ALBERT

Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution March, 1980

Description: The Southern Ocean as defined here is the body of water between the Antarctic Continent and the Antarctic Polar Front, (APF). This ocean is considered important in the global thermodynamic balance of the ocean-atmosphere system because large planetary heat losses are believed to occur at high latitudes. The ocean and atmosphere must transport heat poleward to balance these losses. In the Southern Hemisphere, the oceanic contribution to this flux involves a southward transport of heat across the APF into the Southern Ocean where it is given up to the atmosphere through air-sea interactions. In Part I, the air-sea interactions and structure of the near surface waters of the Southern Ocean are investigated with a three dimensional time dependent numerical model. The surface waters in this region in summer are characterized by a relatively warm surface mixed layer with low salinity. Below this layer, a cold temperature extremum is usually observed in vertical profiles which is believed to be the remnant of a deep surface mixed layer produced in winter. The characteristics of this layer, the surface mixed layer and the observed distribution of wintertime sea ice are reproduced well by this model. Unlike some other sea-ice models the air-sea heat exchange is a free variable. Model estimates of the annual heat loss by the Southern Ocean exhibit the observed meridional variation of heat gained by the ocean along the APF with heat lost further south. The model's area average heat loss is much smaller than that estimated with direct observations. While several model parameterizations were made which could be in error, the model results suggest that the Southern Ocean does give up vast amounts of heat to the atmosphere away from the continental margins. The model results and direct calculations of air-sea exchanges suggest a southward heat flux must occur across the APF. The lateral water mass transition across the front is not discontinuous but occurs over a finite sized zone of fluid which is dominated by intrusive finestructure. The characteristics and dynamics of these features are investigated in Part II to try and assess their importance in the meridional heat budget. Observations made on two cruises to the APF are presented and the space-time scales of the features and thermohaline characteristics are discussed. It is suggested that double diffusive processes dominated by salt fingering are active within the intrusions. An extension of Stern's (1967) model of the stability of a thermohaline front to intrusive finestructure driven by saltfingering where small scale viscous processes are included, is presented to explain why intrusions are observed in frontal zones. The model successfully predicts vertical scales of intrusions observed in the ocean and the observed dependence of the intrusions' slopes across density surfaces on the vertical scale. Since the fastest growing intrusion is not strongly determined by the model, though, it is likely that finite amplitude effects determine the dominant scale of interleaving in the ocean. The analysis predicts that intrusions transport heat, salt and density down the mean gradients of the front. For the APF, this heat flux is poleward which is the direction required by the global heat budget. This model does not describe intrusions at finite amplitude or in steady state and so cannot be used to estimate the magnitude of the poleward heat flux due to intrusions in the APF.

Description: The research reported on here, and my support as a graduate student was provided by the National Science Foundation through grants OCE 75 14056. OCE 76 82036 and OCE 77 28355.

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Smith, G. C., Allard, R., Babin, M., Bertino, L., Chevallier, M., Corlett, G., Crout, J., Davidson, F., Delille, B., Gille, S. T., Hebert, D., Hyder, P., Intrieri, J., Lagunas, J., Larnicol, G., Kaminski, T., Kater, B., Kauker, F., Marec, C., Mazloff, M., Metzger, E. J., Mordy, C., O'Carroll, A., Olsen, S. M., Phelps, M., Posey, P., Prandi, P., Rehm, E., Reid, P., Rigor, I., Sandven, S., Shupe, M., Swart, S., Smedstad, O. M., Solomon, A., Storto, A., Thibaut, P., Toole, J., Wood, K., Xie, J., Yang, Q., & WWRP PPP Steering Grp. Polar ocean observations: A critical gap in the observing system and its effect on environmental predictions from hours to a season. Frontiers in Marine Science, 6, (2019): 429, doi:10.3389/fmars.2019.00429.

Description: There is a growing need for operational oceanographic predictions in both the Arctic and Antarctic polar regions. In the former, this is driven by a declining ice cover accompanied by an increase in maritime traffic and exploitation of marine resources. Oceanographic predictions in the Antarctic are also important, both to support Antarctic operations and also to help elucidate processes governing sea ice and ice shelf stability. However, a significant gap exists in the ocean observing system in polar regions, compared to most areas of the global ocean, hindering the reliability of ocean and sea ice forecasts. This gap can also be seen from the spread in ocean and sea ice reanalyses for polar regions which provide an estimate of their uncertainty. The reduced reliability of polar predictions may affect the quality of various applications including search and rescue, coupling with numerical weather and seasonal predictions, historical reconstructions (reanalysis), aquaculture and environmental management including environmental emergency response. Here, we outline the status of existing near-real time ocean observational efforts in polar regions, discuss gaps, and explore perspectives for the future. Specific recommendations include a renewed call for open access to data, especially real-time data, as a critical capability for improved sea ice and weather forecasting and other environmental prediction needs. Dedicated efforts are also needed to make use of additional observations made as part of the Year of Polar Prediction (YOPP; 2017–2019) to inform optimal observing system design. To provide a polar extension to the Argo network, it is recommended that a network of ice-borne sea ice and upper-ocean observing buoys be deployed and supported operationally in ice-covered areas together with autonomous profiling floats and gliders (potentially with ice detection capability) in seasonally ice covered seas. Finally, additional efforts to better measure and parameterize surface exchanges in polar regions are much needed to improve coupled environmental prediction.

Description: The development of the new generation of floats (PRO-ICE) to be operated under ice was funded by the French project NAOS. Twelve PRO-ICE were funded by NAOS and nine by the Canadian Foundation for Innovation (FCI-30124). The GreenEdge project is funded by the following French and Canadian programs and agencies: ANR (Contract #111112), CNES (project #131425), IPEV (project #1164), CSA, Fondation Total, ArcticNet, LEFE and the French Arctic Initiative (GreenEdge project). The INTAROS project has received funding from the European Union’s Horizon 2020 Research and Innovation Program under grant agreement No. 727890. The setup of the ArcMBA system and the experiment described in section “Quantitative Network Design” were funded by the European Space Agency through its support to science element (contract #4000117710/16/I-NB). SSw was supported by a Wallenberg Academy Fellowship (WAF 2015.0186). The work at CLS (GL, PPr, and PT) has been funded by internal investment, in relation with on-going CNES and ESA funded studies making use of radar data over Polar regions. EMODNET (BK) is funded by the European Commission. NRL Funding (for RA, JC, DH, EM, PPo, OS) provided by NRL Research Option “Determining the Impact of Sea Ice Thickness on the Arctic’s Naturally Changing Environment (DISTANCE), ONR 6.2 Data Assimilation and under program element 0602435N (JC, RA, DH). JT’s Arctic research activities are supported by the U.S. National Science Foundation and ONR. SG was funded by NSF grants/awards PLR-1425989 and OCE 1658001. IR is funded by contributors to the US IABP (including CG, DOE, NASA, NIC, NOAA, NSF, ONR). CAFS is supported by the NOAA ESRL Physical Sciences Division (AS and JI). LB and JX are funded by CMEMS. The WWRP PPP Steering Group is funded by a WMO trust fund with support from AWI for the ICO. The publication fee is provided by ECCC.