Pub Date : 2025-03-31DOI: 10.1016/j.aosl.2025.100617
Haitem M Almdhun , Yusri Yusup , Ehsan Jolous Jamshidi , Abdulghani Swesi , Muhammad Fikri Sigid , Abigail Adomako
The atmospheric surface layer of the tropical coastal ocean is commonly very unstable and experiences weak-wind conditions. How the latent (LE) and sensible (H) heat fluxes behave under such conditions are unclear because of the lack of observation stations in the tropics. Thus, this study aims to analyze LE and H and the microclimate parameters influencing them. The authors deployed an eddy covariance system in a tropical coastal region for seven months. The microclimate parameters investigated were wind speed (U), vapor pressure deficit (Δe), temperature difference (ΔT), wind-vapor pressure deficit (UΔe), wind-temperature difference (UΔT), and atmospheric stability (z/L), where z is height and L is the Monin–Obukhov length. On the daily time scale, the results show that LE was more associated with U than Δe, while H was more related to ΔT than U. Cross-wavelet analysis revealed the strong coherence in the LE–U relationship for periods between one and two days, and for H–ΔT, 0.5 to 1 day. Correlation and regression analyses confirmed the time series analyses results, where strong positive correlation coefficients (r) were obtained between LE and U (r = 0.494) and H and ΔT (r = 0.365). Compared to other water bodies, the transfer coefficient of moisture (CEN) was found to be small (= 0.40 × 10−3) and independent of stability; conversely, the transfer coefficient of heat (CHN) was closer to literature values (= 1.00 × 10−3) and a function of stability.
{"title":"Latent and sensible heat fluxes in a very unstable atmospheric surface layer and weak-wind conditions in a tropical coastal ocean","authors":"Haitem M Almdhun , Yusri Yusup , Ehsan Jolous Jamshidi , Abdulghani Swesi , Muhammad Fikri Sigid , Abigail Adomako","doi":"10.1016/j.aosl.2025.100617","DOIUrl":"10.1016/j.aosl.2025.100617","url":null,"abstract":"<div><div>The atmospheric surface layer of the tropical coastal ocean is commonly very unstable and experiences weak-wind conditions. How the latent (LE) and sensible (<em>H</em>) heat fluxes behave under such conditions are unclear because of the lack of observation stations in the tropics. Thus, this study aims to analyze LE and <em>H</em> and the microclimate parameters influencing them. The authors deployed an eddy covariance system in a tropical coastal region for seven months. The microclimate parameters investigated were wind speed (<em>U</em>), vapor pressure deficit (<em>Δe</em>), temperature difference (<em>ΔT</em>), wind-vapor pressure deficit (<em>UΔe</em>), wind-temperature difference (<em>UΔT</em>), and atmospheric stability (<em>z/L</em>), where <em>z</em> is height and <em>L</em> is the Monin–Obukhov length. On the daily time scale, the results show that LE was more associated with <em>U</em> than <em>Δe</em>, while <em>H</em> was more related to <em>ΔT</em> than <em>U</em>. Cross-wavelet analysis revealed the strong coherence in the LE–<em>U</em> relationship for periods between one and two days, and for <em>H</em>–<em>ΔT</em>, 0.5 to 1 day. Correlation and regression analyses confirmed the time series analyses results, where strong positive correlation coefficients (<em>r</em>) were obtained between LE and <em>U</em> (<em>r</em> = 0.494) and <em>H</em> and <em>ΔT</em> (<em>r</em> = 0.365). Compared to other water bodies, the transfer coefficient of moisture (<em>C<sub>E</sub></em><sub>N</sub>) was found to be small (= 0.40 × 10<sup>−3</sup>) and independent of stability; conversely, the transfer coefficient of heat (<em>C<sub>H</sub></em><sub>N</sub>) was closer to literature values (= 1.00 × 10<sup>−3</sup>) and a function of stability.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"19 1","pages":"Article 100617"},"PeriodicalIF":3.2,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145610571","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}
