Atmospheric and Oceanic Science Letters最新文献

{"title":"A maximum sea surface salinity tongue in the North Brazil continental shelf","authors":"Maria Cadima ,&nbsp;Paola Castellanos ,&nbsp;Estrella Olmedo ,&nbsp;Joaquim Dias ,&nbsp;Edmo J.D. Campos","doi":"10.1016/j.aosl.2024.100521","DOIUrl":"10.1016/j.aosl.2024.100521","url":null,"abstract":"<div><div>The variability of the sea surface salinity measurements provided by the Soil Moisture and Ocean Salinity mission reveals the presence of a local salinity maximum (a salty tongue) in the northwestern tropical Atlantic. The sea surface salinity positive anomaly starts increasing in July, reaches its maximum in January, and then disappears. The local maximum of salinity appears in the late boreal autumn/winter, when the Amazon discharge is minimal and the salty water from the South Atlantic is transported by the North Brazil Current along the shelf break across the equator. The authors validate the satellite observations in this area and assess the vertical structure of the salinity maximum by using <em>in situ</em> measurements and an <em>in situ</em>-interpolated product.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100521"},"PeriodicalIF":2.3,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868402","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":"Improving subseasonal forecasting of East Asian monsoon precipitation with deep learning","authors":"Jiahui Zhou ,&nbsp;Fei Liu","doi":"10.1016/j.aosl.2024.100520","DOIUrl":"10.1016/j.aosl.2024.100520","url":null,"abstract":"<div><div>Accurate subseasonal forecasting of East Asian summer monsoon (EASM) precipitation is crucial, as it directly impacts the livelihoods of billions. However, the prediction skill of state-of-the-art subseasonal-to-seasonal (S2S) models for precipitation remains limited. In this study, the authors developed a convolutional neural network (CNN) regression model to enhance the prediction skill for weekly EASM precipitation by utilizing the more reliably predicted circulation fields from dynamic models. The outcomes of the CNN model are promising, as it led to a 14 % increase in the anomaly correlation coefficient (ACC), from 0.30 to 0.35, and a 22 % reduction in the root-mean-square error (RMSE), from 3.22 to 2.52, for predicting the weekly EASM precipitation index at a leading time of one week. Among the S2S models, the improvement in prediction skill through CNN correction depends on the model's performance in accurately predicting circulation fields. The CNN correction of EASM precipitation index can only rectify the systematic errors of the model and is independent of whether the each grid point or the entire area-averaged index is corrected. Furthermore, u200 (200-hPa zonal wind) is identified as the most important variable for efficient correction.</div><div>摘要</div><div>东亚夏季风(EASM)降水的准确次季节预报至关重要, 因为它直接影响着数十亿人的生计. 然而, 最先进的次季节-季节(S2S)预测模型的预测技巧仍然有限. 本研究开发了一种卷积神经网络(CNN)回归模型, 通过利用动力预测模型预测的更可靠的环流场来提高EASM周降水的预测技巧. 经过CNN模型的订正, 在提前一周预测EASM降水指数时, 11个S2S模式的平均距平相关系数从增加了14 %, 从0.30增加到0.35; 均方根误差减少了22 %, 从3.22减少到2.52. 在这些S2S模式中, 通过CNN订正对预测技巧的提高程度取决于模式在准确预测大气环流变量方面的表现. 对EASM降水指数的CNN订正只能订正模式的系统误差, 与逐个网格订正还是整个区域平均指数订正无关, 并且在不同的提前期内CNN的订正效果基本不变. 此外, 200hPa纬向风被认为是有效订正的最重要变量.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100520"},"PeriodicalIF":2.3,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868401","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":"Upper-ocean cooling rate of the South China Sea in response to extreme cold surges and weak cold-air invasions","authors":"Weiwei Zhang ,&nbsp;Dongxiao Wang ,&nbsp;Marco Y.