Atmospheric and Oceanic Science Letters最新文献

{"title":"Spatiotemporal characteristics of Universal Thermal Climate Index during five-year return period extreme heat events in the Beijing–Tianjin–Hebei region","authors":"Yiguo Xu ,&nbsp;Liqing Tian ,&nbsp;Tingru Cui ,&nbsp;Jun Zhang ,&nbsp;Hui Zhang ,&nbsp;Yating Wang ,&nbsp;Rui Wang","doi":"10.1016/j.aosl.2025.100612","DOIUrl":"10.1016/j.aosl.2025.100612","url":null,"abstract":"<div><div>Frequent extreme heat events exacerbated by global warming pose a significant threat to human health. However, the dynamic changes in human thermal comfort during such regional extremes remain understudied. This study investigates the spatiotemporal characteristics of the Universal Thermal Climate Index (UTCI) during 5-year return period extreme heat events across the Beijing–Tianjin–Hebei (BTH) region of China, utilizing 40 years of meteorological data from 174 stations. A non-stationary Generalized Extreme Value distribution model with a location parameter link function was identified as the optimal model (for 65.3 % of stations) through the Akaike Information Criterion, capturing 16 regional extreme heat events. Results indicate that extreme heat thresholds rise with increasing return periods, with the highest thresholds concentrated around Beijing and Shijiazhuang. Air temperature and mean radiant temperature were found to be the dominant factors influencing UTCI, with daytime air temperature contributing 47.03 % to 50.64 % and nighttime mean radiant temperature contributing up to 48.55 %. Spatially, “extreme heat stress” conditions, as defined by UTCI, were predominantly observed in the southeastern plains of Beijing and southern Hebei Province. Diurnally, UTCI peaked between 1200 and 1600 BT (Beijing time), generally returning to “no heat stress” levels across most areas between 0000 and 0600 BT. These findings provide crucial insights into the dynamics of human thermal comfort during extreme heat events in the BTH region, offering valuable scientific support for developing targeted heat mitigation and adaptation strategies.</div><div>摘要</div><div>本研究旨在探讨京津冀地区五年一遇极端高温事件期间通用热气候指数的时空特征, 弥补极端高温条件下人类热舒适度动态变化研究的不足. 基于40年174站点数据, 采用非平稳广义极值 (GEV) 分布模型, 通过赤池信息准则选取最优模型, 识别出16次极端高温事件. 结果表明, 极端高温阈值随重现期延长而升高, 北京, 石家庄周边最高. 气温和平均辐射温度是UTCI主导因素, 极端高温热应力主要分布于北京东南部平原及河北南部, UTCI在12至16时达峰值, 00至06时降至“无热应力”水平. 本研究为高温应对提供了科学支撑.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100612"},"PeriodicalIF":2.3,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in tropical cyclone response to the Boreal Summer Intraseasonal Oscillation in the western North Pacific under global warming in EC-Earth3P-HR","authors":"Zhefan Gao ,&nbsp;Chaoxia Yuan","doi":"10.1016/j.aosl.2024.100482","DOIUrl":"10.1016/j.aosl.2024.100482","url":null,"abstract":"<div><div>EC-Earth3P-HR reproduces well the observed Boreal Summer Intraseasonal Oscillation (BSISO) and its impacts on tropical cyclone genesis (TCG) in the western North Pacific (WNP). Hence, the historical simulation (1950–1979) and future projection under the SSP5-8.5 scenario (2020–2049) in EC-Earth3P-HR are adopted to explore possible changes in the BSISO's modification of WNP TCG under global warming to enhance the understanding of TC activities in the WNP. Results show that the BSISO circulation in the WNP shifts northeastward under global warming. This leads to enhanced convection in a northwest–southeast-oriented band crossing the WNP. Along the band, the BSISO-related TCG anomalies are enhanced. Analyses of genesis potential index show that changes in the BSISO-related mid-tropospheric relative humidity play the dominant role in modifying the BSISO's impacts on WNP TCG under global warming. The enhanced BSISO convection in the band moistens the middle troposphere, which helps reduce the entrainment of generally dry mid-tropospheric air in the updrafts and the modification of the boundary layer by the downdraft of generally dry mid-tropospheric air, leading to enhanced TCG.