Pub Date : 2025-03-28DOI: 10.1016/j.aosl.2025.100616
Haojie Wu , Haipeng Yu , Xin Wang , Shanling Cheng , Yunsai Zhu , Hongyu Luo
Previous studies have indicated a global reversal of near-surface wind speeds from a declining trend to an increasing trend around 2010; however, it remains unclear whether upper-air wind speeds exhibit a similar reversal. This study evaluates reanalysis products using surface and radiosonde observations to analyze upper-air wind speed variations in the Northern Hemisphere, focusing on their seasonal and latitudinal differences. Results demonstrate that JRA-55 effectively captures wind speed variations in the Northern Hemisphere. Notably, upper-air wind speeds over land experienced a reversal in winter 2010 with significant latitudinal differences. The trend reversal of upper wind speed between the midlatitudes and subtropics presents a dipole pattern. From 1990 to 2010, upper-air wind speeds in the midlatitudes (40°–70°N) significantly declined, while the subtropical zone (20°–40°N) displayed an opposite trend. However, during 2010–2020, wind speeds in the midlatitudes shifted to a significant positive trend, whereas the subtropics experienced a significant negative trend. The variations in Northern Hemisphere winter wind speeds can be attributed to changes in low-level baroclinicity driven by tropical diabatic heating and midlatitude transient eddy feedback. Enhanced diabatic heating and weakened eddy feedback during 1990–2010 contributed to reduced wind speeds in the midlatitudes and increased speeds in the subtropics, while reduced diabatic heating and strengthened eddy feedback during 2010–2020 resulted in increased wind speeds in the midlatitudes and decreased speeds in the subtropics. The reversal of upper-air wind speeds could affect surface wind speeds by downward momentum transfer, which could contribute to the reversal of surface wind speeds.
{"title":"A reversal of upper-air wind speed in the Northern Hemisphere","authors":"Haojie Wu , Haipeng Yu , Xin Wang , Shanling Cheng , Yunsai Zhu , Hongyu Luo","doi":"10.1016/j.aosl.2025.100616","DOIUrl":"10.1016/j.aosl.2025.100616","url":null,"abstract":"<div><div>Previous studies have indicated a global reversal of near-surface wind speeds from a declining trend to an increasing trend around 2010; however, it remains unclear whether upper-air wind speeds exhibit a similar reversal. This study evaluates reanalysis products using surface and radiosonde observations to analyze upper-air wind speed variations in the Northern Hemisphere, focusing on their seasonal and latitudinal differences. Results demonstrate that JRA-55 effectively captures wind speed variations in the Northern Hemisphere. Notably, upper-air wind speeds over land experienced a reversal in winter 2010 with significant latitudinal differences. The trend reversal of upper wind speed between the midlatitudes and subtropics presents a dipole pattern. From 1990 to 2010, upper-air wind speeds in the midlatitudes (40°–70°N) significantly declined, while the subtropical zone (20°–40°N) displayed an opposite trend. However, during 2010–2020, wind speeds in the midlatitudes shifted to a significant positive trend, whereas the subtropics experienced a significant negative trend. The variations in Northern Hemisphere winter wind speeds can be attributed to changes in low-level baroclinicity driven by tropical diabatic heating and midlatitude transient eddy feedback. Enhanced diabatic heating and weakened eddy feedback during 1990–2010 contributed to reduced wind speeds in the midlatitudes and increased speeds in the subtropics, while reduced diabatic heating and strengthened eddy feedback during 2010–2020 resulted in increased wind speeds in the midlatitudes and decreased speeds in the subtropics. The reversal of upper-air wind speeds could affect surface wind speeds by downward momentum transfer, which could contribute to the reversal of surface wind speeds.