In the context of achieving Shanghai's carbon peak goal by 2030 and the precise regulation of regional emission reduction, it is of great significance to study the characteristics of spatial and temporal evolution of carbon emissions and the driving mechanism of Pudong New Area, an economy-intensive area, in order to construct a differentiated governance system and optimize the regional emission reduction path. Based on multivariate data, the IPCC emission factor accounting model and land use accounting model were constructed to calculate the carbon emissions of Pudong New Area from 2013 to 2022. Moreover, the LMDI model and the Tapio decoupling model were utilized to analyze the key driving factors and decoupling status of carbon emissions. The results show that: ① From 2013 to 2022, the areas of construction land and forest land increased, while those of cultivated land, grassland, water bodies, and unused land decreased. The largest change occurred in cultivated land, which was primarily converted into construction land (8 368.74 hm2). ② Carbon emissions in Pudong New Area increased from 98.171 4 million tons in 2013 to 100.110 7 million tons in 2022, exhibiting a spatial distribution pattern characterized by higher emissions in the northwest and southeast regions and lower emissions in the central area. ③ Economic growth and the expansion of construction land were the primary drivers of carbon emissions in Pudong New Area, while the reduction in energy intensity and the decline in population density exerted a significant inhibitory effect. ④ The decoupling state of carbon emissions and economic development in Pudong New Area from 2013 to 2021 showed the dynamic characteristics of alternating strong and weak decoupling, with only 2022 showing an expansion connection.

The replacement of legacy PFAS by emerging alternatives is increasingly prevalent. Due to the unique geographical and complex hydrological conditions of marginal seas, investigating the environmental behaviors of both legacy and emerging PFAS in these regions is necessary. In this study, seawater sampling was conducted in the East China Marginal Seas during 2020 and 2021. Among the 32 PFAS analyzed, 8 (2020) and 9 (2021) were detected in over 30% of samples, with mean concentrations of 4.93±4.17 ng/L and 13.0±13.2 ng/L, respectively. Notably, hexafluoropropylene oxide trimer acid (HFPO-TA, 5.02±4.95 ng/L) and perfluorooctanoic acid (PFOA, 6.04±7.73 ng/L) had comparable concentrations and accounted for 39% and 46% of ΣPFAS, respectively, indicating an increasing substitution of legacy PFAS by emerging alternatives. The Yangtze River estuary showed a pronounced replacement of legacy PFAS by emerging alternatives. Coastal fluorochemical manufacturing and high-performance fluoropolymer use were identified as major drivers of compositional differences. Legacy PFAS showed nearshore retention, with their migration constrained by salinity fronts and water masses, whereas emerging PFAS displayed more complex behaviors, with some capable of crossing salinity fronts and undergoing long-range transport. Ecological risk assessment based on risk quotient (RQ) and hazard index (HI) further revealed spatially elevated risks in nearshore and estuarine zones, driven primarily by PFOA and HFPO-TA. Overall, spatial heterogeneity among marine regions reflects variations in industrial sources and usage patterns, underscoring the necessity of integrating regional industrial structures and pollution characteristics to strengthen ecological risk assessments.

Coastal blue carbon ecosystems (traditional types such as mangroves, salt marshes, and seagrass meadows; emerging types such as tidal flats and mariculture) play pivotal roles in capturing and storing atmospheric carbon dioxide. Reliable assessment of the spatial and temporal variation and the carbon storage potential holds immense promise for mitigating climate change. Although previous field surveys and regional assessments have improved the understanding of individual habitats, most studies remain site-specific and short-term; comprehensive, multi-decadal assessments that integrate all major coastal blue carbon systems at the national scale are still scarce for China. In this study, we integrated 30 m Landsat imagery (1992–2022), processed on Google Earth Engine with a random forest classifier; province-specific, literature-derived carbon density data with quantified uncertainty (mean ± standard deviation); and the InVEST model to track coastal China’s mangroves, salt marshes, tidal flats, and mariculture to quantify their associated carbon stocks. Then the GeoDetector was applied to distinguish the natural and anthropogenic drivers of carbon stock change. Results showed rapid and divergent land use change over the past three decades, with mariculture expanded by 44%, becoming the dominant blue carbon land use; whereas tidal flats declined by 39%, mangroves and salt marshes exhibited fluctuating upward trends. National blue carbon stock rose markedly from 74 Mt C in 1992 to 194 Mt C in 2022, with Liaoning, Shandong, and Fujian holding the largest provincial stock; Jiangsu and Guangdong showed higher increasing trends. The Normalized Difference Vegetation Index (NDVI) was the primary driver of spatial variability in carbon stock change (q = 0.63), followed by precipitation and temperature. Synergistic interactions were also detected, e.g., NDVI and precipitation, enhancing the effects beyond those of single factors, which indicates that a wetter climate may boost NDVI’s carbon sequestration. These findings highlight the urgency of strengthening ecological red lines, scaling climate-smart restoration of mangroves and salt marshes, and promoting low-impact mariculture. Our workflow and driver diagnostics provide a transferable template for blue carbon monitoring and evidence-based coastal management frameworks.

