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As on land, oceans exhibit high temporal and spatial temperature variation. This ocean weather contributes to the physiological and ecological processes that ultimately determine the patterns of species distribution and abundance, yet is often unrecognized, especially in tropical oceans. Here, we tested the paradigm of temperature stability in shallow waters (

A global inventory of extractive species mariculture in wave-exposed temperate waters shows that the longline is the technology used in more than 99% of the sites (Part 1 of this review). In this second part, I compare the static (longline at rest), quasi-static (tidal sea surface elevation, steady currents and mainline lifting operation) and dynamic (wind seas and swells) loading and motion of surface, semi-submerged and fully submerged longlines used to grow bivalves and kelp. This review is based on a hundred papers published on the subject mostly after 2010 and on simple analytical models used to illustrate the many compromises that must be made to ensure the survivability of the structure and the survival (retention), growth and quality of the cultured biomass. Surface longlines are unsuitable for fully exposed environments. To mitigate storm energy it is necessary to minimize the volume of surface buoys and submerge the mainline to the maximum depth possible. There is however a limit to minimizing the volume of surface buoys due to the uplifting of the mainline by currents. In the case of kelp, its optimal growing depth is within a few meters from the sea surface. This limitation can be partly circumvented by having the kelp float above the mainline. In the case of bivalves, mainline depth can be tens of meters below the sea surface. This comes with some disadvantages including difficulties in maintaining the delicate buoyancy balance, particularly for fully submerged longlines without legs, and reduced access to the mainline, particularly for fully submerged longlines with legs. Devices that allow autonomous or remote-controlled changes of mainline depth on a daily, occasional (husbandry and harvest operations) or seasonal basis have been tested but are not yet used commercially on longlines. [ABSTRACT FROM AUTHOR]

This study developed a method to evaluate the effective spatial resolution of sea surface temperature (SST) data produced from observations of a microwave radiometer on satellites. The method was applied to 7-year SST data from the Advanced Microwave Scanning Radiometer 2 (AMSR2) on the Japan Aerospace Exploration Agency's (JAXA) Global Change Observation Mission-Water (GCOM-W) satellite. JAXA has produced three SST products from AMSR2 observations: standard SST, 10-GHz SST, and multi-band SST. They differ in spatial resolution because the frequency used to retrieve the SST has different footprint sizes, although the resolution has not been evaluated so far. We utilized high-resolution infrared SST data from the geostationary meteorological satellite Himawari-8. The Himawari SST was spatially smoothed by a Gaussian function to identify the smoothing scale that most accurately reproduces the AMSR2 SST gradient fields in the same area and time. The similarities between the Himawari and AMSR2 SST gradient fields were assessed using three metrics. The correlation coefficient provided a stable and robust estimate against the noise included in the AMSR2 SSTs. As a result, the effective resolution was estimated at 67 km for the standard SST, 52 km for the 10-GHz SST, and 63 km for the multi-band SST. These are all larger than the nominal resolution expected from the AMSR2 footprint size. The 10-GHz and multi-band SSTs had significantly higher resolutions than the standard SST. [ABSTRACT FROM AUTHOR]

Sea surface temperature (SST) is a key variable in the study of the global climate system and one of the important parameters in the process of air–sea interaction. Therefore, the demand for SST is developing towards high quality and high precision. In this paper, the ability of the multi-layer perceptron (MLP) optimized by the Aquila optimizer (AO) to solve nonlinear problems and the advantages of the deep belief network (DBN) to effectively process complex data are used to construct the IMLP-DBN inversion algorithm. The algorithm takes into account the influences of atmospheric conditions and satellite zenith angles. The data set is the infrared remote sensing data of the moderate resolution imaging spectroradiometer (MODIS) and the actual measurement data of buoys on sunny days and few clouds. Analysis of the inversion results shows that the root mean square error (RMSE) of the inversion value and the measured value is 0.14, and the sum of square errors (SSE) is 0.78. Compared with the MOD28 product data, the RMSE and SSE of the inversion are reduced by 66% and 24%, respectively. [ABSTRACT FROM AUTHOR]

This study focuses on the interannual variability of summertime intraseasonal precipitation intensity (SIPI) over South China (SC) in the 30–90‐day range. The results demonstrate a significant increase in the interannual variability of SIPI over SC around the mid‐1990s. By comparing atmospheric and oceanic anomalies between two periods, P1 (1984–1993) and P2 (1994–2003), we identify that both the Silk Road pattern (SRP) and the western Pacific subtropical high (WPSH) play a role in influencing this interdecadal increase in SIPI interannual variability. These system anomalies are modulated by sea surface temperature anomalies (SSTA) in the North Atlantic (NA) and equatorial East Pacific (EP). During years with positive precipitation anomalies in P2, warming EP SSTA induces anomalous Walker cell and local Hadley cell, weakening the WPSH and enhancing convective activity, and increasing moisture transport over SC. The warming NA SSTA near 45°N triggers a more southerly propagation of SRP, thereby providing additional disturbance energy that enhances summer precipitation over SC. Conversely, during years with negative precipitation anomalies in P2, these processes occur in reverse. The enhanced interannual variability of local convective activity from P1 to P2 leads to a corresponding increase in the interannual variability of the WPSH, which, coupled with an amplified interannual variability of SRP, results in heightened interannual variability of SIPI. Additionally, the composite analysis of 30–90‐day ISO events further substantiates the underlying mechanisms driving the interdecadal amplification of SIPI interannual variability. Diagnostic results reveal that the 30–90‐day horizontal wind induces heightened convergence of background moisture over SC. Plain Language Summary: Precipitation in South China is prevalent and primarily occurs from April to September, leading to significant enormous economic losses and casualties due to flood disasters almost every year during this period. Influenced by the East Asian summer monsoon, summer precipitation in South China exhibits diverse variabilities at multiple scales, including interdecadal, interannual, intraseasonal and synoptic variability. Moreover, the intraseasonal variability of precipitation in South China holds great importance for extended‐range forecasting and has been extensively investigated. With in‐depth research, it has been revealed that there are also significant physical laws governing the long‐term variations in intraseasonal precipitation. This study focuses on investigating the interdecadal changes in the interannual variability in summertime intraseasonal precipitation intensity over South China during the past four decades and exploring the potential underlying mechanisms. The findings can enhance our comprehension of the mechanisms driving long‐term variations in intraseasonal precipitation pattern in South China. Key Points: The interannual variability of 30–90‐day summer intraseasonal precipitation over South China exhibited an increase in the mid‐1990sThe Silk Road pattern (SRP) and the western Pacific subtropical high (WPSH) primarily contribute to this increaseThe occurrence of SRP and WPSH anomalies is modulated by SST warming in the North Atlantic and the equatorial East Pacific, respectively [ABSTRACT FROM AUTHOR]

The South American summer monsoon (SASM) generates important hydroclimatic impacts in (sub‐)tropical South America and isotopic tracers recorded in paleoclimatic archives allow for assessing its long‐term response to Pacific variability prior to modern observations. Stable oxygen isotopes in precipitation integrate hydroclimatic changes during the SASM mature phase from December to February (DJF) in response to the Interdecadal Pacific Oscillation (IPO) and El Niño—Southern Oscillation (ENSO), respectively. Here, results from the isotope‐enabled Community Atmosphere Model v.5 are compared with highly resolved and precisely dated isotopic records from speleothems, tree rings, lake and ice cores during the industrial era (1880–2000 CE) and validated against observations from the International Atomic Energy Agency (IAEA) network. Pacific sea surface temperatures (SSTs) are coupled to the isotopic composition of SASM precipitation through perturbations in the Walker circulation associated with low‐ (IPO) and high‐frequency (ENSO) variability, impacting convective activity over tropical South America and the tropical Atlantic. Changes in convection over this monsoon entrance region ultimately control the downstream oxygen isotopic composition of precipitation recorded in paleoclimate archives. Overall, model results, paleoclimate records and IAEA data agree on the isotopic response to Pacific SST forcing. These results highlight the potential for long isotopic paleoclimate records to reconstruct Pacific climate variability on both high‐ and low‐frequency timescales. Furthermore, the isolation of the IPO signal in a diverse set of isotopic archives invites the reinterpretation of other paleoclimate proxies for identifying this historically overlooked forcing. Plain Language Summary: The summertime rainfall associated with the South American monsoon is important for the hydropower and agricultural sectors in South America as well as to the traditions of many Amazonian indigenous cultures. The amount and spatial extent of the monsoon rainfall patterns are influenced by a variety of factors, including changes in Pacific Ocean sea surface temperatures. While evaluating this link has been mostly limited to meteorological observations, the analysis of heavy and light oxygen atoms, called isotopes, in natural archives such as cave deposits, lake sediments, glacier ice, and tree rings, can help extend this relationship further back in time. In combination with climate models, the ratio between heavy and light isotopes can provide insight for the link between the Pacific Ocean and South American water cycle changes on interannual to multidecadal timescales. This allows us to better understand how the Pacific has influenced the South American monsoon in the past. It also allows us to better define the range of natural climate variability against which future changes can be compared. Key Points: South American summer monsoon variability is influenced by multidecadal and interannual variability of Pacific sea surface temperaturesPaleoclimate records combined with climate model synthesis enhance the interpretation of Pacific Ocean–South America teleconnectionsThe development of new paleoclimate records in South America can be informed by the archived signals of Pacific multidecadal variability [ABSTRACT FROM AUTHOR]

