Journal of Geophysical Research: Atmospheres最新文献

{"title":"Satellite-Estimated Microwave Emissivity and Emission Temperature Over the Arctic Sea Ice: ANN-Based Algorithm","authors":"Eui-Jong Kang,&nbsp;Byung-Ju Sohn,&nbsp;Hwan-Jin Song,&nbsp;Chao Liu","doi":"10.1029/2024JD042265","DOIUrl":"https://doi.org/10.1029/2024JD042265","url":null,"abstract":"<p>Satellite microwave surface-sensitive sounding channels have long faced limitations in polar data assimilation (DA) due to difficulties in specifying radiative boundary conditions over sea ice, particularly during winter. Previous studies have proposed using outputs from sea-ice growth model to estimate microwave emissivities and emission temperatures for DA. However, this approach poses practical challenges, as it operates independently of numerical weather prediction systems. To overcome these challenges, this study introduces an artificial neural network (ANN) technique that transforms the modeling approach into an algorithm capable of directly retrieving radiative boundary conditions from satellite observations. The ANN leverages empirical knowledge that sea-ice emissivity is closely related to ice type and that microwave penetration depth varies with frequency, capturing temperature profiles within sea ice. It targets winter Arctic Ocean, using brightness temperatures (TBs) from ATMS channels 1 to 3 (23, 36, and 51 GHz) as inputs to retrieve emissivity and emission temperature for surface-sensitive channels 6 and 7 (53 and 54 GHz). The ANN algorithm was trained and validated using simulated data sets, demonstrating high accuracy with correlation coefficients of 0.99 and low errors. Further evaluation using ATMS observations from the winters of 2021 and 2022 was conducted by converting the retrievals into top-of-atmosphere TBs, yielding consistent error statistics: correlation coefficients of 0.99, mean deviations of about −0.3 K, and standard deviations of about 0.3 K for both channels. These results confirm the algorithm's stability and robust generalization capabilities, underscoring its potential for integration within DA systems and broader applications to other microwave sensors.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042265","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143914589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Characteristics of Precipitation Patterns in Moisture-Dominated Versus Wind-Dominated Atmospheric Rivers Over Western North America","authors":"Wen-Shu Lin,&nbsp;Joel R. Norris,&nbsp;Michael J. DeFlorio,&nbsp;Jonathan J. Rutz,&nbsp;Jason M. Cordeira,&nbsp;F. Martin Ralph","doi":"10.1029/2024JD041966","DOIUrl":"https://doi.org/10.1029/2024JD041966","url":null,"abstract":"<p>We categorize atmospheric rivers (ARs) that make landfall between northern California and British Columbia during the period of 1980–2023 into two flavors: moisture-dominated (moist-ARs) and wind-dominated ARs (windy-ARs). Although moist-ARs and windy-ARs have similar duration and magnitude of integrated water vapor transport (IVT) at the AR core after they make landfall, their accompanying precipitation patterns are different. Over the duration of the AR, moist-ARs produce higher cumulative precipitation in inland and interior areas while windy-ARs produce higher cumulative precipitation in coastal areas. We explore the mechanisms leading to the precipitation pattern differences from both dynamical and thermodynamical perspectives. Moist-ARs are associated with a weaker but a more zonally extended anomalous trough at 500 hPa, which leads to stronger zonal wind and IVT that favor penetration of moisture and enhanced precipitation inland. Moist-ARs also have more moisture in the upper troposphere everywhere and stronger integrated water vapor and column relative humidity over the ocean and the interior. Windy-ARs are associated with an enhanced trough at 500 hPa and lower pressure at sea level, which promote a stronger low-level southerly wind component and colder temperatures. These together lead to stronger low-level IVT that are more perpendicular to the coastline and mountain ranges and stronger low-level relative humidity near the coastline, despite less total column moisture. Windy-ARs are also associated with stronger IVT convergence and stronger synoptic-scale ascent forcing near coastal areas than moist-ARs.