Abstract. The coastal Ocean Data Analysis Product in North America (CODAP-NA, Version 2026) represents a major expansion of coastal ocean carbonate chemistry synthesis for North American continental margins. Compared to CODAP-NA Version 2021, the updated product integrates newly available cruise observations spanning more than four decades, substantially increasing both the spatial and temporal coverage of coastal biogeochemical measurements across North American continental shelves. Observations from multiple research programs have been harmonized into a unified, internally consistent format through standardized quality control procedures, enabling large-scale analyses of ocean carbon cycling and ocean acidification along the North American margins. This version comprises 446 cruises, 31,864 hydrographic profiles, and 195,489 discrete data records covering continental shelf environments from Alaska to Mexico in the west and from Canada to the Caribbean in the east from 1981 to 2024. Fourteen variables (including temperature, salinity, dissolved oxygen, dissolved inorganic carbon, total alkalinity, pH on the Total Scale, carbonate ion, fugacity of carbon dioxide, silicate, phosphate, nitrate, nitrite, nitrate plus nitrite, and ammonium) were subjected to extensive quality control. CODAP-NA Version 2026 is available as a merged data product in CSV, MATLAB, and NetCDF formats (https://doi.org/10.25921/h2ff-9d66) through the NOAA Ocean Carbon and Acidification Data System (OCADS: https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0315529.html). The original cruise data were archived and are accessible via a summary table at the NCEI Ocean Acidification Data Stewardship repository (https://www.ncei.noaa.gov/access/ocean-carbon-acidification-data-system/synthesis/CODAP-NAv2.html).

The Gulf Stream Index is calculated as the standardized first principal component time series from the empirical orthogonal function (EOF) analysis of the 200 m temperature time series from the EN4.2.1 dataset at the 20 base points, as detailed in Chen et al. [2021].

The Northeast U.S. shelf (NES) is an oceanographically dynamic marine ecosystem and supports some of the most valuable demersal fisheries in the world. A reliable prediction of NES environmental variables, particularly ocean bottom temperature, could lead to a significant improvement in demersal fisheries management. However, the current generation of climate model-based seasonal-to-interannual predictions exhibits limited prediction skill in this continental shelf environment. Here, we have developed a hierarchy of statistical seasonal predictions for NES bottom temperatures using an eddy-resolving ocean reanalysis data set. A simple, damped local persistence prediction model produces significant skill for lead times up to months in the Mid-Atlantic Bight and up to in the Gulf of Maine, although the prediction skill varies notably by season. Considering temperature from a nearby or upstream (i.e., more poleward) region as an additional predictor generally improves prediction skill, presumably as a result of advective processes. Large-scale atmospheric and oceanic indices, such as Gulf Stream path indices (GSIs) and the North Atlantic Oscillation Index, are also tested as predictors for NES bottom temperatures. Only the GSI constructed from temperature observed at 200 m depth significantly improves the prediction skill relative to local persistence. However, the prediction skill from this GSI is not larger than that gained using models incorporating nearby or upstream shelf/slope temperatures. Based on these results, a simplified statistical model has been developed, which can be tailored to fisheries management for the NES. this study, we have developed a collection of statistical models that produce seasonal predictions of NES bottom temperature with 1–12 months lead time. Variables considered in these prediction models include local persistence of bottom temperature from prior months, bottom temperature from an upstream or nearby region, and large-scale atmospheric and oceanic indices representing the North Atlantic Oscillation or position of the Gulf Stream (GS). Only considering local persistence provides significant skill for lead times up to ∼ 5 months in the Mid-Atlantic Bight and up to ∼ 10 months in the Gulf of Maine, although the skill varies by season. Using upstream or nearby bottom temperature and the GS index both generally improve the prediction skill. However, the GS index does not provide higher prediction skill than those upstream or nearby bottom temperatures. A simplified statistical model has been developed, which can be tailored to fisheries management on the NES.

