during 1979-2007, this study identified global monsoon troughs and global atmospheric centers of action (ACAs) on a pentad scale. The global monsoon troughs consist of planetary-scale monsoon troughs and peninsula-scale monsoon troughs. Forced by seasonal variations in solar radiation, the inter-tropical convergence zones (ITCZs) represent the planetary-scale monsoon troughs, which are active and shift over the tropical North Pacific, the tropical North Atlantic, and the tropical South Indian oceans. The peninsula-scale monsoon troughs are originated from regional land-sea topography and varied with contrasts in seasonal land-sea surface temperatures and precipitation. During the boreal summer, five peninsula-scale troughs and one planetary-scale trough are distributed in the Asia-Northwest Pacific (NWP) region. In total, 22 troughs, nine monsoon troughs, and 19 ACAs in the lower troposphere were identified. Relevant ACAs may be useful in constructing regional monsoon and circulation indices. 相似文献
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Z. Liu R. G. Gallimore J. E. Kutzbach W. Xu Y. Golubev P. Behling R. Selin 《Climate Dynamics》1999,15(5):325-340
The use of the equilibrium asynchronous coupling (EAC) scheme is proposed as a strategy to better understand long-term climate
changes in a fully coupled ocean-atmosphere general circulation model. The EAC scheme requires each component model to be
integrated to its equilibrium before being coupled to the other component. Use of this scheme has the distinct advantage of
being able to clarify the nature of the coupling between the ocean and atmosphere, because each asynchronous iteration takes
the form of a sensitivity experiment. Basic features of the EAC scheme are first studied in an energy balance model. It is
found that the convergence rate of the EAC scheme is proportional to the damping rate in the atmosphere or surface ocean,
but is inversely proportional to the coupling strength between the ocean and atmosphere. Furthermore, the seasonal cycle response
converges much faster than the annual mean response. Using realistic parameters, the seasonal cycle response should converge
in a few iterations. The EAC scheme is further applied to a coupled ocean-atmosphere general circulation model to study the
tropical monsoon climate of the early Holocene. The convergence behavior of the sea surface temperature is found to agree
with the theory derived from the energy balance model study. The EAC scheme is further used to investigate the role of ocean-atmosphere
feedback in modifying the response of monsoons to orbital forcings in the early Holocene. It is found that the ocean exerts
a positive feedback on the North African monsoon, but a negative feedback on the Indian monsoon.
Received: 16 March 1998 / Accepted: 24 December 1998 相似文献
4.
Effects of atmosphere-ocean interaction on the interannual variability of winter temperature in Taiwan and East Asia 总被引：1，自引：0，他引：1
This study investigated the ocean-atmosphere interaction effect on the winter surface air temperature in Taiwan. Temperature
fluctuations in Taiwan and marine East Asia correlated better with a SST dipole in the western North Pacific than the SST
in the central/eastern equatorial Pacific. During the warm (cold) winters, a positive (negative) SST anomaly appears in marine
East Asia and a negative (positive) SST anomaly appears in the Philippine Sea. The corresponding low-level atmospheric circulation
is a cyclonic (anticyclonic) anomaly over the East Asian continent and an anticyclonic (cyclonic) circulation in the Philippine
Sea during the warm (cold) winters. Based on the results of both numerical and empirical studies, it is proposed that a vigorous
ocean-atmosphere interaction occurring in the western North Pacific modulates the strength of the East Asian winter monsoon
and the winter temperature in marine East Asia. The mechanism is described as follows. The near-surface circulation anomalies,
which are forced by the local SST anomaly, strengthen (weaken) the northeasterly trade winds in the Philippine Sea and weaken
(strengthen) the northeasterly winter monsoon in East Asia during warm (cold) winters. The anomalous circulation causes the
SST to fluctuate by modulating the heat flux at the ocean surface. The SST anomaly in turn enhances the anomalous circulation.