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143902800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Soil Moisture on the Development of Organized Convective Systems in South America","authors":"Laura Paccini,&nbsp;Kathleen A. Schiro","doi":"10.1029/2024JD042108","DOIUrl":"https://doi.org/10.1029/2024JD042108","url":null,"abstract":"<p>This study investigates the role of soil moisture (SM) on the initiation and organization of convective systems using the convection-permitting ICOsahedral Non-hydrostatic (ICON) model. We conduct two sets of experiments: a Control experiment with interactive SM and a fixed SM experiment (FixedSM) with invariable SM conditions. We focus on two regions in South America: the Amazon and southeastern South America (SESA). Larger organized convective systems are associated with greater SM heterogeneity in both regions, though other large-scale synoptic influences affect the robustness of this relationship in SESA. These results remain largely unaffected by disabling the effects of precipitation on SM in the FixedSM experiment, and complementary analyses using satellite-based estimates of SM and precipitation support these findings. Spatial compositing of mesoscale environments in the Amazon shows the presence of well-defined SM gradients, at a length scale of a few hundred kilometers, many hours <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mn>10</mn>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(mathcal{O}(10))$</annotation>\u0000 </semantics></math> before convective system detection. Larger SM gradients correspond to larger gradients in thermodynamic variables, particularly surface temperature and sensible heat flux, and are associated with larger convective systems. Overall, our findings suggest that surface heterogeneities such as SM gradients not only affect deep convection initiation, as previously suggested, but they can also encourage the growth and organization of convective systems into larger clusters, particularly in the absence of significant synoptic influences.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042108","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143902840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Processes Controlling DMS Variability in Marine Boundary Layer of the Arabian Sea During Post-Monsoon Season of 2021","authors":"Mansi Gupta,&nbsp;L. K. Sahu,&nbsp;Nidhi Tripathi,&nbsp;A. K. Sudheer,&nbsp;Arvind Singh","doi":"10.1029/2024JD042547","DOIUrl":"https://doi.org/10.1029/2024JD042547","url":null,"abstract":"<p>Ship-borne high time-resolution in situ measurements of dimethyl sulfide (DMS) in the marine air of the Arabian Sea reveal large spatiotemporal variations (20−709 ppt) during the post-monsoon season. The DMS mixing ratios in the southeast (98 ± 87 ppt) and northeast (116 ± 120 ppt) coastal regions were higher than in the oligotrophic central Arabian Sea (62 ± 53 ppt). The frequent DMS peaks over the coastal regions were associated with calm winds, lower salinity, higher SST, and elevated chlorophyll concentrations. The time series of DMS along the coastal regions exhibits stronger diurnal variability with higher values during early morning and evening hours compared to the open ocean. The lower daytime DMS throughout the campaign is attributed to the predominance of OH-oxidation loss, while nighttime radical chemistry was modulated by polluted air masses in coastal regions. The DMS levels showed a noticeable response to changes in meteorological and oceanic physiochemical parameters, including salinity gradients (−0.3 to 0.2 psu hr⁻¹), mostly associated with localized upwelling events. A weak negative correlation between DMS and seawater nitrate concentrations indicates the role of nitrogen availability in seawater DMS production. Despite relatively low phytoplankton biomass in the post-monsoon, the estimated DMS fluxes of ∼11 μmol m⁻² d⁻¹ were ∼3-times higher than the values determined two decades ago. Strong spatiotemporal variations and high levels of DMS could have significant implications for regional atmospheric chemistry, including the formation of sulfate aerosols and cloud condensation nuclei in the marine boundary layer over the Arabian Sea.