Meinen Christopher S.

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Meinen
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Christopher S.
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  • Book chapter
    Global Oceans [in “State of the Climate in 2020”]
    (American Meteorological Society, 2021-08-01) Johnson, Gregory C. ; Lumpkin, Rick ; Alin, Simone R. ; Amaya, Dillon J. ; Baringer, Molly O. ; Boyer, Tim ; Brandt, Peter ; Carter, Brendan ; Cetinić, Ivona ; Chambers, Don P. ; Cheng, Lijing ; Collins, Andrew U. ; Cosca, Cathy ; Domingues, Ricardo ; Dong, Shenfu ; Feely, Richard A. ; Frajka-Williams, Eleanor E. ; Franz, Bryan A. ; Gilson, John ; Goni, Gustavo J. ; Hamlington, Benjamin D. ; Herrford, Josefine ; Hu, Zeng-Zhen ; Huang, Boyin ; Ishii, Masayoshi ; Jevrejeva, Svetlana ; Kennedy, John J. ; Kersalé, Marion ; Killick, Rachel E. ; Landschützer, Peter ; Lankhorst, Matthias ; Leuliette, Eric ; Locarnini, Ricardo ; Lyman, John ; Marra, John F. ; Meinen, Christopher S. ; Merrifield, Mark ; Mitchum, Gary ; Moat, Bengamin I. ; Nerem, R. Steven ; Perez, Renellys ; Purkey, Sarah G. ; Reagan, James ; Sanchez-Franks, Alejandra ; Scannell, Hillary A. ; Schmid, Claudia ; Scott, Joel P. ; Siegel, David A. ; Smeed, David A. ; Stackhouse, Paul W. ; Sweet, William V. ; Thompson, Philip R. ; Trinanes, Joaquin ; Volkov, Denis L. ; Wanninkhof, Rik ; Weller, Robert A. ; Wen, Caihong ; Westberry, Toby K. ; Widlansky, Matthew J. ; Wilber, Anne C. ; Yu, Lisan ; Zhang, Huai-Min
    This chapter details 2020 global patterns in select observed oceanic physical, chemical, and biological variables relative to long-term climatologies, their differences between 2020 and 2019, and puts 2020 observations in the context of the historical record. In this overview we address a few of the highlights, first in haiku, then paragraph form: La Niña arrives, shifts winds, rain, heat, salt, carbon: Pacific—beyond. Global ocean conditions in 2020 reflected a transition from an El Niño in 2018–19 to a La Niña in late 2020. Pacific trade winds strengthened in 2020 relative to 2019, driving anomalously westward Pacific equatorial surface currents. Sea surface temperatures (SSTs), upper ocean heat content, and sea surface height all fell in the eastern tropical Pacific and rose in the western tropical Pacific. Efflux of carbon dioxide from ocean to atmosphere was larger than average across much of the equatorial Pacific, and both chlorophyll-a and phytoplankton carbon concentrations were elevated across the tropical Pacific. Less rain fell and more water evaporated in the western equatorial Pacific, consonant with increased sea surface salinity (SSS) there. SSS may also have increased as a result of anomalously westward surface currents advecting salty water from the east. El Niño–Southern Oscillation conditions have global ramifications that reverberate throughout the report.
  • Article
    Continuous, array-based estimates of Atlantic Ocean heat transport at 26.5°N
    (American Meteorological Society, 2011-05-15) Johns, William E. ; Baringer, Molly O. ; Beal, Lisa M. ; Cunningham, S. A. ; Kanzow, Torsten ; Bryden, Harry L. ; Hirschi, J. J. M. ; Marotzke, J. ; Meinen, Christopher S. ; Shaw, B. ; Curry, Ruth G.