</div><div>摘要</div><div>北半球夏季季内振荡 (BSISO) 对西北太平洋 (WNP) 热带气旋形成 (TCG) 有显著的影响, 并且为TC的次季节预报提供重要依据, 因此研究其在全球变暖下的变化有重要意义. EC-Earth3P-HR模式较好地再现了观测到的BSISO及其对TCG的影响. 因此, 采用EC-Earth3P-HR的历史模拟 (1950–1979) 和SSP5-8.5情景 (2020–2049) 下的未来预估, 探讨全球变暖下BSISO对WNP上TCG调制的可能变化. 结果表明, 在全球变暖影响下, WNP上的BSISO环流向东北方向移动, 表现为西北-东南方向分布的增强对流带. 在对流带上, BSISO相关的TCG异常增强. 成因潜力指数分析表明, 全球变暖背景下, 与BSISO相关的对流层中部相对湿度的变化对BSISO对TCG的调制起主导作用. 带内增强的BSISO对流使对流层中部空气变湿润, 这有利于减少上升气流对通常干燥的对流层空气的夹带以及下沉气流对边界层的修正, 从而导致TCG的增强.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100482"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140464770","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":"Statistical seasonal forecasting of tropical cyclone landfalls on Taiwan Island","authors":"Ziqing Chen ,&nbsp;Kelvin T.F. Chan ,&nbsp;Zawai Luo","doi":"10.1016/j.aosl.2024.100554","DOIUrl":"10.1016/j.aosl.2024.100554","url":null,"abstract":"<div><div>Forecasting tropical cyclone (TC) activities has been a topic of great interest and research. Taiwan Island (TW) is one of the key regions that is highly exposed to TCs originated from the western North Pacific. Here, the authors utilize two mainstream reanalysis datasets for the period 1979–2013 and propose an effective statistical seasonal forecasting model—namely, the Sun Yat-sen University (SYSU) Model—for predicting the number of TC landfalls on TW based on the environmental factors in the preseason. The comprehensive predictor sampling and multiple linear regression show that the 850-hPa meridional wind over the west of the Antarctic Peninsula in January, the 300-hPa specific humidity over the open ocean southwest of Australia in January, the 300-hPa relative vorticity over the west of the Sea of Okhotsk in March, and the sea surface temperature in the South Indian Ocean in April, are the most significant predictors. The correlation coefficient between the modeled results and observations reaches 0.87. The model is validated by the leave-one-out and nine-fold cross-validation methods, and recent 9-yr observations (2014–2022). The Antarctic Oscillation, variabilities of the western Pacific subtropical high, Asian summer monsoon, and oceanic tunnel are the possible physical linkages or mechanisms behind the model result. The SYSU Model exhibits a 98% hit rate in 1979–2022 (43 out of 44), suggesting an operational potential in the seasonal forecasting of TC landfalls on TW.</div><div>摘要</div><div>本文利用1979–2013年的两个主流再分析数据集, 提出了一个中山大学 (SYSU) 热带气旋统计季节预报模型, 基于4个季前环境因子对登陆台湾岛的热带气旋数量进行预报. 模型通过了留一法, 九折交叉验证法和近9年观测数据 (2014–2022) 的验证, 模型结果与实际观测的相关系数达0.87. 南极涛动, 西太平洋副热带高压变化, 亚洲夏季风和海洋通道是模型潜在的物理联系或机制. SYSU模型在1979–2022年期间的预报准确率为98%, 表现出其业务应用价值.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100554"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643300","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":"Numerical simulation of size contraction of Typhoon Cempaka (2021)","authors":"Lingfeng Sun ,&nbsp;Qingqing Li","doi":"10.1016/j.aosl.2024.100533","DOIUrl":"10.1016/j.aosl.2024.100533","url":null,"abstract":"<div><div>In 2021, Cempaka, a tiny tropical cyclone, made landfall in China. As the TC intensified prior to landfall, the tropical cyclone size measured with precipitation decreased significantly. A numerical simulation was conducted to examine the possible processes modulating the storm size. Azimuthally mean potential vorticity (PV) was found to decrease mainly in the middle to upper troposphere between 50- and 80-km radii. The PV budget results indicate that the advection and generation of mean PV associated with asymmetric processes, rather than the symmetric processes, primarily contributed to the decrease in mean PV. These asymmetric processes leading to a negative PV tendency were likely associated with inactive outer rainbands. In contrast, the tangential winds simultaneously expanded radially outward, possibly related to inner-core diabatic heating. The findings here emphasize the importance of outer rainband activity in tropical cyclone size change.