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143902842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Winter Ozone and PM 2.5 NAAQS Exceedance in the Northern Colorado Front Range in Relation to Oil and Natural Gas Emissions","authors":"D. Caputi,&nbsp;D. Helmig,&nbsp;L. S. Darby,&nbsp;G. Greenberg,&nbsp;J. Hueber,&nbsp;S. Simoncic,&nbsp;J. Ortega","doi":"10.1029/2024JD041862","DOIUrl":"https://doi.org/10.1029/2024JD041862","url":null,"abstract":"<p>There has been a notable increase in winter and early spring ozone exceedance occurrences in enclosed air basins that contain abundant oil and natural gas (O&amp;NG) activity. High ozone levels can arise from emissions of nitrogen oxides (NO_x) and volatile organic compounds (VOCs) combined with enhanced photochemical reactions. The wintertime temperature inversions trap these emissions near the ground and cause their concentrations to increase, and the high albedo of snow accelerates the photochemical reactions. Although these events have been noted in rural high elevation O&amp;NG development basins in the western United States, here, we report on and analyze a late winter high ozone and particulate matter (PM) event in the densely populated Northern Colorado Front Range (NCFR) in an unenclosed air basin with abundant O&amp;NG production. On 19–20 March 2021, the 8-hr average ozone reached 82 ppb, and 24-hr-averaged PM 2.5 concentrations reached 77 μg m⁻³, resulting in the year's highest PM pollution event. Using a combination of in-situ chemical and meteorological measurements, we show that the buildup of ozone precursors was likely attributable to O&amp;NG emissions in a stable boundary layer in conjunction with Denver Cyclone conditions, a mesoscale feature common in the NCFR that recirculates pollutants. The concurrent PM pollution was likely driven by animal feedlot emissions and diverse sources of NO_x, including O&amp;NG. This event raises concern about the potential of wintertime air quality standard exceedances and cumulative adverse health effects considering an expanding O&amp;NG industry within a densely populated urban and suburban area.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143902841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Data Assimilation of Ceilometer Aerosol Extinction Coefficient Profile Contributes to Predictions of the Three-Dimensional Structures of Aerosols in East China","authors":"Lina Gao,&nbsp;Lipeng Jiang,&nbsp;Wei Sun,&nbsp;Peng Yan,&nbsp;Bing Qi,&nbsp;Chengli Ji,&nbsp;Fa Tao","doi":"10.1029/2024JD042408","DOIUrl":"https://doi.org/10.1029/2024JD042408","url":null,"abstract":"<p>Ceilometer aerosol extinction coefficient (AExtC) profiles in Hangzhou city (HZ) in East China are assimilated from 1 to 31 December 2020 by applying the WRFDA-Chem model system. The analysis field obtained from data assimilation (DA) is set as the chemical initial condition (IC) for WRF-Chem (Weather Research and Forecasting model coupled with Chemistry) aerosol prediction. Observations, including ceilometer AExtC profiles in HZ, ground PM_2.5 in East China are adopted to verify the analysis and predictions. The RMSE (root mean square error between model and observation) improvements for ceilometer AExtC, and PM_2.5 persist for at least 18 forecast hours, with the mean RMSE decreasing by 13% and 8%, respectively. Moreover, the contributions of different observation systems (ceilometer profiles versus ground PM_2.5) to predicting three-dimensional (3D) aerosol structures are also investigated. The contribution of ceilometer DA is comparable to that of direct PM_2.5 DA to the PM_2.5 predictions in HZ and its environs, with RMSE decreased by 8% and 10%, respectively. In areas far from the assimilation stations' locations (HZ city), ceilometer DA showed an even better performance. The performance of ground PM_2.5 DA is inferior to that of the direct ceilometer DA experiment in predicting ceilometer AExtC vertical profiles. The joint assimilation of ceilometer and PM_2.5 data was conducted. Best 3D aerosol structure predictions are obtained through the joint DA of ceilometer profiles and ground PM_2.5.