-T. Leung ,&nbsp;Lin Wang ,&nbsp;Jinchi Xie ,&nbsp;Wen Zhou","doi":"10.1016/j.aosl.2024.100517","DOIUrl":"10.1016/j.aosl.2024.100517","url":null,"abstract":"<div><div>Cold-surge events can lead to temperature drops and strong winds, which then leads to upper-ocean cooling and deepening of the mixed-layer depth, as illustrated in previous studies. In this study, based on the temperature drop of Shanwei meteorological station, two extreme cold surges and five weak cold invasions in the South China Sea are simulated using an ocean–atmosphere coupled model to investigate their different impacts on the upper-ocean temperature. The diffusion term contributes to the difference in temperature tendency of the upper 20 m, while the advection term contributes to the positive difference from 20 to 80 m of the offshore region and negative difference from 80 to 160 m. In addition, the significant differences are attributed primarily to the influence of the upper-ocean temperature gradient, which subsequently impacts the advection term and results in notable differences in temperature tendency at depths from 80 to 160 m.</div><div>摘要</div><div>前人的研究揭示了寒潮事件导致近地气温下降和强风, 也导致上层海洋冷却和混合层深度加深. 本研究根据汕尾气象站的气温变化, 并利用海气耦合模型模拟了南海的两次极端寒流和五次弱冷空气入侵, 研究它们对上层海洋温度变化的不同影响. 研究结果说明了扩散项对上层20米的温度变化差异的贡献, 平流项是导致20至80米的正温度变化差异的主要原因, 平流项也导致80至160米的负温度变化差异. 此外, 这种显著差异主要归因于上层海洋温度梯度的影响, 进而影响平流项, 使80至160米深度的温度变化存在显著差异.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100517"},"PeriodicalIF":2.3,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134621","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":"Effects of ocean wave spectra on the polarized bidirectional reflectance distribution function matrix at Ku‐band and its implications on satellite backscattering simulations","authors":"Lingli He ,&nbsp;Fuzhong Weng","doi":"10.1016/j.aosl.2024.100518","DOIUrl":"10.1016/j.aosl.2024.100518","url":null,"abstract":"<div><div>A polarized bidirectional reflectance distribution function (pBRDF) matrix is developed from two-scale roughness theory with the aim of providing more accurate simulations of microwave emissions and scattering required for ocean–atmosphere coupled radiative transfer models. The potential of the pBRDF matrix is explored for simulating the ocean backscatter at Ku-band. The effects of ocean wave spectra including the modified Durden and Vesecky (DV2), Elfouhaily, and Kudryavtsev spectra on the pBRDF matrix backscatter simulations are investigated. Additionally, the differences in backscattering normalized radar cross-section (NRCS) simulations between the Ku-band geophysical model function and pBRDF matrix are analyzed. The results show that the pBRDF matrix can reasonably reproduce the spatial distribution of ocean surface backscattering energy, but the distribution pattern and numerical values are influenced by ocean wave spectra. The DV2 spectrum is the best one for the pBRDF matrix to simulate horizontally polarized NRCSs, with the exception of scenarios where the incidence angle is below 35°, the wind speed is less than 10 m s⁻¹, and in the cross-wind direction. Also, the DV2 spectrum effectively characterizes the wind speed and relative azimuth angle dependence for vertically polarized NRCSs. The Elfouhaily spectrum is suitable for simulating vertically polarized NRCSs under conditions of low wind speed (below 5 m s⁻¹) and incidence angles under 40°. The Kudryavtsev spectrum excels in simulating vertically polarized NRCSs at high incidence angles (&gt; 40°) and horizontally polarized NRCSs at low incidence angles (&lt; 35°).</div><div>摘要</div><div>为提供微波海洋-大气耦合辐射传输模型所需的精确发射和散射, 基于双尺度粗糙度理论发展了极化双向反射分布函数 (pBRDF) 矩阵. 本研究探讨了pBRDF矩阵是否能够表征ku波段洋面后向散射, 对比了三种常用海浪谱模型对pBRDF矩阵后向散射模拟的影响, 分析了ku波段地球物理模型函数 (GMF) 与pBRDF矩阵在后向散射归一化雷达截面 (NRCS) 模拟中的差异. 结果表明, pBRDF矩阵能够准确再现洋面后向散射能量的空间分布, 但后向散射能量分布受海浪谱影响较大.