</div><div>摘要</div><div>以往研究表明, 全球近地面风速已从下降趋势转为上升趋势; 然而目前尚不清楚高空风速是否也出现了类似的逆转. 本研究发现北半球冬季高空风速在2010年前后也存在逆转现象, 且该现象在中纬度和副热带之间形成了偶极子模态. 从1990年到2010年, 中纬度地区的高空风速显著减弱, 而副热带地区则表现为增强趋势; 在2010–2020年期间, 风速呈现出相反的趋势. 进一步分析表明, 这一逆转现象与热带非绝热加热和中纬度瞬变涡旋反馈所驱动的低层斜压性异常密切相关. 值得注意的是, 高空风速的逆转可能通过动量下传机制影响近地面风速, 这为解释同期地面风速的趋势逆转提供了参考依据.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100616"},"PeriodicalIF":3.2,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903367","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}
Pub Date : 2025-03-14DOI: 10.1016/j.aosl.2025.100615
Xiaowei Wang , Yongqiang Yu , Zipeng Yu , Pengfei Lin
The present study compares the Atlantic Meridional Overturning Circulation (AMOC) in the North Atlantic from two simulations by an oceanic general circulation model with 1° × 1° and 0.1° × 0.1° resolution, respectively, which explores the sensitivity of AMOC to the resolution. The ocean model is the latest version of the LASG/IAP Climate System Model (LICOM3), and it is forced with atmospheric data from phase 2 of the Ocean Model Intercomparison Project (OMIP2). Comprehensive comparison between the two simulations indicates that the simulated AMOC is highly sensitive to the spatial resolution. The high-resolution model (LICOM-H) simulates a deeper mixed-layer depth (MLD), due to increased surface salinity, than that in the low-resolution model (LICOM-L) in the Labrador Sea, and it also has stronger AMOC strength (the maximum climatic mean AMOC from 1958 to 2018 is 23.4 Sv for LICOM-H and 21.2 Sv for LICOM-L) and larger variability of AMOC index (2.3 Sv for LICOM-H and 1.7 Sv for LICOM-L). These differences can mainly be attributed to two main dynamic processes that benefit from high resolution. Firstly, LICOM-H can simulate much stronger boundary currents (∼0.6 m s−1) than LICOM-L (0.3 m s−1) in the upper ocean, which leads to saltier and warmer seawater being transported to the Labrador Sea, where it enhances deep convection. Secondly, in LICOM-H, the stronger variability of AMOC is related to the higher sensitivity of the MLD and transformation to the prescribed atmospheric forcing in the Labrador Sea.
本文比较了1°× 1°和0.1°× 0.1°分辨率的海洋环流模式对北大西洋大西洋经向翻转环流（AMOC）的模拟结果，探讨了AMOC对分辨率的敏感性。海洋模式是LASG/IAP气候系统模式（LICOM3）的最新版本，它是根据海洋模式比较项目（OMIP2）第二阶段的大气数据进行的。两种模拟结果的综合比较表明，模拟的AMOC对空间分辨率高度敏感。与低分辨率模式（LICOM-L）相比，高分辨率模式（LICOM-H）模拟的拉布拉多海混合层深度（MLD）更深，AMOC强度更强（1958 - 2018年气候平均AMOC最大值为23.4 Sv， LICOM-L为21.2 Sv）， AMOC指数变率更大（LICOM-H为2.3 Sv， LICOM-L为1.7 Sv）。这些差异主要归因于受益于高分辨率的两个主要动态过程。首先，与LICOM-L （0.3 m s - 1）相比，LICOM-H可以模拟更强的上层海洋边界流（~ 0.6 m s - 1），这导致更咸、更暖的海水被输送到拉布拉多海，从而增强了深层对流。(2) LICOM-H中AMOC的变率较强，与MLD对拉布拉多海规定大气强迫的敏感性和转换较高有关。摘要本研究关注大西洋经圈翻转环流(大西洋经向翻转环流)对分辨率的敏感性,比较了大气物理研究所自主发展的海洋环流模式LICOM (LASG / IAP气候系统海洋模型)不同分辨率版本对大西洋经向翻转环流的模拟结果,两个版本分辨率分别为1° × 1°和0.1° × 0.1°。LICOM高分辨版本模拟的大西洋经向翻转环流强度和变率较低分辨率版本明显增加,而且在拉布拉多海也模拟出了更深的混合层深度。在上层海洋, 高分辨率版本可以模拟比低分辨率版本强得多的边界流, 这导致更多高盐海水被输送到拉布拉多海, 增强了该区域的深对流. 在高分辨率版本中,大西洋经向翻转环流较强的变率与拉布拉多海混合层深度较高的变率和模式对大气强迫更敏感的响应有关。
{"title":"Impact of refined oceanic model resolution on the simulation of Atlantic meridional overturning circulation in LICOM3","authors":"Xiaowei Wang , Yongqiang Yu , Zipeng Yu , Pengfei Lin","doi":"10.1016/j.aosl.2025.100615","DOIUrl":"10.1016/j.aosl.2025.100615","url":null,"abstract":"<div><div>The present study compares the Atlantic Meridional Overturning Circulation (AMOC) in the North Atlantic from two simulations by an oceanic general circulation model with 1° × 1° and 0.1° × 0.1° resolution, respectively, which explores the sensitivity of AMOC to the resolution. The ocean model is the latest version