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042408","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143901019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Improving Planetary Boundary Layer Height Estimation From Airborne Lidar Instruments","authors":"J. A. Christopoulos,&nbsp;P. E. Saide,&nbsp;R. Ferrare,&nbsp;B. Collister,&nbsp;R. A. Barton-Grimley,&nbsp;A. J. Scarino,&nbsp;J. Collins,&nbsp;J. W. Hair,&nbsp;A. Nehrir","doi":"10.1029/2024JD042538","DOIUrl":"https://doi.org/10.1029/2024JD042538","url":null,"abstract":"<p>The height of the planetary boundary layer (PBLH) influences processes such as pollutant distributions, convection, and cloud formation within the troposphere. Aerosol observables play a critical role in deriving the mixed layer height (MLH) using retrieval techniques like the Haar wavelet covariance transform (WCT), which employs gradients in aerosol backscatter to estimate MLH. Currently, backscatter-only approaches struggle with identifying very shallow stable boundary layers, distinguishing PBL from lofted residual or other aerosol layers, and profiles with very low aerosol loading. Here, we reflect on the WCT method's performance and evaluate different approaches to improve PBLH estimations. We aggregate lidar observables from recent NASA airborne field campaigns and compute MLHs based on the WCT method. Machine learning (ML) approaches are explored to produce PBLH estimates by training lidar information on thermodynamically derived PBLHs over marine and land settings. A linear model is found suitable for producing PBLH estimates in marine settings (improving mean bias by 71 m), while an ensemble tree method proves more suitable for PBLH types over land, as indicated by improved biases (13 m mean bias), errors (179 m mean error and 391 m RMSE), and correlations (+0.3) for the models explored. The algorithms are additionally tested on “unseen” data to gauge differences between MLH and PBLH estimates produced from each of the models. The PBLH estimates, composed of information from lidar and thermodynamic profiles, further support the use of ML for an automated method of PBLH prediction. Overall, these improved predictions will help evaluate models and deepen our understanding of PBL-aerosol interactions.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042538","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143901020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Solar Cycle Detected in Natural Tritium of Ice Layers Before the Nuclear Era","authors":"L. Palcsu,&nbsp;E. László,&nbsp;G. Surányi,&nbsp;M. Túri,&nbsp;D. Vargas,&nbsp;M. Veres,&nbsp;A. Cauquoin,&nbsp;L. Zákány,&nbsp;R. Janovics,&nbsp;I. Csige,&nbsp;M. Temovski","doi":"10.1029/2024JD042678","DOIUrl":"https://doi.org/10.1029/2024JD042678","url":null,"abstract":"<p>The 11-year cycle of the solar activity affects the production rate of cosmogenic isotopes. For tritium in precipitation, it has been just recently proven that this link exists. Here we show, for the first time, a tritium ice core time series which extends back to 1923, covering a time period that avoids the presence of artificial tritium from the thermonuclear weapon tests of the early 1950s. Accurate analyses of low-level tritium enables us to estimate the natural level of tritium in the study site of Colle Gnifetti, Swiss-Italian Alps, as well as its variation. Statistical analyses using sunspot number and the count rate of cosmic ray secondary neutrons have confirmed that the modulation of the solar activity does affect the tritium concentration of ice layers accumulated earlier than the first hydrogen bomb tests. The tritium level of the ice, as well as in precipitation, is still slightly decreasing during the last three decades. The natural level of tritium obtained in this work fits very well to early tritium analyses of European wine samples, as well as model calculations with the isotope-enabled atmospheric general circulation model MIROC5-iso. Further sensitive tritium analyses of ice cores around the world will provide the opportunity to validate these models.