Atmospheric and Oceanic Science Letters最新文献

{"title":"Impact of ocean data assimilation on the seasonal forecast of the 2014/15 marine heatwave in the Northeast Pacific Ocean","authors":"Tiantian Tang,&nbsp;Jiaying He,&nbsp;Huihang Sun,&nbsp;Jingjia Luo","doi":"10.1016/j.aosl.2024.100498","DOIUrl":"10.1016/j.aosl.2024.100498","url":null,"abstract":"<div><div>A remarkable marine heatwave, known as the “Blob”, occurred in the Northeast Pacific Ocean from late 2013 to early 2016, which displayed strong warm anomalies extending from the surface to a depth of 300 m. This study employed two assimilation schemes based on the global Climate Forecast System of Nanjing University of Information Science (NUIST-CFS 1.0) to investigate the impact of ocean data assimilation on the seasonal prediction of this extreme marine heatwave. The sea surface temperature (SST) nudging scheme assimilates SST only, while the deterministic ensemble Kalman filter (EnKF) scheme assimilates observations from the surface to the deep ocean. The latter notably improves the forecasting skill for subsurface temperature anomalies, especially at the depth of 100–300 m (the lower layer), outperforming the SST nudging scheme. It excels in predicting both horizontal and vertical heat transport in the lower layer, contributing to improved forecasts of the lower-layer warming during the Blob. These improvements stem from the assimilation of subsurface observational data, which are important in predicting the upper-ocean conditions. The results suggest that assimilating ocean data with the EnKF scheme significantly enhances the accuracy in predicting subsurface temperature anomalies during the Blob and offers better understanding of its underlying mechanisms.</div><div>摘要</div><div>2013年底至2016年初, 东北太平洋上发生了历史上罕见的极端海洋热浪事件 (称为“Blob”事件) , 形成了从海表延伸至海洋深处300m的强烈且持续的海温暖异常. 本文利用南京信息工程大学全球气候预测系统1.0版本 (NUIST-CFS 1.0) , 采用两种海洋资料同化方案, 探究海洋资料同化差异对这一极端海洋热浪事件季节预测的影响. 本文采用的一种同化方案为仅同化海表面温度 (Surface sea temperature, SST) 的SST-nudging方案, 而另一种方案为在前一种方案的基础上加入确定性集合卡尔曼滤波 (Deterministic Ensemble Kalman Filter, DEnKF) , 同化更多海洋观测数据的EnKF方案. 主要结论为, 利用EnKF方案可显著提高对“Blob”期间次表层温度异常预测的准确性, 这主要源于EnKF方案在预测次表层的水平和垂直热传输方面表现出色. 该研究有助于更好地理解海洋热浪事件潜在物理机制及其季节预测水平.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 1","pages":"Article 100498"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140771707","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 the annual cycle of background SST in the tropical Pacific on the phase and amplitude of ENSO","authors":"Song Jiang ,&nbsp;Congwen Zhu ,&nbsp;Ning Jiang","doi":"10.1016/j.aosl.2024.100496","DOIUrl":"10.1016/j.aosl.2024.100496","url":null,"abstract":"<div><div>The dominant annual cycle of sea surface temperature (SST) in the tropical Pacific exhibits an antisymmetric mode, which explains 83.4% total variance, and serves as a background of El Niño–Southern Oscillation (ENSO). However, there is no consensus yet on its anomalous impacts on the phase and amplitude of ENSO. Based on data during 1982–2022, results show that anomalies of the antisymmetric mode can affect the evolution of ENSO on the interannual scale via Bjerknes feedback, in which the positive (negative) phase of the antisymmetric mode can strengthen El Niño (La Niña) in boreal winter via an earlier (delayed) seasonal cycle transition and larger (smaller) annual mean. The magnitude of the SST anomalies in the equatorial eastern Pacific can reach more than ±0.3℃, regulated by the changes in the antisymmetric mode based on random sensitivity analysis. Results reveal the spatial pattern of the annual cycle associated with the seasonal phase-locking of ENSO evolution and provide new insight into the impact of the annual cycle of background SST on ENSO, which possibly carries important implications for forecasting ENSO.