Representatives

Laura Gallardo (Chile, lgallard@u.uchile.cl)
Veronique Garçon (France, veronique.garcon@legos.obs-mip.fr)
Arne Körtzinger (Germany, akoertzinger@geomar.de)

Present understanding

Upwelling systems, both coastal and equatorial, are natural laboratories for studying the impacts of multiple stressors on air sea-exchange processes and marine ecosystem services. These systems are characterised by high productivity closely related to the presence of an extensive oxygen minimum zone (OMZ) and low pH-high carbon dioxide values. An active research during recent decades has determined the role of upwelling systems in the exchange of climatic active gases such as CO₂, N₂O and CH₄, the OMZ variability and the biogeochemical cycles of nitrogen, carbon and sulphur.

Priorities

In order to better understand the ocean-atmosphere connection, several tem-poral (diurnal, intraseasonal, seasonal, interannual, decadal, and multidecadal) and spatial (mesoscale, local, regional, and global) scales of variability and physical forcing in the system need to be considered. There is still a critical knowledge gap in understanding the driving mechanisms, the extent, and the spatial and temporal variability of ocean deoxygenation in upwelling systems, as well as impacts on marine food webs and biogeochemistry. Understanding how land-air-sea interactions control the dynamics behind the OMZs in the eastern boundary upwelling systems and may potentially exacerbate deoxygenation is not just a matter of scientific interest, but also a major societal concern.

Representatives

Katye Altieri (South Africa, katye.altieri@uct.ac.za)
Maurice Levasseur (Canada, maurice.levasseur@bio.ulaval.ca)
Lisa Miller (Canada, lisa.miller@dfo-mpo.gc.ca)
Jun Nishioka (Japan, nishioka@lowtem.hokudai.ac.jp)
Alfonso Saiz-Lopez (Spain, a.saiz-lopez@ciac.jccm-csic.es)

Present understanding

Changing sea ice coverage in the polar oceans is impacting air-sea exchanges of both energy and climatically active substances. The dynamics and consequences of changes in sea-ice characteristics and distribution in the polar oceans are critical to understanding and modelling feedback effects and future scenarios of climate change. Sea ice was long assumed to inhibit air-sea gas and material exchange, but extensive research over the last ten years has shown that sea ice is a very rich and complex system that actively exchanges with both the atmosphere and the underlying water, and impacts exchanges in surrounding waters.

Priorities

BEPSII
Within sea ice, biotic and abiotic processes interact in changing ways throughout the freeze-melt cycle, and thus, sea ice is an active participant in the biogeochemical cycles of many elements, producing climatically active atmospheric aerosols, modulating the surface ocean ecosystem, contributing to substantial seasonal gas fluxes, and possibly facilitating long-term export and carbon dioxide sequestration in deep waters. The 5-year science plan for the SOLAS-CliC sponsored Biogeochemical Exchange Processes at Sea-Ice Interfaces (BEPSII) research community emphasizes goals to:

• develop dedicated consistent methodologies for sea-ice biogeochemical research;
• establish effective sea-ice biogeochemical data-archiving approaches and databases;
• foster process studies to determine impacts on ecology and biogeochemical cycles;
• foster technological developments and international knowledge transfer towards large-scale, autonomous and high-frequency sampling of sea-ice biogeochemical parameters;
• improve the representation and evaluation of sea-ice biogeochemistry in regional and Earth system numerical models;
• synthesize and integrate observational and modeling efforts;
• continually revise and renew scientific foci, teams, and objectives; and
• develop conceptual models describing sea-ice interactions in or with the Earth system.

CATCH
The CATCH mission is to facilitate atmospheric chemistry research within the international community, with a focus on natural processes specific to cold regions of the Earth. Cold regions include areas which are seasonally or permanently covered by snow and ice, from the high mountains to the polar ice sheets and sea ice zones, as well as regions where ice clouds are found. CATCH scientists will aim to understand and predict:

• How aerosols are formed and processed in cold regions?
• How cold region aerosols act as cloud precursors and impact cloud properties?
• What are the feedbacks between climate change and atmospheric chemistry that are determined by changes in the cryosphere?
• How the ice core record can be used to understanding global environ-mental change? 
• How physical, chemical, biological, and environmental change ecological changes in sea ice and snow impact atmospheric chemistry?
• Establish the background composition (trace gases and aerosols) in cold regions that are undergoing industrialisation, as well as being impacted by climate change.