Southeastern coastal China is sensitive to climate change and is characterized by an advanced economy and aging population. The region faces substantial exposure and vulnerability under climate change, making it a potential hotspot for Compound Heat-Drought Events (CHDEs). Therefore, in this study, we used multi-model integrated prediction data from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to simulate different climate change scenarios, along with the standardized precipitation evapotranspiration index (SPEI), sliding threshold method, and Copula joint probability distribution to define drought, heat, and compound events, respectively. Additionally, we aimed to analyze the temporal and spatial patterns of future CHDE hazards in southeastern coastal China under various climate change scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) and during different periods (2021-2040, 2041-2060, and 2081-2100). To further understand the lag effect of heat events on drought, we applied a lagged logistic regression model to quantify the attributable fraction (AF) for delays ranging from 1 to 7 days. In particular, we used the CN05.1 high-resolution gridded daily observation dataset to compare and analyze CMIP6 model prediction data, verifying their applicability to the study area and the accuracy of the prediction results. Our results indicate that CHDE hazards (number of occurrence days, intensity, and duration) in southeastern coastal China are expected to increase in the future, with a faster increase under the SSP5-8.5 scenario than under the SSP1-2.6, SSP2-4.5, and SSP3-7.0 scenarios. The intensity is projected to increase faster than the number of occurrence days and duration. Under the SSP5-8.5 scenario, the CHDE intensity at the end of the 21st century is projected to reach 3.41 times that during the baseline period (1995-2014), while the corresponding occurrence days and duration are projected to be 1.74 and 1.61 times those of the baseline period, respectively. This indicates that the probability of high-intensity CHDEs is expected to increase significantly considerably in the future. As for the spatial pattern, the spatial heterogeneity of the hazards (occurrence day, intensity, and duration) was more pronounced under the SSP5-8.5 scenario than under the other scenarios, especially during 2081-2100. Under the SSP5-8.5 scenario, the combined hazard indexes exceed 0.6 in southeastern Fujian, eastern Zhejiang, Jiangsu, and Shanghai, with some areas having indexes as high as 0.9. Spatial variability was shaped by factors such as distance from the coastline, availability of water resources, land use patterns, and human activities. Notably, the spatial heterogeneity in the CHDE duration was significantly greater than that in the occurrence days and intensity. Under the SSP5-8.5 scenario, the CHDE duration was approximately 2.23 times higher in the high-value areas than in the low-value regions, whereas the differences in occurrence days and intensity were smaller, at 1.13 and 1.11 times, respectively. This highlights the urgent need for regional adaptation strategies that focus on the persistence of CHDEs. The lagged effect of heat on drought events in southeastern coastal China exhibits an east-west sea-land gradient, with differences between the northern and southern areas. Specifically, the lag effect gradually intensifies from the inland to coastal regions. This may be attributed to the fact that coastal regions are influenced by the combined impact of heat on both the land and ocean and are more likely to experience delayed droughts. In the north-south divergence, northern Jiangsu experienced a stronger influence of heat on subsequent droughts than the other areas. This is primarily because of its predominantly dryland environment, which is highly vulnerable and in which heat events are more likely to trigger drought events. Under the SSP5-8.5 scenario, the AF value exceeded 5% in the northeastern Jiangsu coastline, eastern Zhejiang coastline, and Shanghai, with lag times of up to 7 days in some areas. This indicates that heat events will have a prolonged effect on subsequent droughts. These results provide a scientific foundation for policymakers to formulate effective disaster prevention and mitigation strategies tailored to their regional needs. Furthermore, they support decision making to promote a climate-adapted society and contribute to sustainable development.

