Shumin Jiang , Dejun Dai , Dingqi Wang , Jia Deng , Jia Sun , Ying Li , Jingsong Guo , Fangli Qiao
{"title":"Improvement of finescale parameterization through reducing uncertainty in spectrum estimation","authors":"Shumin Jiang , Dejun Dai , Dingqi Wang , Jia Deng , Jia Sun , Ying Li , Jingsong Guo , Fangli Qiao","doi":"10.1016/j.dynatmoce.2025.101545","DOIUrl":"10.1016/j.dynatmoce.2025.101545","url":null,"abstract":"<div><div>Finescale parameterization (FP) is employed widely to estimate the large-scale distribution of internal wave-induced mixing, which is crucially important for the development of ocean general circulation models. In this study, FP performance was evaluated using hydrographic and microstructure measurements extracted from the Microstructure Program dataset. A general tendency of overestimation with increase in the estimated internal wave energy level was observed. Using the Monte Carlo method, the turbulent dissipation rates under prescribed spectra were estimated to illustrate how uncertainty in spectrum estimation contributes to the bias. The overestimation tendency was replicated under the FP by the commonly used periodogram spectral method. By replacing the periodogram method with an autoregressive (AR) spectral estimator, the overestimation tendency was reduced considerably. Application of FP with the AR method to the collected hydrographic data greatly reduced the bias, with the root mean square error reducing from 0.72 to 0.46, the variance of the bias decreasing from 0.57 to 0.23, and the correlation of the bias with the internal wave energy level reducing from 0.62 to 0.32, in base-10 logarithmic coordinates. Application of FP with the AR spectrum estimator would help in estimating diapycnal mixing within the ocean interior more accurately and increase the robustness of FP.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"110 ","pages":"Article 101545"},"PeriodicalIF":1.9,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592480","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":"Climate variability and heat wave dynamics in India: Insights from land- atmospheric interactions","authors":"C.S. Neethu, B. Abish","doi":"10.1016/j.dynatmoce.2025.101537","DOIUrl":"10.1016/j.dynatmoce.2025.101537","url":null,"abstract":"<div><div>Heat waves have emerged as one of the most severe and destructive meteorological phenomena, significantly threatening human health, agricultural productivity, and ecosystems due to their increasing frequency, duration, and intensity. In India, these extreme events predominantly occur during the pre-monsoon months (March to mid-June), with recent years (2016, 2019, 2022, and 2023) showing a clear intensification in their occurrence. This study aims to explore the dynamics of heat waves, synoptic conditions, surface land-atmosphere interactions, and regional variations in recent years across India, utilizing maximum temperature data from the India Meteorological Department (IMD) and heat wave indices to evaluate their intensity and impact. Analysis of maximum temperature data and heatwave indices highlights a notable rise in heatwave frequency and duration, particularly in northern and central India. The 2-meter (2 m) temperature anomaly in north, central, and southern India exceeded 2.5°C, while the 925hPa temperature showed significant warming trends in north and northwest India. The analysis of the spatial distribution of the planetary boundary layer (PBL) and total cloud cover (TCC) indicates reduced cloud cover and an increased PBL, intensifying heat wave conditions across north and central regions. The warm air advection and sinking air in the descending limb of the Walker circulation ensured a stable and drier atmosphere, favoring heatwave conditions. Moreover, a persistent anticyclonic circulation and its associated high-pressure system enabled heat-trapping within the atmosphere, leading to prolonged and intensified heat wave conditions. The study indicates a shift in the position and strength of the subtropical jet stream (STJ) during these years, highlighting its significant role in developing and intensifying heat waves.