Recent studies have suggested that coherent multidecadal variability exists between North Atlantic atmospheric blocking frequency and the Atlantic multidecadal variability (AMV). However, the role of AMV in modulating blocking variability on multidecadal times scales is not fully understood. This study examines this issue primarily using the NOAA Twentieth Century Reanalysis for 1901-2010. The second mode of the empirical orthogonal function for winter (December-March) atmospheric blocking variability in the North Atlantic exhibits oppositely signed anomalies of blocking frequency over Greenland and the Azores. Furthermore, its principal component time series shows a dominant multidecadal variability lagging AMV by several years. Composite analyses show that this lag is due to the slow evolution of the AMV sea surface temperature (SST) anomalies, which is likely driven by the ocean circulation. Following the warm phase of AMV, the warm SST anomalies emerge in the western subpolar gyre over 3-7 years. The ocean-atmosphere interaction over these 3-7-yr periods is characterized by the damping of the warm SST anomalies by the surface heat flux anomalies, which in turn reduce the overall meridional gradient of the air temperature and thus weaken the meridional transient eddy heat flux in the lower troposphere. The anomalous transient eddy forcing then shifts the eddy-driven jet equatorward, resulting in enhanced Rossby wave breaking and blocking on the northern flank of the jet over Greenland. The opposite is true with the AMV cold phases but with much shorter lags, as the evolution of SST anomalies differs in the warm and cold phases.

The meridional coherence, connectivity, and regional inhomogeneity in long‐term sea surface temperature (SST) variability over the Northwest Atlantic continental shelf and slope from 1982–2018 are investigated using observational data sets. A meridionally concurrent large SST warming trend is identified as the dominant signal over the length of the continental shelf and slope between Cape Hatteras in North Carolina and Cape Chidley, Newfoundland and Labrador, Canada. The linear trends are 0.37 ± 0.06 and 0.39 ± 0.06 °C/decade for the shelf and slope regions, respectively. These meridionally averaged SST time series over the shelf and slope are consistent with each other and across multiple longer observational data sets with records dating back to 1900. The coherence between the long‐term meridionally averaged time series over the shelf and slope and basin‐wide averaged SST in the North Atlantic implies approximately two thirds of the warming trend during 1982–2018 may be attributed to natural climate variability and the rest to externally forced change including anthropogenic warming.

Much attention has been paid to the climatic impacts of changes in the Kuroshio Extension, instead of the Kuroshio in the East China Sea (ECS). This study, however, reveals the prominent influences of the lateral shift of the Kuroshio at interannual time scale in late spring [April–June (AMJ)] on the sea surface temperature (SST) and precipitation in summer around the ECS, based on high-resolution satellite observations and ERA-Interim. A persistent offshore displacement of the Kuroshio during AMJ can result in cold SST anomalies in the northern ECS and the Japan/East Sea until late summer, which correspondingly causes anomalous cooling of the lower troposphere. Consequently, the anomalous cold SST in the northern ECS acts as a key driver to robustly enhance the precipitation from the Yangtze River delta to Kyushu in early summer (May–August) and over the central ECS in late summer (July–September). In view of the moisture budget analysis, two different physical processes modulated by the lateral shift of the Kuroshio are identified to account for the distinct responses of precipitation in early and late summer, respectively. First, the anomalous cold SST in the northern ECS induced by the Kuroshio offshore shift is likely conducive to the earlier arrival of the mei-yu–baiu front at 30°–32°N and its subsequent slower northward movement, which may prolong the local rainy season, leading to the increased rain belt in early summer. Second, the persistent cold SST anomalies in late summer strengthen the near-surface baroclinicity and the associated strong atmospheric fronts embedded in the extratropical cyclones over the central ECS, which in turn enhances the local rainfall.

After leaving the U.S. East Coast, the northward flowing Gulf Stream (GS) becomes a zonal jet and carries along its frontal characteristics of strong flow and sea surface temperature gradients into the North Atlantic at midlatitudes. The separation location where it leaves the coast is also an anchor point for the wintertime synoptic storm track across North America to continue to develop and head across the ocean. We examine the meridional variability of the separated GS path on interannual to decadal time scales as an agent for similar changes in the storm track and blocking variability at midtroposphere from 1979 to 2012. We find that periods of northerly (southerly) GS path are associated with increased (suppressed) excursions of the synoptic storm track to the northeast over the Labrador Sea and reduced (enhanced) Greenland blocking. In both instances, GS shifts lead those in the midtroposphere by a few months.