The historical global temperature record is an essential data product for quantifying the variability and change of the Earth system. In recent years, better characterization of observational uncertainty in global and hemispheric trends has become available, but the methodologies are not necessarily applicable to analyses at smaller regional areas, or monthly or seasonal means, where station sparsity and other systematic issues contribute to greater uncertainty. This study presents a gridded uncertainty ensemble of historical surface temperature anomalies from the Goddard Institute for Space Studies (GISS) Surface Temperature (GISTEMP) product. This ensemble characterizes the complex spatial and temporal correlation structure of uncertainty, enabling better uncertainty propagation for climate and applied science in applications of historical temperature products at spatial scales from global to regional and temporal scales from centennial to monthly. This work details the methodology for generating the uncertainty ensemble, presents key statistics of the uncertainty evolution over space and time, and provides best practices for using the uncertainty ensemble in future studies. Summary statistics from the uncertainty ensemble agree well with the previous GISTEMP global uncertainty assessment, providing confidence in both. Plain Language Summary: NASA's historical surface temperature product, GISTEMP, combines measurements of sea surface temperature and land surface air temperature to estimate how temperature has changed on Earth since 1880. In this study, we combine all known sources of uncertainty in these measurements to determine the best estimate as well as the likely interval for surface temperature in the global average as well as on a latitude‐longitude grid. Results agree with previous uncertainty assessments of GISTEMP as well as uncertainty assessments of other major global temperature products. The uncertainty is quantified through an uncertainty ensemble, or 200 equally likely reconstructions of monthly mean surface temperature. This uncertainty ensemble makes it easy to incorporate the uncertainty in surface temperature in subsequent studies. Key Points: A 200‐member ensemble has been created to quantify uncertainty in the GISTEMP history of surface temperature anomaliesThis ensemble enables more accurate statistical analyses of key global change metricsThe median ensemble estimate agrees well with the operational GISTEMP analysis and other global products [ABSTRACT FROM AUTHOR]

The parameterizations of air‐sea turbulent heat flux are one of the major bottlenecks in atmosphere‐ocean coupled model development, which play a crucial role in sea surface temperature (SST) prediction. Recently, neural networks start to be applied for the development of parameterizations of interface turbulent heat flux. However, these new parameterizations are primairily developed for specific regions and have not been tested in real atmosphere‐ocean coupled models. In this study, we propose a new air‐sea heat flux parameterization using a physical‐informed neural network (PINN) based on multiple observational data sets worldwide. Evaluated with an independent observation data set, it is shown that the PINN can significantly reduce the RMSE of latent heat flux by at least about 48.6% compared to three traditional bulk formulas. Moreover, the PINN can be flexibly updated with new observational data by transfer learning. To test the performance of the new parameterization in realistic application, we implement the PINN into a global ocean‐atmosphere coupled model and make seasonal forecasts for the first time. The PINN markedly reduce the errors of equatorial SST forecast, indicating a good performance of the PINN‐based air‐sea turbulent heat flux scheme. Noticeably, due to limited observational data, the NN‐based parameterizations tend to underestimate heat flux at high wind speeds compared with bulk formula‐based parameterizations. With more data available at extreme conditions, the PINN can be improved via transfer learning and need to be futher evaluated. This study suggests that PINN‐based air‐sea heat flux parameterization is promising to improve SST simulation. Plain Language Summary: The air‐sea turbulent heat flux plays a crucial role in advancing marine science and is the key to improving the accuracy of the sea surface temperature (SST) prediction. The traditional parameterizations for air‐sea turbulent heat flux have large deviations in some circumstances and are hard to update since they are developed based on unique observation datasets. The emergence of artificial intelligence offers a fresh avenue to address this issue. In this study, we develop air‐sea heat flux parameterization based on a PINN and multiple observational data sets, which measured air‐sea heat fluxes directly. Our novel parameterization outperforms three bulk formula‐based parameterizations in offline tests and solves the problem of unphysical result of neural networks. The new parameterization also shows great potential in improving the accuracy of SST prediction in multiple online tests. Key Points: We propose a new air‐sea turbulent heat flux parameterization based on physical‐informed neural network (PINN) which is trained on data in situThe new scheme can accurately calculate the air‐sea turbulent heat flux and perform well in a global seasonal forecastThe PINN can be flexibly updated with new observational data by transfer learning [ABSTRACT FROM AUTHOR]

Stratospheric temperature perturbations (STPs) caused by for example, variations in stratospheric ozone, are an important driver of changes in tropospheric dynamics, particularly pertinent to the long‐term climatic evolution of the Southern Hemisphere. However, the impact of ocean feedbacks on this interaction has not been fully examined. To study it, positive STPs were applied in three otherwise identical, idealized model configurations –atmosphere‐only (A), atmosphere + slab‐ocean (AS), and fully‐coupled atmosphere‐ocean (AO)–and the resulting atmospheric changes compared. In the AO model, changes in the tropics (extratropics) experienced a poleward‐expansion (shift) and positive (negative) feedback after ∼100–200 years, whilst the AS model showed atmospheric and sea surface temperature changes that did not resemble those seen in the AO model. In the AO model, changes in tropical ocean heat content were responsible for the atmospheric changes, attributable to changes in the Ekman transport. These results indicate that full atmosphere‐ocean coupling should be accounted for when studying the long‐term (100+ years) tropospheric response to STPs in the Southern Hemisphere. Validation with higher‐resolution and more realistic models is necessary. Plain Language Summary: In recent decades, the Southern Hemisphere has seen significant climatic changes in response to stratospheric ozone depletion. It is important to understand what impact oceanic feedbacks might have on this response. To that end, experiments were performed, in which temperature perturbations were applied to the stratospheres of three otherwise identical atmospheric models–with/without oceans present–and their results compared. Ocean feedbacks were found to significantly amplify (weaken) and expand (shift) the atmospheric responses toward the poles in the tropics (extratropics) after about 100–200 years. This was caused by wind‐driven changes in sea surface temperatures in the tropics. These results underscore the importance of accounting for oceanic feedbacks when studying long‐term (100+ years) climatic changes, caused by stratospheric changes, in the Southern Hemisphere. However, further verification of these results with higher‐resolution and more realistic models will be necessary to ensure their applicability, and to better quantify their effects. Key Points: Ocean feedbacks significantly alter the atmospheric response to applied stratospheric temperature perturbations after 100–200+ yearsChanges in the tropical and midlatitude ocean heat content, driven by alterations to the Ekman transport, are responsible [ABSTRACT FROM AUTHOR]

Future projections indicate that Indian Summer Monsoon Rainfall (ISMR) faces a "wetter and more variable" climate. However, the reasons remain uncertain. The Last Interglacial (LIG) climate provides a potential analog for future warming. Investigating ISMR responses to these two warming scenarios could help understand the causes of ISMR changes. Using PMIP4 simulations, we find that ISMR became "wetter and more stable" during the LIG, contrasting the future climate. The opposing changes in ISMR variability are related to divergent changes in the El Niño‐Southern Oscillation (ENSO) amplitudes, ENSO‐ISMR relationships, and ENSO‐induced large‐scale atmospheric circulation anomalies. During the LIG, orbital forcing weakened ENSO variability and its impacts on ISMR. A westward positioning of ENSO shifted the atmospheric circulation anomalies westward, suppressing extreme ISMR anomalies. These processes are supported by atmospheric model simulations. Our results suggest that different warming patterns (dynamic effects) are more critical than moisture‐increasing effects in controlling regional climate variability. Plain Language Summary: The Last Interglacial (LIG), approximately 129,000 to 116,000 years before the present, is a potential analog for future warming. We found that the variability of Indian Summer Monsoon Rainfall (ISMR) decreased while its mean state increased during the LIG, which is a "wetter and more stable" climate. This contrasts with the simultaneous increase in both the mean state and variability of ISMR projected in future warming scenarios. The opposing changes in ISMR variability during these two warm periods can be attributed to reverse changes in El Niño‐Southern Oscillation (ENSO) variability and its associated large‐scale circulation. During the LIG, reduced ENSO variability weakened the ENSO‐ISMR relationship. Sea surface temperature anomalies associated with ENSO extended westward in LIG, shifting precipitation and associated heating‐induced atmospheric circulation anomalies westward, which weakened the extreme ISMR anomalies, thus making the ISMR variability stable. This process is further supported by atmospheric general circulation model (CAM5) experiments. Our findings suggest that different external forcing‐induced warming patterns (dynamic effects) can be more critical than moisture‐increasing effects in contributing to regional climate variability change. Key Points: Indian Summer Monsoon Rainfall (ISMR) experienced a more stable climate during the LIG opposite to the change under anthropogenic warmingRelationship between ISMR and ENSO significantly weakened due to the waning ENSO variability induced by orbital forcingA westward positioning of ENSO during the LIG shifted the anomalous large‐scale circulation westward, reducing the extreme ISMR anomalies [ABSTRACT FROM AUTHOR]