Compound climate extremes, such as compound heat and drought events (CHDEs), in combination with population growth and aging, pose a growing risk to the socioeconomic system. However, the potential risks of frequent and intense CHDEs under climate change on group-specific populations and the advantages of achieving carbon neutrality in reducing CHDE damage have not been extensively explored. Our research quantified total and group-specific population exposure to CHDEs in four future scenarios in China and examined the benefits of carbon neutrality. Results show total population exposure to CHDEs will increase significantly in all scenarios, reaching a maximum of 540.55 f 125.52 x 108 person-days in 2081-2100 under shared socioeconomic pathways (SSP) 3-7.0, 3.93 f 0.91 times that of the base period (1995-2014). Exposure in southeastern China, particularly in Shandong, Hebei, Henan, and Jiangsu, is much higher than in inland northwestern China. The increase in exposure for the elderly is higher than that of children and working-age population, with the maximum value reaching 175.84 f 33.71 x 108 person-days, 9.57 f 1.83 times compared to the base period. Achieving carbon neutrality under SSP1-2.6 is projected to significantly reduce total population exposure by 72-84% in the late 21st century (2081-2100) than other scenarios in the same period. The reduction rate for the elderly ranges from 41% to 61%, which is less substantial than for children or working-age population. The effect of climate change is the primary factor in reducing exposure to the total population, children, and working-age population, while its interactive effect with population is the dominant contributor (53-56%) for the elderly. Thus, efforts to achieve carbon neutrality are urgently needed in China to reduce the number and inequality of the population exposed to CHDEs. Special attention should be paid to the elderly, who are particularly vulnerable and disproportionately affected by CHDEs.

Recent research highlights growing risks of compound extremes, such as compound heat and drought extremes (CHDEs), which are likely to increase as climate change progresses. Combined with population growth and aging, CHDEs pose a significant threat to the population system. However, the quantification of its potential risk considering the varied responses of different population groups, remains limited. Focusing on the coastal provinces of China-regions heavily impacted by climate change and intensive human activities, we quantified population exposure to CHDEs considering different global warming thresholds (1.5 degrees C, 2.0 degrees C, and 3.0 degrees C). Our results show population exposure to CHDEs in coastal China will increase significantly under three scenarios, with the maximum increase being 2.75 f 0.40 times in the 3 degrees C scenario compared to the base period (1995-2014). Exposure in northern coastal China, such as Shandong, Jiangsu, and southern Hebei, is much higher than in southern coastal China. Exposures for children, working-age population, and the elderly are all projected to increase, with the most significant increase for the elderly in both percentage and absolute values. In the 3.0 degrees C scenario, elderly exposure will be nearly 9-fold greater than the base period, accounting for over 40 % of total exposure. The climatic effect is the dominant contributor (68 %-85 %) to future exposure changes. Our study indicates that global warming beyond the Paris Agreement target will significantly increase population threatened by CHDEs and exacerbate exposure inequality. Adaptation and mitigation strategies are urgently needed in coastal China, especially for the elderly, who are susceptible and bear a disproportionately heavy burden from CHDEs.

The performance of CMIP6 models in simulating freshwater content (FWC) in the Beaufort Gyre remains unclear. This study evaluated 17 CMIP6 models using both observational and reanalysis datasets. Additionally, a global ice-ocean coupled model based on Finite Volume Community Ocean Model (Global-FVCOM) was incorporated for reference. The results revealed a significant inter-model spread among the CMIP6 models in spatiotemporal variations of FWC, with discrepancies relative to the evaluation data that were larger than those exhibited in Global-FVCOM. These discrepancies were primarily attributed to simulation errors of the salinity structure within the CMIP6 models. Over half of the models indicated that the primary source of FWC error originated from the layers above the base of halocline, where most models underestimated FWC, while others suggested the error originated from the layers between the base of the halocline and the 34.8 psu isohaline, where models tended to overestimate FWC. Based on an overall evaluation using observational and reanalysis datasets, EC-Earth3, MRI-ESM2-0, and FIO-ESM-2-0 showed better performance relative to other CMIP6 models. However, these three models, along with the multi-model mean, exhibited larger errors than Global-FVCOM, suggesting that current CMIP6 models still face challenges in FWC simulation relative to some ice-ocean coupled models. The main aspects contributing to the errors, including discrepancies in uncertainties induced by internal variability, numerical configurations, vertical mixing schemes, model resolutions, freshwater inputs, and atmospheric forcings were further discussed in this study. This study enhances understandings of CMIP6 models’ capabilities to simulate FWC in the Beaufort Gyre region, providing valuable insights for future model improvements.

