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Atmospheric and Oceanic Science Letters 2019年第2期12卷 140-146页

作者： LIN Renping ZHENG Fei DONG Xiao International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences

为了改进耦合模式对东亚夏季风的模拟,本文发展了一个基于中国科学院地球系统模式的海洋资料同化系统。基于该同化系统,本文开展了同化观测海温的试验,并将同化试验的结果与传统的AMIP试验进行比较。结果表明,同化系统显著改进了对西北... 详细信息

为了改进耦合模式对东亚夏季风的模拟,本文发展了一个基于中国科学院地球系统模式的海洋资料同化系统。基于该同化系统,本文开展了同化观测海温的试验,并将同化试验的结果与传统的AMIP试验进行比较。结果表明,同化系统显著改进了对西北太平洋地区降水的气候态和季节循环、与ENSO和东亚夏季风相关联的东亚地区的降水和环流异常等的模拟。本文的工作表明,海气相互作用对东亚夏季风的模拟非常重要。耦合框架下的海洋资料同化系统可以在引入观测信息的同时不切断海气相互作用,这是同化试验较之AMIP试验有显著改进的原因所在。

关键词：海洋资料同化耦合模式东亚夏季风 AMIP

Phase Transition of the Pacific Decadal Oscillation and Decadal Variation of the East Asian Summer Monsoon in the 20th Century

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Advances in Atmospheric sciences 2016年第3期33卷 330-338页

作者： Xiao DONG Feng XUE International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of Sciences

This paper focuses on the relationship between the phase transition of the Pacific decadal oscillation （PDO） and decadal variation of the East Asian summer monsoon （EASM） in the twentieth century. The first transition occurred in the 1940s, with an enhanced SST in the North Pacific and reduced SST in the tropical eastern Pacific and South Indian Ocean. In agreement with these SST changes, a higher SLP was found in most parts of the Pacific, while a lower SLP was found in the North Pacific and most parts of the Indian Ocean. In this case, the EASM was largely enhanced with a southerly anomaly in the lower troposphere along the east coast of China. Correspondingly, there was less rainfall in the Yangtze River valley and more rainfall in northern and southern China. An opposite change was found when the PDO reversed its phase in the late 1970s. In the tropical Indian Ocean and western Pacific, however, the SST was enhanced in both the 1940s and 1970s. As a result, the western Pacific subtropical high （WPSH） tended to extend westward with a larger magnitude in the 1970s. The major features were reasonably reproduced by an atmospheric general circulation model （IAP AGCM4.0） prescribed with observed SST and sea ice. On the other hand, the westward extension of the WPSH was exaggerated in the 1970s, while it was underestimated in the 1940s. Besides, the spatial pattern of the simulated summer rainfall in eastern China tended to shift southward compared with the observation.

关键词： Pacific decadal oscillation East Asian summer monsoon western Pacific subtropical high IAP AGCM4.0

The source of Double ITCZ induced by the SST bias over the tropical western Pacific as reflected in CAS-ESM2 Model

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Science China Earth sciences 2024年第5期67卷 1604-1615页

作者： Jinning TONG Fei ZHENG Jiangbo JIN Ruowen YANG Jiang ZHU Qingcun ZENG Department of Atmospheric sciences Yunnan UniversityKunming 650091China international center for climate and environment Science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

“Double ITCZ”is a common precipitation bias over the tropical Pacific in current climate models and Earth system models,but the reasons for its formation are still worth exploring and discussing.In this study,we adopted the second version of Chinese Academy of sciences Earth System Model(CAS-ESM2),by comparing a set of sea surface temperature(SST)bias correction experiments over the tropical Pacific,to explore the possible mechanism of SST bias on inducing the“Double ITCZ”from the perspective of the climatic annual mean bias in the coupled model.We revealed that the simulated climatic annual mean SST bias over the tropical Pacific can affect the bias of latent heat flux through the saturation specific humidity,and the bias of latent heat flux can further affect that of vertical velocity of humid air by the condensation release mechanism,and finally modulate the simulated bias in precipitation.Furthermore,through the inter-comparison between different experiments,it is found that the source of Double ITCZ might mainly come from the annual mean SST bias over the tropical western Pacific through the proposed air-sea coupled process of“SST-saturated specific humidity-latent heat flux-vertical velocity-precipitation”,indicating a possible way on reducing the couple biases in models over the tropical Pacific to improve the accuracy of CAS-ESM2 for climate simulation.

