我国冬油菜的气候灾损变化及其对ENSO响应

构建冬油菜气候灾损与ENSO事件的可能关系有利于应对气候变化对油料供给的影响。基于12个主产省市1980—2019年的冬油菜单产序列,通过H-P滤波与时序全局主成分分析识别了气候灾损的年代差异。此外,梳理了主要气象灾害以及不同ENSO年型对灾损的影响,进而探讨了9种ENSO指数的预判作用。主要结果如下:①冬油菜种植效率的区域均衡性呈现出显著的上升趋势;②多数省市的气候灾损在1980s和1990s有着更高强度;③冻灾和雹灾对冬油菜种植有着更不利的影响;④ENSO强冷事件支配年份的气候灾损明显更高;⑤极端东部热带太平洋海表温度等因子驱动的分类模型对灾损年景有着较好的预判效果。

ENSOMIM:一种新型ENSO时空预测模型

为了提高厄尔尼诺南方涛动(El Ni?o-southern oscillation,ENSO)预测的准确性,解决卷积核难以捕获ENSO的长距离前兆的问题,将ENSO预测视为一个时空序列预测问题,并提出一种基于注意力机制和循环神经网络的ENSO非稳态时空预测深度学习模型,称为ENSOMIM。该模型通过提出的新型注意力机制BGAM来局部和全局交互地学习空间特征,并使用高阶非线性时空网络对长期的时间序列特征进行编码。由于ENSO观测数据集样本数量少,为了更充分地训练模型,采用迁移学习的方法,使用历史模式模拟数据进行预训练再利用观测数据校正模型。实验结果表明,ENSOMIM更适合于大区域和长期的预测。在1984-2014年验证期间,ENSOMIM的Ni?o3.4指数的全季节相关性技巧比经典的卷积神经网络提高16%,均方误差降低17%,它可以为长达18个月的提前期提供有效预测,并且在23个月的提前期内相关技巧达到0.45。因此,ENSOMIM可以作为预测ENSO事件的有力工具。

Recent Advances in Studies of the Interaction between the East Asian Winter and Summer Monsoons and ENSO Cycle

Recent advances in studies on the interaction between the East Asian monsoon and the ENSO cycle are reviewed in this paper. Through the recent studies, not only have the responding features and processes of the East Asian winter and summer monsoon circulation anomalies and summer rainfall anomalies in East Asia to the ENSO cycle during its different stages been understood further, but also have the thermal and dynamic effects of the tropical \vestern Pacific on the ENSO cycle been deeply analyzed from the observational facts and dynamic theories. The results of observational and theoretical studies showed that the dynamical effect of the atmospheric circulation and zonai wind anomalies in the lower troposphere over the tropical western Pacific on the ENSO cycle may be through the excitation of the equatorial oceanic Kelvin wave and Rossby waves in the equatorial Pacific. These studies demonstrated further that the ENSO cycle originates from the tropical western Pacific. Moreover, these recent studies also showed that the atmospheric circulation and zonai wind anomalies over the tropical western Pacific not only result from the air-sea interaction over the tropical western Pacific, but are also greatly influenced by the East Asian winter and summer monsoons. Additionally, the scientific problems in the interaction between the Asian monsoon and the ENSO cycle which should be studied further in the near future are also pointed out in this paper.