ECV-Ice
SCOR working group 152 on Measuring Essential Climate Variables in Sea Ice (ECV-Ice) is planning two intercalibration experiments in 2018 (primary production and gases, Saroma-Ko, Japan; gases, University of East Anglia, UK). In 2019, ECV-Ice plans to hold another intercalibration experiment (primary production) and a sea-ice school in Cambridge Bay, Canada during early spring. Both BEPSII and ECV-Ice will be holding their 2018 annual meetings during June in association with the POLAR2018 meeting in Davos, Switzerland.

MOSAiC
The upcoming Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) will be the first year-round expedition into the central Arctic exploring the Arctic climate system and will improve observations of underrepresented seasons in polar systems.

Representatives

Maria Cristina Facchini (Italy, mc.facchini@isac.cnr.it)
Laura Gallardo (Chile, lgallard@u.uchile.cl)
Jun Nishioka (Japan, nishioka@lowtem.hokudai.ac.jp)
Anna Rutgersson (Sweden, anna.rutgersson@met.uu.se) 
Guiling Zhang (China, guilingzhang@ouc.edu.cn)

Present understanding

To understand Earth systems, it is important to understand how land–ocean–atmosphere biogeochemical cycles are linked, and coastal waters, including marginal seas, are key environments for such linkage. Coastal waters and marginal seas are all strongly influenced by land via river discharges, which also reflect human influences. Land also influences circulation patterns in both the atmosphere and ocean. Compared with other oceanic regions, coastal waters and marginal seas have high productivity and biogeochemical cycling activity, which are controlled by variable local processes, such as freshwater discharge, interior current systems, tidal mixing, local upwelling, interactions with the continental shelf, and human activities. Both physical and biogeochemical processes in coastal waters and marginal seas are highly variable in time, as well as space. Thus, coastal waters and marginal seas are the places where the biogeochemical interaction of the atmosphere and the ocean is occurring dynamically.

Priorities

The changes in nutrient dynamics (including atmospheric supply) generally affect the abundance, composition and metabolic activity of marine organisms such as phytoplankton and bacteria. Marine phytoplankton can produce volatile organic compounds (VOCs) and marine atmospheric aerosols, which strongly influence on atmospheric chemistry. Therefore, biogeochemical cycles in coastal waters and marginal sea have a tight and sensitive linkage between the ocean and the atmosphere. The enhanced supply of nutrients to coastal regions has also led to widespread bottom hypoxia and subsurface acidification that would affect the production and air-sea fluxes of climatic related trace gases.

Representative

Hermann Bange (Germany, hbange@geomar.de)

Present understanding

There have been significant advances in recent years in our ability to describe and model the Earth system, but our understanding of oceanic and atmospheric processes in the Indian Ocean region is still rudimentary in many respects. This is largely because the Indian Ocean remains under-sampled in both space and time, especially compared to the Atlantic and Pacific Oceans. The situation is compounded by the Indian Ocean being a dynamically complex and highly variable system under monsoonal influence. Many uncertainties remain in terms of how oceanic and atmospheric processes affect climate, extreme events, marine biogeochemical cycles, atmospheric chemistry, meteorology, ecosystems, and human populations in and around the Indian Ocean. There are also growing concerns about food security in the context of global warming and of anthropogenic impacts on coastal environments and fisheries sustainability. One impact of global warming is sea level rise, which leads to coastal erosion, loss of mangroves, and loss of biodiversity. Anthropogenic impacts include pollution, with water quality deterioration as a result of nutrient and contaminant inputs and detrimental ecosystem effects, such as eutrophication and deoxygenation. There is a pressing need for ecosystem preservation in the Indian Ocean for both tourism and fisheries.

SCOR, IOC, and IOGOOS have initiatd a new phase of international research focused on the Indian Ocean (i.e. the 2nd International Indian Ocean Expedition, IIOE-2) that began in late 2015 (see: www.iioe-2.incois.gov.in).

Priorities

The Indian Ocean represents one of the last great frontiers and challenges of oceanographic/atmospheric research. The biogeochemical cycles and ecosystems of the Indian Ocean appear to be particularly vulnerable to anthropogenic impacts (including climate change, eutrophication, atmospheric pollution and aerosol load).

Major research questions to be addressed with high priority are:

• Which processes determine the natural variability of the biogeochemical cycles, ecosystems and atmospheric chemistry over the Indian Ocean?
• What is the effect of the (long-range) transport of air pollution on ocean biogeochemistry, ecosystems, atmospheric chemistry and climate?
• How are human-induced stressors impacting the biogeochemistry and ecosystems of the Indian Ocean?
• How, in turn, are these impacts affecting human populations?