The spatiotemporal evolution of marine heatwaves (MHWs) is explored using a tracking algorithm termed Ocetrac that provides objective characterization of MHW spatiotemporal evolution. Candidate MHW grid points are defined in detrended gridded sea temperature data using a seasonally varying temperature threshold. Identified MHW points are collected into spatially distinct objects using edge detection with weak sensitivity to edge detection and size threshold criteria. These MHW objects are followed in space and time while allowing objects to split and merge. Ocetrac is applied to monthly satellite sea surface temperature data from September 1981 through January 2021. The resulting MHWs are characterized by their intensity, duration, and total area covered. The global analysis shows that MHWs in the Gulf of Maine and Mediterranean Sea evolve within a relatively small region, while major MHWs in the Pacific and Indian Oceans are linked in space and time. The largest and most long lasting MHW using this method lasts for 60 months from November 2013 to October 2018, encompassing previously identified MHW events including those in the Northeast Pacific (2014-2015), the Tasman Sea (2015-2016, 2017-2018), and the Great Barrier Reef (2016).

In the past decade, two large marine heatwaves (MHWs) formed in the northeast Pacific near Ocean Station Papa (OSP), one of the oldest oceanic time series stations. Physical, biogeochemical and biological parameters observed at OSP from 2013 to 2020 are used to assess ocean response and potential impacts on marine life from the 2019 northeast Pacific MHW. The 2019 MHW was preceded by calm and stratified surface conditions, lower dissolved inorganic carbon, and higher pH of surface waters relative to the 2013-2020 period. A spike in the summertime chlorophyll followed by a decrease in surface macronutrients suggests increased productivity in the well-lit stratified upper ocean during summer 2019. More blue whale calls were recorded at OSP in 2019 compared to the prior year. Large subsurface temperature anomalies were also found, suggesting that the earlier northeast Pacific MHW (2013-2015, previously referred to as “Blob”) as well as the long-term increase in sea surface temperatures in the region contributed to the intensity of the 2019 MHW. This study shows how the utility of long-term, continuous oceanographic datasets and analysis with an interdisciplinary lens is necessary to understand the potential impact of MHWs on marine ecosystems.

This study examines the impact of ocean advection and surface freshwater flux on the non-seasonal, upper-ocean salinity variability in two climate model simulations with eddy-resolving and eddy-parameterized ocean components (HR and LR, respectively). We assess the realism of each simulation by comparing their sea surface salinity (SSS) variance with satellite and Argo float estimates. Our results show that, in the extratropics, the HR variance is about five times larger than that in LR and agrees with the Argo estimates. In turn, the extratropical satellite SSS variance is smaller than that from HR and Argo by about a factor of two, potentially reflecting the low sensitivity of radiometers to SSS in cold waters. Using a simplified salinity conservation equation for the upper-50-m ocean layer, we find that the advection-driven variance in HR is, on average, one order of magnitude larger than the surface flux-driven variance, reflecting the action of mesoscale processes.

The reappearance of a northeast Pacific marine heatwave (MHW) sounded alarms in late summer 2019 for a warming event on par with the 2013–2016 MHW known as The Blob. Despite these two events having similar magnitudes in surface warming, differences in seasonality and salinity distinguish their evolutions. We compare and contrast the ocean’s role in the evolution and persistence of the 2013–2016 and 2019–2020 MHWs using mapped temperature and salinity data from Argo floats. An unusual near-surface freshwater anomaly in the Gulf of Alaska during 2019 increased the stability of the water column, preventing the MHW from penetrating as deeply as the 2013–2016 event. This freshwater anomaly likely contributed to the intensification of the MHW by increasing the near-surface buoyancy. The gradual buildup of subsurface heat content throughout 2020 in the region suggests the potential for persistent ecological impacts.

We highlight a mechanism for the co-production of research with local communities as a means of elevating the social relevance of the geosciences, increasing the potential for broader and more diverse participation. We outline the concept of an “equitable exchange” as an ethical framework guiding these interactions. This principled research model emphasizes that “currencies”- the rewards and value from participating in research - may differ between local communities and geoscientists. For those engaged in this work, an equitable exchange emboldens boundary spanning geoscientists to bring their whole selves to the work, providing a means for inclusive climates and rewarding cultural competency.

Water-mass transformation in the North Atlantic plays an important role in the Atlantic Meridional Overturning Circulation (AMOC) and its variability. Here we analyze subpolar North Atlantic water-mass transformation in high- and low-resolution versions of the Community Earth System Model (CESM1) and investigate whether differences in resolution and climatological water-mass transformation impact low-frequency AMOC variability. We find that high-resolution simulations reproduce the water-mass transformation found in a reanalysis-forced high-resolution ocean simulation more accurately than low-resolution simulations. We also find that the low-resolution CESM1 simulations, including one forced with the same atmospheric reanalysis data, have larger biases in surface heat fluxes, sea-surface temperatures and salinities compared to the high-resolution simulations. Despite these major climatological differences, the mechanisms of low-frequency AMOC variability are similar in the high- and low-resolution versions of CESM1. The Labrador Sea WMT plays a major role in driving AMOC variability, and a similar NAO-like sea-level pressure pattern leads AMOC changes. However, the high-resolution simulation shows a more pronounced atmospheric response to the AMOC variability. The consistent role of Labrador Sea WMT in low-frequency AMOC variability across high- and low-resolution coupled simulations, including a simulation which accurately reproduces the WMT found in an atmospheric reanalysis-forced high-resolution ocean simulation, suggests that the mechanisms are similar in the real world.