</div><div>摘要</div><div>基于1982–2022年资料分析, 本文发现, 热带太平洋海温年循环的主导模态为反对称模式, 是ENSO发展的背景场. 然而, 其对ENSO相位和振幅的异常影响尚未可知. 反对称模态异常可以通过Bjerknes反馈影响ENSO的年际变化, 其正 (负) 异常可以通过更早 (更晚) 的季节循环转变时间和更大 (更小) 的年平均值增强冬季El Niño (La Niña) 的强度. 根据随机敏感性实验分析, 与反对称模态变化有关的赤道中东太平洋海温异常可达±0.3℃以上. 研究结果为背景海温年循环对ENSO的影响提供了新的见解, 这可能对ENSO的预测具有重要意义.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 1","pages":"Article 100496"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140781271","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":"Application of the improved dung beetle optimizer, muti-head attention and hybrid deep learning algorithms to groundwater depth prediction in the Ningxia area, China","authors":"Jiarui Cai ,&nbsp;Bo Sun ,&nbsp;Huijun Wang ,&nbsp;Yi Zheng ,&nbsp;Siyu Zhou ,&nbsp;Huixin Li ,&nbsp;Yanyan Huang ,&nbsp;Peishu Zong","doi":"10.1016/j.aosl.2024.100497","DOIUrl":"10.1016/j.aosl.2024.100497","url":null,"abstract":"<div><div>Due to the lack of accurate data and complex parameterization, the prediction of groundwater depth is a challenge for numerical models. Machine learning can effectively solve this issue and has been proven useful in the prediction of groundwater depth in many areas. In this study, two new models are applied to the prediction of groundwater depth in the Ningxia area, China. The two models combine the improved dung beetle optimizer (DBO) algorithm with two deep learning models: The Multi-head Attention–Convolution Neural Network–Long Short Term Memory networks (MH-CNN-LSTM) and the Multi-head Attention–Convolution Neural Network–Gated Recurrent Unit (MH-CNN-GRU). The models with DBO show better prediction performance, with larger <em>R</em> (correlation coefficient), RPD (residual prediction deviation), and lower RMSE (root-mean-square error). Compared with the models with the original DBO, the <em>R</em> and RPD of models with the improved DBO increase by over 1.5%, and the RMSE decreases by over 1.8%, indicating better prediction results. In addition, compared with the multiple linear regression model, a traditional statistical model, deep learning models have better prediction performance.</div><div>摘要</div><div>本研究将两个新模型应用于位于中国西北干旱半干旱区的宁夏地区地下水深度预测. 这两个模型将改进的蜣螂优化 (DBO) 算法与两个深度学习模型相结合, 即多头注意力-卷积神经网络-长短期记忆网络和多头注意力-回旋神经网络-门控递归单元. 带有DBO的模型预测结果表现出更大的相关系数 (R) , 残差预测偏差 (RPD) 和较低的均方根误差 (RMSE) , 预测结果更好. 此外, 与DBO模型相比, 改进后的DBO模型的R和RPD增加了1.5%以上, RMSE降低了1.8%以上, 表明预测结果更好. 与传统的统计模型多元线性回归模型相比, 深度学习模型具有更好的预测性能.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 1","pages":"Article 100497"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140794268","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":"Arctic sea-ice extent: No record minimum in 2023 or recent years","authors":"Ola M. Johannessen ,&nbsp;Tor I. Olaussen","doi":"10.1016/j.aosl.2024.100499","DOIUrl":"10.1016/j.aosl.2024.100499","url":null,"abstract":"<div><div>Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers (mill.km²). This was not a record low, which occurred in 2012, when the minimum was 4.175 mill.km², 0.794 mill.km² less than the minimum in 2023. However, the ice extent had decreased by 0.432 mill.km² compared with 2022. Nevertheless, the summer melting in 2023 was remarkably less than expected when considering the strong heat waves in the atmosphere and ocean, with record temperatures set around the world. In general, there is a high correlation between the long-term decrease in sea-ice extent and the increasing CO₂ in the atmosphere, where the increase of CO₂ in recent decades explains about 80% of the decrease in sea ice in September, while the remainder is caused by natural variability.