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100518"},"PeriodicalIF":2.3,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141145335","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":"Long-term variations of the solar energy in different subregions of Northwest China and associated mechanisms","authors":"Junhui Yu ,&nbsp;Hui Ma ,&nbsp;Shen-Ming Fu ,&nbsp;Xiaoling Su ,&nbsp;Xiqiang Chang ,&nbsp;Yanan Fu","doi":"10.1016/j.aosl.2024.100515","DOIUrl":"10.1016/j.aosl.2024.100515","url":null,"abstract":"<div><div>As a type of clean and pollution-free energy source, solar energy plays an important role in achieving the goals of carbon neutrality and global sustainable development. Northwest China occupies an important position in the national energy strategy due to its rich solar energy. Clarifying the long-term variations of Northwest China's solar energy and understanding the associated mechanisms are crucial to improving the layout of new energy sources and the usage efficiency of solar energy within China. In this study, the authors first divide Northwest China into northwestern and southeastern sections by conducting a rotated empirical orthogonal function analysis on the surface solar radiation (SSR) from 1993 to 2022, and then explore the SSR's variation trends and associated mechanisms within these subregions. It is found that the two subregions, both of which show a significant feature of decadal change, differ notably in their long-term trends: the northwestern section shows a significant increasing trend of ∼8.1 kJ m⁻² yr⁻¹ in the annual mean SSR, and in each season the SSR increases significantly, with a maximum/minimum increasing rate of ∼11.2/∼4.6 kJ m⁻² yr⁻¹ appearing in summer/autumn. A possible mechanism for the SSR's increasing trend is that global warming results in a lower relative humidity within the northwestern section, which decreases the total cloud cover, as it is harder for the atmosphere to reach saturation state. A decreasing total cloud cover results in an increasing SSR within the northwestern section. In contrast, the southeastern section shows no significant trend in annual mean SSR, as the SSRs in summer and autumn show significant decreasing trends, whereas the trends in spring and winter are not significant.</div><div>摘要</div><div>作为一种清洁无污染的新能源, 太阳能对于实现碳中和及可持续发展的目标至关重要. 西北地区太阳能资源丰富, 在我国能源战略中占据着重要地位. 厘清西北地区太阳能的长期变化趋势并揭示其可能的内在机理有助于改善我国的新能源布局并提高太阳能的利用效率. 鉴于此, 作者首先对1993年至2022年的地表太阳辐射 (SSR) 进行了旋转经验正交函数分析, 将西北地区划分为西北和东南两个分区, 然后分别研究了这些分区内SSR的变化趋势和相关机制. 研究发现, 在西北地区的两个分区内, SSR均表现出显著的年代际变化特征, 但两个分区内的SSR趋势存在显著不同. 对于西北分区而言, 其年平均SSR呈现出显著的增长趋势 (增速约为8.1 kJ m⁻² yr⁻¹), 在每个季节, 其季节平均的SSR都显著增加, 最大与最小增速分别为11.2 (夏季) 和4.6 kJ m⁻² yr⁻¹ (秋季). 该区域内SSR增加趋势的一个可能机制是, 全球变暖导致该区域内相对湿度较低, 所以大气更难达到饱和状态, 这直接导致该区域内的总云量减少; 总云量的减少使得云对太阳短波辐射的反射, 散射和吸收减弱, 因此, 该区域内SSR增加. 对于东南分区而言, 由于其夏季和秋季的SSR呈显著的下降趋势, 而春季和冬季的SSR趋势并不显著, 所以该区域内年平均的SSR没有显著的线性趋势.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100515"},"PeriodicalIF":2.3,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141034397","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":"Construction and characteristic analysis of background error covariance coupled with land surface temperature","authors":"Qihang Yang ,&nbsp;Yaodeng Chen ,&nbsp;Luyao Qin ,&nbsp;Yuanbing Wang ,&nbsp;Deming Meng ,&nbsp;Xusheng Yan ,&nbsp;Xinyao Qian","doi":"10.1016/j.aosl.2024.100512","DOIUrl":"10.1016/j.aosl.2024.100512","url":null,"abstract":"<div><div>Land surface temperature (LST) is the key variable in land–atmosphere interaction, having an important impact on weather and climate forecasting. However, achieving consistent analysis of LST and the atmosphere in assimilation is quite challenging. This is because there is limited knowledge about the cross-component background error covariance (BEC) between LST and atmospheric state variables. This study aims to clarify