The 1997/ 98 ENSO Cycle and Its Impact on Summer Climate Anomalies in East Asia

The observed data of the sea surface temperature (SST) anomalies and the sea temperature (ST) in the sub-layer of the equatorial Pacific, the NCEP/ NCAR reanalysis data and the data set of daily precipitation in China are used to analyze the characteristics of the 1997 / 98 ENSO cycle and its impact on summer climate anomalies in East Asia. The results show that the 1997/98 ENSO cycle, the strongest one in the 20th century, might be characterized by rapid development and decay and eastward propagation from the West Pacific warm pool. Influenced by the ENSO cycle, in 1997, the serious drought and hot summer occurred in North China, and in the summer of 1998, the severe floods occurred in the Yangtze River valley, especially in the Dongting Lake and Boyang Lake valleys, South Korea and Japan. The analysis also shows that: influenced by the 1997/98 ENSO cycle, the water vapor transportation by the Asian monsoon in the summer of 1997 was very different from that in the summer of 1998. In the summer of 1997, the water vapor transportation by the Asian summer monsoon was weak in North China and the northern part of the Korea Peninsula. Thus, it caused the drought and hot summer in North China. However, in the summer of 1998, the sea temperature in the sub-layer of the West Pacific warm pool dropped, the western Pacific subtropical high shifted southward. Thus, a large amount of water vapor was transported from the Bay of Bengal, the South China Sea and the tropical western Pacific into the Yangtze River valley of China, South Korea and Japan, and the severe flood occurred there. Key words ENSO cycle - Climate anomaly - Monsoon - Drought and flood This study was supported by the National Key Programme for Developing Basic Sciences under Grant No. G1998040900(I).

从能量学角度理解气候背景场对ENSO热带和热带外遥相关的影响

厄尔尼诺—南方涛动(El Ni?o-Southern Oscillation,简称ENSO)通过遥相关过程影响全球天气气候。在热带地区,ENSO能通过影响热带对流层温度导致遥远海盆降水和海表温度异常;在热带外,ENSO能通过激发准定常罗斯贝波动造成北美、亚洲等地区气候异常。气候背景场对ENSO热带和热带外遥相关有重要影响。一方面,气候背景大气环流场可以通过正压和斜压能量转换影响ENSO遥相关波列的位置和强度。另一方面,热带气候背景海温和对流场会通过影响湿静力能分布影响ENSO热带遥相关过程。这些研究表明分析能量过程有助于理解气候背景场影响ENSO遥相关的机理。本文回顾了近几十年来国内外关于气候背景场对ENSO热带与热带外遥相关影响的能量分析研究进展,在此基础上,回顾了全球变暖背景下ENSO遥相关的可能变化,并提出了一些未来该领域内需要进一步研究的科学问题。

Origin of the TBO-Interaction between Anomalous East-Asian Winter Monsoon and ENSO Cycle

Based on the data analyses by using NCEP/ NCAR reanalysis data and other data (OLR, precipitation and temperature), it is shown that the tropospheric circulation and climate in East Asia and the northwestern Pacific region have the evident quasi-biennial oscillation (TBO) feature. It is also shown that anomalous East Asian winter monsoon can impact the atmospheric circulation and climate variations in the following summer, particularly in East Asian region; there is clear interaction between anomalous East Asian winter monsoon and ENSO cycle. The continuous strong (weak) East Asian winter monsoon can excite El Ni o (La Ni a) through the air-sea interaction, the El Ni o (La Ni a) event can lead the East Asian winter monsoon to be weak (strong) through the teleconnections or remote responses. The strong or weak winter monsoon and ENSO cycle are linked each other. It can be suggested that interaction between anomalous East Asian winter monsoon and ENSO cycle is a fundamental origin of the TBO.

The Westerly Anomalies over the Tropical Pacific and Their Dynamical Effect on the ENSO Cycles during 1980～1994

In this paper, the zonal wind anomalies in the lower troposphere over the tropical Pacific during 1980-1994 are analyzed by using the observed data. The results show that during the formation of the 1982/83, 1986/87 and 1991/92 ENSO events, there were the larger westerly anomalies in the lower troposphere over the equatorial Pacific. Moreover, it is explained by using the correlation analyses that the westerly anomalies over the equatorial Pacific could cause the warm episodes of the equatorial central and eastern Pacific. A simple air-sea coupled model is used to discuss theoretically the dynamical effect of the observed westerly anomalies of wind stress near the sea surface of the equatorial Pacific on the ENSO cycle occurred in the period of 1981-1983. It is shown by using the theoretical calculations of the equatorial oceanic Kelvin wave and Rossby waves responding to the forcing of the observed anomalies of zonal wind stress near the sea surface of the equatorial Pacific that the westerly anomalies of wind stress near the sea surface of the equatorial Pacific make significant dynamical effect on the ENSO cycles occurred in the period of 1982-1983.