</div><div>摘要</div><div>2021年台风“查帕卡”增强过程中风场向外扩张, 但卫星云图显示降水范围减小. 高分辨率数值模拟结果显示, “查帕卡”降水范围减小对应着50–80km半径处对流层中层位涡的减小. 位涡诊断结果表明, 非对称过程是导致上述位涡减小的关键物理过程, 而非对称过程主要同外雨带活动减弱有关. 上述结果强调了外雨带活动对热带气旋尺度变化的潜在重要影响.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100533"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141393846","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":"Collaborative assimilation experiment of Beidou radiosonde and drone-dropped radiosonde based on CMA-TRAMS","authors":"Qiushi Wen ,&nbsp;Xuefen Zhang ,&nbsp;Sheng Hu ,&nbsp;Peitao Zhao ,&nbsp;Shuixin Zhong ,&nbsp;Zhenyu Liu ,&nbsp;Zhongkuo Zhao ,&nbsp;Jiahao Liang ,&nbsp;Guangfeng Dai ,&nbsp;Chenzhong Zhang ,&nbsp;Mengjie Li ,&nbsp;Ling Huang","doi":"10.1016/j.aosl.2024.100555","DOIUrl":"10.1016/j.aosl.2024.100555","url":null,"abstract":"<div><div>Based on the China Meteorological Administration's Tropical Regional Atmosphere Model for the South China Sea (CMA-TRAMS), the authors conducted a collaborative assimilation forecasting experiment utilizing both Beidou radiosonde and drone-dropped (HAIYAN-I) radiosonde data in September 2023. Three assimilation experimental groups were designed as follows: Beidou radiosonde assimilation, drone-dropped radiosonde assimilation, and collaborative assimilation of Beidou and drone-dropped radiosonde data (hereinafter referred to as “Beidou-drop”). Additionally, a control group of operational forecasts without these data assimilations was set up. The results indicate that the operational forecast path in the control group deviated northward from the actual path. Besides, the Beidou-drop group showed the most significant improvement in terms of forecasting the typhoon path at 60 to 90 h lead times. Specifically, the 72 h and 90 h path errors were reduced by 66.8 and 82.4 km, respectively, resulting in a much more accurate forecast of Typhoon Haikui's landing point, at the coastal junction of Fujian and Guangdong. Furthermore, the collaborative assimilation revealed a notable impact on improving the forecast of wind and rain associated with Haikui's landfall, aligning more closely with the real case. A marked rise was also seen in the precipitation score of the Beidou-drop group, where the 50 mm TS (threat score) of the 72 h lead time increased from 0.33 in the control experiment to 0.75, and the 100 mm TS rose from 0.18 to 0.39.</div><div>摘要</div><div>基于中国气象局南海台风模式CMA-TRAMS, 开展了北斗探空和无人机下投探空协同同化预报试验, 分别开展了北斗探空同化, 无人机下投探空同化, 北斗和下投探空 (beidou-drop) 协同同化试验. 结果表明, CMA-TRAMS业务预报路径较实况偏北, 协同同化了北斗和下投探空的路径预报改进效果最显著, 对60–90小时路径预报均有改进, 72小时和90小时路径误差分别较减小66.8 km和82.4 km, 且台风海葵的登陆区域更趋于向实况 (闽粤沿海交界处); 协同同化了北斗和下投探空对台风“海葵”登陆风雨影响更为显著, 与实况更加吻合, 降水评分提升明显, 72小时预报的50 mm TS评分由对照试验的0.33提高至0.75; 100 mm降水TS评分由对照试验的0.18提高至0.39.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100555"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643301","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":"Theory and prediction of tropical cyclones and induced precipitation","authors":"Lili Lei ,&nbsp;Jianfang Fei ,&nbsp;Wen Zhou","doi":"10.1016/j.aosl.2025.100608","DOIUrl":"10.1016/j.aosl.2025.100608","url":null,"abstract":"","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100608"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643422","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":"Westward shift of western North Pacific tropical cyclones in CMIP6-HighResMIP models","authors":"Zhuoying Li ,&nbsp;Wen Zhou","doi":"10.1016/j.aosl.2025.100594","DOIUrl":"10.1016/j.aosl.2025.100594","url":null,"abstract":"<div><div>Against the backdrop of climate change, the activity of tropical cyclones (TCs) has captured widespread attention. Observational datasets indicate a declining trend in the genesis longitude of western North Pacific (WNP) TCs. This study investigates the zonal changes of WNP TCs with CMIP6-HighResMIP models. These models capture the genesis density of WNP TCs fairly well. The results reveal a westward shift in TC genesis longitude. This trend is associated with the significant reduction in the TC frequency over the southeastern WNP. The study also discusses changes in large-scale circulation patterns and the impact of the strengthening Pacific Walker circulation.