whether there is a relationship between the error of LST and atmospheric variables, and whether this relationship varies spatially and temporally. To this end, the BEC coupled with atmospheric variables and LST was constructed (LST-BEC), and its characteristics were analyzed based on the 2023 mei-yu season. The general characteristics of LST-BEC show that the LST is mainly correlated with the atmospheric temperature and the correlation decreases gradually with a rise in atmospheric height, and the error standard deviation of the LST is noticeably larger than that of the low-level atmospheric temperature. The spatiotemporal characteristics of LST-BEC on the heavy-rain day and light-rain day show that the error correlation and error standard deviation of LST and low-level atmospheric temperature and humidity are closely related to the weather background, and also have obvious diurnal variations. These results provide valuable information for strongly coupled land–atmosphere assimilation.</div><div>摘要</div><div>地表温度 (LST) 是涉及陆气相互作用的关键变量, 对天气气候预报具有重要影响. 不过在同化中实现LST与大气的协调分析却并不容易. 这是因为目前对跨陆气圈层的背景误差协方差 (BEC) 的了解较少. 本文旨在探究LST与大气的背景误差是否存在联系, 以及这种联系是否存在时空变化. 为此, 本研究构建了耦合大气变量和LST的BEC, 并基于2023年梅雨季分析了其特征. 总体特征表明: LST误差主要与大气温度相关; 随着大气高度的上升, 误差相关性逐渐减小; LST误差的标准差明显大于低层大气温度. “多雨日”和“少雨日”的时空特征表明, LST与低层大气温湿度误差的相关性及标准差均与天气背景密切相关, 且具有明显的昼夜变化. 上述结果可为后续陆气强耦合同化提供参考.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100512"},"PeriodicalIF":2.3,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868400","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":"Physical characteristics of convective and non-convective cirrus clouds from CALIPSO data over the South China Sea","authors":"Haorui Weng ,&nbsp;Yong Han ,&nbsp;Ximing Deng ,&nbsp;Li Dong ,&nbsp;Yan Liu","doi":"10.1016/j.aosl.2024.100510","DOIUrl":"10.1016/j.aosl.2024.100510","url":null,"abstract":"<div><div>Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics, and enhancing predictive models for weather and climate forecasts. This study utilizes eight years of CALIPSO data (from March 2007 to February 2015) to investigate convective and non-convective cirrus clouds. Explicit new insights include the observation that convective cirrus cloud samples are three times more numerous than non-convective cirrus clouds. Convective cirrus clouds are associated with humid conditions and demonstrate higher ice water content (IWC) values ranging from 10⁻³ to 10⁻¹ g m⁻³, whereas non-convective cirrus clouds tend to be drier, exhibiting IWC values ranging from 10⁻⁴ to 10⁻³ g m⁻³. Both cirrus cloud types exhibit a maximum cloud fraction at 10°N. Convective cirrus reach their peak cloud fraction at an altitude of 14 km, while non-convective cirrus typically occur at altitudes between 15 and 16 km. The seasonal variability of the convective cirrus cloud fraction primarily reflects bottom-up positive specific humidity anomalies originating from convective activity, whereas the non-convective cirrus cloud fraction is influenced by top-down negative temperature anomalies.</div><div>摘要</div><div>南海是陆地, 海洋和大气相互作用强烈的区域, 在此背景下, 深对流活动对于卷云的形成和维持至关重要. 然而, 关于该区域对流性和非对流性卷云物理特征的研究十分有限. 本文基于2007–2015年的CALIPSO数据对南海地区的对流性和非对流性卷云进行了研究. 结果表明, 对流性卷云的样本数是非对流性卷云的三倍; 对流性卷云表现出较高的冰水含量 (IWC) 并伴随着潮湿的环境条件, 而非对流性卷云的冰水含量较低; 此外, 进一步的分析揭示了对流性卷云和非对流性卷云的云量呈现出不同的垂直分布, 对流性卷云的最大云量出现在14 km, 而非对流性卷云则出现在15–16 km; 最后, 阐明了驱动两种类型卷云云量的季节性变化机制, 对流性卷云云量的季节性变化主要受自下而上的正比湿异常影响, 而非对流性卷云则受自上而下的负温度异常驱动.