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 1","pages":"Article 100499"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140790831","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":"Increase in the variability of terrestrial carbon uptake in response to enhanced future ENSO modulation","authors":"Younong Li ,&nbsp;Li Dan ,&nbsp;Jing Peng ,&nbsp;Qidong Yang ,&nbsp;Fuqiang Yang","doi":"10.1016/j.aosl.2024.100508","DOIUrl":"10.1016/j.aosl.2024.100508","url":null,"abstract":"<div><div>El Niño–Southern Oscillation (ENSO) is a major driver of climate change in middle and low latitudes and thus strongly influences the terrestrial carbon cycle through land–air interaction. Both the ENSO modulation and carbon flux variability are projected to increase in the future, but their connection still needs further investigation. To investigate the impact of future ENSO modulation on carbon flux variability, this study used 10 CMIP6 earth system models to analyze ENSO modulation and carbon flux variability in middle and low latitudes, and their relationship, under different scenarios simulated by CMIP6 models. The results show a high consistency in the simulations, with both ENSO modulation and carbon flux variability showing an increasing trend in the future. The higher the emissions scenario, especially SSP5-8.5 compared to SSP2-4.5, the greater the increase in variability. Carbon flux variability in the middle and low latitudes under SSP2-4.5 increases by 30.9% compared to historical levels during 1951–2000, while under SSP5-8.5 it increases by 58.2%. Further analysis suggests that ENSO influences mid- and low-latitude carbon flux variability primarily through temperature. This occurrence may potentially be attributed to the increased responsiveness of gross primary productivity towards regional temperature fluctuations, combined with the intensified influence of ENSO on land surface temperatures.</div><div>摘要</div><div>ENSO是中低纬度地区气候系统的主要驱动因素, 对陆地碳循环有重要影响. 本研究基于10个CMIP6地球系统模式, 分析了不同情景下ENSO变率与中低纬度地区总初级生产力变率的关系. 结果显示, 未来ENSO变率和总初级生产力变率在未来多数模式均显示为增加. 在未来情境下(2051-2100年), 中低纬度地区的总初级生产力变率较历史时期(1951–2000年)增加了30.9%(SSP2-4.5), 58.2%(SSP5-8.5). 进一步分析表明, ENSO主要通过温度影响中低纬度碳通量变率. 这种现象可能归因于总初级生产力对温度的响应增强, 以及ENSO对陆地表面温度的影响.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 1","pages":"Article 100508"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140776937","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":"Role of the Greenland Sea ice anomaly in the late-spring drought over Northwest China","authors":"Yang Liu ,&nbsp;Huopo Chen","doi":"10.1016/j.aosl.2024.100488","DOIUrl":"10.1016/j.aosl.2024.100488","url":null,"abstract":"<div><div>Drought across Northwest China in late spring has exerted a vital effect on the local climate and agricultural production, and has been alleviated during the past decades. This study explored the influence of the preceding Arctic sea ice on the May drought in Northwest China caused by the precipitation deficit. Further analysis indicated that when the Greenland Sea ice concentration is abnormally high during February