Prof. Pierre Lermusiaux has been invited to give a webinar on 19 January 2022, 7:30am EST about “Bayesian Learning of High-Dimensional Dynamical Models” for the AI Chair OceaniX webinar series.

Anya Zhang, a high school senior who joined MSEAS during summer 2021 as an RSI scholar, recently entered the Regeneron Science Talent Search (STS) and was named as one of the top 300 scholars out of 1,805 students in the 2022 competition. Her research with MSEAS reported on “Interactive Ocean Visualization Using VAPOR” and was included in the Regenron STS. Congrats Anya!

Significant lateral density gradients occur throughout the year in the Alboran Sea, giving rise to two main fronts: the Western Alboran Gyre Front (WAGF) and Eastern Alboran Gyre Front (EAGF), where large vertical velocities often develop. To improve the understanding of the processes that underlie the development of the vertical velocities in the fronts, the periods of development were analyzed in the perspective of the frontogenesis, instabilities, non-linear Ekman, and filamentogenesis mechanisms, using multi-platform in-situ observations and a high-resolution realistic simulation in spring 2018. The spatio-temporal characteristics of the WAGF indicate a wider, deeper, and longer-lasting front than the EAGF. Additionally, the WAGF shows stronger and deeper upwelling and downwelling regions. The WAGF vertical velocities (up to |55| m/day) are amplified by an across-front ageostrophic secondary circulation generated by: (a) frontal intensification explained by frontogenesis, which shows a sharpening of buoyancy gradients associated with the Atlantic Jet, (b) nonlinear Ekman effects, that are enhanced by the persistent western wind blowing along the frontal direction, and (c) submesoscale instabilities (symmetric and ageostrophic baroclinic instabilities). The EAGF vertical velocities (up to |38| m/day) are amplified by two asymmetrical ageostrophic cells developed across the front with a narrow upwelling region in the middle. The cell’s circulation is explained by frontal intensification produced by filamentogenesis through a cold filament advection to the Mediterranean Sea interior, that is characterized by pointy isopycnals at the center of the filament. This mechanism is observed in both the model and glider observations.

In this paper, we study the spatio-temporal variability of the sound speed in the Bay of Bengal (BoB) estimated from the Argo observation data during 2011-2020. We perform domain-wide and region specific analysis of the sound speed structure and identify the regions and times of higher variabilities. The domain-wide spatio-temporal variability in the sound speed is maximum in the thermocline layers near 110 m depth. This variability is smaller at around 35-40m depth but increases in the surface layers. The regions of higher temporal and spatial variability vary with depth and time. In the surface layers, the variability is large in the northern part of the Bay but in the subsurface and the layers underneath, it is large along the entire western boundary from the north to south. Due to the combined impact of temperature inversion and the positive salinity gradient, the northern BoB experiences a significant positive vertical gradient in sound speed above the sonic layer depth (SLD) during the postmonsoon and winter periods. This gradient supports strong surface ducting and formation of the shadow zone below the SLD.

Congratulations to Aaron Charous, who won first prize for the Early Career Presenter in Computational Acoustics at the 181st Meeting of the Acoustical Society of America in Seattle. The Computational Acoustics Technical Specialty Group (CA TSG) held its second Young/Early Career Presenter competition at this meeting, with 10 entrants. Three awards are made of up to USD $250 each. The award winners were selected based on the quality of the presented paper, comprising both the content and its delivery. Congrats Aaron!