Biogeochemistry and Physics of the Southern Ocean-Atmosphere System Explored With Data Science

Type Article
Acceptance Date 2021 IN PRESS
Language English
Author(s) Landwehr Sebastian1, 13, Volpi Michele2, Haumann F. Alexander3, 4, Robinson Charlotte M5, Thurnherr Iris6, 7, Ferracci Valerio8, Baccarini Andrea1, 13, Thomas Jenny9, Gorodetskaya Irina10, 11, Tatzelt Christian12, Henning Silvia12, Modini Rob L13, Forrer Heather J14, 15, Lin Yajuan16, 17, 18, Cassar Nicolas16, 17, Simo Rafel19, Hassler Christel9, 20, Moallemi Alireza13, Fawcett Sarah E14, Harris Neil8, Airs Ruth21, Derkani Marzieh H22, Alberello Alberto23, Toffoli Alessandro22, Chen Gang13, Rodríguez-Ros Pablo19, Zamanillo Marina19, Cortés-Greus Pau19, Xue Lei24, Bolas Conor G25, Leonard Katherine C11, 26, Perez-Cruz Fernando2, Walton David4, Schmale Julia1, 13
Affiliation(s) 1 : School of Architecture Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Switzerland
2 : Swiss Data Science Center, ETH Zurich and EPFL, Switzerland
3 : Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, NJ, USA
4 : British Antarctic Survey, Cambridge, UK
5 : Remote Sensing and Satellite Research Group, School of Earth and Planetary Sciences, Curtin University, Kent Street, Bentley, WA 6102, Australia
6 : Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland
7 : Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway
8 : Centre for Environmental and Agricultural Informatics, School of Water, Energy & Environment Cranfield University, College Road, Cranfield MK43 0AL, Bedfordshire
9 : Swiss Polar Institute, Switzerland
10 : Centre for Environmental and Marine Studies, Department of Physics, University of Aveiro, Aveiro, Portugal
11 : CRYOS, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Switzerland
12 : Leibniz Institute for Tropospheric Research, Leipzig, Germany
13 : Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), 5232 Villigen PSI, Switzerland
14 : Department of Oceanography, University of Cape Town, 7701, Cape Town, South Africa
15 : Earth, Ocean and Atmospheric Science Department, Florida State University, Tallahassee, FL, USA, 32306
16 : Division of Earth and Climate Sciences, Nicholas School of the Environment, Duke University, Durham, USA
17 : CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280 Plouzané, France
18 : Duke Kunshan University, China
19 : Institut de Ciències del Mar (ICM-CSIC), Barcelona, Catalonia, Spain
20 : Department F.-A. Forel for Environmental and Aquatic Sciences, University of Geneva
21 : Plymouth Marine Laboratory
22 : Dept. Infrastructure Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Melbourne, Australia
23 : Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
24 : Department of Chemistry, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, USA
25 : ITOPF
26 : CIRES, University of Colorado Boulder, USA
Source Earth System Dynamics (2190-4987) (Copernicus GmbH) In Press
DOI 10.5194/esd-2021-16
Abstract

The Southern Ocean is a critical component of Earth’s climate system, but its remoteness makes it challenging to develop a holistic understanding of its processes from the small to the large scale. As a result, our knowledge of this vast region remains largely incomplete. The Antarctic Circumnavigation Expedition (ACE, austral summer 2016/2017) surveyed a large number of variables describing the dynamic state of the ocean and the atmosphere, the freshwater cycle, atmospheric chemistry, ocean biogeochemistry and microbiology. This circumpolar cruise included visits to twelve remote islands, the marginal ice zone, and the Antarctic coast. Here, we use 111 of the observed variables to study the latitudinal gradients, seasonality, shorter term variations, the geographic setting of environmental processes, and interactions between them over the duration of 90 days. To reduce the dimensionality and complexity of the dataset and make the relations between variables interpretable, we applied a sparse Principal Component Analysis (sPCA), which describes environmental processes through 14 latent variables. To derive a robust statistical perspective on these processes and to estimate the uncertainty in the sPCA decomposition, we have developed a bootstrap approach. We identified temporal patterns from diurnal to seasonal cycles, as well as geographical gradients and “hotspots” of interaction. Our results establish connections of oceanic, atmospheric, biological and terrestrial processes in an innovative way, while confirming many well known relations of the Southern Ocean system. More specifically, we identify: the important role of the oceanic circulations, frontal zones, and islands in shaping the nutrient availability that controls biological community composition and productivity; that sea ice predominantly controls sea water salinity, dampens the wave field, and is associated with increased phytoplankton growth and net community productivity possibly due to iron fertilization and reduced light limitation; and clear regional patterns of aerosol characteristics emerged, stressing the role of the sea state, atmospheric chemical processing, as well as source processes near “hotspots” for the availability of cloud condensation nuclei and hence cloud formation. A set of key variables and their combinations, such as the difference between the air and sea surface temperature, atmospheric pressure, sea surface height, geostrophic currents, upper ocean layer light intensity, surface wind speed and relative humidity, played an important role in the majority of latent variables, highlighting their importance for a large variety of processes and the necessity for Earth System Models to represent them adequately. In conclusion, our study highlights the use of sPCA to identify key ocean-atmosphere interactions across physical, chemical, and biological processes and their associated spatio-temporal scales. The sPCA processing code is available as open-access and we believe that our approach is widely applicable to other environmental field studies.

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Landwehr Sebastian, Volpi Michele, Haumann F. Alexander, Robinson Charlotte M, Thurnherr Iris, Ferracci Valerio, Baccarini Andrea, Thomas Jenny, Gorodetskaya Irina, Tatzelt Christian, Henning Silvia, Modini Rob L, Forrer Heather J, Lin Yajuan, Cassar Nicolas, Simo Rafel, Hassler Christel, Moallemi Alireza, Fawcett Sarah E, Harris Neil, Airs Ruth, Derkani Marzieh H, Alberello Alberto, Toffoli Alessandro, Chen Gang, Rodríguez-Ros Pablo, Zamanillo Marina, Cortés-Greus Pau, Xue Lei, Bolas Conor G, Leonard Katherine C, Perez-Cruz Fernando, Walton David, Schmale Julia Biogeochemistry and Physics of the Southern Ocean-Atmosphere System Explored With Data Science. Earth System Dynamics IN PRESS. Publisher's official version : https://doi.org/10.5194/esd-2021-16 , Open Access version : https://archimer.ifremer.fr/doc/00691/80275/