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"110 ","pages":"Article 101537"},"PeriodicalIF":1.9,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377968","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":"Quasi-homogeneous regions of climatic distributions of wind wave parameters in the Black Sea","authors":"Boris V. Divinsky, Yana V. Saprykina","doi":"10.1016/j.dynatmoce.2025.101535","DOIUrl":"10.1016/j.dynatmoce.2025.101535","url":null,"abstract":"<div><div>The main aim of the study is to identify in the Black Sea quasi-homogeneous spatial areas and corresponding relevant features, the climatic statistical characteristics of which will determine these areas. Numerical modeling and discriminant analysis were applied. As a result of modeling an array of wind wave parameters for the period of 45 years (1979–2023) was obtained. The values of the main parameters (significant wave heights, spectrum peak periods, propagation directions) for this period at 92 points uniformly distributed over the Black Sea were analyzed. The main features, by which the zoning of the Black Sea was carried out, were climatic repeatabilities of the following parameters: significant wave heights in the ranges of <em>h</em><sub>s</sub>< 1 m, 1 <<em>h</em><sub>s</sub>< 3 m, 3 <<em>h</em><sub>s</sub>< 5 m, <em>h</em><sub>s</sub>> 5 m; and spectrum peak periods in the ranges <em>t</em><sub>p</sub>< 3 s, 3 <<em>t</em><sub>p</sub>< 6 s, 6 <<em>t</em><sub>p</sub>< 9 s, <em>t</em><sub>p</sub>> 9 s. According discriminant analysis six quasi-homogeneous areas (clusters) in the Black Sea were identified. The main zoning parameters are wave heights in the ranges 3 <<em>h</em><sub>s</sub>< 5 m and <em>h</em><sub>s</sub>> 5 m and periods 6 <<em>t</em><sub>p</sub>< 9 s. The identified clusters are quite homogeneous in the repeatability of wave action of the north-eastern and north-western directions. The obtained quasi-homogeneous areas of the Black Sea significantly refine the zoning obtained earlier and can be used to study and forecast sea climate change.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"110 ","pages":"Article 101535"},"PeriodicalIF":1.9,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177319","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}
Shaolei Guo , Yuehan Zhang , Xianqi Zhang , Yang Yang , Wanhui Cheng
{"title":"Simulation study of reservoir water environment based on Mike21-taking Baisha reservoir as an example","authors":"Shaolei Guo , Yuehan Zhang , Xianqi Zhang , Yang Yang , Wanhui Cheng","doi":"10.1016/j.dynatmoce.2024.101522","DOIUrl":"10.1016/j.dynatmoce.2024.101522","url":null,"abstract":"<div><div>This study aims to simulate the reservoir area by constructing a coupled model to analyze the variations in the water flow field and the migration patterns of pollutants in the Baisha Reservoir under different flow increments. One of the key challenges in this process is selecting an appropriate model and calibrating its parameters. The MIKE21 hydrodynamic-water quality coupled model was employed to simulate the reservoir area, with extensive experimental calibration of the HD and Ecolab models' parameters based on the actual conditions of Baisha Reservoir. The performance of the models was evaluated, and the results indicated a high level of reliability. In the Ecolab model, three commonly used water quality indicators—BOD, NH₃-N, and NO₃—were considered for simulation and analysis. To examine the changes in the water flow field under different flow increments, three distinct flow increment scenarios were tested. The results showed that the best simulation performance occurred when the flow increment was 30 %, with BOD improvement of 51.02 %, NH₃-N improvement of 26.31 %, and NO₃ improvement of 37.13 %. Furthermore, an ESN model was developed to predict future water quality changes in Baisha Reservoir. The accuracy of the ESN model was validated using the water quality simulation results from Scenario 3, yielding an average relative error of 3.26 %. The water quality concentrations predicted under this scenario were significantly lower than the initial concentrations, providing practical insights into addressing issues related to water quantity and quality in the reservoir.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101522"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160126","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 2D numerical study on Kuroshio currents with free slip coastal boundary","authors":"Sudhakar Matle","doi":"10.1016/j.dynatmoce.2024.101524","DOIUrl":"10.1016/j.dynatmoce.2024.101524","url":null,"abstract":"<div><div>The paper presents a comprehensive analysis of generating a Kuroshio current-like phenomenon using a novel mathematical model and advanced numerical methods. It helps to understand the streamline behavior on the western boundary over the time scales due to the presence of free slip conditions at the north and at the south coastal boundaries.</div><div>The ocean is modeled as a square domain occupied by homogeneous, incompressible fluid of constant density and a variable surface height. Dynamics of the flow are examined in a shallow water system. The salient parameters investigated here are the wind stress coefficient, the stochastic wind force coefficient, and time scales.