The capability to anticipate the exceptionally rapid warming of the Northwest Atlantic Shelf and its evolution over the next decade could enable effective mitigation for coastal communities and marine resources. However, global climate models have struggled to accurately predict this warming due to limited resolution; and past regional downscaling efforts focused on multi‐decadal projections, neglecting predictive skill associated with internal variability. We address these gaps with a high resolution (1/12°) ensemble of dynamically downscaled decadal predictions. The downscaled simulations accurately predicted past oceanic variability at scales relevant to marine resource management, with skill typically exceeding global coarse‐resolution predictions. Over the long term, warming of the Shelf is projected to continue; however, we forecast a temporary warming pause in the next decade. This predicted pause is attributed to internal variability associated with a transient, moderate strengthening of the Atlantic meridional overturning circulation and a southward shift of the Gulf Stream. Plain Language Summary: The Northwest Atlantic Shelf is experiencing a rapid rise in ocean temperatures, one of the fastest globally, impacting the region's marine resources. Global coupled models struggle to accurately simulate this regional warming and have large uncertainties associated with the future evolution of this warming. To address this issue, we developed a high‐resolution decadal prediction system for the Northwest Atlantic Shelf which downscales global decadal predictions using a high‐resolution regional ocean model. The downscaled simulations accurately predict past oceanic variability and forecast a temporary pause in warming over the next decade due to natural changes in the Atlantic meridional overturning circulation and the position of the Gulf Stream. This predictive capability could pave the way for the implementation of effective mitigation strategies, benefiting coastal communities and marine resources alike. Key Points: Dynamical downscaling enhances decadal prediction skill of Northwest Atlantic Shelf sea surface temperaturesA temporary respite from rapid Northwest Atlantic Shelf warming is forecast for the coming decadeThe forecast warming pause is attributed to a modest strengthening of the Atlantic meridional overturning circulation [ABSTRACT FROM AUTHOR]

Existing approaches for predicting total water storage (TWS) rely on land surface or hydrological models using meteorological forcing data. Yet, such models are more adept at predicting specific water compartments, such as soil moisture, rather than others, which consequently impedes accurately forecasting of TWS. Here we show that machine learning can be used to uncover relations between nonseasonal terms of Gravity Recovery and Climate Experiment (GRACE) derived total water storage and the preceding hydrometeorological drivers, and these relations can subsequently be used to predict water storage up to 12 months ahead, and even exceptional droughts on the basis of near real‐time observational forcing data. Validation by actual GRACE observations suggests that the method developed here has the capability to forecast trends in global land water storage for the following year. If applied in early warning systems, these predictions would better inform decision‐makers to improve current drought and water resource management. Plain Language Summary: Traditional methods for predicting short‐term/seasonal variations in land total water storages rely on hydrological models. However, these models have a drawback—they are better at predicting water stored in specific parts of the land system like soil moisture than giving an accurate forecast for the overall integrated land total water storage. In this study, we demonstrate the applicability of machine learning in uncovering relationships between the de‐season and de‐linearized terms of global water storage variability as observed by the Gravity Recovery and Climate Experiment (GRACE) satellites, and the preceding hydrometeorological variables such as sea surface temperature. These relationships can then be utilized to forecast monthly changes in land total water storage up to 1 year ahead, and even to predict exceptional drought events based on near real‐time observational forcing data. The validation by actual GRACE observations, lends further credence to the effectiveness of the method developed here, showcasing its potential to forecast trends in global land total water storage for the upcoming year. The potential applications of these predictions in early warning systems are highly promising, and we anticipate that they can assist decision‐makers in enhancing current drought and water resource management practices. Key Points: We identify a stable lag relationship between hydrometeorological variables and the GRACE derived total water storage change (TWSC)Using this stable lag relationship, we are able to forecast the global TWSC up to 1 year ahead with solely observational data as inputsOur forecasts exhibit high consistency with actual GRACE data in terms of global mean land water storage trends for the following year [ABSTRACT FROM AUTHOR]

This study investigates why observed decadal‐scale climate variability is predominantly pronounced in the Niño4 region compared to other equatorial Pacific areas using both observation and model sensitivity experiments. The initial shift to the negative phase of Tropical Pacific Decadal Variability (TPDV) is primarily driven by the upward and eastward migration of isopycnal negative temperature anomalies along the equator. Subsequently, the wind fields associated with the negative phase of the Pacific Meridional Mode (PMM) induce anomalous vertical currents in the equatorial Pacific. This leads to anomalous upwelling and downwelling of mean temperature in the Niño4 and Niño3 regions, respectively, thereby strengthening and weakening the corresponding subsurface‐produced sea surface temperature anomalies. Our findings clarify the roles of subsurface temperature anomalies in the phase reversal of TPDV and PMM in amplifying decadal variance, specifically in the equatorial central Pacific. Plain Language Summary: Observations have consistently highlighted prominent decadal climate variability in the Niño4 region, yet the underlying cause of this distinct pattern remains largely elusive. In this study, we use composite analysis during the phase transition of Tropical Pacific Decadal Variability (TPDV) and modeling experiments to elucidate the mechanisms governing the observed decadal climate variability in the Niño4 region compared to other equatorial areas. Our findings reveal that the eastward and upward propagation of negative subsurface temperature anomalies primarily drives the phase reversal of TPDV. Following this transition from positive to negative phase, the Pacific Meridional Mode (PMM) plays a crucial role. Specifically, PMM‐associated wind forcing induces anomalous upwelling and downwelling in the Niño4 and Niño3 regions, respectively. This results in anomalous vertical advection of mean temperature, contributing to the strengthening and weakening of decadal variances in these regions. Key Points: Subsurface temperature anomalies initiate the phase reversal of TPDV while PMM plays a key role in equatorial SSTAs post‐transitionVertical heat advection is crucial in reinforcing/weakening decadal variance in the Niño4/Niño3 regionPMM‐associated wind fields induce anomalous vertical advection after the TPDV phase transition [ABSTRACT FROM AUTHOR]

We investigated the gastric evacuation rate (GER) and maintenance ration (MR) for the adult pointhead flounder Cleisthenes pinetorum (77–421 g) at 4°C, 9°C, and 14°C which reflect the bottom, middle, and surface temperatures of their habitat in early summer. GERs were obtained from gravimetric experiments with 34 flounders fed juvenile walleye pollock Gadus chalcogrammus as prey. A 169‐day feeding experiment for 67 pointhead flounders fed krill Thysanoessa inermis was undertaken to measure MR. The effects of a 10°C temperature increase (Q10) on the GER and the MR were 6.55 and 2.04, respectively, indicating that the effect of temperature was greater on GER than on MR. As a result, the differences between the GER and MR, indicating the maximum amount of food ingestible for growth, were 2.8 and 30.7 cal·g−1 day−1 at 4 and 14°C, respectively. The water temperature on the sea floor generally remained at <4°C from winter through summer, but exceeded 10°C in the surface layer of Funka Bay, where pointhead flounders were sampled. Therefore, their growth rate should be considerably limited if they remain in the bottom layer. The unique ecology of this species among the flatfishes of floating from sea floor and feeding at pelagic zones may represent a strategy to compensate for the physiological limitation of growth at low temperatures. [ABSTRACT FROM AUTHOR]

The rainfall variabilities of the West African and South American summer monsoons, pivotal for local and global climate systems, are strongly influenced by tropical Atlantic sea surface temperature anomalies. This study investigates the impacts of two recently identified Atlantic Niño types, central and eastern Atlantic Niño (CAN and EAN), on these monsoon systems using observational data and numerical experiments. During boreal summer, EAN events exhibit increased rainfall over West Africa compared to CAN events, indicating a strengthened West African summer monsoon. Enhanced moisture flux convergence from eastern Atlantic warming drives these wetting conditions during EAN events. Conversely, CAN events have a more pronounced influence on South American monsoon rainfall during austral summer, causing a rainfall anomaly dipole between the Amazon and eastern Brazil, suggesting an eastward shift in the South American summer monsoon rainfall belt. These rainfall changes are linked to cyclonic circulation anomalies over the southwest Atlantic Ocean, attributed to central Atlantic warming during CAN events. Furthermore, a statistical model assesses hindcast skills of rainfall variability in the two summer monsoon regions, affirming the benefits of separating Atlantic Niño into CAN and EAN events for improved seasonal climate predictions. [ABSTRACT FROM AUTHOR]