Reed wetlands in Weishan County, Shandong provinces, are typical and representative wetland ecosystems with exceptional carbon sequestration potential. Evaluating the spatial and temporal characteristics of land use and carbon stock in these reed wetlands, and exploring their carbon sink value is crucial for climate change mitigation and adaptation, and provides a potential to use reed wetlands as a solution for carbon neutrality in China. Using Sentinel active and passive remote sensing data within the Google Earth Engine (GEE) platform, we employed the random forest classification method to identify the land use features in Weishan County. By combining these data with carbon density data obtained from bibliometric sources and the InVEST model, we evaluated the spatial and temporal dynamics of carbon stock in the reed wetlands as well as other land use types. The results indicated that optical data are more effective than radar data for land use classification, achieving the mean value of the overall accuracy of 89%. Reed wetlands contribute significantly to carbon stock, accounting for 28% of the total carbon stock in Weishan County. Other major contributors include forest, water body, agricultural land, artificial land, unused land, and mudflat land. The highest concentration of carbon stock is found along the shores of the four lakes and in the northeastern mountainous areas of Weishan County. The carbon stock capacity of the reed wetland in Weishan County is expected to generate a carbon sink value of 4.95–54 × 10 8 RMB, up to 1%–12% of the county’s GDP. These findings provide a scientific foundation for subsequent reed restoration and management efforts and offer valuable insights for developing relevant carbon neutrality strategies.

Compound extremes, such as heat-drought compound extremes (HDCEs), are intensifying with climate change, posing escalating risks to coastal economies. In coastal China, where rapid socioeconomic development intersects with increasing climate hazards, coastal governance faces growing challenges in managing such compound risks. However, limited research has quantified the economic exposure to HDCEs under various warming scenarios, which is crucial for guiding adaptive governance and sustainable coastal development. This study quantifies sectoral economic exposure to HDCEs under 1.5 degrees C, 2.0 degrees C, and 3 degrees 0 C global warming scenarios, using multi-model climate ensemble and gross domestic product (GDP) projections from the SSP-RCP framework. Results show that total GDP exposure in coastal China in three warming scenarios will increase by 12.54 f 0.63, 15.38 f 1.83, and 61.64 f 8.73 times, respectively, relative to the base period (1995-2014). Notably, northern coastal China exhibits much higher exposure than eastern and southern regions, and the tertiary sector is projected to face the largest increase, reaching up to 125.05 f 17.70 times under the 3.0 degrees C scenario. The dominant contribution (48 %-71 %) to exposure increase stems from the interactive effect between climate and GDP change. By linking these findings to sustainable development goals (SDGs) like SDG8 (Decent work and economic growth) and SDG13 (Climate action), this study provides actionable insights for strengthening adaptive coastal governance. We underscore the urgency of prioritizing the tertiary sector and high-exposure regions in climate adaptation plans. These results contribute to the growing body of scholarship that supports climate-resilient, sector-specific, and globally relevant coastal governance strategies.

BACKGROUND:Food consumption patterns are significant drivers of environmental burdens, prompting increasing interest in dietary transitions. The possibility of adjusting animal-based dietary patterns with different consumption compositions, and the consequent large environmental implications considering the evolution of society and ecosystems in different shared socioeconomic pathways (SSPs), however, have rarely been quantified. Furthermore, their connections with sustainable development goals (SDGs) require clearer elucidation. Taking into account the various eating habits among different groups of people in different regions, we systematically quantified the future consumption of animal-based foods with and without a dietary transition to the healthy pattern and their environmental footprints in China under SSPs 1-5 in 2030 and 2060. RESULTS:Historically, meat consumption in China, dominated by pork, exceeded 66.48% of the recommendations for a healthy dietary pattern. The shift in dietary patterns would greatly increase the demand for aquatic products in the future, reaching a maximum of 1445.61 × 104 t in SSP3 by 2060 (87.36%). The animal-based dietary transition to recommendations would embody environmental benefits by reducing the footprints of carbon, water, land, and nitrogen (by 3.80-10.45%, 5.84-14.46%, 15.83-23.18%, and 0.75-9.49%, respectively) in SSPs in China. A dietary transition would also benefit achieving SDGs from natural and socioeconomic aspects, like SDGs 2 (Zero hunger), 3 (Good health and well-being), 13 (Climate action), and 15 (Life on land). CONCLUSION:Dietary transitions to more aquatic products offer a promising pathway to sustainably nourish the growing population while limiting damage to the planet's integrity. © 2025 Society of Chemical Industry.

