Global Oceans, BAMS State of the Climate in 2021, Chapter 3

• Published in: Bulletin of the American Meteorological Society
• Main Authors: Johnson, Gregory C., Lumpkin, Rick, Boyer, Tim, Bringas, Francis, Cetinić, Ivona, Chambers, Don P., Cheng, Lijing, Dong, Shenfu, Feely, Richard A., Fox-Kemper, Baylor, Frajka-Williams, Eleanor, Franz, Bryan A., Fu, Yao, Gao, Meng, Garg, Jay, Gilson, John, Goni, Gustavo, Hamlington, Benjamin D., Hewitt, Helene T., Hobbs, William R., Hu, Zeng-Zhen, Huang, Boyin, Jevrejeva, Svetlana, Johns, William E., Katsunari, Sato, Kennedy, John J., Kersalé, Marion, Killick, Rachel E., Leuliette, Eric, Locarnini, Ricardo, Lozier, M. Susan, Lyman, John M., Merrifield, Mark A., Mishonov, Alexey, Mitchum, Gary T., Moat, Ben I., Nerem, R. Steven, Notz, Dirk, Perez, Renellys C., Purkey, Sarah G., Rayner, Darren, Reagan, James, Schmid, Claudia, Siegel, David A., Smeed, David A., Stackhouse, Paul W., Sweet, William, Thompson, Philip R., Volkov, Denis L., Wanninkhof, Rik
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Greenland; Pacific; Indian; North Atlantic; North Atlantic oscillation
• Online Access: http://nora.nerc.ac.uk/id/eprint/533242/; https://nora.nerc.ac.uk/id/eprint/533242/1/%5B15200477%20-%20Bulletin%20of%20the%20American%20Meteorological%20Society%5D%20Global%20Oceans.pdf; https://doi.org/10.1175/BAMS-D-22-0072.1

Patterns of variability in ocean properties are often closely related to large-scale climate pattern indices, and 2021 is no exception. The year 2021 started and ended with La Niña conditions, charmingly dubbed a “double-dip” La Niña. Hence, stronger-than-normal easterly trade winds in the tropical south Pacific drove westward surface current anomalies in the equatorial Pacific; reduced sea surface temperature (SST) and upper ocean heat content in the eastern tropical Pacific; increased sea level, upper ocean heat content, and salinity in the western tropical Pacific; resulted in a rim of anomalously high chlorophyll-a (Chla) on the poleward and westward edges of the anomalously cold SST wedge in the eastern equatorial Pacific; and increased precipitation over the Maritime Continent. The Pacific decadal oscillation remained strongly in a negative phase in 2021, with negative SST and upper ocean heat content anomalies around the eastern and equatorial edges of the North Pacific and positive anomalies in the center associated with low Chla anomalies. The South Pacific exhibited similar patterns. Fresh anomalies in the northeastern Pacific shifted towards the west coast of North America. The Indian Ocean dipole (IOD) was weakly negative in 2021, with small positive SST anomalies in the east and nearly-average anomalies in the west. Nonetheless, upper ocean heat content was anomalously high in the west and lower in the east, with anomalously high freshwater flux and low sea surface salinities (SSS) in the east, and the opposite pattern in the west, as might be expected during a negative phase of that climate index. In the Atlantic, the only substantial cold anomaly in SST and upper ocean heat content persisted east of Greenland in 2021, where SSS was also low, all despite the weak winds and strong surface heat flux anomalies into the ocean expected during a negative phase of the North Atlantic Oscillation. These anomalies held throughout much of 2021. An Atlantic and Benguela Niño were both evident, with ...