of the LASG/IAP Climate System Model (LICOM3), and it is forced with atmospheric data from phase 2 of the Ocean Model Intercomparison Project (OMIP2). Comprehensive comparison between the two simulations indicates that the simulated AMOC is highly sensitive to the spatial resolution. The high-resolution model (LICOM-H) simulates a deeper mixed-layer depth (MLD), due to increased surface salinity, than that in the low-resolution model (LICOM-L) in the Labrador Sea, and it also has stronger AMOC strength (the maximum climatic mean AMOC from 1958 to 2018 is 23.4 Sv for LICOM-H and 21.2 Sv for LICOM-L) and larger variability of AMOC index (2.3 Sv for LICOM-H and 1.7 Sv for LICOM-L). These differences can mainly be attributed to two main dynamic processes that benefit from high resolution. Firstly, LICOM-H can simulate much stronger boundary currents (∼0.6 m s<sup>−1</sup>) than LICOM-L (0.3 m s<sup>−1</sup>) in the upper ocean, which leads to saltier and warmer seawater being transported to the Labrador Sea, where it enhances deep convection. Secondly, in LICOM-H, the stronger variability of AMOC is related to the higher sensitivity of the MLD and transformation to the prescribed atmospheric forcing in the Labrador Sea.</div><div>摘要</div><div>本研究关注大西洋经圈翻转环流 (AMOC) 对分辨率的敏感性, 比较了大气物理研究所自主发展的海洋环流模式LICOM (LASG/IAP Climate system Ocean Model) 不同分辨率版本对AMOC的模拟结果, 两个版本分辨率分别为1° × 1°和0.1° × 0.1°. LICOM高分辨版本模拟的AMOC强度和变率较低分辨率版本明显增加, 而且在拉布拉多海也模拟出了更深的混合层深度. 在上层海洋, 高分辨率版本可以模拟比低分辨率版本强得多的边界流, 这导致更多高盐海水被输送到拉布拉多海, 增强了该区域的深对流. 在高分辨率版本中, AMOC较强的变率与拉布拉多海混合层深度较高的变率和模式对大气强迫更敏感的响应有关.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"19 2","pages":"Article 100615"},"PeriodicalIF":3.2,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145986709","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}
Pub Date : 2025-03-12DOI: 10.1016/j.aosl.2025.100614
Issa Rwambo , Yi Fan , Peilong Yu , Changyu Chu , Matthews Nyasulu , Philemon King'uza
Tanzania is mainly subject to a bimodal rainfall pattern, characterized by two distinct seasons: the long rains, occurring from March to May, and the short rains, which typically take place from October to December (OND). Short rains are usually less intense but still significantly influence local agriculture. Therefore, with station-based observations and reanalysis data, the current paper examines the interannual variability of OND precipitation in Tanzania from 1993 to 2022 and explores the possible impacts from El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) as well as the mechanisms. It is found that the Tanzania OND precipitation is above (below) normal in 1997, 2006, 2011, and 2019 (1993, 1998, 2005, and 2016). The composite difference between wet (dry) years and the climatology indicates that the anomalous lower-level convergence (divergence) and upward (downward) motion are the critical circulation characters for above (below) precipitation. Further analysis indicates ENSO and the IOD are the two main oceanic systems modulating OND precipitation in Tanzania. El Niño and a positive IOD could induce easterly anomalies and weaken the Walker circulation over the Indian Ocean, consequently leading to lower-level convergence in water vapor flux, upward anomalies, and more than normal precipitation in Tanzania. In contrast, La Niña and a negative IOD produce opposite circulation anomalies and less than normal precipitation over Tanzania. Moreover, through partial correlation and Generalized Equilibrium Feedback Analysis, the individual contributions of ENSO and the IOD to circulation are investigated. It is found that although both the IOD and ENSO impact the Walker circulation, the feedback to the IOD is stronger than ENSO. These results provide critical insights into the oceanic drivers and their mechanistic pathways underlying precipitation anomalies in Tanzania.