to April, the dry conditions in Northwest China tend to be alleviated. The increase of sea ice in the Greenland Sea can excite a meridional circulation, which causes sea surface temperature (SST) anomalies in the North Atlantic via the sea–air interaction, manifested as significant warm SST anomalies over the south of Greenland and the subtropical North Atlantic, but negative SST anomalies over the west of the Azores. This abnormal SST pattern maintains to May and triggers a zonal wave train from the North Atlantic through Scandinavia and Central Asia to Northwest China, leading to abnormal cyclones in Northwest China. Consequently, Northwest China experiences a more humid climate than usual.</div><div>摘要</div><div>晚春西北地区干旱的发生对西北地区气候和农业生产等具有重要的影响, 但在近几十年, 西北干旱状况呈现出缓解的趋势. 本文研究了前期北极海冰异常对5月中国西北地区 (降水短缺引起的) 干旱异常的影响. 进一步研究表明, 二至四月格陵兰海海冰偏多时, 西北地区干旱有所缓解. 偏多的格陵兰海海冰可激发出经向环流异常, 环流异常通过海–气相互作用在北大西洋产生海温异常, 主要表现为格陵兰岛以南和北大西洋副热带海温偏高, 亚速尔群岛以西海温偏低. 这种海温异常可持续到5月, 并引发从北大西洋经斯堪的纳维亚半岛和中亚至中国西北地区的纬向波列, 并在西北地区产生气旋环流异常, 从而导致该地区水汽辐合, 干旱状况有所缓解.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 1","pages":"Article 100488"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137395","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":"Visible and shortwave-infrared spectral characteristics of mixed-phase clouds in typical satellite radiometer channels","authors":"Lijun Hu ,&nbsp;Bin Yao ,&nbsp;Shiwen Teng ,&nbsp;Byung-Ju Sohn ,&nbsp;Hongchun Jin ,&nbsp;Chao Liu","doi":"10.1016/j.aosl.2024.100588","DOIUrl":"10.1016/j.aosl.2024.100588","url":null,"abstract":"<div><div>Mixed-phase clouds (MPCs) involve complex microphysical and dynamical processes of cloud formation and dissipation, which are crucial for numerical weather prediction and cloud-climate feedback. However, satellite remote sensing of MPC properties is still challenging, and there is seldom MPC result inferred from passive spectral observations. This study examines the spectral characteristics of MPCs in the shortwave-infrared (SWIR) channels over the wavelength of 0.4–2.5 µm, and evaluates the potential of current operational satellite spectroradiometer channels for MPC retrievals. With optical properties of MPCs based on the assumption of uniform mixing of both ice and liquid water particles, the effects of MPC ice optical thickness fraction (IOTF) and effective radius on associated optical properties are analyzed. As expected, results indicate that the MPC optical properties show features for ice and liquid water clouds, and their spectral variations show noticeable differences from those for homogeneous cases. A radiative transfer method is employed to examine the sensitivity of SWIR channels to given MPC cloud water path (CWP) and IOTF. MPCs have unique signal characteristics in the SWIR spectrum. The 0.87-µm channel is most sensitive to CWP. Meanwhile, the 1.61- and 2.13-µm channels are more sensitive to water-dominated MPCs (IOTF approaching 0), and the 2.25-µm channel is sensitive to both water-dominated and ice-dominated MPCs (IOTF approaching 1). Such spectral differences are potentially possible to be used to infer MPC properties based on radiometer observations, which will be investigated in future studies.</div><div>摘要</div><div>混合相态云对数值天气预报和云-气候反馈研究都至关重要, 但是对其特性的卫星定量反演还存在巨大挑战。本论文利用辐射传输模拟, 研究混合相云在0.4–2.5 µm光谱范围内的光谱特征, 评估当前典型星载被动光谱辐射计观测反演混合相态云的潜力, 研究发现, 混合相态云的光学特性同时呈现出冰云和液态水云的特点, 而它们的光谱变化特征与冰云或液态水云存在一定差别。其中, 0.87-µm通道对CWP最敏感, 1.61- 和2.13-µm 通道对水云占主导的混合云更加敏感, 2.25-µm通道则对所有混合云都有一定的敏感性, 这些光谱差异可用于反演混合云的特性, 这也将是未来研究重点关注的内容.