A halocline in the Arctic Ocean significantly slows the upward heat flux from deep warm water,thereby inhibiting the melting of surface sea ice.The western Arctic Ocean exhibits a double-halocline(DH)structure due to the complexity of the water mass.Using in situ measurements,we analyzed the vertical structural characteristics of DH and its interannual variation.The results indicated that the DH primarily occurs at the Northwind Ridge and the southern Canada Basin,extending westward to the Chukchi Abyssal Plain and northward to the northern boundary of the Canada Basin.From 2002 to 2022,there were changes in water masses that determined the structure of the DH.The significant increase in Pacific Water has resulted in 42%and 65%increases in freshwater and the heat content of the DH,respectively,along with a 14%reduction in stratification.Pacific Winter Water characterized by salinity of 33 has exhibited a gradually decreasing trend,suggesting that the lower halocline may be difficult to ventilate.The combined effects of Ekman pumping,mesoscale eddies,and positive buoyancy forcing(heat and freshwater input)from Pacific Water have altered the thickness and stratification of the DH.This study has enhanced our understanding of the evolution of vertical heat flux in the upper western Arctic Ocean.

Storm surges caused by tropical cyclones (TCs) have long ranked first among all types of marine disasters in casualties and economic losses, and can lead to further regional exacerbation of consequences stemming from these losses along different coastlines. Understanding the spatial footprints of storm surges is thus highly important for developing effective risk management and protection plans. To this end, we designed an ideal storm surge model based on Finite Volume Community Ocean Model to explore the relationship between TC intensity and the spatial footprint of storm surges, and its intrinsic mechanism. The spatial footprints of both positive and negative storm surges were positively correlated with TC intensity; however, the latter was more sensitive to the intensity when the TC intensity is weaker than CAT3 TC’s. The average positive storm surge footprint of CAT1 was 574 km, with CAT3 and CAT5 increasing by 6% and 25%, respectively, compared to CAT1. The average spatial footprint of the negative storm surge of CAT1 was 1407 km, with CAT3 and CAT5 increasing by 18% and 29%, respectively, compared to CAT1. The decomposition and mechanism analysis of the storm surge show that the main contributing component of the total surge at the south end of the storm’s landfall and during the time of the forerunner was the Ekman surge, whereas the contribution of the normal surge component to the north and during the time of the main surge and resurgence was dominant. In addition, not all the spatial footprints of the storm surge components increased with the TC intensity, as the total surge did, similar to the Ekman surge. These quantitative analyses and intrinsic mechanisms provide a theoretical basis for predicting and evaluating storm surge risks.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a large class of toxic contaminants. Nutrients are closely related to the ecological health of aquatic systems. Both have received widespread global attention. This study investigated the concentrations, compositions, and spatial distributions of PFAS and nutrients in surface water from two constructed wetlands and the nearby drinking water treatment plants (DWTPs). We explored the natural environmental factors and human activities that affect the composition and distribution of pollutants in wetlands and assessed the ability of the DWTPs to remove contaminants. Concentrations of ∑32PFAS varied from 153 to 405 ng/L. Hexafluoropropylene oxide trimer acid (HFPO-TA) was the predominant substance accounting for 45% of ∑32PFAS concentrations. It might originate from the emissions of indirect sources of PFAS related manufacturers. The detection rate of 6:2 fluorotelomer carboxylic acid (6:2 FTCA) was 100% with concentrations ranging from 0.915 to 19.7 ng/L. 6:2 FTCA might come from the biotransformation of indirect sources in the air. Concentrations of total nitrogen (TN) and total phosphorus (TP) were from 1.47 to 3.54 mg/L, and non-detect (ND) to 0.323 mg/L, respectively. Constructed wetlands could effectively remove PFAS under nutrient stress, however, the removal of PFAS depends on the characteristics of specific compounds and their sources. The removal rates for PFAS and nutrients could be promoted through artificial dredging. But wetland bioremediation could have two opposing effects. On the one hand, plants can take up pollutants from water via roots, leading to pollutant removal and purification. On the other hand, plants may also absorb precursor intermediates from the air through leaves and release them into the water, leading to increased pollutant concentrations. Thirty-two emerging PFAS were identified by high resolution mass spectrum. The drinking water treatment process removed PFAS and nutrients below the drinking water quality standards of China, however, 9 non-target PFAS compounds were still found in tap water. These results provide case support and a theoretical basis for the pollution control and sustainable development of typical ecological wetlands used as drinking water sources.

