Atmospheric and Oceanic Science Letters最新文献

{"title":"Effect of different cold air intensities and their lagged effects on outpatient visits for respiratory illnesses in Handan in different seasons","authors":"Xingshan Zhang ,&nbsp;Guiqin Fu ,&nbsp;Liang Zhao ,&nbsp;Ji Wang ,&nbsp;Caimeng Liang ,&nbsp;Juanhuai Wang ,&nbsp;Meng Li","doi":"10.1016/j.aosl.2023.100398","DOIUrl":"10.1016/j.aosl.2023.100398","url":null,"abstract":"<div><p>The authors analyzed cold air processes of different intensities and their effect on the number of patients with respiratory illnesses visiting a hospital outpatient department in Handan City in different seasons from 2016 to 2019. For cold air events of the same intensity (apart from cold waves), the number of patients with respiratory illnesses visiting the outpatient department was highest in winter. During the cold waves, the number of patients increased sharply to greater than 55 patients per day, and the number of patients was higher in spring than in autumn. The probability density of the number of patients with respiratory illnesses visiting the outpatient department gradually changed to a positive skewness as the cold air intensity increased. Although the incidence of respiratory illnesses was the highest in winter and lowest in summer, the impact of cold air on respiratory illnesses was the largest in summer and spring, when the number of people with respiratory illnesses visiting the outpatient department increased by 18.4% and 13.3% two and five days after a cold air day. By contrast, the number people visiting the outpatient department with respiratory illnesses in winter only increased by 3.2% three days after a cold air day. The lag time of the health impact decreased with increasing cold air intensity in summer, autumn and winter, whereas the lag time was always long in spring. These findings provide a targeted basis for a scientific response to the risks to human health caused by global climate change.</p><p>摘要</p><p>本文利用2016年到2019年邯郸市气象要素和呼吸系统疾病门诊数据, 分析了不同季节不同强度的冷空气过程及其对呼吸系统疾病的影响. 结果显示: 尽管呼吸系统疾病在冬季高发, 夏季最低, 但冷空气对呼吸系统疾病的影响在夏, 春季最大, 就诊人数分别在冷空气日后两天和五天增加18.4%和13.3%, 而冬季就诊人数在冷空气日后三天仅增加3.2%.冷空气对疾病影响的滞后时间在夏, 秋和冬季随冷空气强度的增加而减少, 而春季的滞后时间总是很长. 这些发现可为科学应对气候异常导致的人群健康风险提供针对性依据.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100398"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423000843/pdfft?md5=591bb1f7f5d6fcade6bf3e4ff516227d&pid=1-s2.0-S1674283423000843-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46038483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Progress and future prospects of decadal prediction and data assimilation: A review","authors":"Wen Zhou ,&nbsp;Jinxiao Li ,&nbsp;Zixiang Yan ,&nbsp;Zili Shen ,&nbsp;Bo Wu ,&nbsp;Bin Wang ,&nbsp;Ronghua Zhang ,&nbsp;Zhijin Li","doi":"10.1016/j.aosl.2023.100441","DOIUrl":"10.1016/j.aosl.2023.100441","url":null,"abstract":"<div><p>Decadal prediction, also known as “near-term climate prediction”, aims to forecast climate changes in the next 1–10 years and is a new focus in the fields of climate prediction and climate change research. It lies between seasonal-to-interannual predictions and long-term climate change projections, combining the aspects of both the initial value problem and external forcing problem. The core technique in decadal prediction lies in the accuracy and efficiency of the assimilation methods used to initialize the model, which aims to provide the model with accurate initial conditions that incorporate observed internal climate variabilities. The initialization of decadal predictions often involves assimilating oceanic observations within a coupled framework, in which the