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 4","pages":"Article 100588"},"PeriodicalIF":2.3,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169741","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":"Evaluation of surface wind speed over East Asia and the adjacent ocean in three reanalyses using satellite and in-situ observations","authors":"Siyuan Li ,&nbsp;Kai Wang ,&nbsp;Hao Miao ,&nbsp;Xuedan Zhu ,&nbsp;Yanjie Liu ,&nbsp;Jinxiao Li ,&nbsp;Wei Wang ,&nbsp;Xiao Zheng ,&nbsp;Juan Feng ,&nbsp;Xiaocong Wang","doi":"10.1016/j.aosl.2024.100587","DOIUrl":"10.1016/j.aosl.2024.100587","url":null,"abstract":"<div><div>Surface wind speed (SWS) not only plays a crucial role in regulating the Earth's energy and hydrological cycle, but also is an important source of sustainable renewable energy. This study assesses the credibility of SWSs in three reanalyses (ERA5, MERRA2, and JRA-55) in East Asia using both satellite and in-situ observations. Results show all three reanalyses can capture the spatial pattern of SWS as in observations, yet there are notable differences in magnitude. On land, ERA5 and MERRA2 overestimate the SWS by about 0.6 and 1.5 m s⁻¹, respectively, whereas JRA-55 underestimates it. The biases over the oceans are opposite to those on land and are relatively small due to the assimilation of observations of oceanic surface winds. Overall, JRA-55 and ERA5 offer better estimates of seasonal means and variances of SWS than MERRA2. The observed SWS shows a negative trend of −0.08 m s⁻¹/10 yr on land and a positive trend of 0.09 m s⁻¹/10 yr in the western North Pacific. Only JRA-55 shows similar trends to observations over both land and ocean, while ERA5 and MERRA2 show varying degrees of deviation from the observations. Further investigation shows that there is a strong link between the trend of SWS and that of the large-scale circulation, and that a large part of the SWS trend can be attributed to changes in large-scale circulations.</div><div>摘要</div><div>利用卫星和地面站点观测数据, 本文对再分析产品中的地表风速 (SWS) 进行了可信度评估. 研究结果表明, 再分析产品能够较好地再现SWS的观测分布特征, 但在风速的量级上则存在显著差异. 具体而言, 在陆地区域, ERA5和MERRA2分别高估了约0.6 m s⁻¹和1.5 m s⁻¹, 而JRA-55则存在低估现象; 而在海洋区域, 偏差情况与陆地相反. 总体来看, JRA-55和ERA5在模拟SWS的气候态及其变率方面, 更加接近观测数据. 其中, JRA-55中SWS的年代际趋势与观测数据最为一致.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 5","pages":"Article 100587"},"PeriodicalIF":2.3,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696475","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":"Impacts of meteorological conditions on the NASM pollution data assimilation system","authors":"Shan Zhang ,&nbsp;Liqun Li ,&nbsp;Linfeng Shang ,&nbsp;Dongji Wang ,&nbsp;Guangtao Niu ,&nbsp;Xuejun Guo ,&nbsp;Xiangjun Tian","doi":"10.1016/j.aosl.2024.100586","DOIUrl":"10.1016/j.aosl.2024.100586","url":null,"abstract":"<div><div>Since meteorological conditions are the main factor driving the transport and dispersion of air pollutants, an accurate simulation of the meteorological field will directly affect the accuracy of the atmospheric chemical transport model in simulating PM_2.5. Based on the NASM joint chemical data assimilation system, the authors quantified the impacts of different meteorological fields on the pollutant simulations as well as revealed the role of meteorological conditions in the accumulation, maintenance, and dissipation of heavy haze pollution. During the two heavy pollution processes from 10 to 24 November 2018, the meteorological fields were obtained using NCEP FNL and ERA5 