{"title":"Interannual variability of short rains in Tanzania and the influences from ENSO and the Indian Ocean Dipole","authors":"Issa Rwambo , Yi Fan , Peilong Yu , Changyu Chu , Matthews Nyasulu , Philemon King'uza","doi":"10.1016/j.aosl.2025.100614","DOIUrl":"10.1016/j.aosl.2025.100614","url":null,"abstract":"<div><div>Tanzania is mainly subject to a bimodal rainfall pattern, characterized by two distinct seasons: the long rains, occurring from March to May, and the short rains, which typically take place from October to December (OND). Short rains are usually less intense but still significantly influence local agriculture. Therefore, with station-based observations and reanalysis data, the current paper examines the interannual variability of OND precipitation in Tanzania from 1993 to 2022 and explores the possible impacts from El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) as well as the mechanisms. It is found that the Tanzania OND precipitation is above (below) normal in 1997, 2006, 2011, and 2019 (1993, 1998, 2005, and 2016). The composite difference between wet (dry) years and the climatology indicates that the anomalous lower-level convergence (divergence) and upward (downward) motion are the critical circulation characters for above (below) precipitation. Further analysis indicates ENSO and the IOD are the two main oceanic systems modulating OND precipitation in Tanzania. El Niño and a positive IOD could induce easterly anomalies and weaken the Walker circulation over the Indian Ocean, consequently leading to lower-level convergence in water vapor flux, upward anomalies, and more than normal precipitation in Tanzania. In contrast, La Niña and a negative IOD produce opposite circulation anomalies and less than normal precipitation over Tanzania. Moreover, through partial correlation and Generalized Equilibrium Feedback Analysis, the individual contributions of ENSO and the IOD to circulation are investigated. It is found that although both the IOD and ENSO impact the Walker circulation, the feedback to the IOD is stronger than ENSO. These results provide critical insights into the oceanic drivers and their mechanistic pathways underlying precipitation anomalies in Tanzania.</div><div>摘要</div><div>坦桑尼亚降水模态呈现双峰型, 其显著特征为两个不同的雨季: 长雨季 (3月至5月) 和短雨季 (10月至12月 (OND)). 短雨季降水强度通常较弱, 但对当地农业仍具有重要影响. 基于站点观测和再分析数据, 本文研究了1993–2022年坦桑尼亚OND降水的年际变化特征, 并探讨了厄尔尼诺-南方涛动 (ENSO) 和印度洋偶极子 (IOD) 的可能影响及其机制. 研究发现, 坦桑尼亚OND降水在1997, 2006, 2011和2019年偏多 (1993, 1998, 2005和2016年偏少) . 降水偏多 (偏少) 年与气候态之间的差值场合成分析表明, 异常低层辐合 (辐散) 和上升 (下沉) 运动是降水偏多 (偏少) 的关键环流特征. 进一步分析发现, ENSO和IOD是调控坦桑尼亚OND降水年际变化的主要海洋系统. 厄尔尼诺事件和正位相IOD会引发印度洋低层东风异常并削弱其上空Walker环流, 从而导致坦桑尼亚水汽通量在低层辐合, 上升运动异常和降水增多. 相反, 拉尼娜事件和负位相IOD会引起相反的环流异常, 导致该地区降水减少. 通过偏相关分析和广义平衡反馈方法, 本文量化了ENSO和IOD对环流的独立贡献. 结果表明, 虽然IOD和ENSO均会影响Walker环流, 但IOD的作用强于ENSO. 这些发现为理解坦桑尼亚降水异常的海洋驱动因子及其机理路径提供了重要科学依据.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100614"},"PeriodicalIF":3.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903212","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}
Pub Date : 2025-03-08DOI: 10.1016/j.aosl.2025.100611
Yuqing Tian , Ke Fan , Hongqing Yang , Zhiqing Xu
Based on a normalized difference vegetation index (NDVI) dataset for 1982–2021, this work investigates the principal modes of interannual variability in summer NDVI over eastern Siberia using the year-to-year increment method and empirical orthogonal function (EOF) analysis. The first three principal modes (EOF1–3) of the year-to-year increment of summer NDVI (NDVI_DY) exhibit a regionally consistent mode, a western–eastern dipole mode, and a northern–southern dipole mode, respectively. Further analysis shows that sea surface temperature (SST) in the tropical Indian Ocean in February–March and western Siberian soil moisture in April could influence EOF1. EOF2 is modulated by April Northwest Pacific SST and western Siberian soil moisture in May. May North Atlantic SST and sea ice in the Kara Sea in the preceding October significantly affect EOF3. Using the year-to-year increment method and multiple linear regression analysis, prediction schemes for EOF1–3 are developed based on these predictors. To assess the predictive skill of these schemes, one-year-out cross-validation and independent hindcast methods are employed. The temporal correlation coefficients between observed EOF1–3 and the cross-validation results are 0.62, 0.46, and 0.37, respectively, exceeding the 95 % confidence level. In addition, reconstructed schemes for summer NDVI are developed using predicted NDVI_DY and the observed principal modes of NDVI_DY. Independent hindcasts of NDVI anomalies during 2019–2021 also present consistent distributions with the observed results.