The East/Japan Sea (EJS), a marginal sea of the Northwestern Pacific, is one of the ocean regions showing the most rapid warming and greatest increases in ocean heatwaves over the last several decades. Predictability and skillful prediction of the summer season EJS variability are crucial, given the increasing severity of ocean temperature events impacting fisheries and reinforcing climate conditions like the East Asian rainy season, which in turn affects adjacent high-population density areas over East Asia. We use observations and the Geophysical Fluid Dynamics Laboratory (GFDL) Seamless System for Prediction and Earth System Research (SPEAR) seasonal forecast system to investigate the summertime EJS Sea Surface Temperature (SST) predictability and prediction skill. The observations and seasonal prediction system show that the summer season EJS SST can be closely linked to the previous winter air-sea coupling and predictable 8–9 months in advance. The SPEAR seasonal prediction system demonstrates skillful forecast of EJS SST events from summer to late fall, with added skill for long-lead forecasts initialized in winter. We find that winter large-scale atmospheric circulations linked to Barents Sea variability can induce persistent surface wind anomalies and corresponding northward Ekman heat transport over the East China Sea. The ocean advection anomalies that enter the EJS in prior seasons appear to play a role in developing anomalous SST during summer, along with instantaneous atmospheric forcing, as the source of long-lead predictability. Our findings provide potential applications of large-scale ocean-atmosphere interactions in understanding and predicting seasonal variability of East Asian marginal seas. [ABSTRACT FROM AUTHOR]

While deep learning models have shown promising capabilities in ENSO prediction, their inherent black-box nature often leads to a lack of physical consistency and interpretability. Here, we introduce ENSO-PhyNet, a Transformer-based model for ENSO prediction, which incorporates heat budget dynamical processes through self-attention computations. The model predicts sea surface temperature (SST) in the equatorial Pacific and achieves skillful predictions of the Niño 3.4 index with a lead time of up to 22 months. The self-attention maps reveal how the model makes predictions by focusing on specific processes in certain regions. Case analyses of recent El Niño and La Niña events underscore the impact of thermocline feedback and zonal advection feedback on the warming of the 2015 event, as well as the crucial role of anomalous easterlies in the emergence of the second-year La Niña in 2021. These findings demonstrate the model's interpretability and its ability to identify signals that are physically consistent with the development of ENSO events. [ABSTRACT FROM AUTHOR]

Energetic cyclonic mesoscale eddies, which are called cold-core rings and are shed southward from the Kuroshio Extension jet and form closed streamlines, affect the atmosphere through the heat exchange across the sea surface. To investigate the effect of rings on the atmosphere, we performed atmosphere and ocean observations across a cold-core ring centered around 34.5° N, 150.0° E using a research vessel from November 2021 to January 2022 and a shallow-water profiling float from November 23 to 28, 2021. As heat is released from the sea surface, no significant spatial contrast in the sea surface and mixed layer temperatures was detected across the ring. Meanwhile, the sea surface wind was occasionally observed to be weak around the ring, possibly through the air–sea interactions. The wind drop-off maintained a turbulent heat flux small around the ring. The wind field associated with the wind drop-off was examined by the rotary empirical orthogonal function analysis of the satellite sea surface wind data. The minimum of the sea surface wind is found to shift northward relative to the ring center and to be more than approximately 5 m s - 1 lower than the surrounding region. The shallow-water profiling float deployed around the ring center observed a rapid freshening event in the mixed layer, which can be attributed to the water intrusion from the north of the Kuroshio Extension jet through the interaction with the jet. This suggests that the cold water from the north continually affects the atmosphere without leaving traces in the shipboard sea surface temperature observations. [ABSTRACT FROM AUTHOR]

The observational data of the air-sea interface and upper ocean elements from a buoy array deployed in the northern South China Sea from June to November 2014 is analyzed. The COARE 3.0 algorithm was adopted to examine the variability of air-sea heat fluxes and their contributions to near-surface ocean temperature changes. During the observation period, air-sea heat exchange in the northern South China Sea is primarily determined by solar shortwave radiation and latent heat flux, with net heat flux mostly negative, indicating that the ocean predominantly loses heat. In autumn, net heat flux loss significantly increased by an average of 34.4 W/m2, primarily due to enhanced latent heat loss driven by stronger winter monsoon. During typhoon period, net air-sea heat flux was significantly suppressed, mainly due to reduced solar shortwave radiation, with minimal contribution from sensible heat flux. Near-surface ocean temperature exhibited a seasonal cooling trend, averaging 29.7°C in summer and 28.4°C in autumn. The maximum cooling during typhoon reached 3.1°C, with minimal contribution from air-sea heat flux. During the monsoon transition period, weaker winds led to a slight increase in near-surface ocean temperature, with air-sea heat flux contributing 70.2% and 56.3% to this process. During winter monsoon, more uniform water column mixing resulted in a gradual decrease in near-surface ocean temperature, with air-sea heat flux contributing over 60% to this process. [ABSTRACT FROM AUTHOR]

The influence of greenhouse warming on mesoscale air-sea interactions, crucial for modulating ocean circulation and climate variability, remains largely unexplored due to the limited resolution of current climate models. Additionally, there is a lack of theoretical frameworks for assessing changes in mesoscale coupling due to warming. Here, we address these gaps by analyzing eddy-resolving high-resolution climate simulations and observations, focusing on the mesoscale thermal interaction dominated by mesoscale sea surface temperature (SST) and latent heat flux (LHF) coupling in winter. Our findings reveal a consistent increase in mesoscale SST-LHF coupling in the major western boundary current regions under warming, characterized by a heightened nonlinearity between warm and cold eddies and a more pronounced enhancement in the northern hemisphere. To understand the dynamics, we develop a theoretical framework that links mesoscale thermal coupling changes to large-scale factors, which indicates that the projected changes are collectively determined by historical background wind, SST, and the rate of SST warming. Among these factors, the large-scale SST and its warming rate are the primary drivers of hemispheric asymmetry in mesoscale coupling intensification. This study introduces a simplified approach for assessing the projected mesoscale thermal coupling changes in a warming world. This study shows that greenhouse warming intensifies mesoscale thermal coupling in western boundary currents, primarily driven by large-scale sea surface temperature and its warming rate, with key implications for ocean circulation and climate variability. [ABSTRACT FROM AUTHOR]

Perhaps the most dynamic component of the Arctic sea ice cover is the marginal ice zone (MIZ), the transitional region between dense pack ice to the north and open ocean to the south. It widens by a factor of four while seasonally migrating more than 1600 km poleward in the Bering–Chukchi Sea sector, impacting climate dynamics, ecological processes, and human accessibility to the Arctic. Here we showcase a transformative mathematical modeling approach to understanding changes in MIZ location and width, focusing on their seasonal cycles as observed by satellites. We view the MIZ as a liquid-solid phase transition region, or mushy zone, on the scale of the Arctic Ocean. Invoking the physics of phase changes, the MIZ is modeled as a dynamic, multiscale composite material layer; this model captures 96% of the annual cycle of MIZ location and 78% of the annual cycle of MIZ width. Temperature in the upper ocean is described by a nonlinear heat equation with effective parameters obtained using homogenization theory for a random medium of ice floes in a sea water host. Observations and simulations together indicate that MIZ location closely tracks the below-ice 273 K isotherm while the width of the MIZ follows vertical heat flux convergence, but with a three-week lag. [ABSTRACT FROM AUTHOR]

Vibrio coralliilyticus is a pathogen of coral and shellfish, leading to devastating economic and ecological consequences worldwide. Although rising ocean temperatures correlate with increased V. coralliilyticus pathogenicity, the specific molecular mechanisms and determinants contributing to virulence remain poorly understood. Here, we systematically analyzed the type VI secretion system (T6SS), a contact-dependent toxin delivery apparatus, in V. coralliilyticus. We identified 2 omnipresent T6SSs that are activated at temperatures in which V. coralliilyticus becomes virulent; T6SS1 is an antibacterial system mediating interbacterial competition, whereas T6SS2 mediates anti-eukaryotic toxicity and contributes to mortality during infection of an aquatic model organism, Artemia salina. Using comparative proteomics, we identified the T6SS1 and T6SS2 toxin arsenals of 3 V. coralliilyticus strains with distinct disease etiologies. Remarkably, T6SS2 secretes at least 9 novel anti-eukaryotic toxins comprising core and accessory repertoires. We propose that T6SSs differently contribute to V. coralliilyticus's virulence: T6SS2 plays a direct role by targeting the host, while T6SS1 plays an indirect role by eliminating competitors. Vibrio coralliilyticus is a pathogen of coral and shellfish that is becoming more virulent as ocean temperatures rise, causing significant damage. This study shows that V. coralliilyticus has two type VI secretion systems (T6SSs) that are activated at high temperatures; one targets bacterial competitors, while the other launches up to 9 novel toxins against eukaryotic hosts like shrimps. [ABSTRACT FROM AUTHOR]

Southern Ocean (SO) sea surface temperatures (SSTs) warmed from approximately 1949–1978 and cooled slightly from 1979–2013. We compare the remote impacts of these SO trends using historical coupled model experiments in which the model's SO SST anomalies are nudged to observations. Compared to the control (no nudging) ensemble, the nudged ensemble shows enhanced SST warming in the tropical southeast Pacific and Atlantic, and greater Antarctic sea ice loss, during the SO warming period: analogous to the impacts of SO cooling but of opposite sign. The SO-driven response in the tropical Pacific (Atlantic) is statistically significant when considering the trend difference between the two periods, and accounts for 34% (59%) of the observed non-radiatively forced trend. Surface heat budget analysis indicates wind-evaporation-SST feedback dominates over shortwave cloud feedback in amplifying the SO-driven SST trends in the tropics during the SO warming period, opposite to that for the SO cooling period. [ABSTRACT FROM AUTHOR]

