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Grace wants to participate in her community festival's princess float, but first she must decide what sort of a princess she wants to be--from an African princess in kente cloth robes to a floaty pink fairy tale princess.

Phytoplankton photoacclimation is a well‐documented response to changes in light and nutrient availability, with the Chlorophyll a to phytoplankton Carbon ratio (θ$\\theta $  = Chl: Cphyto${\\mathrm{C}}_{\\text{phyto}}$ ) increasing at low light and decreasing under high light to optimize growth rate. Accurate estimation of phytoplankton growth rates and Net Primary Production (NPP) from space requires knowledge of θ$\\theta $ , but cloud cover creates gaps. Current NPP models fill in the gaps by interpolating Chl (and other inputs) from clear‐sky pixels, ignoring the possibility of photoacclimation underneath clouds. Using data from ≈${\\approx} $ 9,000 matchups between BioGeoChemical‐Argo floats and cloud cover from the Moderate Resolution Imaging Spectroradiometer, we compared the response of θ$\\theta $to irradiances under cloudy and clear skies. We found that phytoplankton photoacclimate similarly regardless of sky conditions at the global scale. This study highlights an incorrect assumption in current NPP estimates and suggests ways to improve global assessments of both chlorophyll and NPP. Plain Language Summary Phytoplankton, like plants on land, change their pigment concentration in response to light and nutrient levels. Under high light, they have fewer photosynthetic pigments in their cells and more when under low light (assuming nutrients are plentiful), a process referred to as photoacclimation. Phytoplankton productivity is commonly computed as a function of pigment concentration and incoming solar radiation, hence the importance of accurately characterizing photoacclimation when evaluating oceanic productivity. At any given time ≈${\\approx} $ 70% of the ocean is cloudy, with productivity algorithms applied equally under both cloudy and clear skies. Due to the inability of satellites to collect surface data under clouds, productivity algorithms must estimate data under clouds based on clear sky pixels. Currently, they do so by interpolating the concentration of pigments in clear sky pixels. Thus, when clouds reduce radiations reaching the ocean (which they do at spatially large scales), the resulting cloudy productivity is reduced. Here we show, using data from satellites and automated observations from profiling floats, that phytoplankton cells adjust their pigmentation to the reduced light under cloud cover, thereby reducing the impact of clouds on productivity. This work provides a simple pathway to remove a bias in oceanic productivity estimates. Key Points At the global scale, phytoplankton exhibit similar photoacclimation responses under both cloudy and clear skies Seasonal variations in photoacclimation occur, but these changes are mostly consistent between sky conditions Neglecting photoacclimation under clouds likely leads to a significant underestimation of growth rate and therefore of primary production

134 Cs and 137 Cs were released to the North Pacific Ocean by two major likely pathways, direct discharge from the Fukushima NPP1 accident site and atmospheric deposition off Honshu Islands of Japan, east and northeast of the site. High density observations of 134 Cs and 137 Cs in the surface water were carried out by 17 cruises of cargo ships and several research vessel cruises from March 2011 till March 2012. The main body of radioactive surface plume of which activity exceeded 10 Bq m-3 travelled along 40° N and reached the International Date Line on March 2012, one year after the accident. A distinct feature of the radioactive plume was that it stayed confined along 40° N when the plume reached the International Date Line. A zonal speed of the radioactive plume was estimated to be about 8 cm s-1 which was consistent with zonal speeds derived by Argo floats at the region.

The seasonal variability of phytoplankton vertical distribution is investigated in the South Pacific where observations are scarce and scattered. We used 13 BioGeoChemical‐Argo floats deployed across diverse oceanic environments. The seasonal latitudinal displacement of the Tasman front induces transitions from mesotrophic to oligotrophic conditions. This shift results in Chlorophyll‐a concentration vertical distribution changing from bloom types to Subsurface Chlorophyll Maxima (SCM) types, with intermediate hybrid types between these extremes. Such hybrid profiles frequently occur in the equatorial Pacific, highlighting a large‐scale pattern rather than local island mass effect. In oligotrophic regions, seasonal variations of light availability and stratification dynamics below the mixed layer likely relate SCM to an increase in carbon biomass or photoacclimation. A biomass increase is frequently observed, contrary to previous studies, suggesting that subsurface phytoplankton biomass may have been largely underestimated. This calls for further observations of the water column in these remote undersampled open ocean areas.

Carbon export driven by submesoscale, eddy‐associated vertical velocities (“eddy subduction”), and particularly its seasonality, remains understudied, leaving a gap in our understanding of ocean carbon sequestration. Here, we assess mechanisms controlling eddy subduction's spatial and seasonal patterns using 15 years of observations from BGC‐Argo floats in the Southern Ocean. We identify signatures of eddy subduction as subsurface anomalies in temperature‐salinity and oxygen. The anomalies are spatially concentrated near weakly stratified areas and regions with strong lateral buoyancy gradients diagnosed from satellite altimetry, particularly in the Antarctic Circumpolar Current's standing meanders. We use bio‐optical ratios, specifically the chlorophyll a to particulate backscatter ratio (Chl/bbp) to find that eddy subduction is most active in the spring and early summer, with freshly exported material associated with seasonally weak vertical stratification and increasing surface biomass. Climate change is increasing ocean stratification globally, which may weaken eddy subduction's carbon export potential. Plain Language Summary Oceans play an important role in global climate by soaking up and sequestering atmospheric carbon dioxide. Photosynthetic activity at the surface turns carbon dioxide into organic carbon, and if this carbon leaves the surface to the deep ocean, it can be locked away from the atmosphere. One way this occurs is through the physical circulation associated with swirling eddies, which can rapidly transport organic carbon‐rich surface waters and “inject” them into deep waters. However, we still don't fully understand the seasonal timing of this process, or what drives its spatial distribution. We investigated this in the Southern Ocean, which is very important to global climate, using data collected by drifting robots. We find that this process is the most active in regions where eddies drive strong surface stirring, and during the spring, when weak stratification allows injections to penetrate deep into the ocean. Because this process is poorly represented in climate models, these findings will improve our understanding of how the ocean absorbs carbon. Key Points Eddy subduction in the Southern Ocean is observed as subsurface anomalies in spice and oxygen measured by autonomous profiling floats Spatial distribution is controlled by weak stratification and strong lateral buoyancy gradients, diagnosed using satellite altimetry Bio‐optical proxies suggest that eddy subduction is most active in spring/early summer, driven by weak vertical stratification