关键词： SST bias Double ITCZ Nudging SST CAS-ESM2

An Ocean Data Assimilation System in the Indian Ocean and West Pacific Ocean

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Advances in Atmospheric sciences 2015年第11期32卷 1460-1472页

作者： YAN Changxiang ZHU Jiang XIE Jiping International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of Sciences

The development and application of a regional ocean data assimilation system are among the aims of the Global Ocean Data Assimilation Experiment. The ocean data assimilation system in the regions including the Indian and West Pacific oceans is an endeavor motivated by this goal. In this study, we describe the system in detail. Moreover, the reanalysis in the joint area of Asia, the Indian Ocean, and the western Pacific Ocean （hereafter AIPOcean） constructed using multi-year model integration with data assimilation is used to test the performance of this system. The ocean model is an eddy-resolving, hybrid coordinate ocean model. Various types of observations including in-situ temperature and salinity profiles （mechanical bathythermograph, expendable bathythermograph, Array for Real-time Geostrophic Oceanography, Tropical Atmosphere Ocean Array, conductivity-temperature-depth, station data）, remotely-sensed sea surface temperature, and altimetry sea level anomalies, are assimilated into the reanalysis via the ensemble optimal interpolation method. An ensemble of model states sampled from a long-term integration is allowed to change with season, rather than remaining stationary. The estimated background error covariance matrix may reasonably reflect the seasonality and anisotropy. We evaluate the performance of AIPOcean during the period 1993-2006 by comparisons with independent observations, and some reanalysis products. We show that AIPOcean reduces the errors of subsurface temperature and salinity, and reproduces mesoscale eddies. In contrast to ECCO and SODA products, AIPOcean captures the interannual variability and linear trend of sea level anomalies very well. AIPOcean also shows a good consistency with tide gauges.

关键词： ocean data assimilation reanalysis ensemble optimal interpolation background error covariance

A Study on the Physical Processes of the Formation of the ENSO Cycle

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Advances in Atmospheric sciences 2014年第6期31卷 1395-1406页

作者： ZONG Haifeng International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of Sciences

The physical processes involved in the formation of the ENSO cycle,as well as the possible roles of the Hadley circulation （HC）,Walker circulation （WC）,and the propagating waves of the Southern Oscillation/Northern Oscillation （SO/NO） in its formation,were studied using composite and regression methods.The analysis showed that the convection and heat release triggered by ENSO in the central-eastern equatorial Pacific are the primary drivers for the 3-5 year cycle of the HC,WC and the meridional/zonal circulation.The HC plays a key role in the influence of ENSO on the circulation outside the tropics through angular momentum transportation.Meanwhile,the feedback effects of the anomalous circulation in the mid-high latitudes on ENSO are accomplished by the propagating waves of SO/NO associated with the evolutions of HC and WC.These propagating waves are the main agents of the connections among the meridional/zonal circulation outside the tropics,the Asian/Australian monsoon,the anomalous easterly/westerly winds over the tropical Pacific,and ENSO events.It was found that the 3-5 year cycle of the meridional/zonal circulation forced by ENSO is quite different from the several-week variation of the circulation index triggered by the inner dynamic processes of the atmosphere.The former occurs at the global scale with a definite flow pattern,while the latter occurs only in a wide area without a definite flow pattern.Finally,a physical model for the formation of the ENSO cycle composed of two fundamental processes at the basin and global scale,respectively,is proposed.

关键词： ENSO cycle meridional/zonal circulation Hadley circulation propagating waves Southern Oscillation/Northern Oscillation

Anomalous Western Pacific Subtropical High during El Nino Developing Summer in Comparison with Decaying Summer

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Advances in Atmospheric sciences 2018年第3期35卷 360-367页

作者： Feng XUE Xiao DONG Fangxing FAN International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The anomalous behavior of the western Pacific subtropical high （WPSH） in E1 Nifio developing summer is studied based on the composite results of eight major E1 Nifio events during 1979-2013. It is shown that the WPSH tends to retreat eastwards with weak intensity during the developing summer. The anomaly exhibits an intraseasonal variation with a weaker anomaly in June and July and a stronger anomaly in August, indicating that different underlying physical mechanisms may be responsible for the anomalous WPSH during early and late summer periods. In June and July, owing to the cold advection anomaly characterized as a weak northerly anomaly from high latitudes, geopotential height in East Asia is reduced and the WPSH tends to retreat eastwards slightly. By contrast, enhanced convection over the warm pool in August makes the atmosphere more sensitive to E1 Nifio forcing. Consequently, a cyclonic anomaly in the western Pacific is induced, which is consistent with the seasonal march of atmospheric circulation from July to August. Accordingly, geopotential height in the western Pacific is reduced significantly, and the WPSH tends to retreat eastwards remarkably in August. Different from the developing summer, geopotential height in the decaying summer over East Asia and the western Pacific tends to enhance and extend northwards from June to August consistently, reaching the maximum anomaly in August. Therefore, the seasonal march plays an important role in the WPSH anomaly for both the developing and decaying summer.

关键词： western Pacific subtropical high El Nifio developing summer decaying summer seasonal march

Anomalous Western Pacific Subtropical High during Late Summer in Weak La Nia Years: Contrast between 1981 and 2013

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Advances in Atmospheric sciences 2016年第12期33卷 1351-1360页

作者： Feng XUE Fangxing FAN International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