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100510"},"PeriodicalIF":2.3,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140765886","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":"Response of warm season secondary pollutants to emissions and meteorology in the North China Plain region during 2018–2022","authors":"Yueqi Gao ,&nbsp;Siyu Wang ,&nbsp;Zhaolei Zhang ,&nbsp;Wenxuan Yu ,&nbsp;Shuai Wang ,&nbsp;Shengqiang Zhu ,&nbsp;Peng Wang ,&nbsp;Yan Li ,&nbsp;Yele Sun ,&nbsp;Hongliang Zhang","doi":"10.1016/j.aosl.2024.100495","DOIUrl":"https://doi.org/10.1016/j.aosl.2024.100495","url":null,"abstract":"<div><p>Air quality in China has continued to improve since 2013, although severe pollution events still occur over the North China Plain (NCP). It is noticeable that contributions from secondary pollutants have increased, but understanding of their formation and variations with changing emissions and meteorological conditions remains limited. In this study, the warm season of May to September from 2018 to 2022 was selected to explore the response of secondary pollutants to meteorology and emissions using the Community Multi-scale Air Quality model (CMAQ). Fine particulate matter (PM_2.5) concentrations over the NCP decreased significantly by 31%–37% from 2018 to 2022, while ozone (O₃) and nitrogen dioxide (NO₂) generally showed decreasing trends by 1% and 0.5% per year, respectively. Secondary inorganic aerosol (including sulfate, nitrate, and ammonium) and secondary organic aerosol (SOA) also decreased significantly, by 9% and 6% per year, respectively. The results showed that emissions contributed 96% to the decreases in PM_2.5 concentrations, while O₃ fluctuated due to meteorological changes. Although the decreases in sulfate and ammonium were mainly associated with emission reductions, that of nitrate was more sensitive to meteorological changes. Meteorological and emission changes were similarly important for the overall decrease in SOA, with anthropogenic SOA being more sensitive to emissions control, while biogenic SOA was more easily attributed to meteorological changes. This research emphasizes the importance of controlling anthropogenic emissions in relieving summer secondary pollution in the NCP region.</p><p>摘要</p><p>自2013年起, 中国空气质量虽改善, 但华北平原(NCP)重污染仍存在且二次污染加剧, 而人们对其成因和变化了解有限. 本研究利用2018–2022年数据, 借助CMAQ模型探讨此污染响应. 结果显示, 在2018–2022年间, PM_2.5浓度显著下降31%–37%, O₃和NO₂的年下降速率分别为1%和0.5%. SIA和SOA也显著减少, 每年分别减少9%和6%. PM_2.5主要因排放减少而下降, 而O₃则受气象影响而波动. 硫酸盐和铵下降的主因是减排, 而硝酸盐对气象变化敏感. 排放和气象变化对SOA的总体减少同样重要, 但人为SOA对排放控制敏感, 生物SOA易受气象变化影响. 研究强调了控制人为排放对缓解NCP地区夏季二次污染的重要性.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 4","pages":"Article 100495"},"PeriodicalIF":2.3,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283424000448/pdfft?md5=2d0d1882ae07f4c2f637d44fcd09f8e5&pid=1-s2.0-S1674283424000448-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141329177","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":"Comparative study on the performance of ConvLSTM and ConvGRU in classification problems—taking early warning of short-duration heavy rainfall as an example","authors":"Meng Zhou ,&nbsp;Jingya Wu ,&nbsp;Mingxuan Chen ,&nbsp;Lei Han","doi":"10.1016/j.aosl.2024.100494","DOIUrl":"https://doi.org/10.1016/j.aosl.2024.100494","url":null,"abstract":"<div><p>Convolutional long short-term memory (ConvLSTM) and convolutional gated recurrent unit (ConvGRU) are two widely adopted deep learning models that combine recurrent mechanisms with convolutional operations for spatiotemporal sequences forecasting. To clarify the convergence speed and classification ability of the above two models, using the same model architecture to predict the same classification problem is necessary. This research treats the district-level warning of short-duration heavy rainfall in Beijing as a binary classification problem in deep learning, and composite radar reflectivity data of the Beijing–Tianjin–Hebei radar network and rainfall data from automatic weather stations in Beijing are used for training and performance evaluation. The results show that the convergence speed of ConvGRU is approximately 25% faster than that of ConvLSTM. The early-warning performances of ConvLSTM and ConvGRU have similar trends with region, time, and rain intensity, but most of the scores of ConvLSTM are higher, and in a few cases, ConvGRU has higher scores.