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Alice Della Penna

Research Associate






B.S. Physics, University of Turin, 2010

M.S. Physics of Complex Systems, University of Turin, 2012

Ph.D. Interdisciplinary Approaches to Life Sciences, Paris Diderot University, 2016

Ph.D. Quantitative Marine Science, University of Tasmania, 2016


2000-present and while at APL-UW

Detecting mesopelagic organisms using biogeochemical-Argo floats

Haëntjens, N., A. Della Penna, N. Briggs, L. Karp-Boss, P. Gaube, H. Claustre, and E. Boss, "Detecting mesopelagic organisms using biogeochemical-Argo floats," Geophys. Res. Lett., 47, doi:10.1029/2019GL086088, 2020.

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28 Mar 2020

During the North Atlantic Aerosols and Marine Ecosystems Study in the western North Atlantic, float‐based profiles of fluorescent dissolved organic matter and backscattering exhibited distinct spike layers at ~ 300 m. The locations of the spikes were at depths similar or shallower to where a ship‐based scientific echo sounder identified layers of acoustic backscatter, an Underwater Vision Profiler detected elevated concentration of zooplankton, and mesopelagic fish were sampled by a mesopelagic net tow. The collocation of spike layers in bio‐optical properties with mesopelagic organisms suggests that some can be detected with float‐based bio‐optical sensors. This opens the door to the investigation of such aggregations/layers in observations collected by the global biogeochemical‐Argo array allowing the detection of mesopelagic organisms in remote locations of the open ocean under‐sampled by traditional methods.

Global satellite-observed daily vertical migrations of ocean animals

Behrenfeld, M.J., P. Gaube, A. Della Penna, R.T. O'Malley, W.J. Burt, Y. Hu, P.S. Bontempi, D.K. Steinberg, E.S. Boss, D.A. Siegel, C.A. Hostetler, P.D. Torfell, and S.C. Doney, "Global satellite-observed daily vertical migrations of ocean animals," Nature, 576, 257-261, doi:10.1038/s41586-019-1796-9, 2019.

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27 Nov 2019

Every night across the world's oceans, numerous marine animals arrive at the surface of the ocean to feed on plankton after an upward migration of hundreds of metres. Just before sunrise, this migration is reversed and the animals return to their daytime residence in the dark mesopelagic zone (at a depth of 200–1,000 m). This daily excursion, referred to as diel vertical migration (DVM), is thought of primarily as an adaptation to avoid visual predators in the sunlit surface layer and was first recorded using ship-net hauls nearly 200 years ago. Nowadays, DVMs are routinely recorded by ship-mounted acoustic systems (for example, acoustic Doppler current profilers). These data show that night-time arrival and departure times are highly conserved across ocean regions and that daytime descent depths increase with water clarity, indicating that animals have faster swimming speeds in clearer waters. However, after decades of acoustic measurements, vast ocean areas remain unsampled and places for which data are available typically provide information for only a few months, resulting in an incomplete understanding of DVMs. Addressing this issue is important, because DVMs have a crucial role in global ocean biogeochemistry. Night-time feeding at the surface and daytime metabolism of this food at depth provide an efficient pathway for carbon and nutrient export.

Here we use observations from a satellite-mounted light-detection-and-ranging (lidar) instrument to describe global distributions of an optical signal from DVM animals that arrive in the surface ocean at night. Our findings reveal that these animals generally constitute a greater fraction of total plankton abundance in the clear subtropical gyres, consistent with the idea that the avoidance of visual predators is an important life strategy in these regions. Total DVM biomass, on the other hand, is higher in more productive regions in which the availability of food is increased. Furthermore, the 10-year satellite record reveals significant temporal trends in DVM biomass and correlated variations in DVM biomass and surface productivity. These results provide a detailed view of DVM activities globally and a path for refining the quantification of their biogeochemical importance.

Vertical motions and their effects on a biogeochemical tracer in a cyclonic structure finely observed in the Ligurian Sea

Rousselet, L., and 14 others including A. Della Penna, "Vertical motions and their effects on a biogeochemical tracer in a cyclonic structure finely observed in the Ligurian Sea," J. Geophys. Res., 124, 3561-3574, doi:10.1029/2018JC014392, 2019.

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1 Jun 2019

Vertical velocities can be estimated indirectly from in situ observations by theoretical frameworks like the ω‐equation. Direct measures of vertical exchanges are challenging due to their typically ephemeral spatiotemporal scales. In this study we address this problem with an adaptive sampling strategy coupling various biophysical instruments. We analyze the 3‐D organization of a cyclonic mesoscale structure finely sampled during the Observing Submesoscale Coupling At High Resolution cruise in the Ligurian Sea during fall 2015. The observations, acquired with a moving vessel profiler, highlight a subsurface low‐salinity layer (≅50 m), as well as rising isopycnals, generated by geostrophic cyclonic circulation, in the structure's center. Reconstructed 3‐D fields of density and horizontal velocities are used to estimate the vertical velocity field down to 250 m by applying the adiabatic QG ω‐equation, for the first time in this region. The vertical motions are characterized by multipolar patterns of downward and upward velocities on the edges of the structure and significantly smaller vertical velocities in its center. Both the 3‐D distribution of particles (size ≥100 μm), measured with a laser optical plankton counter, and the Synechococcus and Prochlorococcus abundances (cell per cubic meter) measured by flow cytometry are consistent with the 3‐D velocity field. In particular, a secondary vertical recirculation is identified that upwells particles (from 250 to 100 m) along isohalines to the structure's center. Besides demonstrating the effect of vertical patterns on biogeochemical distributions, this case study suggests to use particle matter as a tracer to assess physical dynamics.

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Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center