A possible role of the South China Sea in ENSO cycle

A data-based hypothesis on the role of the South China Sea (SCS) in ENSO cycle is proposed: during El Nino, there are westerly wind anomaly over the western equatorial Pacific and positive SST anomaly in the eastern equatorial Pacific. Meanwhile anomalous convection moves to the central Pacific with anomalous sinking over Indonesian Archipelago. The latter can cause southerly wind anomaly over the north of South China Sea (NSCS) and makes the NSCS warmer. The warm NSCS can attract the anomalous convection to it in some degree. This attraction is in favor for producing easterly wind anomaly over the western equatorial Pacific, so it helps to form a cycle.

ENSO cycle and climate anomaly in China

The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly （SOTA） and the associated anomalous atmospheric circulation over the Asian North Pacific during the E1 Nifio-Southern Oscillation （ENSO） were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research （NCEP/NCAR） atmospheric reanalysis data and simple ocean data simulation （SODA）. The relationship between the ENSO and the climate of China was revealed. The main results indicated the following： 1） there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2） during the mature phase of E1Nifio, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of E1 Nifio, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Nifm event causes an opposite, but weaker effect; 3） the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the ＂atmospheric-bridge＂, where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper.

The relationship between ENSO cycle and temperature,precipitation and runoff in the Qilian mountain area

El Nino and La Nina are the events concerned internationally. The corresponding relationship between El Nino events, temperature, precipitation and runoff in the Qilian mountain area are analyzed according to the date from the weather and the hydrometric stations in the area, the results show that effects of El Nino events to temperature, precipitation and runoff are different in the different time and zones. When El Nino occurs, temperature rises, but precipitation and runoff decrease in the whole Qilian mountain area, especially in the east and middle parts of the area. Temperature rises, precipitation and runoff still decrease in the eastern Qilian mountain area in the next year El Nino occurring, but decrease extent is fewer. There are not obvious relationship between temperature, precipitation and runoff with El Nino events in the western Qilian mountain area.

ROLE OF EQUATORIAL PACIFIC OCEAN SUBSURFACE OCEANIC TEMPERATURE MODE IN ENSO CYCLE

Based on the simple ocean data assimilation(SODA) reanalysis dataset from the University of Maryland and the method of Empirical Orthogonal Functions(EOF),the characteristics of interannual and interdecadal variabilities of the equatorial Pacific subsurface oceanic temperature anomaly(SOTA) are captured.The first and second modes of the equatorial Pacific SOTA in the interannual and interdecadal variations are found respectively and the effect of the second mode on the ENSO cycle is discussed.Results show that the first mode of SOTA's interannual and interdecadal variabilities exhibit a dipole pattern,indicating that the warm and cold temperature anomalies appear simultaneously in the equatorial subsurface Pacific.The second mode shows coherent large-scale temperature anomalies in the equatorial subsurface Pacific,which is a dominant mode in the evolution of ENSO cycle.The temporal series of the second mode has a significant lead correlation with the Ni?o-3.4 index,which can make a precursory prediction signal for ENSO.The function of this prediction factor in SOTA is verified by composite and case analyses.

ENSO组合模态可预测性的季节-年代际变化

厄尔尼诺-南方涛动组合模态(C-mode)是厄尔尼诺衰减期西北太平洋上空异常反气旋发展的主要驱动力,通常可以形成水汽输送通道,导致我国南部地区降水增多并发生严重的洪涝灾害,而在拉尼娜期间则情况相反。利用1981—2020年美国国家环境预报中心和美国国家大气研究中心再分析数据集的表面风场资料分析了C-mode可预测性的季节-年代际变化。结果表明:C-mode在2000年以后的可预测性明显下降,主要原因是其变率减小、强度减弱、信噪比降低等。在季节尺度上,C-mode存在“秋季预报障碍”,这与信号的季节循环密切关联,当C-mode在秋季进入衰退期时,信号强度最弱、变率最小,因此其秋季的可预测性降低。

Intraseasonal Oscillation: the Global Coincidence and Its Relationship with ENSO Cycle