observed signals are transmitted through the coupled processes to other components such as the atmosphere and sea ice. However, recent studies have increasingly focused on exploring coupled data assimilation (CDA) in coupled ocean–atmosphere models, based on which it has been suggested that CDA has the potential to significantly enhance the skill of decadal predictions. This paper provides a comprehensive review of the research status in three aspects of this field: initialization methods, the predictability and prediction skill for decadal climate prediction, and the future development and challenges for decadal prediction.</p><p>摘要</p><p>年代际预测, 也称为“近期气候预测”, 旨在预测未来1–10年内的气候变化, 是气候预测和气候变化研究领域的一个新关注点. 它位于季节至年际预测和长期气候变化预测之间, 结合了初值问题和外部强迫问题的两个方面. 年代际预测的核心技术在于用于模式初始化的同化方法的准确性和效率, 其目标是为模式提供准确的初始条件, 其中包含观测到的气候系统内部变率. 年代际预测的初始化通常涉及在耦合框架内同化海洋观测, 其中观测到的信号通过耦合过程传递到其他分量, 如大气和海冰. 然而, 最近的研究越来越关注在海洋-大气耦合模式中探索耦合数据同化 (CDA) , 有人认为CDA有潜力显著提高年代际预测技巧. 本文综合评述了该领域的三个方面的研究现状: 初始化方法, 年代际气候预测的可预测性和预测技巧, 以及年代际预测的未来发展和挑战.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100441"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S167428342300140X/pdfft?md5=7d4498658a4fb0fa6a4a28c7d43c2c63&pid=1-s2.0-S167428342300140X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136094982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Slowing down of the summer Southern Hemisphere Annular Mode trend against the background of ozone recovery","authors":"Fei Zheng","doi":"10.1016/j.aosl.2023.100375","DOIUrl":"10.1016/j.aosl.2023.100375","url":null,"abstract":"<div><p>Observations show significant trends in Southern Hemisphere extratropical climate in the late 20th century, including a strong positive trend in the austral summer Southern Hemisphere Annular Mode (SAM) accompanied by warming of the Antarctic Peninsula and melting sea ice in the Bellingshausen Sea. Statistical analysis and model simulations have shown that these trends were driven mainly by Antarctic stratospheric ozone depletion. Here, results show that the widely reported summer SAM trend has flattened since around the year 2001 against the background of the ozone recovery, supporting results from previous model simulations that predicted a slowing down of the well-documented positive summer SAM trend. Four SAM indices based on different definitions from different datasets show consistency in this slowdown. Furthermore, changes in surface air temperature (SAT) in the Antarctic and sea-ice concentration (SIC) around the Antarctic are detected. Different from the SAM, in which the signs of trends only slow down but do not reverse after the ozone recovery, the signs of trends in Antarctic SAT and SIC have reversed. The warming of the Antarctic Peninsula has turned into a cooling trend, and the melting of sea ice in the Bellingshausen Sea has turned into an increasing trend. Additional diagnostics studies with observational and model data could go a long way towards enhancing our understanding of changes in Southern Hemisphere surface climate against the background of ozone recovery.</p><p>摘要</p><p>20世纪末期, 南半球热带外地区经历了显著的气候变化, 包括夏季南半球环状模(SAM)的显著上升趋势, 伴随着南极半岛的增暖和别林斯高晋海的海冰融化. 这些趋势主要是由20世纪末期南极平流层臭氧消耗所驱动的. 本文发现, 自2001年左右以来, 在南极平流层臭氧恢复的背景下, 观测到的夏季SAM的上升趋势已经趋于平缓, 验证了前人利用数值模拟预测的夏季SAM上升趋势减缓现象. 与SAM在臭氧恢复后趋势只减缓但没有逆转不同, 南极地表气温和海冰的趋势发生了逆转. 南极半岛由变暖趋势转为降温趋势, 别林斯高晋海域的海冰由融化趋势转为增多趋势.