Dynamics of Atmospheres and Oceans最新文献

{"title":"Mapping the dynamics of global sea surface nitrate using ocean color data","authors":"Ibrahim Shaik ,&nbsp;P.V. Nagamani ,&nbsp;Yash Manmode ,&nbsp;Sandesh Yadav ,&nbsp;Venkatesh Degala ,&nbsp;G. Srinivasa Rao","doi":"10.1016/j.dynatmoce.2024.101507","DOIUrl":"10.1016/j.dynatmoce.2024.101507","url":null,"abstract":"<div><div>Sea Surface Nitrate (SSN) is crucial for assessing phytoplankton growth and the initiation of new production within the marine environment. Precise estimation of SSN concentrations plays a significant role in understanding marine ecosystem dynamics. In this study, the deep learning model TabularNet (TabNet) was assessed using quality-controlled in-situ measurements from the Global Ocean Data Analysis Project (GLODAP). These measurements included Sea Surface Temperature (SST), Sea Surface Salinity (SSS), Chlorophyll-a concentration (Chla), and nitrate, collected from various regions of the global ocean to achieve accurate SSN estimation. The TabNet model demonstrated superior performance and robustness, achieving accurate global SSN estimations using satellite data. The model yielded a root mean square error (RMSE) of 2.02 μmol/kg, a mean bias (MB) of −0.32 μmol/kg, a mean ratio (MR) of 0.78, and a coefficient of determination (R²) of 0.96. Furthermore, a comparative analysis of TabNet against Random Forest (RF) and Feed Forward Neural Network (FFNN) models was conducted. The results highlighted the robust performance of TabNet in accurately estimating SSN dynamics. TabNet effectively utilized in-situ and satellite data, providing accurate SSN dynamics. This technique offers valuable insights for monitoring global surface ocean nitrate dynamics, enhancing our ability to understand and manage marine ecosystems.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101507"},"PeriodicalIF":1.9,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652132","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":"The vortex splitting process from interaction between a mesoscale vortex and two islands","authors":"Mingze Ji ,&nbsp;Xiongbo Zheng ,&nbsp;Fangli Qiao ,&nbsp;Jingyi Lu ,&nbsp;He Liu ,&nbsp;Xiaole Li","doi":"10.1016/j.dynatmoce.2024.101506","DOIUrl":"10.1016/j.dynatmoce.2024.101506","url":null,"abstract":"<div><div>Mesoscale vortices are major carriers of oceanic material and energy transfer, transporting large amounts of high-energy, temperature-anomalous water bodies during their movement. This significantly impacts both the ocean and the atmosphere. Based on the distribution of the North Brazil Curren rings and the Lesser Antilles in the eastern Caribbean Sea, we use the Regional Ocean Model System ocean circulation model to construct an idealized vortex. Simulations are conducted by varying the distances between the two islands and the scales of the islands to analyze how different parameters affect the vortex path and structural evolution. Using theoretical derivation and numerical simulation results, we construct a dimensionless parameter involving vortex diameter, island diameter, and the distance between the islands to determine the conditions under which vortex splitting occurs. The reliability of this dimensionless parameter is verified using experimental data and satellite data from St. Vincent and Barbados from April 6 to May 6, 2000.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101506"},"PeriodicalIF":1.9,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652130","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":"The curious case of a strong relationship between ENSO and Indian summer monsoon in CFSv2 model","authors":"Priyanshi Singhai ,&nbsp;Arindam Chakraborty ,&nbsp;Kaushik Jana ,&nbsp;Kavirajan Rajendran ,&nbsp;Sajani Surendran ,&nbsp;Kathy Pegion","doi":"10.1016/j.dynatmoce.2024.101504","DOIUrl":"10.1016/j.dynatmoce.2024.101504","url":null,"abstract":"<div><div>An ensemble of forecasts is necessary to identify the uncertainty in predicting a non-linear system like climate. While ensemble averages are often used to represent the mean state and diagnose physical mechanisms, they can lead to information loss and inaccurate assessment of the model’s characteristics. Here, we highlight an intriguing case in the seasonal hindcasts of the Climate Forecast System version 2 (CFSv2). While all ensemble members often agree on the sign of predicted El Niño Southern Oscillation (ENSO) for a particular season, non-ENSO climate forcings, although present in some of the individual members, are disparate. As a result, an ensemble mean retains ENSO anomalies while diminishing non-ENSO signals. This difference between ENSO and non-ENSO signals significantly influences moisture convergence and Indian summer monsoon rainfall (ISMR). This stronger influence of ENSO on seasonal predictions increases ENSO–ISMR correlation in ensemble mean seasonal hindcasts. Thus, this discrepancy in the ENSO–ISMR relationship is not present in the individual ensemble members, considered individually or together (without averaging) as independent realizations. Therefore, adequate care should be taken while evaluating physical mechanisms of teleconnection in ensemble mean predictions that can often be skewed due to constructive or destructive superposition of different impacts.