Based on the atmospheric reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), the interannual variability of the atmospheric intraseasonal oscillation (ISO) and its relationships with the El Ni?o/Southern Oscillation (ENSO) cycle have been investigated. This work reveals that there exists global coincidence in the interannual variation of ISO among different latitude bands and that relationships between the interannual variation of ISO and the global sea surface temperature (SST) or the outgoing longwave radiation (OLR) are very complicated. We also find that the correlation coefficient between ISO and Ni?o33 SST anomaly has apparent decadal scale variability, which means that the inter-relationship is stronger in some periods and weaker in other periods. Key words Intraseasonal oscillation - Global coincidence - ENSO cycle This work was supported jointly by the Chinese Academy of Sciences Key project under contract KZCX2-203, and the National Natural Science Foundation of China under the Grant Nos. 49735160 and 49805004.

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

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.

Sensitivity of Nonlinearity on the ENSO Cycle in a Simple Air-Sea Coupled Model

In this paper,the influence of the El NioSouthern Oscillation (ENSO) cycle on the sensitivity of nonlinear factors in the numerical simulation is investigated by conducting numerical experiments in a simple air-sea coupled model for ENSO prediction.Two sets of experiments are conducted in which zonal nonlinear factors,meridional nonlinear factors,or both are incorporated into the governing equations for the atmosphere or ocean.The results suggest that the ENSO cycle is very sensitive to the nonlinear factor of the governing equation for the atmosphere or ocean.Thus,incorporating nonlinearity into air-sea coupled models is of exclusive importance for improving ENSO simulation.

舟山海域夏季上升流的年际变化及其与ENSO的关系

本文利用1968—2021年的海表温度和风场数据,分析舟山海域夏季上升流强度的年际变化,并结合同期的Ni?o 3.4指数分析ENSO(El Ni?o-Southern Oscillation)对上升流的影响。温度和风上升流指数表明,1982—2021年夏季舟山海域上升流均呈下降趋势,下降速率分别为0.062℃·10a^(−1)和0.35m^(3)·s^(-1)·(100m·a)^(-1)。近年来,沿岸风应力的减弱是影响温度上升流指数减弱的一个重要因素。统计更长时间段内(1968—2021年)El Ni?o和La Niño年风上升流指数的强度发现,El Ni?o年平均风上升流指数较小,仅为-10.33m^(3)·s^(-1)·(100m)^(-1)。La Niño年平均风上升流指数较大为7.60m^(3)·s^(-1)·(100m)^(-1),高于El Ni?o和气候态,且多达4级(比例为75%)。进一步分析ENSO与舟山海域风上升流指数的关系发现,ENSO主要通过影响风的变化进而影响上升流的强度。El Ni?o年,舟山海域东南风减弱,导致上升流强度较弱,甚至发生下降流。La Niño年主要为偏南风且风速较大,更有利于上升流的发展。

ENSO对中国沿海夏季降水影响的区域特征研究

利用降水和海表温度格点数据以及中国沿海台站降水数据,分析中国沿海夏季降水对ENSO时空响应特点,并探讨中国沿海夏季降水年代际变化原因。结果表明:1)中国沿海夏季降水受ENSO影响区域特征明显,以连云港和云澳为界可分为3个区域。渤黄海沿海夏季降水与Niño3.4指数呈负相关,东海沿海呈正相关,南海沿海相关关系不显著。2)年代际尺度上,中国沿海夏季降水与Niño3.4指数关系不稳定。渤黄海沿海夏季降水与Niño3.4指数负相关在1980年之前和2010年之后较为显著,东海沿海的正相关在20世纪80年代之后变得不显著,南海沿海的相关关系不显著。3)年代际尺度上,渤黄海沿海夏季年代际降水与同期Niño3.4指数、前一年冬季AO指数和当年春季AAO指数呈显著负相关,而东海沿海都呈显著正相关,南海沿海夏季年代际降水与当年春季北极海冰指数呈明显负相关。对于Niño3.4指数,中东太平洋偏高的海表温度能在500hPa位势高度场激发出负太平洋-日本型遥相关波列,使得渤黄海沿海夏季年代际降水减少和东海沿海增多;当前一年冬季AO和当年春季AAO为正相位时,850 hPa风场在贝加尔湖南部的异常反气旋引导中高纬地区气流南下,引起东亚夏季风减弱,造成渤黄海沿海夏季年代际降水减少;另外,西北太平洋副热带高压强度偏强且位置偏西引起上升运动增强,导致东海沿海夏季年代际降水增多;春季北极海冰年代际变化能在850hPa风场和500hPa位势高度场上,激发出导致南海沿海夏季降水年代际变化相反的大气环流形势。

