Suchergebnisse

Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) control the abyssal limb of the global overturning circulation and play a major role in oceanic heat uptake and carbon storage. However, current general circulation models are unable to resolve the observed AABW and NADW formation and transport processes. One key process, that of overflows, motivates the application of overflow parameterisations. We present a sensitivity study of both AABW and NADW properties to three current parameterisations using a z*-coordinate ocean-sea ice model within a realistic-topography sector of the Atlantic Ocean.Overflow parameterisations that affect only tracer equations are compared to a fully dynamical Lagrangian point particle method. An overflow parameterisation involving partial convective mixing of tracers is most efficient at transporting dense NADW water downslope. This parameterisation leads to a maximum mean increase in density in the north of 0.027kgm-3 and a decrease in age of 525years (53%). The relative change in density and age in the south is less than 30% of that in the north for all overflow parameterisations. The reduced response in the south may result from the differing dense water formation and overflow characteristics of AABW compared to NADW. Alternative approaches may be necessary to improve AABW representation in z*-coordinate ocean climate models. ; BMS was supported by the Australian Government Department of the Environment, and CSIRO through the Australian Climate Change Science Programme. AMH was supported by an Australian Research Council Future Fellowship FT120100842. SMH was supported by the ARC Centre of Excellence for Climate System Science (Grant CE110001028)

Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) control the abyssal limb of the global overturning circulation and play a major role in oceanic heat uptake and carbon storage. However, current general circulation models are unable to resolve the observed AABW and NADW formation and transport processes. One key process, that of overflows, motivates the application of overflow parameterisations. We present a sensitivity study of both AABW and NADW properties to three current parameterisations using a z*-coordinate ocean-sea ice model within a realistic-topography sector of the Atlantic Ocean.Overflow parameterisations that affect only tracer equations are compared to a fully dynamical Lagrangian point particle method. An overflow parameterisation involving partial convective mixing of tracers is most efficient at transporting dense NADW water downslope. This parameterisation leads to a maximum mean increase in density in the north of 0.027kgm-3 and a decrease in age of 525years (53%). The relative change in density and age in the south is less than 30% of that in the north for all overflow parameterisations. The reduced response in the south may result from the differing dense water formation and overflow characteristics of AABW compared to NADW. Alternative approaches may be necessary to improve AABW representation in z*-coordinate ocean climate models. ; BMS was supported by the Australian Government Department of the Environment, and CSIRO through the Australian Climate Change Science Programme. AMH was supported by an Australian Research Council Future Fellowship FT120100842. SMH was supported by the ARC Centre of Excellence for Climate System Science (Grant CE110001028)

The distribution of data contributed to the Coupled Model Intercomparison Project Phase 6 (CMIP6) is via the Earth System Grid Federation (ESGF). The ESGF is a network of internationally distributed sites that together work as a federated data archive. Data records from climate modelling institutes are published to the ESGF and then shared around the world. It is anticipated that CMIP6 will produce approximately 20 PB of data to be published and distributed via the ESGF. In addition to this large volume of data a number of value-added CMIP6 services are required to interact with the ESGF; for example the citation and errata services both interact with the ESGF but are not a core part of its infrastructure. With a number of interacting services and a large volume of data anticipated for CMIP6, the CMIP Data Node Operations Team (CDNOT) was formed. The CDNOT coordinated and implemented a series of CMIP6 preparation data challenges to test all the interacting components in the ESGF CMIP6 software ecosystem. This ensured that when CMIP6 data were released they could be reliably distributed. No. DE-ACO2-05CH11231 and authors at Lawrence Livermore National Laboratory (LLNL) under contract DE-AC52-07NA27344 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). ; Funding Agencies|US Department of EnergyUnited States Department of Energy (DOE) [DE-AC02-05CH11231, DE-AC52-07NA27344]; European UnionEuropean Commission [824084]; French National Research Agency project CONVERGENCEFrench National Research Agency (ANR) [ANR-13-MONU-0008-02]; National Collaborative Research Infrastructure Strategy (NCRIS)-funded National Computational Infrastructure (NCI) Australia; Australian Research Data Commons (ARDC)