针对近地表细颗粒物含量的卫星遥感精度问题,系统提出了"偏振交火"的卫星遥感策略和模型,开发了高精度偏振扫描仪(POSP)和多角度偏振成像仪(DPC)双偏振载荷套件,装载在大气环境监测卫星上并成功发射.本文在介绍"偏振交火"原理的基础上,系统论述了载荷工程的实现方法和在轨应用方法,初步展示和评估了在轨应用效果.在轨初步应用结果显示:双偏振载荷间能够实现稳定交火工作,视场匹配精度优于0.077 POSP像元;基于L1级数据初步开展了双偏振载荷间的辐射和偏振交叉定标/验证,共有波段拟合优度(R2)分别达到0.999和0.993;基于"偏振交火"载荷观测数据融合反演的近地表PM2.5与地基网络监测结果的相关性为0.684,偏差落在期望误差(EE)范围内的比例为88.36%.初步在轨结果达到了预期应用目标,显示了"偏振交火"方案在气溶胶污染监测方面的应用潜力.

Deep-lake (reservoir) ecosystems provide valuable ecosystem services (ES) and generate significant ecosystem service values (ESV); however, reservoir ecosystems have suffered great losses from environmental changes and human activities. Currently, studies on ES and its correlations with stressors remain insufficient and the integration of ES into ecological restoration and management poses numerous challenges. Here, we combined four types of stressors with six ES closely related to human well-being to discuss their interactions in Qiandao Lake (a representative deep lake in China). Our results indicate that all ESV showed a consistent growth trend throughout the study period, reaching 5203.8 million CNY in 2018, and the cultural service value surpassed the provisioning service value for the first time in 2004. Almost all the ESV were limited during the cyanobacterial bloom in Qiandao Lake. Redundancy analysis and partial least squares structural equation modeling jointly revealed that socioeconomic development was the most important direct driver of the increase in ESV (0.770) and that hydro-meteorological conditions (0.316) and pollutant loads (0.274) positively affected ESV by mediating lake trophic status. The trophic status of the lake is the result of the interaction of multiple stressors, which has a negative impact on ESV. Therefore, to continuously protect the provisioning and cultural service values of deep-lake ecosystems from damage, the government must rationally formulate SED goals and reduce pollutant loads during lake development, operation, and utilization. This work provides valuable insights into the interactions between ES, which are closely related to human well-being, and stressors in deep-lake ecosystems.

Mesoscale eddy dipoles are oceanographic structures that can transport ocean water parcels horizontally and vertically in ways that differ from individual mesoscale eddies. The most conspicuous additional feature that presents in dipoles is the cold filament (CF) that can be spontaneously generated between a dipole’s anticyclonic eddy (AE) and cyclonic eddy (CE). A case study in this paper shows that the interaction between the CF and the CE component of the dipole is associated with the structural evolution of the dipole. This interaction is verified in synthesis and normalization studies of the CF dipoles. The CF-dipole interaction entrains CF water into the center of the dipole’ CE and leads to a cold and high chlorophyll center in the upper layer of the CE. The formation of this cold center changes the dipole’s structure by eliminating the phase difference between the thermal and dynamic centers of the dipole. The entrainment also provides a new mechanism for the development of high chlorophyll levels in the CE. In the analysis of the HYCOM (Hybrid Coordinate Ocean Model) simulation of a synthetic CF dipole, the AE has a three-zone structure while the CE only has two. The convergence of the CE’s outermost zone results in a biased interaction.