Many coastal areas host rich marine ecosystems and are also centers of economic activities, including fishing, shipping and recreation. Due to the socioeconomic and ecological importance of these areas, predicting relevant indicators of the ecosystem state on sub-seasonal to interannual timescales is gaining increasing attention. Depending on the application, forecasts may be sought for variables and indicators spanning physics (e.g., sea level, temperature, currents), chemistry (e.g., nutrients, oxygen, pH), and biology (from viruses to top predators). Many components of the marine ecosystem are known to be influenced by leading modes of climate variability, which provide a physical basis for predictability. However, prediction capabilities remain limited by the lack of a clear understanding of the physical and biological processes involved, as well as by insufficient observations for forecast initialization and verification. The situation is further complicated by the influence of climate change on ocean conditions along coastal areas, including sea level rise, increased stratification, and shoaling of oxygen minimum zones. Observations are thus vital to all aspects of marine forecasting: statistical and/or dynamical model development, forecast initialization, and forecast validation, each of which has different observational requirements, which may be also specific to the study region. Here, we use examples from United States (U.S.) coastal applications to identify and describe the key requirements for an observational network that is needed to facilitate improved process understanding, as well as for sustaining operational ecosystem forecasting. We also describe new holistic observational approaches, e.g., approaches based on acoustics, inspired by Tara Oceans or by landscape ecology, which have the potential to support and expand ecosystem modeling and forecasting activities by bridging global and local observations.

The Gulf Stream plays an important role in North Atlantic climate variability on a range of timescales. The North Atlantic is notable for large decadal variability in sea surface temperatures (SST). Whether this variability is driven by atmospheric or oceanic influences is a disputed point. Long time series of atmospheric and ocean variables, in particular long time series of Gulf Stream position, reveal differing sources of SST variability on quasi‐decadal and multidecadal timescales. On quasi‐decadal timescales, an oscillatory signal identified in the North Atlantic Oscillation (NAO) controls SST evolution directly via air‐sea heat fluxes. However, on multidecadal timescales, this relationship between the NAO and SST changes, while the relationship between the NAO and Gulf Stream position remains consistent in phase and resonant in amplitude. Recent changes in the Gulf Stream Extension show a weakening and broadening of the current, consistent with increased instability. We consider these changes in the context of a weakening Atlantic overturning circulation.

A World Ocean Circulation Experiment Hydrographic Program along with a Global Repeat Hydrography Program occupied sections along 66°W in the North West Atlantic Ocean in 2003 and 2012. Hydrographic variables, tracers and LADCP measurements were collected in situ. This section together with the North American and South American Coasts create a closed volume, excluding any flow through the Panama Canal. Combining mass, silica and LADCP information with constraints in an inverse box model we obtain a strong eastward flow of the Gulf Stream (100.1 ± 4.6 Sv in 2003 and 123.8 ± 4.4 Sv in 2012), and westward flows of the Caribbean Current (−24.4 ± 1.0 Sv in 2003 and −24.2 ± 1.1 Sv in 2012) and Deep Western Boundary Current (DWBC). The DWBC carries the ventilated waters of the Labrador Sea and the Nordic Seas. Comparing the results of 2003 and 2012, an insignificant reduction is observed in the DWBC transport (−17.3 ± 2.9 Sv and −15.0 ± 2.5 Sv for 2003 and 2012, respectively). The net heat fluxes do not show major changes through the section during both cruises (−0.23 ± 0.08 PW in 2003 and−0.21 ± 0.12 PW in 2012). In contrast, freshwater fluxes present positive values in the dry season (0.24 Sv in spring 2012) and negative values in the wet season (−0.32 Sv in fall 2003). The difference between both cruises may be due to seasonal variability in the area.