The Sechelt inlet system (SIS), situated on the inner Sunshine Coast of British Columbia, lies within the territory of the shíshálh Nation. This study focuses on ∼1000 years of shíshálh shellfish harvesting from 930-0 cal. BP. Specifically, we investigated the seasonal timing of shellfish collection, relative shellfish harvesting pressure and paleo-temperature reconstruction at four archaeological sites. Thirty archaeological butter clam shells (Saxidomus gigantea) from the SIS underwent high-resolution shell oxygen isotope (δ18O) analysis and 662 individual archaeological shell fragments were analysed for growth stage determination. The δ18O results showed a pattern of year-round collection with an emphasis on spring collection at village sites. Results from shell growth stage analysis suggest an intensive pattern of shellfish harvesting in the region, regardless of the site type. Archaeological shells show a larger δ18Oshell range, possibly reflecting a greater sea surface temperature amplitude than modern shells (i.e. a difference of ∼6.5°C; modern range: ∼3.7–20.4°C; archaeological range: ∼ −0.8–22.4°C). We contextualise our results with previous studies of seasonal timing and intensity of shellfish harvesting from the Pacific Northwest Coast, while interpreting these new data in the context of shíshálh occupation and landscape use. [ABSTRACT FROM AUTHOR]

Studies covering key elements of the marine ecosystem based on current and long-term data have made it possible to assess both the current situation in terms of copper concentrations in commercially used fish and benthic plants and in surface bottom sediments, as well as enabled the analysis of the temporal variability of copper levels in relation to changes in its inflow to the southern Baltic Sea. By applying the threshold values, determining the boundary between good and not good status of the marine environment, set in this study, it was found that good environmental status has been achieved in the case of Cu in seawater and plants and has not been achieved in the case of sediments and fish for consumption. The study showed that climate change, the main feature of which is an increase in seawater temperature, significantly impacts the distribution and levels of copper in individual elements of the marine environment. It influences the vegetative season length and bioaccumulation efficiency and is of key importance for copper toxicity. [ABSTRACT FROM AUTHOR]

Cold filaments (CFs) in the southwestern South China Sea (SCS) impact local hydrodynamics and the ecological environment. In this study, the effects of typhoons passing over the northern SCS on CFs are investigated using multi-source observational and reanalysis data. Statistical analysis of CF responses to typhoons over the past 24 years shows that during typhoon periods in the northern SCS, the CFs are intensified. We further analyze the remote effect of typhoons on the CF during Typhoon Kalmaegi in 2014, which caused a sea surface temperature (SST) drop of more than 3 °C in the CF region. The strengthened along-coast wind induced strong upwelling off the Vietnam coast. The maximum vertical velocity in the CF reaches three times the usual value. Meanwhile, influenced by the peripheral wind field of Kalmaegi, cold coastal water accumulated at the CF region due to the shafting of the offshore current. Both strong offshore currents and coastal upwellings enhanced the intensity of the CF. These findings demonstrate that typhoons not only directly affect ocean dynamic processes along their path but also present significant remote influences on coastal dynamics in other regions. This study enhances the understanding of CF evolution and sea–air interactions during extreme events. [ABSTRACT FROM AUTHOR]

The surface velocity of the Amery Ice Shelf (AIS) is vital to assessing its stability and mass balance. Previous studies have shown that the AIS basin has a stable multi-year average surface velocity. However, spatiotemporal variations in the surface velocity of the AIS and the underlying physical mechanism remain poorly understood. This study combined offset tracking and DInSAR methods to extract the monthly surface velocity of the AIS and obtained the inter-annual surface velocity from the ITS_LIVE product. An uneven spatial distribution in inter-annual variation in the surface velocity was observed between 2000 and 2022, although the magnitude of variation was small at less than 20.5 m/yr. The increase and decrease in surface velocity on the eastern and western-central sides of the AIS, respectively, could be attributed to the change in the thickness of the AIS. There was clear seasonal variation in monthly average surface velocity at the eastern side of the AIS between 2017 and 2021, which could be attributed to variations in the area and thickness of fast-ice and also to variations in ocean temperature. This study suggested that changes in fast-ice and ocean temperature are the main factors driving spatiotemporal variation in the surface velocity of the AIS. [ABSTRACT FROM AUTHOR]

Sea surface temperature (SST) is an important factor in the marine environment and has significant impacts on climate, ecology, and maritime activities. Most existing SST prediction methods consider the ocean as a uniform field and use a uniform grid to predict SST. However, the marine environment is a complex system, and factors such as solar radiation, differences in land and sea thermal properties, and ocean circulation lead to uneven spatial distributions of SSTs. We propose a non-uniform grid construction method based on an SST spatial gradient to encode SST data, as well as a Non-uniform Grid Graph Convolutional Network (NGGCN) model. The NGGCN consists of two spatiotemporal modules, each of which extracts spatial features from the GCN module, captures temporal correlations through the GRU module, and performs feature restoration and output results through the fully connected module. We selected data from the Yellow Sea and Bohai Sea to validate the effectiveness of the NGGCN in predicting SST at different time scales and prediction steps. The results indicate that our model shows a significant improvement in prediction performance compared to other models. [ABSTRACT FROM AUTHOR]

Sea surface temperature (SST) is a crucial physical parameter in meteorology and oceanography. This study demonstrates that the influence of earth incidence angle (EIA) on the SST retrieved from the microwave radiation imager (MWRI) onboard FengYun-3 (FY-3) meteorological satellites should not be ignored. Compared with algorithms that do not consider the influence of EIA in the regression, those that integrate the EIA into the regression can enhance the accuracy of SST retrievals. Subsequently, based on the recalibrated Level 1B data from the FY-3/MWRI, a long-term SST dataset was reprocessed by employing the algorithm that integrates the EIA into the regression. The reprocessed SST data, including FY-3B/MWRI SST during 2010-2019, FY-3C/MWRI SST during 2013-2019, and FY-3D/MWRI SST during 2018-2020, were compared with the in-situ SST and the SST dataset from the Operational Sea Surface Temperature and Ice Analysis (OSTIA). The results show that the FY-3/MWRI SST data were consistent with both the in-situ SST and the OSTIA SST dataset. Compared with the Copernicus Climate Change Service V2.0 SST, the absolute deviation of the reprocessed SST, with a quality flag of 50, was less than 1.5°C. The root mean square errors of the FY-3/MWRI orbital, daily, and monthly SSTs, with a quality flag of 50, were approximately 0.82°C, 0.69°C, and 0.37°C, respectively. The primary discrepancies between the FY-3/MWRI SST and the OSTIA SST were found mainly in the regions of the western boundary current and the Antarctic Circumpolar Current. Overall, this reprocessed SST product is recommended for El Niño and La Niña events monitoring. [ABSTRACT FROM AUTHOR]

To effectively address ecosystem health risks, it is crucial to use detection methods that efficiently cover vast areas with good spatial resolution. These methods should enhance understanding of how phytoplankton blooms might evolve due to climate change. Satellite Ocean Color sensors are advantageous for detecting and monitoring phytoplankton blooms over time. This study uses the Inherent Optical Properties (IOP) index, which considers light absorption by phytoplankton (Ab_phy) and by detritus plus colored dissolved organic matter (Ab_adg), to detect phytoplankton blooms in six subareas within the San Matías Gulf (SMG; Patagonia, Argentina). The findings reveal a significant increase in bloom alerts over the last 20 years in the northwestern and southwestern subareas. Temporal changes in chlorophyll a (Chla) and sea surface temperature (SST) were observed, both showing an increase over the studied period. Environmental features like the diffusive attenuation coefficient (Kd_490) and Ab_phy also showed positive trends in four of the six subareas. The positive trends in SST and Kd_490 suggest a potential reduction in the euphotic zone depth. Additionally, the presence of phytoplankton biomass, indicated by Chla and Ab_phy, is linked to reduced light penetration in the water column due to absorption by the cells and self-shading. A decrease in Ab_adg was observed, while photosynthetically active radiation (PAR) showed no significant trend over the last two decades. These patterns could significantly impact the frequency and timing of phytoplankton blooms, altering their community composition and phenology. Such changes have profound implications for the entire marine food web and the ecosystem services within the SMG. The results underscore the importance of incorporating optical data for monitoring phytoplankton blooms across multiple areas. [ABSTRACT FROM AUTHOR]

The thermohaline regime trends of the Black Sea basin in the period 2000–2021 were studied based on the data from three retrospective analyses (reanalyses) of the hydrophysical fields of the Black Sea. It is shown that the cumulative effect of an increase in the average sea surface temperature (SST) and increasingly milder winter conditions in the Black Sea over the last seven to eight years led to a record-breaking warming and then to the disappearance of the ventilated cold intermediate layer (CIL) of the Black Sea in its traditional meaning by 2020. In addition, in the past seven to eight years, accelerated warming of seawaters has been observed within the permanent (main) pycnocline. Changes in the thermal regime of the upper layer of the sea are accompanied by a continuing increase in salinity in the main pycnocline. [ABSTRACT FROM AUTHOR]