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100375"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423000612/pdfft?md5=cf32b3b5c0aefdb765bc15a2074aacb3&pid=1-s2.0-S1674283423000612-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46715627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A generative adversarial network–based unified model integrating bias correction and downscaling for global SST","authors":"Shijin Yuan,&nbsp;Xin Feng,&nbsp;Bin Mu,&nbsp;Bo Qin,&nbsp;Xin Wang,&nbsp;Yuxuan Chen","doi":"10.1016/j.aosl.2023.100407","DOIUrl":"10.1016/j.aosl.2023.100407","url":null,"abstract":"<div><p>This paper proposes a global sea surface temperature (SST) bias correction and downscaling unifying model based on the generative adversarial network. The generator of the model uses a bias correction module to correct the numerical model forecasting results. Then it uses a reusable shared downscaling module to improve the resolution of the corrected data gradually. The discriminator of the model evaluates the quality of the bias correction and downscaling results as a criterion for adversarial training. And a physics-informed dynamics penalty term is included in the adversarial loss function to improve the performance of the model. Based on the 1°-resolution SST forecasting results of the GFDL SPEAR (Seamless System for Prediction and Earth System Research) model, the authors select the Remote Sensing System observations as the refined targets and carry out validation experiments for three typical events at different scales and regions (ENSO, Indian Ocean dipole, and oceanic heatwave events). The model reduces the forecasting error by about 90.3% while increasing the resolution to 0.0625°×0.0625°, breaking the limitation of the resolution of the observation data, and the structural similarity with the observation results is as high as 96.46%.</p><p>摘要</p><p>本文提出了一种基于生成对抗网络的全球海表面温度(sea surface temperature, SST)偏差订正及降尺度整合模型. 该模型的生成器使用偏差订正模块将数值模式预测结果进行校正, 再用可复用的共享降尺度模块将订正后的数据分辨率逐次提高. 该模型的判别器可鉴别偏差订正及降尺度结果的质量, 以此为标准进行对抗训练. 同时, 在对抗损失函数中含有物理引导的动力学惩罚项以提高模型的性能. 本研究基于分辨率为1°的GFDL SPEAR模式的SST预测结果, 选择遥感系统(Remote Sensing System)的观测资料作为真值, 面向月尺度ENSO与IOD事件以及天尺度海洋热浪事件开展了验证试验: 模型在将分辨率提高到0.0625°×0.0625°的同时将预测误差减少约90.3%, 突破了观测数据分辨率的限制, 且与观测结果的结构相似性高达96.46%.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100407"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423000934/pdfft?md5=10497f0d5bbfb7bbd5824af1f6b97326&pid=1-s2.0-S1674283423000934-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49301910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ascending phase of solar cycle 25 tilts the current El Niño–Southern oscillation transition","authors":"Wenjuan Huo ,&nbsp;Ziniu Xiao ,&nbsp;Liang Zhao ,&nbsp;Fei Liu","doi":"10.1016/j.aosl.2023.100397","DOIUrl":"10.1016/j.aosl.2023.100397","url":null,"abstract":"<div><p>A La Niña condition in the equatorial Pacific began in the early summer of 2020 and has lasted more than two and a half years (referred to as the 2020 La Niña hereafter). Predicting its temporal evolution had attracted a lot of attention. Considering the possible phase-locked impact of the 11-year solar cycle on the tropical Pacific variability, in this study the authors present the possible modulations by the solar cycle 25 (SC25) started from December 2019, on the future temporal evolution of the 2020 La Niña. Based on statistical features of historical solar cycles, the authors propose three possible scenarios of the timing of the SC25 maximum year and discuss its possible impacts on the temporal evolution of the 2020 La Niña in the next two years. The ongoing ascending phase of SC25 dampens the development of a super El Niño condition to some extent in 2023.</p><p>摘要</p><p>自2020年初夏, 赤道太平洋地区出现拉尼娜现象并持续两年半多(以下简称2020拉尼娜), 对其未来演变的预测引起了很多关注, 考虑到11年太阳周期活动对热带太平洋SST异常可能存在锁相影响, 本研究分析了当前太阳活动周(即第25太阳周(SC25))对目前热带太平洋ENSO现象未来演变的调节作用, 基于历史太阳周的统计特征, 作者对第25太阳周达到其最大值的时间提出三种可能的情景, 并讨论了不同情景下的太阳活动对未来两年ENSO演变的可能影响, 第25太阳周的持续上升阶段在一定程度上抑制了当前2023厄尔尼诺现象发展为超级事件.