</div><div>摘要</div><div>在全球变暖背景下, 热带气旋的活动变化引起广泛关注. 观测数据表明, 西北太平洋热带气旋年平均生成经度呈减小趋势. 本研究利用CMIP6-HighResMIP模式对西北太平洋热带气旋活动的经度变化进行研究, 这些高分辨率模式较好地捕捉了西北太平洋热带气旋的生成密度. 研究显示西北太平洋地区热带气旋生成经度呈现西移的趋势, 这一趋势与西北太平洋地区东南部热带气旋频率的显著减少有关. 本研究还讨论了大尺度环流模式的变化以及太平洋沃克环流的加强所造成的影响.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100594"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643432","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":"Impacts of lateral boundary conditions from numerical models and data-driven networks on convective-scale ensemble forecasts","authors":"Junjie Deng ,&nbsp;Jin Zhang ,&nbsp;Haoyan Liu ,&nbsp;Hongqi Li ,&nbsp;Feng Chen ,&nbsp;Jing Chen","doi":"10.1016/j.aosl.2025.100589","DOIUrl":"10.1016/j.aosl.2025.100589","url":null,"abstract":"<div><div>The impacts of lateral boundary conditions (LBCs) provided by numerical models and data-driven networks on convective-scale ensemble forecasts are investigated in this study. Four experiments are conducted on the Hangzhou RDP (19th Hangzhou Asian Games Research Development Project on Convective-scale Ensemble Prediction and Application) testbed, with the LBCs respectively sourced from National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) forecasts with 33 vertical levels (Exp_GFS), Pangu forecasts with 13 vertical levels (Exp_Pangu), Fuxi forecasts with 13 vertical levels (Exp_Fuxi), and NCEP GFS forecasts with the vertical levels reduced to 13 (the same as those of Exp_Pangu and Exp_Fuxi) (Exp_GFSRDV). In general, Exp_Pangu performs comparably to Exp_GFS, while Exp_Fuxi shows slightly inferior performance compared to Exp_Pangu, possibly due to its less accurate large-scale predictions. Therefore, the ability of using data-driven networks to efficiently provide LBCs for convective-scale ensemble forecasts has been demonstrated. Moreover, Exp_GFSRDV has the worst convective-scale forecasts among the four experiments, which indicates the potential improvement of using data-driven networks for LBCs by increasing the vertical levels of the networks. However, the ensemble spread of the four experiments barely increases with lead time. Thus, each experiment has insufficient ensemble spread to present realistic forecast uncertainties, which will be investigated in a future study.</div><div>摘要</div><div>本文探讨了基于人工智能大模型的边界条件对对流尺度集合预报的影响. 四组实验的边界条件分别来自美国国家环境预报中心 (NCEP) 全球预报系统 (GFS) 的33层预报 (Exp_GFS) , 13层预报 (Exp_GFSRDV) , 盘古 (Pangu) 的预报 (Exp_Pangu) 和伏羲 (Fuxi) 的预报 (Exp_Fuxi) . 结果表明, Exp_Pangu的预报表现与Exp_GFS相当, 而Exp_Fuxi的预报表现略逊于Exp_Pangu, 这可能是因为盘古的预报在大尺度上比伏羲更准确, 因此人工智能大模型能有效地为对流尺度集合预报提供边界条件. 此外, 在四组实验中, Exp_GFSRDV的预报结果最差, 这表明通过增加神经网络的垂直层数, 有潜力进一步改进使用人工智能大模型提供边界条件的预报结果. 然而, 四组实验的集合离散度几乎不会随着预报时长的增加而变大, 因此其集合离散度不足以表征预报的不确定性, 这点将在后续进一步研究.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100589"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643362","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 initial conditions contributing to the rapid intensification of typhoons through ensemble sensitivity analysis","authors":"Yixuan Ren,&nbsp;Lili Lei,&nbsp;Jian-Feng Gu,&nbsp;Zhe-Min Tan,&nbsp;Yi Zhang","doi":"10.1016/j.aosl.2024.100552","DOIUrl":"10.1016/j.aosl.2024.100552","url":null,"abstract":"<div><div>While steady improvements have been achieved for the track forecasts of typhoons, there has been a lack of improvement for intensity forecasts. One challenge for intensity forecasts is to capture the rapid intensification (RI), whose nonlinear characteristics impose great difficulties for numerical models. The ensemble sensitivity analysis (ESA) method is used here to analyze the initial conditions