Storms drive outgassing of CO2 in the subpolar Southern Ocean

The subpolar Southern Ocean is a critical region where CO2 outgassing influences the global mean air-sea CO2 flux (FCO2). However, the processes controlling the outgassing remain elusive. We show, using a multi-glider dataset combining FCO2 and ocean turbulence, that the air-sea gradient of CO2 (∆pCO2) is modulated by synoptic storm-driven ocean variability (20 µatm, 1–10 days) through two processes. Ekman transport explains 60% of the variability, and entrainment drives strong episodic CO2 outgassing events of 2–4 mol m−2 yr−1. Extrapolation across the subpolar Southern Ocean using a process model shows how ocean fronts spatially modulate synoptic variability in ∆pCO2 (6 µatm2 average) and how spatial variations in stratification influence synoptic entrainment of deeper carbon into the mixed layer (3.5 mol m−2 yr−1 average). These results not only constrain aliased-driven uncertainties in FCO2 but also the effects of synoptic variability on slower seasonal or longer ocean physics-carbon dynamics.

Observing Life in the Sea Using Environmental DNA

The use of environmental DNA (eDNA) for studying the ecology and variability of life in the sea is reviewed here in the context of US interagency Marine Biodiversity Observation Network (MBON) projects. Much of the information in this paper comes from samples collected within US National Marine Sanctuaries. The field of eDNA is relatively new but growing rapidly, and it has the potential to disrupt current paradigms developed on the basis of existing measurement methods. After a general review of the field, we provide specific examples of the type of information that eDNA provides regarding the changing distribution of life in the sea over space (horizontally and vertically) and time. We conclude that eDNA analyses yield results that are similar to those collected using traditional observation methods, are complementary to them, and because of the breadth of information provided, have the potential to improve conservation and management practices. Moreover, through technology development and standardization of methods, eDNA offers a means to scale biological observations globally to a level similar to those currently made for ocean physics and biogeochemistry. This scaling can ultimately result in a far better understanding of global marine biodiversity and contribute to better management and sustainable use of the world ocean. Improved information management systems that track methods and associated metadata, together with international coordination, will be needed to realize a global eDNA observation network.

Transforming Ocean Science: Fostering a Network for Cooperative Science Research on Commercial Ships (Science RoCS)

Our goal is to transform ocean science through industry partnerships with commercial shippers, creating “integrated observing platforms” with a global reach that will revolutionize the science community's ability to characterize variability in ocean physics, chemistry, and biology across spatial and temporal scales. For the past 100+ years, oceanographers have been able to directly access just a fraction of the global ocean. With only a few dozen research vessels worldwide versus more than 50,000 commercial vessels in operation today, and industry eager to participate in ocean science, the environment is brimming with opportunities. We envision a future where commercial vessels are, as a matter of course, designed and built with a suite of scientific sensors to measure water properties and currents, as well as chemical and biological parameters optimized for a vessel's trade route to address societally relevant questions, with the data disseminated broadly to all stakeholders. Targeted collaborations between science and commercial shippers have existed for decades and the foundation has been laid. Now it is time to build on this experience by using the science community's vast network, relationships, and expertise in sensor technology and science to make data collection on commercial ships the new norm.

AIR-WATER INTERACTION OF PADDLE WAVES UNDER WIND FORCING

The air-water interaction has been long studied in ocean physics, due to its importance to natural hazard and impact on human activities. Several studies in the literature provided advancements for a better comprehension of gases, mass and momentum exchanges at the interface. However, the subject is wide and many aspects are still unsolved, especially it is quite hard to extract data from the air and water boundary layer. A non-intrusive useful method to acquire data at the air-water interface is Particle Image Velocimetry (PIV), which can extrapolate a huge amount of information in water. We perform an experimental study of regular waves generated by paddles propagating under the action of the wind. We discuss the importance of sea surface boundary layer under waves and winds based on laboratory experiments and scale analysis.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/X-3OQnJKMf8

IN MEMORY OF EVGENY ARKADIEVICH KULIKOV (27.01.1950 – 21.11.2020)

On November 21, 2020, at the age of 70, one of the world’s largest specialists in the science of tsunami, Doctor of Physical and Mathematical Sciences, Chief Researcher of the Tsunami Laboratory in the Shirshov Institute of Oceanology, the Russian Academy of Sciences, Evgueny Arkadievich Kulikov, suddenly passed away. From 1980 to 1986 he was the Head of the Ocean Physics Laboratory in the Tsunami Department of the Sakhalin Complex Research Institute / Institute of Marine Geology and Geophysics, Far East Scientific Center of the USSR Academy of Sciences (Yuzhno-Sakhalinsk). From 2004 to 2018, E.A. Kulikov headed the Tsunami Laboratory of the Shirshov Institute of Oceanology, Russian Academy of Sciences. E.A. Kulikov had students and colleagues all over the world – in Russia from Sakhalin to Moscow, in Europe, Canada, and the U.S.A. He left a bright mark in oceanology, in the science of tsunami, as well as in the memory of numerous friends and colleagues around the world as a remarkable scientist, teacher, and wonderful person. The presented article describes the main scientific stages of E.A. Kulikov.

Filtering tide-generated internal waves using Convolutional Neural Networks

<p>Starting from 2021, Surface  Water Ocean Topography (SWOT) satellite altimetry mission will provide an unprecedented amount of Sea Surface Height (SSH) measurements. In addition to allowing for a higher spatial resolution, SWOT will deliver two-dimensional horizontal SSH data thanks to its wide swath capacities, which is a remarkable leap compared to conventional current altimeters.</p><p>With the aim of extracting a clean SSH signal from the SWOT measurements, several challenges are expected to be encountered. In this work, we focus on filtering the footprints of Internal Gravity Waves (IGWs), this is of high interest for physical oceanographers who seek to better understand mesoscale and submesoscale ocean physics.</p><p>Thanks to recent developments in ocean numerical simulation, we can now have access to a considerable amount of simulation data with exceptional high spatial resolutions up to 1/60° and hourly temporal resolution. Here, we benefit from an advanced North Atlantic simulation of the ocean circulation (eNATL60) that models tidal motions, and design a supervised machine learning experiment that aims to test several techniques for filtering IGWs.</p><p>In particular, we show that deep convolutional neural networks are a relevant candidates for this task and presents promising results with regard to conventional linear filtering techniques. We also show how our method can be adapted to the context of the fast-sampling phase of SWOT, and can also take advantage from the presence of additional data such as Sea Surface Temperature.</p>

The Water Mass Transformation Framework for Ocean Physics and Biogeochemistry

<p>To understand the role of the ocean in the climate system, it is no longer sufficient to study either physics or biogeochemistry. Future efforts need to combine these disciplines to truly understand our future climate. The water mass transformation (WMT) weaves together circulation, thermodynamics, and biogeochemistry into a description of the ocean that complements traditional Eulerian and Lagrangian methods. Here we present a derivation of a WMT framework that offers an analysis that renders novel insights and predictive capabilities for studies of ocean physics and biogeochemistry that determine ocean tracer uptake, circulation and storage. We will discuss application for this framework for biogeochemical studies and its potential for inferring unmeasurable biogeochemical processes from estimates of the measurable physical processes.</p>