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Roles of Wind Stress and Subsurface Cold Water in the Second-Year Cooling of the 2017/18 La Nina Event

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Advances in Atmospheric Sciences 2020年第8期37卷 847-860页

作者： licheng feng Rong-Hua ZHANG Bo YU Xue HAN National Marine Environmental Forecasting Center Ministry of Natural ResourcesBeijing 100081China Key Laboratory of Marine Hazards Forecasting National Marine Environmental Forecasting CenterMinistry of Natural ResourcesBeijing 100081China Key Laboratory of Ocean Circulation and Waves Institute of Oceanologyand Center for Ocean Mega-ScienceChinese Academy of SciencesQingdao 266071China Pilot National Laboratory for Marine Science and Technology Qingdao 266237China Center for Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi’an 710061China Beijing Weather Forecast Center Beijing 100089China

After the strong 2015/16 El Nino event,cold conditions prevailed in the tropical Pacific with the second-year cooling of the 2017/18 La Ni?a *** coupled models failed to predict the cold SST anomalies(SSTAs)in *** using the ERA5 and GODAS(Global Ocean Data Assimilation System)products,atmospheric and oceanic factors were examined that could have been responsible for the second-year cooling,including surface wind and the subsurface thermal state.A time sequence is described to demonstrate how the cold SSTAs were produced in the central-eastern equatorial Pacific in late *** July 2017,easterly anomalies strengthened in the central Pacific;in the meantime,wind stress divergence anomalies emerged in the far eastern region,which strengthened during the following months and propagated westward,contributing to the development of the second-year cooling in *** the subsurface,weak negative temperature anomalies were accompanied by upwelling in the eastern equatorial Pacific,which provided the cold water source for the sea ***,both the cold anomalies and upwelling were enhanced and extended westward in the centraleastern equatorial *** changes were associated with the seasonally weakened EUC(the Equatorial Undercurrent)and strengthened SEC(the South Equatorial Current),which favored more cold waters being accumulated in the central-equatorial ***,the subsurface cold waters stretched upward with the convergence of the horizontal currents and eventually outcropped to the *** subsurface-induced SSTAs acted to induce local coupled air–sea interactions,which generated atmospheric–oceanic anomalies developing and evolving into the second-year cooling in the fall of 2017.

关键词： 2017/18 La Nina second-year cooling in 2017 wind stress anomalies subsurface cold anomalies

The influence of ENSO on sea surface temperature variations in the China seas

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Acta Oceanologica Sinica 2013年第9期32卷 21-29页

作者： LIU Na WANG Hui LING Tiejun feng licheng Key Laboratory of Research on Marine Hazards Forecasting National Marine Environmental Forecasting CenterState Oceanic Administration National Marine Environmental Forecasting Center State Oceanic Administration

Positive SST anomalies usually appear in remote ocean such as the China seas during an ENSO event. By analyzing the monthly data of HadISST from 1950 to 2007, it shows that the interannual component of SST anomalies peak approximately 10 months after SST anomalies peak in the eastern equatorial Pacific. As the ENSO event progresses, the positive SST anomalies spread throughout the China seas and eastward along the Kuroshio extension. Atmospheric reanalysis data demonstrate that changes in the net surface heat flux entering into the China seas are responsible for the SST variability. During E1 Nifio, the western north Pacific anticyclone is generated, with anomalous southwester lies prevailing along the East Asian coast. This anticyclone reduces the mean surface wind speed which decreases the surface heat flux and then increases the SST. The delays between the developing of this anticyclone and the south Indian Ocean anticyclone with approximately 3-6 months cause the 2-3 months lag of the surface heat flux between the China seas and the Indian Ocean. The northwestern Pacific anticyclone is the key process bridging the warming in the eastern equatorial Pacific and that in the China seas.