{"title":"Principal modes of summer NDVI in eastern Siberia and its climate prediction schemes","authors":"Yuqing Tian , Ke Fan , Hongqing Yang , Zhiqing Xu","doi":"10.1016/j.aosl.2025.100611","DOIUrl":"10.1016/j.aosl.2025.100611","url":null,"abstract":"<div><div>Based on a normalized difference vegetation index (NDVI) dataset for 1982–2021, this work investigates the principal modes of interannual variability in summer NDVI over eastern Siberia using the year-to-year increment method and empirical orthogonal function (EOF) analysis. The first three principal modes (EOF1–3) of the year-to-year increment of summer NDVI (NDVI_DY) exhibit a regionally consistent mode, a western–eastern dipole mode, and a northern–southern dipole mode, respectively. Further analysis shows that sea surface temperature (SST) in the tropical Indian Ocean in February–March and western Siberian soil moisture in April could influence EOF1. EOF2 is modulated by April Northwest Pacific SST and western Siberian soil moisture in May. May North Atlantic SST and sea ice in the Kara Sea in the preceding October significantly affect EOF3. Using the year-to-year increment method and multiple linear regression analysis, prediction schemes for EOF1–3 are developed based on these predictors. To assess the predictive skill of these schemes, one-year-out cross-validation and independent hindcast methods are employed. The temporal correlation coefficients between observed EOF1–3 and the cross-validation results are 0.62, 0.46, and 0.37, respectively, exceeding the 95 % confidence level. In addition, reconstructed schemes for summer NDVI are developed using predicted NDVI_DY and the observed principal modes of NDVI_DY. Independent hindcasts of NDVI anomalies during 2019–2021 also present consistent distributions with the observed results.</div><div>摘要</div><div>本文基于1982–2021年的归一化植被指数 (Normalized Difference Vegetation Index, NDVI) 数据集, 利用年际增量法和经验正交函数方法提取了夏季东西伯利亚地区NDVI的年际变化主模态. NDVI年际增量 (NDVI_DY) 的前3个主模态 (EOF1–3) 分别呈全区一致, 东西偶极子和南北偶极子变化特征. 进一步分析影响其主模态变化的影响因子显示, 前期2–3月热带印度洋海温和4月西西伯利亚土壤湿度是全区一致模态的关键影响因子, 东西偶极子模态受前期4月西北太平洋海温和5月西西伯利亚土壤湿度的调控, 前期5月北大西洋海温和前一年10月喀拉海海冰与南北偶极子模态相联. 本文利用上述前期关键影响因子, 基于多元线性回归分析和年际增量方法建立了夏季东西伯利亚地区NDVI_DY主模态的预测模型. 其中, 观测的EOF1–3对应的时间序列与各模态交叉检验结果的时间相关系数分别为0.62, 0.46和0.37, 均超过了95 %的置信水平. 此外, 利用预测的各模态对应时间序列和观测的主模态, 本文进一步建立了夏季东西伯利亚地区NDVI的场重建预测模型. 2019–2021年夏季东西伯利亚地区独立后报的NDVI距平的空间分布也与观测一致.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100611"},"PeriodicalIF":3.2,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903348","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}
Pub Date : 2025-03-07DOI: 10.1016/j.aosl.2025.100612
Yiguo Xu , Liqing Tian , Tingru Cui , Jun Zhang , Hui Zhang , Yating Wang , Rui Wang
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.