</div><div>It is proved that streamlines are crowded on the western boundary through numerical study, and also these are bifurcated when the wind stress coefficient is 3.12. The bifurcation of the flow indicates the stability. It is also reported that the Milstein method and a standard numerical method are in good agreement while the Fokker–Planck equation-based method and the Milstein method are partially agreed. The solution by the Milstein method diverged while the solution by the Fokker–Planck method converged when <span><math><mrow><mi>ω</mi><mo>≥</mo><mn>0</mn><mo>.</mo><mn>2</mn></mrow></math></span>.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101524"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Impacts of two types of El Niño events on spring surface air temperature over Sri Lanka","authors":"Pathmarasa Kajakokulan , Raju Attada , Dzung Nguyen-Le , Jasti S. Chowdary","doi":"10.1016/j.dynatmoce.2024.101517","DOIUrl":"10.1016/j.dynatmoce.2024.101517","url":null,"abstract":"<div><div>The relationship between El Niño events and surface air temperature (SAT) over Sri Lanka (SL) has been well documented. However, the impact of the two different types of El Niño flavors on seasonal SAT variability in SL remains to be thoroughly investigated. Therefore, to identify the effect of two different types of El Niño on SAT over SL, we analyzed reanalysis and observational datasets from 1981 to 2020. This study mainly focused on the boreal spring season during the decaying phase of El Niño events. We show the presence of a strong SAT cooling in spring over the SL during the decaying phase of Central Pacific (CP) El Niño events, while intense spring SAT warming over SL is particularly pronounced during the Eastern Pacific (EP) El Niño decaying phase. It is found that low-level convergence over SL and the east coast of India associated with easterlies extending from the southern flank of the westward-shifted Western North Pacific anticyclones (WNPA) lead to updrafts. This results in enhanced cloud conditions and decreased incoming shortwave radiation, thereby causing strong cooling during CP El Niño events. Conversely, during EP El Niño, the WNPA shifts eastward, and the easterlies are confined around the equator, which helps develop the anti-cyclonic circulation over the Bay of Bengal (BoB). As a result, anomalous low-level divergence induces a strong downdraft over SL. This leads to cloud-free conditions and significantly enhanced incoming shortwave radiation during EP El Niño events, helping to enhance the SAT warming over SL. In addition, a composite analysis of CP and EP El Niño events demonstrated that strong cool (warm) conditions are prevalent in CP (EP) El Niño decaying spring years. This study highlights two distinct types of El Niño as a significant driver for understanding the SAT variability in Sri Lanka.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101517"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160123","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 comparative study of the sensitivity of an ocean model outputs to atmospheric forcing: ERA-Interim vs. ERA5 for Adriatic Sea Ocean modelling","authors":"Javad Babagolimatikolaei","doi":"10.1016/j.dynatmoce.2024.101525","DOIUrl":"10.1016/j.dynatmoce.2024.101525","url":null,"abstract":"<div><div>Advancements in atmospheric data have the potential to improve the accuracy of ocean modeling, as these models rely heavily on atmospheric parameters as key forcing inputs. One such dataset is the ECMWF reanalysis, with ERA5 being the latest version, succeeding ERA-Interim (ERA-I or ERAI). However, limited research has explored whether ERA5 improves ocean model accuracy compared to ERA-I. We use the ROMS model on the Adriatic Sea under two atmospheric forcing scenarios: ERA-I and ERA5. Results show that ERA5 calculates higher temperature and salinity values than ERA-I. ERA5 shows better alignment with satellite and Mediterranean reanalysis data than ERA-I. For temperature, ERA5 has a higher bias range (–2.29℃ to 0.83℃) compared to ERA-I (–2.34℃ to 0.80℃) and achieves a lower minimum bias, particularly in summer (0.02℃). Against Mediterranean reanalysis data, ERA5’s temperature bias range (–2.06℃ to 1.54℃) is lower range than ERA-I’s (–3.14℃ to 1.51℃). For salinity, ERA5 also has a smaller bias range (–0.02 PSU to 0.27 PSU) and achieves zero bias in spring, indicating a more accurate seasonal alignment than ERA-I. The warmer water temperatures in ERA5 are attributed to higher values of atmospheric parameters such as shortwave radiation flux, sensible heat flux, and air temperature, while, increased salinity is linked to more negative latent heat flux up to 10 W/m<sup>2</sup>, longwave radiation up to 5 W/m<sup>2</sup>, and higher wind speeds. These factors collectively lead to improved ocean modeling performance in ERA5.