Evidence of large‐scale biodiversity degradation in marine ecosystems has been reported worldwide, yet most research has focused on few species of interest or on limited spatiotemporal scales. Here we assessed the spatial and temporal changes in the taxonomic and functional composition of fish communities in European seas over the last 25 years (1994–2019). We then explored how these community changes were linked to environmental gradients and fishing pressure. We show that the spatial variation in fish species composition is more than two times higher than the temporal variation, with a marked spatial continuum in taxonomic composition and a more homogenous pattern in functional composition. The regions warming the fastest are experiencing an increasing dominance and total abundance of r‐strategy fish species (lower age of maturity). Conversely, regions warming more slowly show an increasing dominance and total abundance of K‐strategy species (high trophic level and late reproduction). Among the considered environmental variables, sea surface temperature, surface salinity and chlorophyll‐a most consistently influenced communities' spatial patterns, while bottom temperature and oxygen had the most consistent influence on temporal patterns. Changes in communities' functional composition were more closely related to environmental conditions than taxonomic changes. Our study demonstrates the importance of integrating community‐level species traits across multi‐decadal scales and across a large region to better capture and understand ecosystem‐wide responses and provides a different lens on community dynamics that could be used to support sustainable fisheries management. [ABSTRACT FROM AUTHOR]

The catch of butterfly kingfish Gasterochisma melampus, a large pelagic species in southern temperate waters, is strongly biased (73%) towards females. Whether this is caused by differences in sex-specific spatiotemporal distributions or mortality of sexes is investigated herein. Analysis of sex ratios using a generalized additive model (GAM) for year, month, latitude, longitude, sea surface temperature, and fork length from Japanese longline catch data for areas where immature and adult fish occur revealed the influence of space and time on sex ratios to be small, and that of fork length to be large. Based on observation of the increments in vertebrae of immature fish (N = 179), the fork length at the time of increment formation was back-calculated from distances between increments on the anterior and posterior cones, generating 2–8 measurements per vertebra and 865 data points in total. Growth equations were calculated for each sex, with females growing faster. The age composition of males and females in the catch was similar, meaning that the mortality rate in males is unlikely to be higher than that of females. The data suggest that biased sex ratios in catches are representative of the natural sex ratio in a population for fish more than 60 cm in fork length. [ABSTRACT FROM AUTHOR]

Total Alkalinity (TA) is identified as one of the EssentialClimateVariable (ECV) by the GlobalClimateObservingSystem (GCOS) for climate change impact assessment studies. This also plays an important role in understanding the oceanic carbon cycle, and ocean acidification. The existing global algorithms are Sea Surface Salinity (SSS) based and inadequate for precise estimation of TA fields and their dynamics due to precluding physical and biological parameters such as Sea Surface Temperature (SST), Chlorophyll-a concentration (Chl-a) and its influencing parameters (nutrients). In the present study, a novel algorithm known as the ImprovedSingleLinearRegression (ISLR) was devised based on SSS and Nitrate (Ni) concentration. The ISLR was formulated using simultaneous in-situ measurements of SSS and Ni acquired across the global oceans. The primary objective was to mitigate uncertainties and generate consistent TA fields for the global surface ocean. ISLR performance was assessed with independent satellite and in-situ TA observations. The validation results demonstrate the ISLR approach superior performance, characterized by significant low errors (mean relative error (MRE) = 0.04 µmol kg−1; mean normalized bias (MNB) = -0.0003 µmol kg−1; and root mean square error (RMSE) = 10.08 µmol kg−1) with a high correlation coefficient (R2 = 0.96). The ISLR derived TA fields were used to study the spatiotemporal variability and seasonal dynamics of the global oceans. [ABSTRACT FROM AUTHOR]

Despite common background La Niña conditions, Australia was very dry in November 2020 and wet in November 2021. This paper aims to provide an explanation for this difference. Large-scale drivers of Australian rainfall, including El Niño–Southern Oscillation, Indian Ocean dipole, Southern Annular Mode, and Madden–Julian oscillation, were examined but did not provide obvious clues for the differences. We found that the absence (in 2020) or presence (in 2021) of an enhanced thermal wind and subtropical jet over the Australian continent contributed to the rainfall anomalies. In general, La Niña sets up warm sea surface temperatures around northern Australia, which enhances the meridional temperature gradient over the continent and hence thermal wind and subtropical jet. In November 2021, these warm sea surface temperatures, coupled with a persistent midlatitude trough, which advected cold air over the Australian continent, led to an enhanced meridional temperature gradient and subtropical jet over Australia. The enhanced jet provided favorable conditions for the development of rain-bearing weather systems across Australia. In 2020, the continent was warm, displacing the latitude of maximum meridional temperature gradient south of the continent, resulting in fewer instances of the subtropical jet over Australia, and little development of weather systems over the continent. We highlight that although La Niña tilts the odds to wetter conditions for Australia, in any given month, variability in temperatures over the continent can contribute to subtropical jet variability and resulting rainfall in ways which confound the normal expectation from La Niña. Significance Statement: Forecasts of El Niño–Southern Oscillation are eagerly awaited, as the state of this climate driver has profound impacts on the likelihood of rainfall in regions around the world. While El Niño and La Niña do change rainfall likelihoods, the actual outcomes of these events are sometimes counter to expectation. This work explores one of the confounding factors to those expectations in the Australian context—the role of the meridional temperature gradient over the continent in modifying the storm track over Australia, which can disrupt the expected El Niño and La Niña teleconnections. We present case studies for two La Niña springs, highlighting that the Australian continent can help shape its own weather toward wetter or drier outcomes. [ABSTRACT FROM AUTHOR]

While a record-high in situ water temperature of 38.4 °C on July 24, 2023, has been measured from a local site in Florida's Manatee Bay, satellite images revealed more extensive record-high water temperature in South Florida estuaries and the Florida Keys Reef Tract in July 2023 as a response to the 2023 heatwave, with an average sea surface temperature (SST) anomaly of 1.59 °C above the 2003–2022 mean. Long-term annual SST anomalies and long-term SST trend components of the time series both show significant warming trends in these regions between 2003 and 2023 (0.70 °C/decade), which is 67% higher than in the Gulf of Mexico (0.42 °C/decade). Furthermore, the warming trend appears to have accelerated over the past decade. In the context of global warming in the twenty-first century, such a warming trend and response to heatwaves may lead to more heat stress on the precious coral reefs and seagrasses both in and downstream from these already fragile estuaries. [ABSTRACT FROM AUTHOR]

Understanding how natural and anthropogenic disturbances affect the structure and functioning of marine ecosystems is central to predicting future dynamics. Placentia Bay is an Ecologically and Biologically Significant Area (EBSA) in the North Atlantic exposed to multiple stressors (e.g., rising sea surface temperatures, tanker traffic, and aquaculture). To investigate changes in the community and functional structure of soft-sediment macrofauna as well as environmental drivers of observed variation, we compared contemporary (2019–2020) and historical (1998) samples at eight stations (n = 77) collected 21 years apart. Although community and functional structure differed between these time points, functional traits were maintained (i.e., no loss of 36 trait modalities). Overall, 37% of species/taxa were only observed in either the historical or contemporary community, and the contemporary community exhibited lower macrofaunal density but had similar richness, resulting in higher evenness and diversity. Highly tolerant subsurface deposit feeders having small body sizes (< 10 mm) and direct development dominated the historical community. The contemporary community had nearly equal proportions of surface and subsurface deposit feeders with small to medium body sizes (< 10–50 mm) with pelagic larvae, and the proportion of highly tolerant species/taxa was reduced. These changes likely reflect the reduction in polychaetes (91 vs. 58%) and increased bivalves (4 vs. 25%) relative to the historical time point. Community variation was driven by changes in the sedimentary habitat. Contemporary versus historical sediments were ~ 4.5x coarser (possibly due to storms) with higher levels of sedimentary organic matter. This work contributes to advancing the understanding of relationships between benthic macrofauna, functional traits, and the sedimentary habitat in coastal environments. [ABSTRACT FROM AUTHOR]

Global ocean warming and extreme climate events pose a severe threat to marine biodiversity by inducing species redistribution and ecosystem reorganization. It is important to quantify the impacts of marine heatwaves (MHWs) on marine cetacean habitats to avoid rapid ecosystem shifts. Here we utilized detected breakpoints and early warning indicators derived from sightings data spanning from 2009 to 2021 to assess the distribution change of Indo-Pacific humpback dolphin (Sousa chinensis). We found that (1) during the 2014 MHWs, the encounter rates (number of on-effort sightings per 100 km) of humpback dolphins in Hong Kong waters significantly decreased, with the breakpoint occurring during the autumn of 2014; (2) Since 2014, Hong Kong waters have experienced more prolonged and frequent MHWs, with a significant reduction of core habitat by 26%; according to Granger causality analysis, changes in sea surface temperature drove shifts in dolphin distribution; (3) Our analysis revealed a co-existence of rapid annual increases in MHWs and high habitat usage, with the marine park located in Southwest Lantau being particularly at risk. This study on dolphin distribution shifts and their relationships with marine heatwaves in Southern China made a contribution to our understanding of the action of marine cetaceans' response to climate change. Additionally, it highlights the importance of considering MHWs in dolphin conservation efforts. [ABSTRACT FROM AUTHOR]