Over the past ~40 years, the distribution of silver hake on the Northeast U.S. shelf is found to be significantly correlated with changes in the latitude of Gulf Stream path. The correlation coefficient between the fall Gulf Stream position and the center of biomass of spring silver hake reaches 0.75 when the Gulf Stream leads the silver hake for 6 months. Based on this lead-lag relationship and low-frequency variability of Gulf Stream position with a dominant periodicity of ~9–10 years, the Gulf Stream position is used as a predictor for the center of biomass of silver hake in linear autoregressive (AR) models. The goal of this study is then to optimize the AR model for the prediction of silver hake based on the observed changes in Gulf Stream position. Fall Gulf Stream position is first predicted out to 5 years using a 5th order AR model and the observed Gulf Stream position in preceding years. An optimization process is proposed to choose best AR coefficients based on a newly proposed combined skill parameter. Furthermore, the robustness of our Gulf Stream prediction is verified by comparing the observed Gulf Stream path index data from 2009 to 2012, which are not used for optimizing the AR model, and the predicted Gulf Stream path values for the same time period. We then use this predicted Gulf Stream position to further predict the center of biomass of silver hake in the subsequent spring. Three different methods are used and compared for the silver hake prediction. The predicted silver hake time series can explain as much as 69% of the variance of the observation for the 1st year prediction and 41% for the 5th year prediction. Our results indicate that including Gulf Stream as a predictor produces better prediction skills of silver hake center of biomass than the AR model prediction solely based on the observed silver hake time series.

A moored array spanning the continental slope southeast of Cape Cod sampled the equatorward-flowing Deep Western Boundary Current (DWBC) for a 10 year period: May 2004 to May 2014. Daily profiles of subinertial velocity, temperature, salinity, and neutral density are constructed for each mooring site and cross-line DWBC transport time series are derived for specified water mass layers. Time-averaged transports based on daily estimates of the flow and density fields in Stream coordinates are contrasted with those derived from the Eulerian-mean flow field, modes of DWBC transport variability are investigated through compositing, and comparisons are made to transport estimates for other latitudes. Integrating the daily velocity estimates over the neutral density range of 27.8-28.125 kg/m(3) (encompassing Labrador Sea and Overflow Water layers), a mean equatorward DWBC transport of 22.8 x 10(6) +/- 1.9 x 10(6) m(3)/s is obtained. Notably, a statistically significant trend of decreasing equatorward transport is observed in several of the DWBC components as well as the current as a whole. The largest linear change (a 4% decrease per year) is seen in the layer of Labrador Sea Water that was renewed by deep convection in the early 1990s whose transport fell from 9.0 x 10(6) m(3)/s at the beginning of the field program to 5.8 x 10(6) m(3)/s at its end. The corresponding linear fit to the combined Labrador Sea and Overflow Water DWBC transport decreases from 26.4 x 10(6) to 19.1 x 10(6) m(3)/s. In contrast, no long-term trend is observed in upper ocean Slope Water transport. These trends are discussed in the context of decadal observations of the North Atlantic circulation, and subpolar air-sea interaction/water mass transformation. Plain Language Summary A sustained measurement program located southeast of Cape Cod observed the equatorward limb of the Atlantic Ocean overturning circulation for the period 2004-2014. The data are analyzed to document the time-averaged structure and volume transport of the Deep Western Boundary Current and explore its modes of variability. Integrating the daily velocity estimates over the Labrador Sea and Overflow Water layers, a mean equatorward DWBC transport of 22.8 x 10(6) +/- 1.9 x 10(6) m(3)/s is obtained. A statistically significant trend of decreasing equatorward transport is observed in several of the DWBC components as well as the current as a whole. These trends are discussed in the context of decadal observations of the North Atlantic circulation, and subpolar air-sea interaction/water mass transformation.