</p><p>摘要</p><p>卷积长短期记忆单元ConvLSTM和卷积门控循环单元ConvGRU是两种广泛应用的深度学习单元, 通过将循环机制与卷积运算相结合, 常常用于时空序列的预测. 为了明确上述两种模型的收敛速度和分类能力, 需要使用相同的模型架构对相同的分类问题进行预测. 本研究将北京短时强降水区级预警问题看作深度学习中的二分类问题, 使用京津冀雷达网的组合反射率数据和北京区域内的自动气象站降雨数据进行深度学习模型的训练和评估. 结果表明, ConvGRU的收敛速度比 ConvLSTM快约25%. ConvLSTM和ConvGRU的预警性能随地区, 时间, 降雨强度的变化趋势相似, 但大部分ConvLSTM的得分较高, 少数情况下ConvGRU的得分较高.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 4","pages":"Article 100494"},"PeriodicalIF":2.3,"publicationDate":"2024-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283424000436/pdfft?md5=d082409c9531e54b588a9ddaef04a312&pid=1-s2.0-S1674283424000436-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141329176","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":"Predominant types of regional cold waves in North China and their historical changes","authors":"Xinyi Cheng ,&nbsp;Yiyi Zhang ,&nbsp;Jiandong Li ,&nbsp;Xin Hao","doi":"10.1016/j.aosl.2024.100487","DOIUrl":"10.1016/j.aosl.2024.100487","url":null,"abstract":"<div><p>Cold wave (CW) events in East Asia have a significant impact on the social economy, ecosystems, and human health. Based on daily CW records from October to March during 1980–2019 and <em>K</em>-means clustering, this study identified two types of regional CW (T1 and T2) in China. T1 regional CWs mainly struck Northeast China, whereas T2 regional CWs primarily affected the northern and eastern regions of China. Compared to T1, T2 regional CWs were more intense, lasted longer, and had a broader region of influence. During 1980–2019, there was a significant increase in the frequency of T1 regional CWs, while the frequency of T2 regional CWs showed no trend. Although amplification of the Siberian high was observed in both T1 and T2 regional CW events, there were differences in the wave train patterns in the middle troposphere between the two regional CWs. During T1 regional CW events, a wave train with negative–positive 500-hPa geopotential height anomalies over Siberia–Mongolia weakened the East Asian trough, causing an eastward movement of cold air from Siberia. The increasing trend of T1 regional CW frequency may be attributable to the linear trends of 500-hPa geopotential height caused by global warming. The wave train associated with T2 regional CW events formed ridge–trough–ridge circulation anomalies over the Ural Mountains, Mongolia, and North China. This led to a southeastward intrusion of the cold air. The conclusions of this paper indicate that the Siberian high amplification and mid-tropospheric wave train pattern should be jointly considered in forecasting regional CW events in China.</p><p>摘要</p><p>寒潮事件对东亚地区的社会经济, 生态系统和人体健康影响巨大. 根据1980−2019 年间10月至次年3月的每日寒潮记录和<em>K</em>-means聚类, 本文识别出了中国两种不同类型的区域性寒潮(T1 和 T2). T1区域性寒潮主要影响东北地区, T2区域性寒潮则主要影响华北和东部地区. 与T1区域性寒潮相比, T2区域性寒潮强度更强, 持续时间更长, 影响范围更广. 1980–2019年期间, T1区域性寒潮的频率显著增加, 而T2区域性寒潮的频率则没有趋势变化. T1和T2区域性寒潮事件均与西伯利亚高压增强有关, 然而与它们相关的对流层中层波列明显不同. 在T1区域性寒潮事件发生期间, 西伯利亚-蒙古上空出现负-正模态的500-hPa位势高度异常波列, 削弱了东亚大槽, 导致西伯利亚冷空气东移. T1区域寒潮频次增加趋势可能与全球变暖引起的500-hPa位势高度的线性趋势变化有关. 与T2区域寒潮事件相关的波列则在乌拉尔山脉, 蒙古和华北地区形成了脊-槽-脊环流异常, 导致冷空气向东南方向入侵. 本文得出结论, 由于两类区域寒潮影响不同, 西伯利亚高压增强和对流层中层波列模态在我国区域性寒潮事件的预报中应综合考虑.</p></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"17 4","pages":"Article 100487"},"PeriodicalIF":2.3,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674283424000369/pdfft?md5=3a06bf0bbac0e996080884917e2113ab&pid=1-s2.0-S1674283424000369-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140279609","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}