Background and Aims Globally, rising seawater temperatures contribute to the regression of marine macroalgal forests. Along the Istrian coastline (northern Adriatic), an isolated population of Gongolaria barbata persists in a coastal lagoon, representing one of the last marine macroalgal forests in the region. Our objective was to examine the impact of extreme temperatures on the morphology and physiology of G. barbata and test its potential for recovery after simulating marine heatwave (MHW) conditions. Methods We explored the occurrence of marine heatwaves in southern Istria, adjacent to the study area, in addition to extreme temperatures inside the area itself. Subsequently, we performed a thermotolerance experiment, consisting of a stress and recovery phase, in which we exposed G. barbata thalli to four extreme (28, 30, 32 and 34 °C) and one favourable (18 °C) temperature. We monitored morphological and physiological responses. Key Results Our findings indicate a significant rise in frequency, duration and intensity of MHWs over decades on the southern Istrian coast. Experimental results show that G. barbata demonstrates potential for both morphological and physiological recovery after exposure to temperatures as high as 32 °C. However, exposure to 34 °C led to thallus decay, with limited ability to regenerate. Conclusions Our results show that G. barbata has a remarkable resilience to long-term exposure to extreme temperatures ≤32 °C and suggest that short-term exposure to temperatures beyond this, as currently recorded inside the lagoon, do not notably affect the physiology or morphology of local G. barbata. With more MHWs expected in the future, such an adapted population might represent an important donor suitable for future restoration activities along the Istrian coast. These results emphasize the resilience of this unique population, but also warn of the vulnerability of marine macroalgal forests to rising seawater temperatures in rapidly changing climatic conditions. [ABSTRACT FROM AUTHOR]

To test the potential of high‐resolution satellite image analysis for assessing and predicting the mesoscale (<10 km in this study) effects of climate and environmental change on temperature and primary productivity in fishing grounds, we conducted satellite image analysis around an island in a coastal strait west of Japan from 2018 to 2023. We observed a distinct north–south gradient in sea surface temperature (SST) and chlorophyll a concentration (CHL) over approximately 20 km of the transect, which was likely affected by the current system. The model configuration suggests that the frequency of southward currents during winter–spring can control the magnitude of spring phytoplankton blooms. In the study region, an increase in SST at a rate of 0.06–0.13°C y−1 occurred during the study period, accompanied by a decrease in CHL. The north–south gradient in the rate of change suggests that the variation in the temperature and flow rate of the Kuroshio Current into the study area was due to these abrupt changes. The relationship between the annual mean SST and CHL was also spatially heterogeneous, showing a higher sensitivity of CHL to SST in the southwest of the island than in the north. In addition to the intrusion of warm and oligotrophic Kuroshio waters, the spread of less saline and more eutrophic coastal waters likely influenced this spatial heterogeneity. The satellite image analysis in the present study successfully revealed mesoscale mosaics of environmental conditions in coastal fishery grounds. [ABSTRACT FROM AUTHOR]

Chub mackerel (Scomber japonicus, Scombridae) and blue mackerel (Scomber australasicus) are two important fishery resources in the western North Pacific that spawn eggs during the same season. Although estimating the total egg production (TEP) is important for evaluating the spawning stock biomass of mackerel species, it is difficult to accurately identify formalin‐preserved eggs collected during ichthyoplankton surveys. Hence, a new identification criterion that incorporates the effects of water temperature on egg size was developed in this study. The diameter of 37,304 mackerel eggs collected over 16 years (2006–2021) was measured, and frequency distributions of egg size across sea surface temperature (SST) ranges at 1°C interval were constructed. The frequency distributions were classified into two groups using a Gaussian mixture model; based on the results of DNA analysis, the small group was chub mackerel, while the large group was blue mackerel. The SST at the sampling stations and the mean egg size of both groups were negatively correlated. The new identification criterion, incorporating the relationship between SST and egg size, provided reasonable estimates of the TEP of the two mackerel species compared with the conventional criterion. The new species identification approach is applicable to other fish taxa in the western North Pacific. [ABSTRACT FROM AUTHOR]

The Bay of Bengal (BoB) region is becoming increasingly important in international politics due to its strategic location as a transit route between the Atlantic and Pacific oceans. The BoB is bordered by India, Indonesia, Bangladesh, Thailand, Myanmar, and Sri Lanka, with a combined population of 1.7 billion and a GDP of $1.7 trillion. The region is a critical chokepoint for maritime shipping, with approximately 90,000 ships passing through the Malacca Strait each year. The BoB is also experiencing growth in the blue economy, with a focus on sectors such as fishing, offshore energy, shipping, and coastal tourism. However, the region faces challenges such as security issues, environmental vulnerabilities, political instability, and non-traditional maritime crimes. Piracy and armed robbery are prevalent in the BoB, and the region is a transit point for illicit trade, including narcotics and contraband. Irregular maritime migration is also a significant issue, driven by economic insecurity, conflict, and climate vulnerability. The BoB is highly susceptible to natural disasters and climate change, which affect ocean productivity, habitats, and biological processes. The region is marked by communal and ethnic conflicts, and there is a growing power rivalry between China and India. Regional organizations such as BIMSTEC have been established to address these issues, but their effectiveness has been limited. This special issue aims to explore the contestation for control in the BoB region, the role of regional organizations, and the [Extracted from the article]

Coupled ocean and prescribed sea surface temperature (SST) experiments are performed to investigate the drivers of Northern Hemisphere (NH) midlatitude winter circulation and blocking changes in warmer climates. In coupled experiments, a historical simulation is compared to a simulation following an end of the twenty-first-century shared socioeconomic pathway (SSP5-8.5) emission scenario. The SSP5-8.5 simulation yields poleward-shifted jets and an enhanced stationary wave pattern compared to the historical simulation. In terms of blocking, a reduction is found across North America and over the Pacific Ocean with the suggestion of more blocking over parts of Eurasia. Separately, prescribed SST experiments are performed decomposing the SSP5-8.5 SST response into a uniform warming component plus a spatially dependent change in SST pattern. SSP5-8.5 changes in circulation are primarily driven by a uniform warming of SST. Uniform warming is also found to account for most of the SSP5-8.5 blocking reduction over North America and the Pacific Ocean, but not over Eurasia. El Niño–like changes to the SST pattern also yield less blocking over the Pacific and North America. However, adding the responses of uniform and pattern experiments yields a nonlinear overreduction of blocking compared to the SSP5-8.5 experiment. Regional analyses of block energetics suggest that much of the reductions in blocking in warming simulations are driven by decreased baroclinic conversion in some regions and enhanced dissipation from diabatic sources in others. Significance Statement: Atmospheric blocks are persistent anticyclones that can cause severe weather such as heat waves and cold spells. Climate models generally project that on a warmer Earth, blocking frequency is poised to decrease in the Northern Hemisphere by the end of the twenty-first century. The cause, however, remains unclear. In this study, we investigate the response of mean atmospheric circulation and atmospheric blocking when separately considering the warming of sea surface temperatures (SST) and changing the SST pattern. We find that most of the reduction in blocking can be explained by a uniform warming of SST. Energetics analyses suggest that this reduction is driven by blocks' inhibited extraction of mean flow potential energy in some regions and by enhanced diabatic dissipation in others. [ABSTRACT FROM AUTHOR]

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2019 witnessed one of the strongest positive Indian Ocean Dipole. A very strong positive subsurface mode (pSSM) co-evolved in the Tropical Indian Ocean (TIO) during September–October–November 2019, which strengthened further during December–January–February (DJF) 2019–2020. This is the first occurrence of such a very strong pSSM in the recent decades, which strengthened during DJF without any favourable forcing from the Pacific. The TIO further displayed anomalous basin-wide surface warming from winter 2019 to summer 2020. It is found from both observations and model experiments that ocean dynamics associated with pSSM played a major role in the TIO basin-wide warming during 2020. The subsurface–surface interaction along the downwelling Rossby wave path from boreal winter to spring, the reflected Kelvin waves and surface currents have contributed to the basin-wide surface warming of the TIO from DJF (2019–2020) onwards. The mixed layer heat budget analysis reveals that the surface heat fluxes were not favourable for the basin-wide surface warming, thereby undermining the role of any Pacific forcing through atmospheric pathways. The ocean model sensitivity experiments further highlight the importance of Indian Ocean dynamics in the co-evolution of subsurface temperature and sea surface temperature over TIO, especially during the 2019–2020 event. Research highlights: A strong subsurface dipole mode evolved in the Tropical Indian Ocean temperature during 2019–2020. Indian Ocean basin-wide surface warming persisted up to summer 2020, highlighting the role of ocean dynamics. Indian Ocean dynamics associated with the subsurface mode is responsible for the evolution of basin-wide surface warming. Ocean model experiments support the role of ocean dynamics in the evolution of basin-wide surface warming. [ABSTRACT FROM AUTHOR]