The North Atlantic atmospheric circulation response to the meridional shifts of the Gulf Stream (GS) path is examined using a large ensemble of high-resolution hemispheric-scale Weather Research and Forecasting Model simulations. The model is forced with a broad range of wintertime sea surface temperature (SST) anomalies derived from a lag regression on a GS index. The primary result of the model experiments, supported in part by an independent analysis of a reanalysis dataset, is that the large-scale quasi-steady North Atlantic circulation response is remarkably nonlinear about the sign and amplitude of the SST anomaly chosen over a wide range of GS shift scenarios. The nonlinear response prevails over the weak linear response and resembles the negative North Atlantic Oscillation (NAO), the leading intrinsic mode of variability in the model and the observations. Further analysis of the associated dynamics reveals that the nonlinear responses are accompanied by the shift of the North Atlantic eddy-driven jet, which is reinforced, with nearly equal importance, by the high-frequency transient eddy feedback and the low-frequency wave-breaking events. Additional sensitivity simulations confirm that the nonlinearity of the circulation response is a robust feature found over the broad parameter space encompassing not only the varied SST but also the absence/presence of tropical influence, the varying lateral boundary conditions, and the initialization scheme. The result highlights the fundamental importance of the intrinsically nonlinear transient eddy dynamics and the eddy–mean flow interactions in generating the nonlinear downstream response to the meridional shifts in the Gulf Stream.

Dominant European winter precipitation patterns over the past century, along with their associated extratropical North Atlantic circulation changes, are evaluated using cluster analysis. Contrary to the four regimes traditionally identified based on daily wintertime atmospheric circulation patterns, five distinct seasonal precipitation regimes are detected here. Recurrent precipitation patterns in each regime are linked to changes in atmospheric blocking, storm track, and sea surface temperatures across the North Atlantic region. Multidecadal variability in the frequency of the precipitation patterns reveals more (fewer) winters with wet conditions in northern (southern) Europe in recent decades and an emerging distinct pattern of enhanced wintertime precipitation over the northern British Isles. This pattern has become unusually common since the 1980s and is associated with changes in moisture transport and more frequent atmospheric river events. The observed precipitation changes post‐1950 coincide with changes in storm track activity over the central/eastern North Atlantic toward the northern British Isles.

Shipboard velocity and water property data from 18 transects across the North Atlantic Deep Western Boundary Current (DWBC) near 40 degrees N are examined to study the evolution of the Denmark Strait Overflow Water (DSOW) component of the DWBC and mixing between DSOW and the interior. The examined transects along Line W - which stretches from the continental shelf south of New England to Bermuda - were made between 1994 and 2014. The shipboard data comprise measurements at regular stations of velocity from lowered acoustic Doppler current profilers, CTD profiles and trace gas chloro-fluorocarbon (CFC) concentrations from bottle samples at discrete depths. Comparison of the Line W velocity sections with concurrent sea surface height maps from satellite altimetry indicates that large cyclones in the deep ocean accompany intermittent quasi-stationary meander troughs in the Gulf Stream path at Line W. A composite of 5 velocity sections along Line W suggests that a typical cyclone reaches swirl speeds of greater than 30 cm s(-1) at 3400-m depth and has a radius (distance between the center and the maximum velocity) of 75 km. Tracer data suggest that these cyclones affect not only the deep velocity structure along Line W, but also provide a mechanism for water exchange between the DWBC's DSOW and the interior. Vigorous exchange is corroborated by a mismatch in the CFC-11:CFC-12 and CFC-113:CFC-12 ratio ages calculated for DSOW at Line W. During the most recent 5-year period (2010-2014), a decrease in DSOW density has been driven by warming (increasing by almost 0.1 degrees C) as salinity has increased only slightly (by 0.003, which is close to the 0.002 uncertainty of the measurements). The abyssal ocean offshore of the DWBC and Gulf Stream and deeper than 3000-m depth has freshened at a rate of 6 x 10(-4) yr(-1) since at least 2003. Density here remains nearly unchanged over this period, due to temperature compensation, though a linear cooling trend in the abyssal ocean (to compensate the freshening) is not statistically significant. (C) 2015 Elsevier Ltd. All rights reserved.