Model-observation and reanalyses comparison at key locations for heat transport to the Arctic (D2.1)

• Main Authors: Moat, Ben, Herbaut, Christophe, Larsen, Karin Margretha, Hansen, Bogi, Sinha, Bablu, Sanchez-Franks, Alejandra, Houpert, Loic, Liu, Yang, Hazeleger, Wilco, Attema, Jisk, Yeager, Stephen, Small, Justin, Valdimarsson, Hedinn, Berx, Barbara, Cunningham, Stuart, Hallam, Samantha, Woodgate, Rebecca, Lee, Craig, Kwon, Young Oh, Flemming, Laura, Mercier, Herle, Jochumsen, Kerstin, Mecking, Jennifer, Holliday, Penny Holliday, Josey, Simon
• Format: Report
• Language: English
• Published: 2020
• Subjects: Arctic; Norwegian Sea; Greenland; Greenland-Scotland Ridge; North Atlantic
• Online Access: https://zenodo.org/record/3631100; https://doi.org/10.5281/zenodo.3631100

Assessment of key lower latitude influences on the Arctic and their simulation Summary Blue-Action Work Package 2 (WP2) focuses on lower latitude drivers of Arctic change, with a focus on the influence of the Atlantic Ocean and atmosphere on the Arctic. In particular, warm water travels from the Atlantic, across the Greenland-Scotland ridge, through the Norwegian Sea towards the Arctic. A large proportion of the heat transported northwards by the ocean is released to the atmosphere and carried eastward towards Europe by the prevailing westerly winds. This is an important contribution to northwestern Europe's mild climate. The remaining heat travels north into the Arctic. Variations in the amount of heat transported into the Arctic will influence the long term climate of the Northern Hemisphere. Here we assess how well the state of the art coupled climate models estimate this northwards transport of heat in the ocean, and how the atmospheric heat transport varies with changes in the ocean heat transport. We seek to improve the ocean monitoring systems that are in place by introducing measurements from ocean gliders, Argo floats and satellites. These state of the art computer simulations are evaluated by comparison with key trans-Atlantic observations. In addition to the coupled models ‘ocean-only’ evaluations are made. In general the coupled model simulations have too much heat going into the Arctic region and the transports have too much variability. The models generally reproduce the variability of the Atlantic Meridional Ocean Circulation (AMOC) well. All models in this study have a too strong southwards transport of freshwater at 26°N in the North Atlantic, but the divergence between 26°N and Bering Straits is generally reproduced really well in all the models. Altimetry from satellites have been used to reconstruct the ocean circulation 26°N in the Atlantic, over the Greenland Scotland Ridge and alongside ship based observations along the GO-SHIP OVIDE Section. Although it is still a challenge to estimate ...