{"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 , Liqing Tian , Tingru Cui , Jun Zhang , Hui Zhang , Yating Wang , 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}
Pub Date : 2025-03-07DOI: 10.1016/j.aosl.2025.100613
Yi Zheng , Bo Sun , Wanling Li , Siyu Zhou , Jiarui Cai , Huixin Li , Shengping He
The discrepancy in the trends of the global zonal mean (GZM) intensity of the Hadley circulation (HCI) between reanalysis data and model simulations has been a problem for understanding the changes in HCI and the influence of external forcings. To understand the reason for this discrepancy, this study investigates the trends of intensity of regional HCI of the Northern Hemisphere over the eastern Pacific (EPA), western Pacific (WPA), Atlantic (ATL), Africa (AFR), the Indian Ocean (IDO), and residual area (RA), based on six reanalysis datasets and 13 CMIP6 models. In reanalysis data, the trends in regional HCI over EPA and ATL (WPA and AFR) contribute to (partially offset) the increasing trend in GZM HCI, while the trends in regional HCI over IDO are different in different reanalysis data. The CMIP6 models skillfully reproduce the trends in regional HCI over EPA, ATL, WPA, and AFR, but simulate notable decreasing trends in regional HCI over IDO, which is a key reason for the opposite trends in GZM HCI between reanalysis data and models. The discrepancy in IDO can be attributed to differences in the simulation of diabatic heating and zonal friction between reanalysis data and models. Optimal fingerprint analysis indicates that anthropogenic (ANT) and non-greenhouse gas (NOGHG) forcings are the dominant drivers of the HCI trends in the EPA and ATL regions. In the WPA (AFR) region, NOGHG (ANT) forcing serves as the primary driver. The findings contribute to improving the representation of regional HCI trends in models and improving the attribution of external forcings.
{"title":"Attribution of regional Hadley circulation intensity changes in the Northern Hemisphere","authors":"Yi Zheng , Bo Sun , Wanling Li , Siyu Zhou , Jiarui Cai , Huixin Li , Shengping He","doi":"10.1016/j.aosl.2025.100613","DOIUrl":"10.1016/j.aosl.2025.100613","url":null,"abstract":"<div><div>The discrepancy in the trends of the global zonal mean (GZM) intensity of the Hadley circulation (HCI) between reanalysis data and model simulations has been a problem for understanding the changes in HCI and the influence of external forcings. To understand the reason for this discrepancy, this study investigates the trends of intensity of regional HCI of the Northern Hemisphere over the eastern Pacific (EPA), western Pacific (WPA), Atlantic (ATL), Africa (AFR), the Indian Ocean (IDO), and residual area (RA), based on six reanalysis datasets and 13 CMIP6 models. In reanalysis data, the trends in regional HCI over EPA and ATL (WPA and AFR) contribute to (partially offset) the increasing trend in GZM HCI, while the trends in regional HCI over IDO are different in different reanalysis data. The CMIP6 models skillfully reproduce the trends in regional HCI over EPA, ATL, WPA, and AFR, but simulate notable decreasing trends in regional HCI over IDO, which is a key reason for the opposite trends in GZM HCI between reanalysis data and models. The discrepancy in IDO can be attributed to differences in the simulation of diabatic heating and zonal friction between reanalysis data and models. Optimal fingerprint analysis indicates that anthropogenic (ANT) and non-greenhouse gas (NOGHG) forcings are the dominant drivers of the HCI trends in the EPA and ATL regions. In the WPA (AFR) region, NOGHG (ANT) forcing serves as the primary driver. The findings contribute to improving the representation of regional HCI trends in models and improving the attribution of external forcings.</div><div>摘要</div><div>基于6套再分析资料和13个CMIP6模式, 研究发现模式能够较好地再现北半球东太平洋, 西太平洋, 大西洋和非洲的哈德来环流强度变化趋势. 但在印度洋区域, 再分析数据与模式模拟的趋势存在较大差异. 这一差异主要归因于模式与再分析数据在非绝热加热和纬向摩擦力模拟上的不同表现. 最优指纹法分析表明, 人为强迫和非温室气体强迫是北半球局地哈德来环流强度变化的主要驱动因素. 本研究揭示了人类活动对北半球不同区域哈德来环流变化的重要影响, 并阐明了再分析资料与CMIP6模式中北半球哈德来环流变化差异的原因.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100613"},"PeriodicalIF":3.2,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903349","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}
Pub Date : 2025-03-01DOI: 10.1016/j.aosl.2024.100482
Zhefan Gao , Chaoxia Yuan
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.
{"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 , 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}
Pub Date : 2025-03-01DOI: 10.1016/j.aosl.2024.100554
Ziqing Chen , Kelvin T.F. Chan , Zawai Luo
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.
{"title":"Statistical seasonal forecasting of tropical cyclone landfalls on Taiwan Island","authors":"Ziqing Chen , Kelvin T.F. Chan , 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}
Pub Date : 2025-03-01DOI: 10.1016/j.aosl.2024.100533
Lingfeng Sun , Qingqing Li
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.
{"title":"Numerical simulation of size contraction of Typhoon Cempaka (2021)","authors":"Lingfeng Sun , 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}
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