Zooplankton and micronekton are key links in tropical Pacific food webs, which include tuna as top-level predators. Zooplankton and micronekton vertically migrate to deeper depths to avoid visual predators, including tuna, during the day and then return to shallower depths to feed at night. Vertical migration depths vary spatially in the tropical Pacific and are correlated with oxygen, light, and temperature. El Niño-Southern Oscillation (ENSO) causes vertical shifts in the thermocline and oxycline. The accessibility of prey during the day should therefore vary interannually depending on the ENSO phase. We use available acoustic doppler current profiler (ADCP) data from cruises within the tropical Pacific between 1990 and 2019 to investigate the timescales and potential drivers of variability in zooplankton and micronekton vertical distributions in this region. Preliminary results suggest that ENSO-associated variations in vertical migration depths differ across the Exclusive Economic Zones (EEZs) of small island nations in the tropical Pacific. These variations are compared to temperature and oxygen-driven tuna vertical habitat variability to assess potential impacts on tuna.

The Kuroshio current separates from the Japanese coast to become the Kuroshio Extension (KE) characterized by a strong latitudinal density front, high levels of mesoscale (eddy) energy, and high chlorophyll (CHL). Recent work has also shown that the KE carries subsurface nutrients into the region horizontally. While satellite measurements of CHL show evidence of the impact of eddies on the standing stock of phytoplankton, there have been very limited in situ estimates of productivity over synoptic scales in this region. Here, we present highly spatially resolved estimates of net community production (NCP) for the KE region derived from underway O2/Ar measurements made in spring, summer, and early autumn. We find large seasonal differences in the relationships between NCP, CHL, and sea level anomaly (SLA, a proxy for local thermocline depth deviations driven by mesoscale eddies). The KE front is a pronounced hotspot of NCP in spring when NCP is almost completely decorrelated with CHL. Conversely, we find that NCP and CHL are strongly correlated in summer away from the front. We explore the mechanistic underpinnings of the relationship between NCP and CHL and suggest that the KE nutrient stream as well as vertical motions associated with mesoscale eddies might be a key factor in supporting an NCP hotspot that is seasonally decoupled from CHL at the KE front. Our observations also highlight seasonal and regional (de)coupling between NCP and CHL which may impact the accuracy of CHL-based estimates of productivity.

Scientific meetings organized by professional organizations have been keystone activities of scientific culture and career advancement. They provide opportunities to share research results, promote discussion on current and emerging research and education needs, apprentice early career participants into the community, and foster professional partnerships. However, scientific meetings are not equally inviting or accessible for all scientists, particularly those from historically marginalized communities. Organizers of scientific meetings have historically not ensured diverse representation of speakers and those in leadership roles, or have not provided needed networking opportunities and professional learning to foster scientists from historically marginalized communities, who often do not have the visibility or networking opportunities needed for persistence and success in a scientific career. As a result, scientific meetings can be an isolating and stressful experience. People from historically excluded identities can encounter structural barriers, such as lack of childcare or safe bathroom spaces, and can experience harassment and bullying. Within professional societies, policies and procedures as well as unwritten norms, can perpetuate bias and exclusion. For instance, certain attire, hair styles, and speaking tone may be targeted as counter to historical norms of professionalism, which were established before BIPOC and women entered the STEM fields in larger numbers. But these challenges also present opportunities to change. Scientific meetings can instead serve as influential intervention points to advance an inclusive environment and climate for geoscientists from across institutions, career stages, and backgrounds. We present a few actionable strategies that professional societies and convening organizations can take before, during, and after scientific meetings to make them more equitable, accessible, and anti-racist. We offer guidance for scientific meeting policies, procedures, awards systems, and leadership opportunities to build structure for inclusion. We also share recommendations for how professional societies can support members to advocate for more equitable and anti-racist culture within scientific meetings and at their home institutions.

This study investigates the influence of oceanic and atmospheric processes in extratropical thermodynamic air-sea interactions resolved by satellite observations (OBS) and by two climate model simulations run with eddy-resolving high-resolution (HR) and eddy-parameterized low-resolution (LR) ocean components. Here, spectral methods are used to characterize the sea surface temperature (SST) and turbulent heat flux (THF) variability and co-variability over scales between 50-10000 km and 60 days-80 years in the Pacific Ocean. The relative roles of the ocean and atmosphere are interpreted using a stochastic upper-ocean temperature evolution model forced by noise terms representing intrinsic variability in each medium, defined using climate model data to produce realistic rather than white spectral power density distributions. The analysis of all datasets shows that the atmosphere dominates the SST and THF variability over zonal wavelengths larger than ~2000-2500 km. In HR and OBS, ocean processes dominate the variability of both quantities at scales smaller than the atmospheric first internal Rossby radius of deformation (R1, ~600-2000 km) due to a substantial ocean forcing coinciding with a weaker atmospheric modulation of THF (and consequently of SST) than at larger scales. The ocean-driven variability also shows a surprising temporal persistence, from intraseasonal to multidecadal, reflecting a red spectrum response to ocean forcing similar to that induced by atmospheric forcing. Such features are virtually absent in LR due to a weaker ocean forcing relative to HR.