Both 1981 and 2013 were weak La Nifia years with a similar sea surface temperature （SST） anomaly in the tropical Pacific, yet the westem Pacific subtropical high （WPSH） during August exhibited an opposite anomaly in the two years. A comparison indicates that, in the absence of a strong SST anomaly in the tropics, the cold advection from Eurasian high latitudes and the convection of the western Pacific warm pool play important roles in influencing the strength and position of the WPSH in August. In August 1981, the spatial pattern of 500 hPa geopotential height was characterized by a meridional circulation with a strong ridge in the Ural Mountains and a deep trough in Siberia, which provided favorable conditions for cold air invading into the lower latitudes. Accordingly, the geopotential height to the north of the WPSH was reduced by the cold advection anomaly from high latitudes, resulting in an eastward retreat of the WPSH. Moreover, an anomalous cyclonic circulation in the subtropical western Pacific, excited by enhanced warm pool convection, also contributed to the eastward retreat of the WPSH. By contrast, the influence from high latitudes was relatively weak in August 2013 due to a zonal circulation pattern over Eurasia, and the anomalous anticyclonic circulation induced by suppressed warm pool convection also facilitated the westward extension of the WPSH. Therefore, the combined effects of the high latitude and tropical circulations may contribute a persistent anomaly of the WPSH in late summer, despite the tropical SST anomaly being weak.

关键词： western Pacific subtropical high late summer tropical circulation high latitude circulation warm pool convection

Assessing the Impacts of Initial Snow Conditions over the Tibetan Plateau on China Precipitation Prediction Using a Global climate Model

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Atmospheric and Oceanic Science Letters 2014年第2期7卷 81-86页

作者： CHEN Hong International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences

Two ensemble experiments were conducted using a general atmospheric circulation model. These experiments were used to investigate the impacts of initial snow anomalies over the Tibetan Plateau(TP) on China precipitation prediction. In one of the experiments, the initial snow conditions over the TP were climatological values; while in the other experiment, the initial snow anomalies were snow depth estimates derived from the passive microwave remote-sensing data. In the current study, the difference between these two experiments was assessed to evaluate the impact of initial snow anomalies over the TP on simulated precipitation. The results indicated that the model simulation for precipitation over eastern China had certain improvements while applying a more realistic initial snow anomaly, especially for spring precipitation over Northeast China and North China and for summer precipitation over North China and Southeast China. The results suggest that seasonal prediction could be enhanced by using more realistic initial snow conditions over TP, and microwave remote-sensing snow data could be used to initialize climate models and improve the simulation of eastern China precipitation during spring and summer. Further analyses showed that higher snow anomalies over TP cooled the surface, resulting in lower near- surface air temperature over the TP in spring and summer. The surface cooling over TP weakened the Asian summer monsoon and brought more precipitation in South China in spring and more precipitation to Southeast China during summer.

关键词：西藏的高原起始的雪异例预兆的技巧降水

Simulation of the western North Pacific subtropical high in El Ni?o decaying summers by CMIP5 AGCMs

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Atmospheric and Oceanic Science Letters 2017年第2期10卷 146-155页

作者： DONG Xiao FAN Fang-Xing LIN Ren-Ping JIN Jiang-Bo LIAN Ru-Xu International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

本文分析了耦合模式比较计划第五阶段(CMIP5)中的各大气环流模式对西北太平洋副热带高压系统在厄尔尼诺衰减期夏季的模拟。结果表明大部分模式都能够重现厄尔尼诺衰减期夏季的副高所伴随的大尺度环流的空间分布特征。大多数模式都可以... 详细信息

本文分析了耦合模式比较计划第五阶段(CMIP5)中的各大气环流模式对西北太平洋副热带高压系统在厄尔尼诺衰减期夏季的模拟。结果表明大部分模式都能够重现厄尔尼诺衰减期夏季的副高所伴随的大尺度环流的空间分布特征。大多数模式都可以合理地模拟出副高在厄尔尼诺衰减期夏季的位置相对于其气候平均态位置的向西偏移。这些模式对7至8月副高夏季季节内北跳的模拟强于对其东撤的模拟;几乎所有的模式都可以准确地模拟出副高的北跳,而只有三分之一的模式能够模拟出副高的东撤。模式中的副高在厄尔尼诺衰减期夏季位置的偏差很大程度上取决于其气候平均态位置的偏差。

关键词：西北太平洋副热带高压厄尔尼诺衰减期夏季耦合模式比较计划第五阶段大气环流模式季节内变化

An Investigation of the Formation of the Heat Wave in Southern China in Summer 2013 and the Relevant Abnormal Subtropical High Activities

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Atmospheric and Oceanic Science Letters 2014年第4期7卷 286-290页

作者： PENG Jing-Bei The International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences

In the summer of 2013, an unprecedented heat wave was experienced over a vast area of southern China. The great areal extent, duration, and strength of this high temperature are very rare. For the 2013 hot spell, the major and direct influence mostly came from the anomaly of the western Pacific subtropical high(WPSH). The abnormally strong and stable WPSH was associated with specific surrounding circulations. The eastward extension of a stronger Qinghai-Xizang high favored the westward extension of the WPSH. The weaker cold air activity from the polar region led to the northward shift of the WPSH and helped it to remain stable. In the tropics, the western segment of the ITCZ was abnormally strong in the period, and supported the maintenance of the WPSH from the south. In addition, the interdecadal variation of the WPSH provided a decadal background for the anomaly variation of the WPSH that summer.

关键词：西太平洋副热带高压中国南方异常高压活动西太平洋副高夏季冷空气活动热带辐合带