Such an ocean-atmosphere interaction results in the rapid development of the anomalous circulation in the western North Pacific
and the anomalous winter temperature in marine East Asia. This interaction is phase-locked with the seasonal cycle and occurs
most efficiently in the boreal winters.
Received: 22 October 1999 / Accepted: 5 June 2000 相似文献
5.
A Primary Study of Interaction Between Monsoon and Sea Surface Temperature in the Neighborhood Sea Area in South Aisa 下载免费PDF全文
下载免费PDF全文 1. Introduction South Asian monson is an important weather and climate phenomenon, and it is also an important con- stituent of the global atmospheric circulation, thus people pay more attention to it (Hahn and Manabe, 1975; Zhu and Zhao, 1987; Zhu et al., 1991; Zhou and Yang, 1994; Wu and Huang, 2001; Li et al., 1999). For example, Zhu and Zhao (1987) studied the effects of terrain on South Asian monsoon by the equato- rial atmospheric balance model, indicating that ter- rain effect is … 相似文献
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季风与ENSO的选择性相互作用:年循环和春季预报障碍的影响 总被引：1，自引：1，他引：0
本文主要基于对Webster and Yang（1992）一文的回顾,讨论了年循环在季风和ENSO相互作用中的作用、春季预报障碍（SPB）、Webster-Yang指数（WYI）、以及亚洲夏季风的前期讯号等内容。亚洲季风和ENSO作为全球天气和气候变率的主要来源,它们之间的相互作用存在明显的年变化和季节“锁相”特征:在北半球秋冬季,亚洲季风对流活动最弱,此时ENSO的信号最强;但是到了北半球春季,亚洲季风对流快速爆发,而此时的ENSO信号却迅速衰减。亚洲季风和ENSO位相的错位变化使得热带海—气系统的不稳定性在北半球春季达到最大,此时任意一个微小的扰动都容易快速增长,最终导致基于ENSO的预报技巧减小。亚洲夏季风环流本质上可以看成是大气对副热带地区潜热加热的低频罗斯贝波响应,它具有很强的垂直风切变,这是WYI定义的物理基础。WYI数值越大,代表垂直东风切变越大,即亚洲季风环流增强,反之亦然。利用WYI与前期大气环流场、欧亚雪盖、土壤湿度等物理量进行回归分析,结果表明:当亚洲夏季风增强时,前期冬季和春季,在北印度洋和亚洲副热带地区上空出现东风异常,同时在更高纬度地区伴随出现西风的异常;此外,副热带地区如印度次大陆、中南半岛和东亚的土壤湿度增大;中纬度地区尤其是青藏高原中西部的积雪密度明显减小。这些前期讯号的发现有助于我们构建动力统计模型,进而提高对亚洲夏季风的季节预报水平。 相似文献
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本文研究了1980—1984年冬季19次东亚寒潮爆发过程中低频扰动的传播特征和行星尺度作用。揭示出冷空气的向南传播主要是一种低频模态的10—20天周期的振荡。另一方面，与寒潮爆发有关的西伯利亚冷高压作为北半球冬季对流层的主要冷源会导致一系列行星尺度过程的响应。这主要表现为辐散环流的上升支迅速地从印尼—马来西亚地区东移到东太平洋，使正常的沃克环流反向。这种情况十分相似于由非厄尔尼诺年到厄尔尼诺年辐散环流的运动。从动力学上，这种辐散环流有利于东太平洋以及北美西岸的天气发展。 相似文献
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气候系统模式FGOALS-s1.1对热带降水年循环模态的模拟 总被引：5，自引：0，他引：5
文中评估了中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG/IAP)新一代耦合气候模式Fgoals_s1.1对热带降水年循环模态的模拟能力。通过与观测表层海温(SST)强迫的大气模式SAMIL试验结果比较,分析了海气耦合过程对年循环模态模拟效果的影响。结果表明Fgoals_s1.1能合理再现热带地区降水年循环模态的基本特征。Fgoals_s1.1模拟出了年平均降水场中的主要降水中心,但模拟的赤道和南太平洋降水偏多,而北太平洋降水则偏少。Fgoals_s1.1的季风模态降水呈现与观测一致的关于赤道反对称的特征,其模拟偏差大部分来自大气分量,尤其是在赤道外。Fgoals_s1.1的主要缺陷在于它对春秋非对称模态模拟能力低于单独大气模式,这主要是由于耦合模式模拟的SST距平的年循环位相与观测相反。SST纬向梯度的位相偏差使得太平洋沃克环流和印度洋的反沃克环流在春季强于秋季,最终导致模拟的春秋非对称模态的偏差。Fgoals_s1.1模拟的季风区范围接近观测,存在的问题在于模拟的西北太平洋季风区、东亚季风区都偏小。本文结果表明,大气模式偏差仅是Fgoals_s1.1在降水年循环模态模拟上的偏差的部分来源,改进模式模拟的SST,特别是赤道地区SST季节循环,是今后Fgoals_s1.1发展过程中急需解决的问题。 相似文献