ENSO循环海表温度演变多样性的客观分类

厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)是热带太平洋最显著的年际气候变率模态,其海温异常(Sea Surface Temperature Anomalies,SSTA)的演变过程呈周期性和锁相性特征。本文从ENSO循环角度出发,使用K均值聚类法(K-Means Clustering Analysis,KMA)对1961-2021年ENSO的SSTA演变进行分类,得到ENSO循环的SSTA演变3类和5类两种客观分类结果。当分3类时,ENSO循环的SSTA基本演变特征分别为暖发展、暖衰减和冷持续过程;而分5类时,超强和普通暖事件发展、衰减过程在强度和纬向分布上的差异能够被进一步反映出来。为解释该差异,本文又引入结合主成分分析(Empirical Orthogonal Function,EOF)的KMA方法。通过将EOF主模态分为两大类,分别代表ENSO循环的纬向一致发展模态和纬向非对称发展模态,分离了ENSO循环中赤道太平洋SSTA纬向一致和纬向非对称发展过程。在此基础上,结合KMA聚类分析结果对不同类别的ENSO循环特征进行分析,发现纬向非对称发展模态叠加在纬向一致发展模态上,可最终导致ENSO的SSTA年循环纬向发展速度的不对称。对ENSO纬向一致和非对称演变模态进行回归重构,发现风、温跃层厚度异常可能是造成SSTA纬向非对称演变的关键。本文客观定义ENSO演变的不同类型,为ENSO多样性的气候动力学及其气候影响研究提供了一定参考。

马来西亚东北部Setiu潟湖1970年以来沉积环境演化及其对ENSO的响应

马来半岛位于低纬热带地区,厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)如何影响该区域的气候,尤其是降水仍然存在争议。本文以马来半岛东北部登嘉楼州Setiu潟湖钻孔NTT-3为研究对象,通过分析粒度、总有机碳及总氮含量、C/N比值和XRF岩心扫描等,探讨该钻孔的沉积环境变化及其对ENSO的响应。研究结果显示,钻孔记录中自1970年前后(84 cm处)出现两种不同的变化趋势。1970年之前钻孔下部沉积物粒度、有机和无机地球化学特征趋势波动明显,沉积速率较低。而1970年以来,潟湖沉积环境总体稳定,沉积物中的有机组分主要来自红树林,同时伴有河流输入的淡水浮游植物的贡献。频谱分析结果显示1970年以来钻孔上部存在明显的ENSO周期变化。强厄尔尼诺现象基本对应低Zr/Rb比值和低Zr/Ti比值,而强拉尼娜(La Nina)现象基本对应高Zr/Rb比值和高Zr/Ti比值。该结论不仅支持了现代观测对马来半岛东部沿海地区气候变化的认识,同时也在地质记录中发现了ENSO变化的直接证据,对全面认识和理解ENSO对亚洲气候变化的影响、区域陆海相互作用过程和环境响应等方面具有重要现实意义。

NORTHERN HEMISPHERE SUMMER TELECONNECTIONS INTERAN-NUAL OSCILLATION AND ITS POSSIBLE RELATION TO ENSO CYCLE

The intense of Northern Hemisphere summer East Asia/Pacific and snow-forced pattern telecon-nections have been documented in terms of 43-year summer 500 hPa height data. The analysis results show the phase relationship between these summer teleconnections at quasi-4-year oscillation. The possible relation to ENSO cycle at such time scale has also been deduced.