A critical driver of the ocean carbon cycle is the downward flux of sinking organic particles, which acts to lower the atmospheric carbon dioxide concentration. This downward flux is reduced by more than 70% in the mesopelagic zone (100 to 1000 meters of depth), but this loss cannot be fully accounted for by current measurements. For decades, it has been hypothesized that the missing loss could be explained by the fragmentation of large aggregates into small particles, although data to test this hypothesis have been lacking. In this work, using robotic observations, we quantified total mesopelagic fragmentation during 34 high-flux events across multiple ocean regions and found that fragmentation accounted for 49 ± 22% of the observed flux loss. Therefore, fragmentation may be the primary process controlling the sequestration of sinking organic carbon.

The monthly global 2° × 2° Extended Reconstructed Sea Surface Temperature (ERSST) has been revised and updated from version 4 to version 5. This update incorporates a new release of ICOADS release 3.0 (R3.0), a decade of near-surface data from Argo floats, and a new estimate of centennial sea ice from HadISST2. A number of choices in aspects of quality control, bias adjustment, and interpolation have been substantively revised. The resulting ERSST estimates have more realistic spatiotemporal variations, better representation of high-latitude SSTs, and ship SST biases are now calculated relative to more accurate buoy measurements, while the global long-term trend remains about the same. Progressive experiments have been undertaken to highlight the effects of each change in data source and analysis technique upon the final product. The reconstructed SST is systematically decreased by 0.077°C, as the reference data source is switched from ship SST in ERSSTv4 to modern buoy SST in ERSSTv5. Furthermore, high-latitude SSTs are decreased by 0.1°–0.2°C by using sea ice concentration from HadISST2 over HadISST1. Changes arising from remaining innovations are mostly important at small space and time scales, primarily having an impact where and when input observations are sparse. Cross validations and verifications with independent modern observations show that the updates incorporated in ERSSTv5 have improved the representation of spatial variability over the global oceans, the magnitude of El Niño and La Niña events, and the decadal nature of SST changes over 1930s–40s when observation instruments changed rapidly. Both long-(1900–2015) and short-term (2000–15) SST trends in ERSSTv5 remain significant as in ERSSTv4.

Helicopter ditching incidents occur frequently. To improve the crew’s ability to escape during a helicopter ditching, installing an emergency flotation device is a common practice both domestically and internationally. Flotation performance is a key indicator of a helicopter ditching incident, directly impacting the crew’s escape time. This paper uses numerical simulation to investigate the effect of the emergency flotation device float configuration on the helicopter’s flotation performance. Simulations were performed in Level 5 irregular wave sea conditions: helicopters without floats, equipped with basic floats, and equipped with ellipsoidal floats. Simulation results show that a helicopter without floats capsized within 10 seconds. A helicopter equipped with both types of floats could float stably in sea state 5. Furthermore, the floating performance of helicopters equipped with floats of different configurations varied. Compared with the basic floats, the maximum absolute value of the pitch angle change of the helicopter equipped with ellipsoidal floats decreased by 25%, and the maximum absolute value of the roll angle change decreased by 30%.

Metals that are active catalysts for methane (Ni, Pt, Pd), when dissolved in inactive low–melting temperature metals (In, Ga, Sn, Pb), produce stable molten metal alloy catalysts for pyrolysis of methane into hydrogen and carbon. All solid catalysts previously used for this reaction have been deactivated by carbon deposition. In the molten alloy system, the insoluble carbon floats to the surface where it can be skimmed off. A 27% Ni–73% Bi alloy achieved 95% methane conversion at 1065°C in a 1.1-meter bubble column and produced pure hydrogen without CO₂ or other by-products. Calculations show that the active metals in the molten alloys are atomically dispersed and negatively charged. There is a correlation between the amount of charge on the atoms and their catalytic activity.

Oceanic mesoscale eddies contribute important horizontal heat and salt transports on a global scale. Here we show that eddy transports are mainly due to individual eddy movements. Theoretical and observational analyses indicate that cyclonic and anticyclonic eddies move westwards, and they also move polewards and equatorwards, respectively, owing to the β of Earth’s rotation. Temperature and salinity (T/S) anomalies inside individual eddies tend to move with eddies because of advective trapping of interior water parcels, so eddy movement causes heat and salt transports. Satellite altimeter sea surface height anomaly data are used to track individual eddies, and vertical profiles from co-located Argo floats are used to calculate T/S anomalies. The estimated meridional heat transport by eddy movement is similar in magnitude and spatial structure to previously published eddy covariance estimates from models, and the eddy heat and salt transports both are a sizeable fraction of their respective total transports. Modelling studies suggest that oceanic mesoscale eddies play an important role in the global transport of heat and salt, yet there are few direct observations. Dong et al. present a method to calculate eddy transport through the use of satellite data and Argo profiles and confirm model-based estimates.