    Continuous estimates of the oceanic meridional heat transport in the Atlantic are derived from the Rapid Climate Change–Meridional Overturning Circulation (MOC) and Heatflux Array (RAPID–MOCHA) observing system deployed along 26.5°N, for the period from April 2004 to October 2007. The basinwide meridional heat transport (MHT) is derived by combining temperature transports (relative to a common reference) from 1) the Gulf Stream in the Straits of Florida; 2) the western boundary region offshore of Abaco, Bahamas; 3) the Ekman layer [derived from Quick Scatterometer (QuikSCAT) wind stresses]; and 4) the interior ocean monitored by “endpoint” dynamic height moorings. The interior eddy heat transport arising from spatial covariance of the velocity and temperature fields is estimated independently from repeat hydrographic and expendable bathythermograph (XBT) sections and can also be approximated by the array. The results for the 3.5 yr of data thus far available show a mean MHT of 1.33 ± 0.40 PW for 10-day-averaged estimates, on which time scale a basinwide mass balance can be reasonably assumed. The associated MOC strength and variability is 18.5 ± 4.9 Sv (1 Sv ≡ 106 m3 s−1). The continuous heat transport estimates range from a minimum of 0.2 to a maximum of 2.5 PW, with approximately half of the variance caused by Ekman transport changes and half caused by changes in the geostrophic circulation. The data suggest a seasonal cycle of the MHT with a maximum in summer (July–September) and minimum in late winter (March–April), with an annual range of 0.6 PW. A breakdown of the MHT into “overturning” and “gyre” components shows that the overturning component carries 88% of the total heat transport. The overall uncertainty of the annual mean MHT for the 3.5-yr record is 0.14 PW or about 10% of the mean value.
  • Article
    Atlantic meridional overturning circulation: Observed transport and variability
    (Frontiers Media, 2019-06-07) Frajka-Williams, Eleanor ; Ansorge, Isabelle ; Baehr, Johanna ; Bryden, Harry L. ; Chidichimo, Maria Paz ; Cunningham, Stuart A. ; Danabasoglu, Gokhan ; Dong, Shenfu ; Donohue, Kathleen A. ; Elipot, Shane ; Heimbach, Patrick ; Holliday, Naomi Penny ; Hummels, Rebecca ; Jackson, Laura C. ; Karstensen, Johannes ; Lankhorst, Matthias ; Le Bras, Isabela A. ; Lozier, M. Susan ; McDonagh, Elaine L. ; Meinen, Christopher S. ; Mercier, Herlé ; Moat, Bengamin I. ; Perez, Renellys ; Piecuch, Christopher G. ; Rhein, Monika ; Srokosz, Meric ; Trenberth, Kevin E. ; Bacon, Sheldon ; Forget, Gael ; Goni, Gustavo J. ; Kieke, Dagmar ; Koelling, Jannes ; Lamont, Tarron ; McCarthy, Gerard D. ; Mertens, Christian ; Send, Uwe ; Smeed, David A. ; Speich, Sabrina ; van den Berg, Marcel ; Volkov, Denis L. ; Wilson, Christopher G.
    The Atlantic Meridional Overturning Circulation (AMOC) extends from the Southern Ocean to the northern North Atlantic, transporting heat northwards throughout the South and North Atlantic, and sinking carbon and nutrients into the deep ocean. Climate models indicate that changes to the AMOC both herald and drive climate shifts. Intensive trans-basin AMOC observational systems have been put in place to continuously monitor meridional volume transport variability, and in some cases, heat, freshwater and carbon transport. These observational programs have been used to diagnose the magnitude and origins of transport variability, and to investigate impacts of variability on essential climate variables such as sea surface temperature, ocean heat content and coastal sea level. AMOC observing approaches vary between the different systems, ranging from trans-basin arrays (OSNAP, RAPID 26°N, 11°S, SAMBA 34.5°S) to arrays concentrating on western boundaries (e.g., RAPID WAVE, MOVE 16°N). In this paper, we outline the different approaches (aims, strengths and limitations) and summarize the key results to date. We also discuss alternate approaches for capturing AMOC variability including direct estimates (e.g., using sea level, bottom pressure, and hydrography from autonomous profiling floats), indirect estimates applying budgetary approaches, state estimates or ocean reanalyses, and proxies. Based on the existing observations and their results, and the potential of new observational and formal synthesis approaches, we make suggestions as to how to evaluate a comprehensive, future-proof observational network of the AMOC to deepen our understanding of the AMOC and its role in global climate.