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042678","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143901022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Differences Among Thermal, Dynamic, and Material Boundary Layers Over Complex Terrain","authors":"Yulong Tan,&nbsp;Jinyuan Xin,&nbsp;Xiang Qin,&nbsp;Yongjing Ma,&nbsp;Jianzhong Xu,&nbsp;Yuming Du,&nbsp;Chunlin Shang,&nbsp;Liyuan Zhao,&nbsp;Yongli Tian,&nbsp;Qingyun Fan,&nbsp;Xingjun Zhou,&nbsp;Yuanzhe Ren,&nbsp;Peng Wang,&nbsp;Feng Hao,&nbsp;Ninglu Yin,&nbsp;Xinbing Ren,&nbsp;Kecheng Peng,&nbsp;Danjie Jia,&nbsp;Xiaole Pan,&nbsp;Jie Li,&nbsp;Zifa Wang,&nbsp;Asim Qayyum Butt","doi":"10.1029/2024JD043043","DOIUrl":"https://doi.org/10.1029/2024JD043043","url":null,"abstract":"<p>Planetary boundary layers (PBL) characterized by thermal, dynamic, and material types and their spatiotemporal structures were simultaneously detected with ground-based remote sensing instruments in summer by parcel method, Richardson number (Ri), and photoextinction coefficients at Wuhai City. The research site is located at the exit of the valley combined with desert, lake, and the Yellow River, which result in the diurnal variation and inconsistency of three types of PBL. Convective boundary layer (CBL) reaches 3,500 m in daytime while the top of stable boundary layer (SBL) reaches 1,500 m at night. The depth of surface layer, mixing layer (ML), residual layer (RL), entrainment zone (EZ), and temperature inversion are closely correlated with diurnal temperature variation. Substantial variability in CBL and SBL heights up to hundreds of meters was observed in high spatiotemporal resolution. Dynamic PBL representing dynamic stability from Ri fluctuates around 1,000 m during nighttime and rises to about 1,500 m during daytime. Material PBL, representing the distribution of atmospheric substances driven by solar heating, is classified into residual height of material boundary layer and accumulation height of material boundary layer to describe the capacity of dispersion and accumulation affected by CBL and SBL, respectively. Material PBL demonstrates similar trends to the thermal PBL in the daytime ranging from 1,500 to 3,500 m and shows similar variation with dynamic PBL in the nighttime due to orographic winds. This study emphasizes the differences among various kinds of PBL and importance of high resolution in meso-micro scale study of PBL researches.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143901016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of Conventional and Mass-Flux PBL Schemes for Simulating Three Modes of Cloud-Boundary Layer Coupling Over the Southern Ocean","authors":"Xiao-Ming Hu,&nbsp;Greg M. McFarquhar,&nbsp;Bowen Zhou,&nbsp;Ming Xue","doi":"10.1029/2025JD043679","DOIUrl":"https://doi.org/10.1029/2025JD043679","url":null,"abstract":"<p>Planetary boundary layer (PBL) structure over the ocean and the model capability to simulate such structure are less well-understood than their counterparts over land. In this study, observations and WRF simulations are examined to study the boundary layer structure over the Southern Ocean, focusing on the coupling between the oceanic boundary layer and the cloud layer above. Based on the lower tropospheric vertical profiles and cross-sections, three cloud-boundary layer coupling modes are identified including a coupled mode with a weak positive surface heat flux (type 1), and two decoupled modes in the presence of either a negative surface heat flux driving a shallow stable boundary layer (type 2) or a strong positive surface heat flux (type 3). Numerical simulations are conducted for representative cases of each mode using the conventional YSU PBL scheme without and with the cloud-induced top-down mixing option (referred to as YSUtopdown), as well as the MYNN and the MYNN eddy-diffusivity mass-flux scheme (MYNN-EDMF) that adopts a holistic treatment of mixed-layer thermals and shallow convective clouds. The MYNN-EDMF scheme offers the best representation of the decoupled type 3 mode where its capability to simulate different vertical extents of local mixing and nonlocal mass flux is found to be essential. Two key parameters in MYNN-EDMF dictating shallow cloud formation are also identified. The YSUtopdown scheme develops a deeper boundary layer than the YSU scheme and exhibits more consistency with observations for the coupled type 1 mode. For the decoupled type 2 mode, all four schemes perform similarly well.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 9","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143901018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}