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101504"},"PeriodicalIF":1.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593276","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":"Study on the genesis and development trend of tropical depressions under different large-scale backgrounds","authors":"Xiaowen Wei ,&nbsp;Xiuping Yao ,&nbsp;Xun Li ,&nbsp;Zhiyan Wu ,&nbsp;Qingchuan Wu","doi":"10.1016/j.dynatmoce.2024.101501","DOIUrl":"10.1016/j.dynatmoce.2024.101501","url":null,"abstract":"<div><div>Based on self-organizing maps (SOM), large-scale backgrounds associated with tropical depression (TD) genesis over the western North Pacific (WNP) in 1949–2021 are classified into four circulation patterns, monsoon gyre (MG) pattern, monsoon confluence (MC) pattern, monsoon trough (MT) pattern and easterly wave (EW) pattern. TDs generated in the MC pattern has the southernmost average genesis location and the highest development probability, while TDs occurred in the EW pattern are averagely located northernmost and their probability of development is the lowest. TDs formed in the MG, MT and EW patterns are most active in August, whereas in the MC pattern, TD genesis number peaks in October. Advantageous conditions for TD genesis vary in different circulation patterns. The vigorous vorticity \"embryo\" provides stronger initial disturbances for MG pattern; The strong upper-level divergence and the weak deep-layer VWS provide sufficient dynamic conditions for the MC pattern; The MT pattern possess the highest SST, which supplies an ample supply of heat and moisture; The EW pattern has less beneficial conditions compared with other three patterns. The Extreme Gradient Boosting (XGBoost) method is applied to quantify the relative importance of individual factors to TD development trend. 500-hPa vorticity, 200-hPa divergence and SST are major dynamic and thermal affecting factors for TD development, the importance of which all ranked at top four in the four patterns; VWS plays an indispensable role in TD development for the MC and EW patterns; Comparely,850-hPa vorticity and vertically integrated water vapor flux are not as important as above environmental factors in deciding whether a TD develops.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101501"},"PeriodicalIF":1.9,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571933","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":"Role of met-oceanic response to the intensification of tropical cyclones: A comparative analysis on cyclone Tauktae and Yaas","authors":"Amit Kumar Jena ,&nbsp;Manasa Ranjan Behera ,&nbsp;Sachiko Mohanty ,&nbsp;Srineash VK","doi":"10.1016/j.dynatmoce.2024.101502","DOIUrl":"10.1016/j.dynatmoce.2024.101502","url":null,"abstract":"<div><div>The present study investigates the physical response of surface met-ocean variables during the tropical cyclones (TCs) Tauktae (14–19 May) and Yaas (23–28 May) along the eastern Arabian Sea and western Bay of Bengal respectively using multi-platform datasets. This study synthesizes scientific understanding of the complex interplay between TCs, Marine heat waves (MHWs), and vertical wind shear; and focuses on their combined effects on ocean dynamics. The TC Tauktae developed and rapidly intensified without encountering any MHW event and required longer lifespan (∼3 days) to reach its peak as an Extremely Severe Cyclonic Storm (ESCS). Conversely, prolonged MHW event, persisting for five-fold duration (26 days), significantly influenced the intensification of TC Yaas into a Very Severe Cyclonic Storm (VSCS) within a shorter duration (∼1.5 days). TC Yaas intensified due to vertical wind shear, which transported heat and moisture from the Arabian Sea, creating favorable environment for its growth and development. Furthermore, the low vertical wind shear preceding Yaas provides favorable conditions for the persistence of MHW events. The presence of an anticyclonic eddy along the track played a crucial role in the intensification of TC Tauktae and Yaas. Before TC Yaas, elevated shortwave radiation and reduced longwave radiation played a significant role in sustaining the MHW event, unlike TC Tauktae. After the landfall of TC Yaas, the barrier layer thickness and mixed layer heat content were still high, whereas these were low in case of Tauktae. This signifies that higher translational speed of TC Yaas, relative to Tauktae, leads to reduced churning effects within the ocean, allowing for the retention of a substantial amount of heat within the mixed layer.