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101525"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160134","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":"Uncertainty reduction in ENSO periodicity projection based on the Wyrtki index","authors":"Ximei Zhao , Bo Lu","doi":"10.1016/j.dynatmoce.2024.101516","DOIUrl":"10.1016/j.dynatmoce.2024.101516","url":null,"abstract":"<div><div>Using the Wyrtki index, which comprehensively characterizes the dynamics of ENSO, we evaluated the fitting performance of 24 CMIP6 models for the ENSO dynamic processes during the period from 1980 to 2014. We identified the high-skill (HS) models with better simulation capabilities and the low-skill (LS) models with poorer simulation abilities. Compared to observational and reanalysis data, the HS models better simulate the average state of the tropical Pacific and the associated dynamic processes of ENSO from 1980 to 2014. In contrast, the LS models show a colder equatorial cold tongue, a steeper thermocline slope, and stronger trade winds in the central and western Pacific. The zonal advection feedback in the LS models is weaker, while the thermocline feedback is stronger, which may contribute to the deviations observed in the LS models when simulating the historical ENSO periodicity. The HS models indicate a trend of shorter conventional ENSO periodicity for the period from 2066 to 2100, which contrasts sharply with the conclusion drawn from the 24 CMIP6 models that show no significant change in ENSO periodicity duration. Additionally, the period of CP ENSO is projected to become shorter under SSP585 scenario for the HS models and all models. In contrast, the CP ENSO period change is insignificant for the LS models.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101516"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160124","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":"Multi-timescale variability of tropical convection in the Indo-western Pacific Ocean","authors":"Yanjun Qi, Ting Zhong","doi":"10.1016/j.dynatmoce.2024.101508","DOIUrl":"10.1016/j.dynatmoce.2024.101508","url":null,"abstract":"<div><div>The convective activity is one of the most important features of the tropics, which is closely related to climate variability on multiple time scales. Observational evidence of the coexistence of different time scales in the variation of tropical convective activity was presented in previous studies. This paper mainly reviews the recent progress of variability of convective system over the Indo-western Pacific sector on diurnal, synoptic, intraseasonal, interannual, and decadal-interdecadal time scales, as well as the associated physical processes. The interannual variability of tropical convective activity is strongly modulated by the anomalous large-scale Walker circulation, which is tied to ENSO event. Periodical intraseasonal oscillations in convection are the prominent feature in the tropical Indo-western Pacific Ocean. The tropical cyclones and monsoonal precipitation occurred at the equator and off-equator are closely linked to the synoptic-scale variation of convective activity, northward- and northwestward-propagating intraseasonal oscillation of convection in the Asian monsoon region during boreal summer. The impact of anomalous tropical convective system and associated large-scale circulation on climate variability is of great importance to surrounding countries in the Asian summer monsoon region.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101508"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743191","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 regional coupled ocean-atmosphere model simulation over Eastern Tropical Africa","authors":"Vasubandhu Misra , C.B. Jayasankar","doi":"10.1016/j.dynatmoce.2024.101520","DOIUrl":"10.1016/j.dynatmoce.2024.101520","url":null,"abstract":"<div><div>In this study we examine a 25-year simulation of a Regional Coupled Ocean-Atmosphere Model (RCOM) forced by global atmospheric and ocean reanalysis at the lateral boundaries over eastern equatorial Africa which includes parts of the Great Horn of Africa (GHA). It is a first of its kind use of a RCOM for the region. The model shows several observed features of the regional climate with bimodal peaks in the seasonal cycle interspersed with regions of unimodal peak, significant diurnal and intra-seasonal variations of precipitation especially over Lake Victoria and robust seasonal cycle of the upper western India Ocean. Nonetheless the model shows significant dry bias of seasonal precipitation that is persistent throughout the year, which is also reflected at diurnal and intra-seasonal scales. The mixed layer and thermocline depths are found to be shallower in the model simulation suggesting a far more stratified upper western Indian Ocean than the observations indicate.</div></div>","PeriodicalId":50563,"journal":{"name":"Dynamics of Atmospheres and Oceans","volume":"109 ","pages":"Article 101520"},"PeriodicalIF":1.9,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160128","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}