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The performance of the new multi-model seasonal prediction system developed in the frame work of the ENSEMBLES EU project for the seasonal forecasts of India summer monsoon variability is compared with the results from the previous EU project, DEMETER. We have considered the results of six participating ocean-atmosphere coupled models with 9 ensemble members each for the common period of 1960–2005 with May initial conditions. The ENSEMBLES multi-model ensemble (MME) results show systematic biases in the representation of mean monsoon seasonal rainfall over the Indian region, which are similar to that of DEMETER. The ENSEMBLES coupled models are characterized by an excessive oceanic forcing on the atmosphere over the equatorial Indian Ocean. The skill of the seasonal forecasts of Indian summer monsoon rainfall by the ENSEMBLES MME has however improved significantly compared to the DEMETER MME. Its performance in the drought years like 1972, 1974, 1982 and the excess year of 1961 was in particular better than the DEMETER MME. The ENSEMBLES MME could not capture the recent weakening of the ENSO-Indian monsoon relationship resulting in a decrease in the prediction skill compared to the “perfect model” skill during the recent years. The ENSEMBLES MME however correctly captures the north Atlantic-Indian monsoon teleconnections, which are independent of ENSO. 相似文献
10.
Summary The Tropospheric Biennial Oscillation (TBO), a major interannual variation phenomenon in the Indo-Pacific region, is the result
of strong ocean-atmosphere coupling over the Asian-Australian monsoon area. Along with other meteorological and oceanographic
parameters, the tropical circulation also exhibits interannual oscillations. Even though the TBO is the result of strong air–sea
interaction, the circulation cells during TBO years are, as yet, not well understood. In the present study, an attempt has
been made to understand the interannual variability of the mean meridional circulation and local monsoon circulation over
south Asia in connection with the TBO. The stream function computed from the zonal mean meridional wind component of NCEP/NCAR
reanalysis data for the years 1950–2003 is used to represent the mean meridional circulation. Mean meridional mass transport
in the topics reverses from a weak monsoon to a strong monsoon in the presence of ENSO, but in normal TBO years mean transport
remains weak across the Northern Hemisphere. The meridional temperature gradient, which drives the mean meridional circulation,
also shows no reversal during the normal TBO cycle. The local Hadley circulation over the monsoon area follows the TBO cycle
with anomalous ascent (descent) in strong (weak) monsoon years. During normal TBO years, the Equatorial region and Indian
monsoon areas exhibit opposite local Hadley circulation anomalies.
Authors’ addresses: Prasanth A. Pillai, Research Scholar, Department of Atmospheric Sciences, Cochin University of Science
and Technology, Lakeside Campus, Cochin 682016, India; K. Mohan Kumar, Professor & Dean, Department of Atmospheric Sciences,
Faculty of Marine Sciences, Cochin University of Science and Technology, Lakeside Campus, Cochin 682016, India. 相似文献