At mid‐latitudes, a narrow band of near‐surface wind convergence (NSWC) overlies the western boundary currents in long‐term climatology as a response to steep sea surface temperature gradients. The underlying dynamics shaping mean convergence in the mid‐latitude region have been investigated in detail. In polar regions, surface temperature gradients are intense along the sea ice edges. However, literature concerning NSWC near sea ice edges is limited. This study investigates time‐mean NSWC along sea ice edges and its shaping processes, focusing on the Greenland Sea, based on atmospheric reanalysis. In cold‐season climatology, positive NSWC overlies the sea ice edge, resulting in a localized upward motion reaching the free atmosphere. The mean NSWC was insensitive to sea ice thickness and surface roughness in the regional model. This study suggests that, in addition to local atmospheric boundary processes, extreme NSWC events play a vital role in shaping the mean distribution. Although these features are similar to those along the Gulf Stream, atmospheric fronts appear to play a relatively minor role in the Greenland Sea. Instead, the frequent cyclone generation near the sea ice edge and the anticyclonic circulation over Greenland in conjunction with the transient synoptic circulation seem essential. In the warm season, positive NSWC was virtually missing in the Greenland Sea, unlike in the Gulf Stream region, reflecting the shallow virtual temperature response to the surface thermal forcing. This study contributes to understanding the mechanisms by which sea ice variability affects large‐scale atmospheric circulation in remote regions. Plain Language Summary: Previous studies have argued that sea ice variability in Arctic regions could affect large‐scale atmospheric circulation in remote regions. However, the underlying mechanisms remain unclear. A deeper understanding of the impact of sea ice on the local atmosphere will aid in revealing these mechanisms. The present study investigates small‐scale (less than 1,000 km) atmospheric features close to sea‐ice edges, where surface temperature gradients are intense and can exert distinct impacts on the atmosphere. In the winter, the sea‐ice edge distinctly modulates the near‐surface wind, leading to an narrow band of intense upward wind. This upward wind reaches the middle of the atmosphere, suggesting that these features could relate to the effect of sea ice variability on large‐scale atmospheric circulation in remote regions. The physical processes modulating the mean near‐surface winds near the sea‐ice edge are found to be similar to those along the warm currents at the western edge of the basins (such as the Gulf Stream). However, atmospheric fronts appear to play a less important role. Instead, the frequent cyclone generation near the sea‐ice edge and the combination of the clockwise near‐surface wind around Greenland and near‐surface wind blowing from the ocean to sea‐ice regions appear essential. Key Points: A distinct band of mean near‐surface wind convergence overlies the sea ice edge in the Greenland Sea during winterThe mean near‐surface wind convergence along the sea ice edge is insensitive to ice thickness and surface roughness in a numerical modelThe anticyclonic circulation over Greenland and transient synoptic circulation are essential for shaping the time‐mean wind convergence [ABSTRACT FROM AUTHOR]

The recently‐observed poleward shift in western North Pacific tropical cyclone (TC) genesis has increased the TC threat to East Asia. We find that the poleward shift of TC genesis since 1979 is linked to mega‐ENSO. A downscaling analysis of TC genesis latitude given the constraint of mega‐ENSO using 30 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) show a continued increasing poleward shift with additional warming. We use the dynamic genesis potential index as a TC proxy in future CMIP6 simulations. These simulations show enhanced TC formation in the subtropics and decreased TC formation in the tropics. Modeled TCs in CMIP6 high‐resolution models that well represent mega‐ENSO project future poleward shifts in TC genesis. Both observations and simulations show that extra‐tropical North Pacific sea surface temperature warming associated with mega‐ENSO are the primary driver of the TC genesis poleward shift. Our study provides new insights into climate change‐driven TC migration. Plain Language Summary: The observed poleward shift in tropical cyclone (TC) genesis over the western North Pacific has increased the threat from these storms to East Asia. Until now, it remains unclear whether TC genesis will continue to move poleward in the future, due to both a relatively short reliable observational TC record as well as model inconsistencies. This study provides evidence that the poleward migration of TC genesis will likely continue due to anthropogenic warming. We find that there is a strong relationship between TC genesis latitude and a mode of Pacific sea surface temperature (SST) variability termed mega‐ENSO. We find using a suite of 30 climate models comprising the Coupled Modeled Intercomparison Project Phase 6 (CMIP6) that future poleward trends in TC genesis latitude are likely to continue. This poleward shift is observed whether using projected trends in mega‐ENSO or an index that measures the conduciveness of the environment for TC formation. Modeled tropical cyclones in high resolution simulations from CMIP6 also show a continued projected poleward shift in TC genesis. This poleward shift in TC genesis appears largely related to changes in extra‐tropical SST warming associated with mega‐ENSO. Key Points: The recently‐observed poleward shift of tropical cyclone (TC) genesis is related strongly to mega‐ENSOChanges in modeled TCs and a TC proxy in a warming climate show a consistent northward TC genesis migrationExtra‐tropical sea surface temperature warming associated with mega‐ENSO appears responsible for poleward TC genesis movement [ABSTRACT FROM AUTHOR]

As a practical reflection of the opportunity window of Madden‐Julian Oscillation (MJO), there are intermittent periods of relatively high forecasting skills, namely the forecast skill windows. Robust forecast skill windows are identified based on the subseasonal‐seasonal reforecast database, during which the majority of models show high forecast skills. A total of 15 MJO forecast skill windows during 1993–2020 have been identified. Most of the forecast skill windows are closely associated with active MJO events with high amplitude. Whether a high‐skill forecast window appears significantly depends on the magnitude of MJO intensity during the same period. The maintenance of active strong MJO events is potentially related with the warmer surface sea temperature anomalies in the western Pacific. Further research into such processes may unveil the MJO development mechanism and improve the MJO forecast skill. Plain Language Summary: With the continuous development of the economy and society, there is an increasing demand for subseasonal‐seasonal forecasts. The forecast skills of Madden‐Julian Oscillation (MJO) show significant high and low variabilities, associated with specific conditions. MJO forecast skill windows are confirmed based on subseasonal‐seasonal (S2S) forecast products in this study. These windows represent the periods when most models in the S2S database can accurately capture the MJO signal, indicating the MJO forecast skill experiences intermittent enhancements. When the MJO intensity is high in the same period, the high‐skill forecast window is more likely to appear. One potential reason for the maintenance of strong MJO is the anomalously warmer sea surface temperature in the western Pacific, along with other potential factors, providing the opportunity to forecast MJO with high skill. When the opportunity arises, the forecast skill of MJO improves, highlighting the significance of exploring the processes leading to the occurrence of these skill windows. This provides a pathway for more accurate MJO forecasting and improves the predictability of S2S. Key Points: Robust forecast skill windows of Madden‐Julian Oscillation (MJO) are identified based on the subseasonal‐seasonal reforecast databaseThe forecast skill windows are mostly related to strong MJO amplitudeWarmer sea surface temperature anomalies in the western Pacific potentially favors the maintenance of active strong MJO events [ABSTRACT FROM AUTHOR]

Midlatitude Europe (ME) emerges as a prominent heatwave hotspot with rapid increases in summer surface air temperature and heatwave days since 1979, surpassing the global land averages by approximately 2.6 and 2.3 times, respectively. The circulation analogs‐based dynamic adjustment reveals that approximately 38% and 35% of these trends result from shifts in zonal dipolar circulation patterns over the North Atlantic (NA) and Europe, crucial for the enhanced warming compared to the global land average. The circulation changes are associated with warming sea surface temperatures in the NA. This warming pattern resembles the Atlantic Multidecadal Variability and is predominantly induced by greenhouse gases. Moreover, the stronger air temperature response in ME to decreased aerosols amplifies warming, contributing to the rapid increase in heatwave frequency. These findings highlight a prominent influence of anthropogenic forcings on the swift surge of European heatwaves compared to global land, with a potential implication for adaptation strategies and risk management. Plain Language Summary: Midlatitude Europe is experiencing a significant increase in heatwaves, with summer temperatures and heatwave occurrences rising much faster than the global land averages since 1979. One of the key contributors to this rapid warming is the changes in zonal dipolar circulation patterns over the NA and Europe, which are linked to the warm sea surface temperatures in the NA. This warming pattern, resembling the Atlantic Multidecadal Variability, is largely caused by greenhouse gases and additionally influenced by reduced aerosols and natural forcing. Furthermore, the stronger response of air temperatures in midlatitude Europe to decreased aerosol emissions intensifies summer warming, contributing to a rapid increase in heatwave days. These findings highlight the significant impact of anthropogenic forcings on the observed surge of heatwaves in Europe compared to global land, with an important implication for developing strategies to adapt to these changing climate conditions and managing the associated risks. Key Points: Midlatitude Europe exhibits more rapid increases in summer heatwave frequency than the global land averages in recent decadesAtmospheric circulation changes contributing about one third of the observed warming trend, further intensify the rapid increases in summer heatwave frequencyLocal air temperature response to reduced aerosol emissions contributes about half of the enhanced warming compared to the global land average [ABSTRACT FROM AUTHOR]