关键词： sea surface temperature China seas ENSO anticyclone

Processes Leading to Second-Year Cooling of the 2010–12 La Ni?a Event,Diagnosed Using GODAS

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Advances in Atmospheric Sciences 2015年第3期32卷 424-438页

作者： feng licheng ZHANG Rong-Hua WANG Zhanggui CHEN Xingrong National Marine Environmental Forecasting Center State Oceanic Administration Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences Earth System Science Interdisciplinary Center (ESSIC) University of MarylandCollege ParkMaryland USA 20740

Isopycnal analyses were performed on the Global Ocean Data Assimilation System （GODAS） to determine the oceanic processes leading to so-called second-year cooling of the La Nina *** 2010-12,a horseshoe-like pattern was seen,connecting negative temperature anomalies off and on the Equator,with a dominant influence from the South *** the 2010 La Nina event,warm waters piled up at subsurface depths in the western tropical *** in early 2011,these warm subsurface anomalies propagated along the Equator toward the eastern basin,acting to reverse the sign of sea surface temperature （SST） anomalies （SSTAs） there and initiate a warm ***,throughout early 2011,pronounced negative anomalies persisted off the Equator in the subsurface depths of the South *** isopycnal surfaces outcropped in the central equatorial Pacific,negative anomalies from the subsurface spread upward along with mean circulation pathways,naturally initializing a cold *** the summer,a cold SSTA reappeared in the central basin,which subsequently strengthened due to the off-equatorial effects mostly in the South *** SSTAs acted to initiate local coupled air-sea interactions,generating atmospheric-oceanic anomalies that developed and evolved with the second-year cooling in the fall of ***,the cooling tendency in mid-2012 did not develop into another La Nina event,since the cold anomalies in the South Pacific were not strong *** analysis of the 2007-09 La Nina event revealed similar processes to the 2010-12 La Nina event.

关键词： La Ni(n)a second-year cooling off-equatorial effects isopycnal analyses circulation pathways GODAS

Experimental study on Cr(Ⅵ) reduction by Pseudomonas aeruginosa

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Journal of Environmental Sciences 2004年第5期16卷 797-801页

作者： LIUYun-guo XUWei-hua ZENGGuang-ming TANGChun-fang licheng-feng DepartmentofEnvironmentalScienceandEngineering HunanUniversityChangsha410082China

Investigation on Cr(Ⅵ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) can be effectively reduced to Cr(Ⅲ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr(Ⅵ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of cells inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43.76% and 28.86% respectively. The optimum pH for Cr(Ⅵ) reduction was 7.0, with reduction efficiency of 61.71% being achieved. With the increase of initial Cr(Ⅵ) concentration, the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr(Ⅵ) reduction also increased. The mechanism of Cr(Ⅵ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr(Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr(Ⅲ) was not precipitated in the form of Cr(OH) 3.

关键词： Pseudomonas aeruginosa Cr(Ⅵ) reduction reduction rate Cr(Ⅵ) remediation

The 2020–2021 prolonged La Niña evolution in the tropical Pacific

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Science China Earth Sciences 2022年第12期65卷 2248-2266页

作者： Chuan GAO Maonan CHEN Lu ZHOU licheng feng Rong-Hua ZHANG Key Laboratory of Ocean Circulation and Waves Institute of OceanologyCenter for Ocean Mega-ScienceChinese Academy of SciencesQingdao 266071China Laoshan Laboratory Qingdao 266237China School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100029China Center for Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi’an 710061China National Marine Environmental Forecasting Center Ministry of Natural ResourcesBeijing 100081China