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101502"},"PeriodicalIF":1.9,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531110","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":"A robust stepwise jump in the Arctic wintertime warming in 2005 coherent with the increased clear-sky downward longwave radiation flux","authors":"Mikhail M. Latonin ,&nbsp;Anna Yu. Demchenko","doi":"10.1016/j.dynatmoce.2024.101503","DOIUrl":"10.1016/j.dynatmoce.2024.101503","url":null,"abstract":"<div><div>In some areas of the Arctic, the Earth's surface temperature and near-surface air temperature are rising faster than in others. The purpose of this study is to identify, based on the ERA5 climate reanalysis data, the spatiotemporal structure of climatic changes in the Arctic during 1959–2022. The main emphasis is put on the following three parameters: mean surface clear-sky downward longwave radiation flux, near-surface air temperature, and skin temperature. A statistical model of stepwise changes was applied to the time series of the studied characteristics at each grid point of the entire Arctic (67°N–90°N). The results obtained indicate a close relationship between all parameters in the winter season. The dominant year of stepwise changes in the Arctic is 2005. Moreover, it is precisely this transition from one state of the climate system to another that is statistically significant over a large territory, which is located mainly in the Eastern Hemisphere. The time series averaged over the identified areas are highly correlated with each other, and the year 2005 characterizes the change from a sharp increase in values to their variability without a pronounced trend. The available satellite observations fully confirm the temporal structure of the stepwise changes for the studied parameters and largely confirm its spatial structure. Thus, the clear-sky downward longwave radiation flux is one of the leading factors in the formation of the thermal regime of the Arctic.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101503"},"PeriodicalIF":1.9,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531056","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":"Adjustment of the marine atmospheric boundary-layer to the North Brazil Current during the EUREC4A-OA experiment","authors":"Hervé Giordani ,&nbsp;Carlos Conejero ,&nbsp;Lionel Renault","doi":"10.1016/j.dynatmoce.2024.101500","DOIUrl":"10.1016/j.dynatmoce.2024.101500","url":null,"abstract":"<div><div>The region of Barbados is characterized by the presence of the North Brazil Current (NBC), which transports warm water along the Brazilian coasts and creates a large-scale northeast–southwest SST-gradient of 3 °C 1300 km<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>. This study examines how the marine atmospheric boundary-layer (MABL) adjusts to the NBC SST-front represented by the SST analyses produced by the operational forecasting systems ECMWF and Mercator Ocean International (MOI). The NBC SST-front imprints large-scale dipole-anomalies in the surface buoyancy flux, sea level pressure, sea surface wind intensity, vertical shear of zonal wind (main component of trade winds), liquid water content and precipitable water in the MABL ranging from <span><math><mrow><mn>50</mn><mtext>%</mtext></mrow></math></span> to <span><math><mrow><mn>100</mn><mtext>%</mtext></mrow></math></span>, compared to no NBC. The mesoscale SST structures associated with the difference between MOI and ECMWF induce MABL anomalies that are an order of magnitude weaker than those associated with the NBC SST-front. This adjustment is only statistically significant in areas where SST differences are greater than 0.3 °C. The dynamics of the MABL adjustment is investigated through the precipitable water and temperature budgets. The NBC increases the water loss by advection (<span><math><mrow><mo>≃</mo><mn>1</mn><mspace></mspace><msup><mrow><mi>mm day</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>) and entrainment (<span><math><mrow><mo>≃</mo><mn>2</mn><mspace></mspace><msup><mrow><mi>mm day</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>) and increases the gain of water by surface evaporation (<span><math><mrow><mo>≃</mo><mn>2</mn><mspace></mspace><msup><mrow><mi>mm day</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>), while the SST difference between MOI and ECMWF increases the magnitudes of advection, entrainment and surface evaporation around <span><math><mrow><mn>10</mn><mtext>%</mtext></mrow></math></span>. Regarding the energy budget, the NBC forces warming by surface sensible heat flux, water vapor and cloud-induced infrared radiation flux (<span><math><mrow><mo>≃</mo><mn>1</mn><mspace></mspace><msup><mrow><mi>K day</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>), which are partially balanced by negative horizontal advection. The SST difference between MOI and ECMWF alters the heat budget components by <span><math><mrow><mn>10</mn><mtext>%</mtext></mrow></math></span>.