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100397"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423000831/pdfft?md5=a6f5262d5f1f52135ea93bfd73da61fa&pid=1-s2.0-S1674283423000831-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49560861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decadal prediction skill for Eurasian surface air temperature in CMIP6 models","authors":"Yanyan Huang ,&nbsp;Ni Huang ,&nbsp;Qianfei Zhao","doi":"10.1016/j.aosl.2023.100377","DOIUrl":"10.1016/j.aosl.2023.100377","url":null,"abstract":"<div><p>The Eurasian surface air temperature (SAT) is experiencing decadal variations against the background of global warming. The prediction skill for the seasonal mean SAT in CMIP6 Decadal Climate Prediction Project (DCPP) models is investigated in this study. The large decadal variations of winter and autumn Eurasian SAT are barely predicted by the CMIP6 models. IPSL-CM6A-LR and the multimodel ensemble have skill in predicting the variations of spring Eurasian SAT, with significant anomaly correlation coefficients, but not for the amplitude, with negative mean-square skill scores. Significant skill is apparent for the summer SAT over Mongolia and North China, with the CMIP6 models showing their best skill for the summer Eurasian SAT. Compared to external forcing, model skills for Eurasian SAT may derive more from the initialization. It should be noted that there are model system errors in the form of false strong relationships of SAT between winter and other seasons when in fact the variations of other seasons’ SATs are independent of the winter SAT in observations.</p><p>摘要</p><p>评估CMIP6年代际预测试验对季节平均SAT的预测技巧的结果表明: 模式不能有效预测冬季和秋季SAT的年代际变率. IPSL-CM6A-LR和多模式集合平均对于春季SAT展现了预测技巧, 其中对于变率的预测技巧好于振幅的结果. 基于蒙古和我国华北地区的显著预测技巧, 模式对于夏季SAT表现出最佳的预测水平. 与外部强迫相比, 模式对于SAT的预测技巧可能来自初始化. 模式中的一个明显系统性误差值得注意, 即模式中冬季SAT的变率可以持续到其他季节, 而在观测中其他季节的SAT变化与冬季SAT相对独立.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100377"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423000636/pdfft?md5=b2b4956ec9f6d94409a50086c1073cad&pid=1-s2.0-S1674283423000636-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47129218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Tibetan Plateau bridge: Influence of remote teleconnections from extratropical and tropical forcings on climate anomalies","authors":"Yimin Liu ,&nbsp;Wei Yu ,&nbsp;Jilan Jiang ,&nbsp;Tingting Ma ,&nbsp;Jiangyu Mao ,&nbsp;Guoxiong Wu","doi":"10.1016/j.aosl.2023.100396","DOIUrl":"10.1016/j.aosl.2023.100396","url":null,"abstract":"<div><p>Recent advances in the bridging roles played by the Tibetan Plateau (TP) are reviewed in terms of the remote influence of circulation anomalies over the North Atlantic Ocean on Asian monsoon and El Niño-Southern Oscillation (ENSO) events, and in a clear link between the tropical oceans and Asian climate anomalies. The authors firstly introduce how the winter and spring anomalies in the North Atlantic Ocean affect the seasonal transition over the South Asian monsoon region and subsequent ENSO events on the interannual timescale. A distinct negative sensible heating-baroclinic structure in May over the TP is found to provide an intermediate bridging effect in this Atlantic-Asian-Pacific connection. In summer, the North Atlantic Oscillation is significantly correlated with the variations of East China summer rainfall, and it is the TP's latent heating that plays the bridging role within. On the other hand, such a TP bridging effect also exists in the connection from the tropical oceans to extreme precipitation events over eastern China in summer, and from the midlatitude wave train to the biweekly oscillation of South China rainfall in spring.