reanalysis data, each used to drive the WRF model, to analyze the differences in the simulated PM_2.5 concentration. The results show that the meteorological field has a strong influence on the concentration levels and spatial distribution of the pollution simulations. The ERA5 group had relatively small simulation errors, and more accurate PM_2.5 simulation results could be obtained. The RMSE was 11.86 μg m⁻³ lower than that of the FNL group before assimilation, and 5.77 μg m⁻³ lower after joint assimilation. The authors used the PM_2.5 simulation results obtained by ERA5 data to discuss the role of the wind field and circulation situation on the pollution process, to analyze the correlation between wind speed, temperature, relative humidity, and boundary layer height and pollutant concentrations, and to further clarify the key formation mechanism of this pollution process.</div><div>摘要</div><div>气象条件对于污染物的累积, 清除, 传输和扩散有关键的作用. 本文将分别使用FNL 和ERA5再分析资料作为天气模式WRF的初始场, 基于构建的联合数据同化系统, 定量评估气象场对模拟PM_2.5浓度的作用, 同时揭示不同气象要素对于污染物积累, 维持和消散的影响. 研究表明ERA5资料在各个区域的污染模拟结果更接近观测值, 分析了风速, 温度, 相对湿度以及边界层高度与污染物浓度之间的相关性, 并进一步阐明污染过程的形成机制.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 4","pages":"Article 100586"},"PeriodicalIF":2.3,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169740","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":"Characteristics and possible causes of the Meiyu over the Yangtze–Huaihe River Basin in 2023","authors":"Yao Ha ,&nbsp;Haixia Dai ,&nbsp;Shuai Song ,&nbsp;Yaming Zhao ,&nbsp;Wei Lu","doi":"10.1016/j.aosl.2024.100585","DOIUrl":"10.1016/j.aosl.2024.100585","url":null,"abstract":"<div><div>The Meiyu in the Yangtze–Huaihe River basin (YHRB) in 2023 was featured by delayed onset and retreat, a shorter duration, and below-normal Meiyu precipitation. The relatively weak cold air invading southward from the mid-to-high latitudes in late May–early June contributed to the delayed onset of Meiyu season, and the persistent rainfall caused by Typhoon “Talim” and Super Typhoon “Doksuri” led to the delayed retreat. The westward-shifted and intensified western Pacific subtropical high (WPSH), coupled with the eastward-shifted and strengthened south Asian high (SAH), as well as the Eurasian mid-to-high latitude circulation featuring “two troughs–one ridge”, resulting in the below-average Meiyu precipitation with the heaviest rainfall primally in eastern YHRB. Further analysis indicates that the 2023 Meiyu was influenced by the combined effects of the decaying La Niña, warm sea surface temperature (SST) anomalies in the North Pacific west wind drift area, and less than normal snow cover over the Tibetan Plateau. Warmer than normal SST in the western Pacific warm pool and the North Pacific westerly drift region favored the narrow meridional circulation at middle latitudes and WPSH, whereas the strengthened SAH and East Asian summer monsoon were impacted by persistently reduced snow cover over the northeastern Tibetan Plateau.</div><div>摘要</div><div>2023年中国江淮流域入梅和出梅日期均偏晚, 梅雨量整体偏少. 本文研究发现, 5月末6月初中高纬冷空气偏弱是入梅偏晚的原因, 台风“泰利”和强台风“杜苏芮”引起的持续性降水导致了出梅偏晚. 中低纬地区偏西偏强的西太平洋副热带高压和偏东偏强的南亚高压叠置, 配合欧亚中高纬 “两槽一脊”环流型, 使得江淮流域梅雨量偏少, 且降水集中在江淮流域东部. 进一步分析表明, 2023年梅雨期中国受La Niña 衰减位相的影响, 西太平洋暖池和北太平洋西风漂流区的暖海温异常导致中纬度环流经向性偏弱, 西太平洋副热带高压偏西, 偏强. 而南亚高压和东亚夏季风异常主要受到青藏高原东北部积雪持续异常偏少的影响.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 5","pages":"Article 100585"},"PeriodicalIF":2.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696474","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}