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101500"},"PeriodicalIF":1.9,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586334","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":"Analysis and prediction of mesoscale eddy kinetic energy variations in the Kuroshio extension","authors":"Ma Xiaodong ,&nbsp;Zhang Lei ,&nbsp;Xu Weishuai ,&nbsp;Li Qinghong ,&nbsp;Li Maolin","doi":"10.1016/j.dynatmoce.2024.101497","DOIUrl":"10.1016/j.dynatmoce.2024.101497","url":null,"abstract":"<div><div>The Kuroshio Extension (KE) region, a crucial area in the Northwest Pacific Ocean, exhibits eddy kinetic energy with various scales of periodicity. Understanding how to extract its characteristic features and analyze and predict their periodic correlations has become vital for studying the regulatory mechanisms of eddy kinetic energy in the KE region. This paper first introduces a mesoscale eddy hybrid identification algorithm based on the flow field vector and the closed flow field. Using this algorithm, we gather mesoscale eddy identification data from the KE region to extract the monthly average series of five typical features of the KE region. Subsequently, wavelet theory is applied to analyze the cycles of these main features, identifying the common cycles of the KE region as the primary focus for analyzing the vorticity kinetic energy. This analysis includes cycle correlations with globally recognized indices, and it predicts these correlations. Further analysis of the main characteristic cycles through wavelet theory reveals that the KE region's eddy kinetic energy is significantly influenced by solar activity over long periods and by the North Pacific ocean-atmosphere interaction over shorter, interannual periods. Finally, this paper introduces a W-LSTM (Wavelet Decomposition based Long Short-term Memory Networks) prediction model based on wavelet decomposition for the KE region, covering January 2023–December 2023. The model demonstrates its effectiveness, achieving a Root Mean Square Error (RMSE) of 0.2530 and a correlation coefficient of 0.8259 between the predicted data and the actual observations.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101497"},"PeriodicalIF":1.9,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531109","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":"The atmospheric Ekman flows with time-dependent eddy viscosity","authors":"Yi Guan","doi":"10.1016/j.dynatmoce.2024.101496","DOIUrl":"10.1016/j.dynatmoce.2024.101496","url":null,"abstract":"<div><div>In this paper, we consider nonsteady modified atmospheric Ekman equations in the <span><math><mrow><mi>f</mi><mo>−</mo></mrow></math></span>plane approximation. We non-dimensionalize the equations of the motion in the <span><math><mrow><mi>f</mi><mo>−</mo></mrow></math></span>plane. For two types of time-dependent eddy viscosity, by means of Laplace transform, we get the explicit formulas, respectively.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101496"},"PeriodicalIF":1.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311182","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":"Formation mechanisms and biogeochemical response of coastal salinity front in the central eastern Arabian Sea","authors":"Vishnu Narayanan Nampoothiri S ,&nbsp;Sudheesh V ,&nbsp;Kausar Fatima Bepari,&nbsp;B. Bikram Reddy,&nbsp;Naseera K,&nbsp;Rasheed K,&nbsp;Anil Kumar Vijayan,&nbsp;Gupta G.V.M","doi":"10.1016/j.dynatmoce.2024.101498","DOIUrl":"10.1016/j.dynatmoce.2024.101498","url":null,"abstract":"<div><div>This study investigates the formation mechanisms and impact of a coastal salinity front observed in the central eastern Arabian Sea (EAS) coast, particularly off Mangalore (∼13°N), during the peak summer monsoon in August 2018. The interplay of intense monsoon rainfall, river runoff and coastal upwelling created a dynamic frontal zone characterised by distinct physical and biogeochemical properties in the central EAS. The study revealed that observed salinity fronts are formed due to the breaking of freshwater lenses by strong upwelled waters and the subsequent offshore transport of low-salinity plumes by prevailing current and Ekman transport. The high nutrient concentrations enhanced the chlorophyll <em>a</em> concentration 15–20 times higher (10.12 mg/m³) in the frontal zone compared to the non-frontal station. The dominance of diatoms in the frontal zone indicates herbivorous control in the coastal food web. Accumulation of plastic debris and foam-like particles in the frontal zone poses ecological risks and threatens aquatic life.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"108 ","pages":"Article 101498"},"PeriodicalIF":1.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311181","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}