</p><p>摘要</p><p>本文回顾了青藏高原桥梁作用方面的最新研究进展, 涉及北大西洋气候异常对春, 夏亚洲季风和厄尔尼诺-南方涛动 (ENSO) 事件的遥相关影响, 热带海洋异常和中国东部极端气候异常之间的联系以及华南春雨的季节内变化等. 介绍了年际时间尺度上, 冬-春季北大西洋海表温度强迫如何影响南亚季风的季节性转变以及随后ENSO事件的触发. 5月份青藏高原上空显著的负感热斜压结构, 为北大西洋影响亚洲季风和ENSO提供了桥梁效应. 夏季北大西洋涛动与华东夏季降水变化显著相关, 高原潜热在这一关系中起着桥梁作用. 另一方面, 这种高原桥梁效应也存在于从热带海洋异常到东亚夏季极端降水事件的连接中, 以及从中纬度波列到华南春雨准双周振荡的联系中.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 1","pages":"Article 100396"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S167428342300082X/pdfft?md5=a54d8161651e72af1aefa57f1b8a743e&pid=1-s2.0-S167428342300082X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44938350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A teleconnection pattern of upper-tropospheric circulation anomalies over the Eurasian continent associated with the interannual variability of atmospheric convection over the tropical western North Pacific in July","authors":"Peishan Chen ,&nbsp;Riyu Lu","doi":"10.1016/j.aosl.2023.100451","DOIUrl":"10.1016/j.aosl.2023.100451","url":null,"abstract":"<div><p>It has been well documented that the interannual variation of atmospheric convection over the tropical western North pacific (WNP) affects the East Asian climate in summer significantly, and can be influenced by the preceding winter ENSO. However, there is also a large portion of WNP convection variability that cannot be explained by the preceding ENSO. This study suggests that, particularly in July, the WNP convection anomalies are closely associated with a teleconnection pattern of upper-tropospheric circulation anomalies over the Eurasian continent, which is characterized by an anomalous cyclone over Europe, an anticyclone over Central Asia, and a zonally elongated cyclone over East Asia. This teleconnection pattern can also be detected by the first leading mode of upper-tropospheric circulation in July. The authors conclude, based on the present results and those of previous studies, that the teleconnection pattern induces WNP convection anomalies through Rossby wave breaking near the Asian jet exit region, and this impact is comparable to that of the preceding winter ENSO.</p><p>摘要</p><p>热带西北太平洋大气对流的年际变化对东亚夏季气候有着显著影响, 而且受到前冬ENSO的影响. 然而, 还有相当多的西北太平洋对流年际变化不能由前冬ENSO解释. 本文表明, 7月西北太平洋对流受到欧亚大陆对流层上层遥相关型的显著影响, 且这一影响与前冬ENSO的影响程度相当. 该遥相关型表现为位于欧洲的气旋式环流异常, 中亚的反气旋式环流异常和东亚带状延伸的气旋式环流异常, 并表现为7月对流层上层环流的第一主模态. 基于本文的结果并结合前人的研究, 作者认为这一遥相关型能通过亚洲急流出口区附近的罗斯贝波破碎引起西北太平洋对流异常.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 3","pages":"Article 100451"},"PeriodicalIF":2.3,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423001502/pdfft?md5=bc0ce1f6201faff46e8e7a75ff9cce35&pid=1-s2.0-S1674283423001502-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global trends of tropopause folds in recent decades","authors":"Yufeng Lin ,&nbsp;Wenshou Tian ,&nbsp;Haiyang Xue ,&nbsp;Jiali Luo ,&nbsp;Jiankai Zhang ,&nbsp;Hongying Tian ,&nbsp;Wenjun Liang","doi":"10.1016/j.aosl.2023.100450","DOIUrl":"10.1016/j.aosl.2023.100450","url":null,"abstract":"<div><p>Tropopause folds represent a primary mechanism for stratosphere-troposphere exchange. This study employs a 3D labeling method with ERA5 reanalysis data spanning from 1979 to 2020 to elucidate the spatiotemporal variations of tropopause folds. The results reveal distinct seasonal and regional variations in trends of tropopause folds. Notably, tropopause folds exhibit an increasing trend, with the magnitude varying seasonally. Significant increasing trends of tropopause folds are observed in northern spring, summer, and winter, primarily along subtropical jets. Further analysis reveals that the increase in tropopause folds is related to the strengthening of frontogenesis due to enhanced atmospheric baroclinicity, while the intensification of meridional potential temperature gradients enhances secondary circulations and may further promote an increase in folds activities.