The evolution of sea surface temperature(SST)in the tropical Pacific during 2020–2021 indicates a second-year cooling in late 2021 again,following the 2020 La Niña *** physical explanations are still lacking,and there is a clear need to understand the underlying processes *** data and reanalysis products are used to describe the characteristics and spatiotemporal evolution of upper-ocean thermal anomalies;an intermediate coupled model(ICM)is also used to perform numerical experiments to confirm these observation-based *** evolution of subsurface thermal anomalies is critically important to that of SST in the central-eastern equatorial Pacific;the effects of the former on the latter can be well represented by the temperature of subsurface waters entrained into the mixed layer(Te),a field that reflects a subsurface forcing on *** SST evolution is sensitively dependent on the intensities of the local effect associated with Te anomalies in the eastern equatorial Pacific and the remote effect associated with subsurface anomalies from the western *** early-and mid-2021,a competition was present between these local and remote effects associated with Te *** the remote warming effect dominates the local cooling effect,the cold SST condition in the east is likely to turn into neutral and warm conditions;otherwise,it tends to *** addition,the negative Te anomalies were sustained and enhanced by off-equatorial processes due to equatorial wave reflections at the eastern boundary associated with the 2020 La Niña *** SST evolution in mid-2021 corresponded to a situation in which the warming effect associated with positive subsurface thermal anomalies from the west were not strong enough to counteract the local cooling effect associated with negative anomalies in the *** due course,cold SST anomalies in the east developed again and the second-year cooling reoccurred in late 2021,with a turning point in

关键词： Prolonged La Niña evolution in 2020-2021 Subsurface effect on SST Remote and local processes Modeling experiments

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Influence of the Atlantic Multidecadal Oscillation and Interdecadal Pacific Oscillation on Antarctic surface air temperature during 1900 to 2015

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Acta Oceanologica Sinica 2024年第3期43卷 48-58页

作者： Cuijuan Sui Lejiang Yu Alexey YuKarpechko licheng feng Shan Liu Key Laboratory of Marine Hazards Forecasting National Marine Environmental Forecasting CenterMinistry of Natural ResourcesBeijing 100081China Key Laboratory for Polar Science Polar Research Institute of ChinaMinistry of Natural ResourcesShanghai 200136China Finnish Meteorological Institute HelsinkiFI-00101Finland

The importance of the Atlantic Multidecadal Oscillation(AMO)and Interdecadal Pacific Oscillation(IPO)in influencing zonally asymmetric changes in Antarctic surface air temperature(SAT)has been ***,previous studies have primarily concentrated on examining the combined impact of the contrasting phases of the AMO and IPO,which have been dominant since the advent of satellite observations in *** study utilizes long-term reanalysis data to investigate the impact of four combinations of+AMO+IPO,–AMO–IPO,+AMO–IPO,and–AMO+IPO on Antarctic SAT over the past 115 ***+AMO phase is characterized by a spatial mean temperature amplitude of up to 0.5℃over the North Atlantic Ocean,accompanied by positive sea surface temperature(SST)anomalies in the tropical eastern Pacific and negative SST anomalies in the extratropical-mid-latitude western Pacific,which are indicative of the+IPO *** Antarctic SAT exhibits contrasting spatial patterns during the+AMO+IPO and+AMO–IPO ***,during the–AMO+IPO period,apart from the Antarctic Peninsula and the vicinity of the Weddell Sea,the entire Antarctic region experiences a warming *** most pronounced signal in the SAT anomalies is observed during the austral autumn,whereas the combination of–AMO and–IPO exhibits the smallest magnitude across all the *** wavetrain excited by the SST anomalies associated with the AMO and IPO induces upper-level and surface atmospheric circulation anomalies,which alter the SAT ***,downward longwave radiation anomalies related to anomalous cloud cover play a crucial *** the future,if the phases of AMO and IPO were to reverse(AMO transitioning to a negative phase and IPO transitioning to a positive phase),Antarctica could potentially face more pronounced warming and accelerated melting compared to the current observations.

关键词： Atlantic Multidecadal Oscillation(AMO) Interdecadal Pacific Oscillation(IPO) surface air temperature Antarctic wavetrain Rossby wave source

A semi-analytical model for the propagation of Rossby waves in slowly varying flow

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Chinese Science Bulletin 2011年第25期56卷 2727-2731页

作者： LIU Fei CHAO JiPing HUANG Gang feng licheng Key Laboratory of Regional Climate-Environment Research for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China International Pacific Research Center University of Hawaii at Manoa Honolulu 96822 USA National Marine Environmental Forecasting Center Beijing 100081 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100083 China

