US SOLAS Science Report

The Surface Ocean – Lower Atmosphere Study (SOLAS) (http://www.solas-int.org/) is an international research initiative focused on understanding the key biogeochemical-physical interactions and feedbacks between the ocean and atmosphere that are critical elements of climate and global biogeochemical cycles. Following the release of the SOLAS Decadal Science Plan (2015-2025) (Brévière et al., 2016), the Ocean-Atmosphere Interaction Committee (OAIC) was formed as a subcommittee of the Ocean Carbon and Biogeochemistry (OCB) Scientific Steering Committee to coordinate US SOLAS efforts and activities, facilitate interactions among atmospheric and ocean scientists, and strengthen US contributions to international SOLAS. In October 2019, with support from OCB, the OAIC convened an open community workshop, Ocean-Atmosphere Interactions: Scoping directions for new research with the goal of fostering new collaborations and identifying knowledge gaps and high-priority science questions to formulate a US SOLAS Science Plan. Based on presentations and discussions at the workshop, the OAIC and workshop participants have developed this US SOLAS Science Plan. The first part of the workshop and this Science Plan were purposefully designed around the five themes of the SOLAS Decadal Science Plan (2015-2025) (Brévière et al., 2016) to provide a common set of research priorities and ensure a more cohesive US contribution to international SOLAS.

Analysis of the isopycnal advection in the Lofoten basin (the Norwegian sea)

<p>The Lofoten Basin in the Norwegian Sea is a real reservoir of the Atlantic Waters. The shape of the Basin in the form of a bowl and a great depth with its monotonous increase to the centre results in the Atlantic Water gradually deepen and fill the Basin. The deepening of the Atlantic Waters in the Lofoten Basin determines not only the structure of its waters but also the features of the ocean-atmosphere interaction. Flowing through the transit regions, the Atlantic Waters lose heat to the atmosphere, mix with the surrounding water masses and undergo a transformation, which causes the formation of deep ocean waters. At the same time, the heat input with the Atlantic waters significantly exceeds its loss to the atmosphere in the Lofoten Basin.</p><p>We study isopycnal advection and diapycnal mixing in the Lofoten Basin. We use the GLORYS12V1 oceanic reanalysis data and analyze four isosteric δ-surfaces. We also calculate the depth of their location. We establish that δ-surfaces have the slope eastward with maximal deepening where the quasi-permanent Lofoten Vortex is located. We analyze the temperature distribution on the isosteric δ-surfaces as well as the interannual and seasonal variability of their location depth.</p><p>The maximal depth on the isosteric surfaces is observed in 2010, which is known as the year of the largest mixed layer depths in the Lofoten Basin according to the ARGO buoys. We demonstrate the same correspondence to in 2000, 2010, 2013.</p><p>The maximal depth on the isosteric surfaces is observed is reached in summer. The maximal areas with the greatest depths also are observed in summer in contrast to a minimum in winter. This means certain inertia of changes in the thermohaline characteristics of Atlantic Waters as well as a shift of 1-2 seasons of the influence of deep convection on isosteric surfaces.</p><p>It is shown that isopycnal advection in the Lofoten Basin makes a significant contribution to its importance as the main thermal reservoir of the Nordic Seas.</p>

Fuel for Cyclones: Quantification of Ocean‐Atmosphere Energy Exchange during Tropical Cyclones in the Bay of Bengal Using Indian Ocean Moored Observatories

Based on the in-situ subsurface thermal and salinity measurements from the Ocean Moored Buoy Network for Northern Indian Ocean (OMNI) during the passage of very severe tropical cyclones (TCs) in the Bay of Bengal, we have identified that the depth of ocean‐atmosphere interaction is limited by the depth of the pycnocline. During the TC Vardha and Phailin with cyclone-period-averaged wind speeds of 8 and 21 m/s, respectively, the maximum possible rates of water-vapor generation during the cyclone period, computed based on the salinity changes and considering precipitation, are 1.0 and 9.3 kg/m2/h, respectively. For the same wind speeds, based on the ocean heat content (OHC) changes, it is quantified that ~78% and 89% of the OHC changes are in the form of latent heat. The real-time availability of the in-situ subsurface parameters can be used in the ocean-atmosphere coupled models and intensification studies.

Mesoscale Air–Sea Interaction and Its Role in Eddy Energy Dissipation in the Kuroshio Extension

ABSTRACT Using the high-resolution Community Earth System Model (CESM) output, this study investigates air–sea interaction and its role in eddy energy dissipation in the Kuroshio Extension (KE) region. Based on an eddy energetics analysis, it is found that the baroclinic pathway associated with temperature variability is the main eddy energy source in this region. Both the air–sea heat flux and wind stress act as eddy killers that remove energy from oceanic eddies. Heat exchange between atmosphere and oceanic eddies dominates the dissipation of eddy temperature variance within the surface layer and accounts for 36% of the total dissipation in the upper 350-m layer. Compared to the heat exchange, the role of wind power in damping the eddy kinetic energy (EKE) is relatively small. Only 18% of EKE dissipation in the upper 350 m is attributed to eddy wind power. Misrepresentation of the damping role of mesoscale ocean–atmosphere interaction can result in an incorrect vertical structure of eddy energy dissipation, leading to an erroneous representation of vertical mixing in the interior ocean.