</p><p>摘要</p><p>对流层顶折卷是平流层-对流层物质交换的主要机制. 本研究采用三维标记方法, 利用1979-2020年间的ERA5再分析数据, 分析了对流层顶折卷的时空变化特征及机理. 研究结果表明, 全球对流层顶折卷的多年变化趋势存在明显的季节性和区域性差异. 总体上, 对流层顶折卷呈增加趋势, 其中北半球的春季,夏季和冬季, 对流层顶折卷主要沿副热带急流区呈现明显增加的趋势. 进一步分析表明, 对流层顶折卷发生频率的增加与大气斜压性增大导致的锋生增强有关, 而经向位温梯度的增大使得次级环流增强, 也可能促进了对流层顶折卷活动的增多.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 3","pages":"Article 100450"},"PeriodicalIF":2.3,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423001496/pdfft?md5=44158e527c2085ba24446671977b54cd&pid=1-s2.0-S1674283423001496-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138988887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the factors influencing cloud-core vertical accelerations during deep convection formation in the WRF model","authors":"Na Li ,&nbsp;Jin Wang ,&nbsp;Lingkun Ran ,&nbsp;Lei Yin ,&nbsp;Xiba Tang ,&nbsp;Yuchen Liu","doi":"10.1016/j.aosl.2023.100448","DOIUrl":"10.1016/j.aosl.2023.100448","url":null,"abstract":"<div><p>By introducing a linear diagnostic equation to compute perturbation pressure, the vertical momentum equation of the WRF model in the <em>η</em> coordinate is rederived, which constructs a direct relationship between vertical acceleration and physical factors we concern in the deep convection initiation (DCI) process. Important physical processes to the rapid growth of convective cloud are studied, aiming to fully understand the DCI process in the model. It is found that the DCI process is highly related to a cloud-core vertical acceleration. Due to this acceleration, the updraft is strengthened and the cloud is able to develop higher. Based on the diagnostic results of the vertical momentum equation, some different processes contributing to the high-level cloud-core accelerations in the model are found. A divergent pattern of the three-dimensional wind field is favorable for vertical acceleration. An inner physical process is that the horizontally convergent mass should be pumped up instantly by the vertical updraft to sustain a strong vertical acceleration. Second-order vertical inhomogeneity of perturbation geopotential also has an impact. Because of geopotential changes by vertical velocity (geopotential equation), this factor implies larger vertical motions will induce larger accelerations. The effects of the vertical gradient of perturbation potential temperature and moisture may be cancelled out since phase transitions can heat the convective air, but simultaneously decrease the water vapor content. Moisture makes a direct contribution to vertical acceleration, but is mostly cancelled out by the drag of cloud hydrometeors. Clearly understanding the direct impact of the basic prognostic variables on convection may help to identify the reason why DCI predictions within the model fail.</p><p>摘要</p><p>本文将扰动气压利用一个线性诊断关系代替, 重新推导了WRF模式框架地形追随坐标系下的垂直动量方程, 建立了垂直加速与对流触发 (DCI) 影响因子 (如温度, 水汽等) 的直接联系. 研究发现, DCI过程与对流核垂直加速相关, 三维副散, 扰动位势在垂直方向的二阶非均匀性, 扰动位温垂直梯度, 比湿及其垂直梯度, 水凝物拖曳, 均是能够直接影响垂直加速和对流触发的物理因子, 这些量与模式基本预报量相关, 通过解析基本预报量对对流发展的直接影响, 可能有助于理解模式对DCI过程预测失败的原因.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 3","pages":"Article 100448"},"PeriodicalIF":2.3,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283423001472/pdfft?md5=457d7c97d8e3f0c8a14d66b0dee2ce4d&pid=1-s2.0-S1674283423001472-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139019014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}