Instead of using complicated general circulation models (GCMs), a simple semi-analytical model based on ray theory has been used to study energy evolution and ray path of Rossby waves in slowly varying mean flows. Our model yields similar results to those calculated from barotropic models, and also provides a chance to study Rossby waves in the slowly varying flows with both vertical and meridional shears. The model results show that upward Rossby waves can only grow in westerlies, and decay when further ascend. The baroclinic Rossky waves are restrained by the β effect in lower latitude. In the westerly jet with meridional and vertical shears, the barotropic Rossby waves originated from south of the westerly jet, and these can grow while propagating upper-northward. The baroclinic Rossby waves originated from north of the westerly jet and can grow while propagating upward and southward. Such a semi-analytical model provides a simple forecasting tool to allow study of the local weather anomalies to the heating/topography forcing associated with the global warming.

关键词： Rossby波半解析模型传播模式大气环流模型变流西风急流 GCMS 射线路径

Differences in spring precipitation over southern China associated with multiyear La Ni?a events

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Acta Oceanologica Sinica 2024年第2期43卷 1-10页

作者： Guangliang Li licheng feng Wei Zhuang Fei Liu Ronghua Zhang Cuijuan Sui National Marine Environmental Forecasting Center Ministry of Natural ResourcesBeijing 100081China State Key Laboratory of Marine Environmental Science College of Ocean and Earth SciencesXiamen UniversityXiamen 361102China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China Key Laboratory of Tropical Atmosphere-Ocean System of Ministry of Education/School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai 519082China School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China

Composite analyses were performed in this study to reveal the difference in spring precipitation over southern China during multiyear La Ni?a events during 1901 to 2015. It was found that there is significantly below-normal precipitation during the first boreal spring, but above-normal precipitation during the second year. The difference in spring precipitation over southern China is correlative to the variation in western North Pacific anomalous cyclone(WNPC), which can in turn be attributed to the different sea surface temperature anomaly(SSTA) over the Tropical Pacific. The remote forcing of negative SSTA in the equatorial central and eastern Pacific and the local air-sea interaction in the western North Pacific are the usual causes of WNPC formation and *** in the first spring is stronger than those in the second spring. As a result, the intensity of WNPC in the first year is stronger, which is more likely to reduce the moisture in southern China by changing the moisture transport, leading to prolonged precipitation deficits over southern China. However, the tropical SSTA signals in the second year are too weak to induce the formation and maintenance of WNPC and the below-normal precipitation over southern China. Thus, the variation in tropical SSTA signals between two consecutive springs during multiyear La Ni?a events leads to obvious differences in the spatial pattern of precipitation anomaly in southern China by causing the different WNPC response.

关键词： multiyear La Nina precipitation anomaly anomalous western North Pacific cyclone southern China

CLUSTERING VIA DIMENSIONAL REDUCTION METHOD FOR THE PROJECTION PURSUIT BASED ON THE ICSA

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Journal of Electronics(China) 2010年第4期27卷 474-479页

作者： Gou Shuiping feng Jing Jiao licheng Key Laboratory of Intelligent Perception and Image Understanding for the Ministry of Education Institute of Intelligent Information Processing Xidian University Xi＇an 710071 China

The performance of the classical clustering algorithm is not always satisfied with the high-dimensional datasets, which make clustering method limited in many application. To solve this problem, clustering method with Projection Pursuit dimension reduction based on Immune Clonal Selection Algorithm (ICSA-PP) is proposed in this paper. Projection pursuit strategy can maintain consistent Euclidean distances between points in the low-dimensional embeddings where the ICSA is used to search optimizing projection direction. The proposed algorithm can converge quickly with less iteration to reduce dimension of some high-dimensional datasets, and in which space, K-mean clustering algorithm is used to partition the reduced data. The experiment results on UCI data show that the presented method can search quicker to optimize projection direction than Genetic Algorithm (GA) and it has better clustering results compared with traditional linear dimension reduction method for Principle Component Analysis (PCA).

关键词： Projection Pursuit (PP) Immune Clonal Selection Algorithm (ICSA) Genetic Algorithm (GA) K-means clustering