that contribute to typhoon intensity forecasts, especially with RI. Six RI processes from five typhoons (Chaba, Haima, Meranti, Sarika, and Songda) in 2016, are applied with ESA, which also gives a composite initial condition that favors subsequent RI. Results from individual cases have generally similar patterns of ESA, but with different magnitudes, when various cumulus parameterization schemes are applied. To draw the initial conditions with statistical significance, sample-mean azimuthal components of ESA are obtained. Results of the composite sensitivity show that typhoons that experience RI in 24 h favor enhanced primary circulation from low to high levels, intensified secondary circulation with increased radial inflow at lower levels and increased radial outflow at upper levels, a prominent warm core at around 300 hPa, and increased humidity at low levels. As the forecast lead time increases, the patterns of ESA are retained, while the sensitivity magnitudes decay. Given the general and quantitative composite sensitivity along with associated uncertainties for different cumulus parameterization schemes, appropriate sampling of the composite sensitivity in numerical models could be beneficial to capturing the RI and improving the forecasting of typhoon intensity.</div><div>摘要</div><div>针对台风强度特别是快速增强 (RI) 的预报难点, 本文对2016年5个台风的6次RI过程应用集合敏感性分析 (ESA), 以分析有利于RI的初始条件. 对于不同的个例和积云参数化方案, ESA获得的有利于台风RI的集合敏感性相似但量级存在差异. 复合敏感性揭示了经历RI的台风所需的初始条件, 其有更强的主环流, 更显著的暖心及增加的低层湿度. ESA估计的集合敏感性随预报时长增加而减弱. 通过采样复合敏感性可有望改进集合初始条件及台风强度预报.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100552"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643423","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":"Characteristics of tropical cyclone outflow over the western North Pacific","authors":"Yidan Lin ,&nbsp;Kekuan Chu ,&nbsp;Zhe-Min Tan","doi":"10.1016/j.aosl.2024.100479","DOIUrl":"10.1016/j.aosl.2024.100479","url":null,"abstract":"<div><div>This study employs the self-organizing map method to investigate the upper-tropospheric outflow patterns of tropical cyclones (TCs) over the western North Pacific from 1979 to 2019, using the 200 hPa horizontal wind fields from the ERA5 reanalysis datasets. According to the number and orientation of TC outflow channels, as well as the wind speed, the outflow patterns are classified into five categories: southwestward single-channel pattern S1 (26.1%); northwestward single-channel pattern S2 (23.6%); northeastward single-channel pattern S3 (23.6%); double-channel outflow pattern D (20.8%); and high latitude outflow pattern H (6.0%). Composite analysis shows that the orientations of the TC outflow channels are aligned with the direction of the environmental vertical wind shear and closely related to the distribution of the environmental inertial instability, upper-level divergence, and inner-core convective activities. TC intensity and intensity changes for different outflow patterns are also significantly different. Patterns S1 and S2 usually appear in the development phase and are thus prone to TC intensification, while patterns S3 and H usually occur in the weakening phase and are thus prone to TC weakening. The double-channel pattern (D) has the largest mean intensity and accounts for more than 60% of super-typhoon samples.</div><div>摘要</div><div>本文基于欧洲中期天气预报中心第五代大气再分析数据集 (ERA5) 的200 hPa水平风场数据, 借助自组织映射网络方法对1979–2019年间西北太平洋热带气旋的流出层特征进行了客观分型研究. 根据流出通道的数量, 方向以及风速大小等特征, 西北太平洋热带气旋流出层主要可分为五种流出类型: 西南向单流出通道型 (26.1%); 西北向单出流通道型 (23.6%); 东北向单流出通道型 (23.6%), 双流出通道型 (20.8%) 以及高纬度流出通道型 (6.0%). 不同流出通道类型对应的热带气旋高层热力, 动力结构具有显著差异, 流出通道的方向与高层惯性稳定度, 散度场, 以及热带气旋内核区对流活动的分布等密切相关. 同时, 流出通道类型与热带气旋的强度及强度变化也具有密切联系. 西南和西北向单通道流出型主要发生在增强阶段, 具有东北向单流出通道和高纬流出通道的热带气旋则更倾向于衰减. 双流出通道型的热带气旋样本具有最大的平均强度, 且热带气旋强度越强, 双流出通道出现的频率越大, 占强热带气旋样本的60%以上.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100479"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139892492","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}