21
In the equatorial Atlantic, the entire coupled system is offkey in coupled global climate models due to the misrepresentation of crucial physical processes. However, alternative
ways exist to study the tropical Atlantic with the help of
models. Akin to early modeling studies of the El NiñoSouthern Oscillation, statistical models can provide some
insight into the equatorial Atlantic (e.g., Wang and Chang
2008; Chang et al. 2004). Simulations with ocean-only
GCMs help to understand the oceanic response to atmospheric processes (e.g., Lübbecke et al. 2010). Additionally,
regional climate models of the equatorial Atlantic have been
employed successfully to study different aspects of the
region (e.g., Seo et al. 2006; Burls et al. 2011, 2012). Lastly,
computational power continues to increase and allows for
higher spatial resolution. If the equatorial Atlantic contains
predictive potential, future generations of improved CGCMs
are likely to unlock it at some point.
The research into various biases, their origins, their
dynamics, and, most importantly, possible ways to reduce
them, remains a core challenge of the global climate modeling community.
Acknowledgements We would like to thank Richard Greatbatch, Peter
Brandt, Mojib Latif, Rebecca Hummels, and Martin Claus for discussing the manuscript with us at an early stage and contributing valuable
ideas.
While we finished work on the first submitted draft of the manuscript, our colleague and friend Martin Krebs passed away. We hope
this study will serve as a reminder of Martin’s outstanding scientific
work. TD will fondly remember how she discussed first ideas for the
manuscript with Martin and how they came up with a rather wayward
way to illustrate how much energy was lost from the Atl3 region during
the formation of the cold tongue. Turns out that 2.6 times the total
global energy consumption of 2011 is enough to power roughly 70 billion generic 600 W fridges for 4 months.
Appendix
This article is related to the YOUMARES 8 conference session no. 3: “Physical Processes in the Tropical and Subtropical
Oceans: Variability, Impacts, and Connections to Other
Components of the Climate System”. The original Call for
Abstracts and the abstracts of the presentations within this
session can be found in the appendix “Conference Sessions
and Abstracts”, chapter “1 Physical Processes in the Tropical
and Subtropical Oceans: Variability, Impacts, and Connections
to Other Components of the Climate System”, of this book.
References
Banzon V, Smith TM, Chin TM et al (2016) A long-term record of
blended satellite and in situ sea-surface temperature for climate
monitoring, modeling and environmental studies. Earth Syst Sci
Data 8(1):165–176. https://doi.org/10.5194/essd-8-165-2016
Bjerknes J (1969) Atmospheric teleconnections from the equatorial
Pacific. Mon Weather Rev 97(3):163–172
Bourlès B, Lumpkin R, McPhaden MJ et al (2008) The Pirata program:
history, accomplishments, and future directions. Bull Am Meteorol
Soc 89(8):1111–1125. https://doi.org/10.1175/2008BAMS2462.1
Brandt P, Schott FA, Provost C et al (2006) Circulation in the
central equatorial Atlantic: mean and intraseasonal to seasonal variability. Geophys Res Lett 33(7):L07609. https://doi.
org/10.1029/2005GL025498
Brandt P, Hormann V, Bourlès B et al (2008) Oxygen tongues and
zonal currents in the equatorial Atlantic. J Geophys Res Oceans
113(4):C04012. https://doi.org/10.1029/2007JC004435
Brandt P, Caniaux G, Bourlès B et al (2011a) Equatorial upper-ocean
dynamics and their interaction with the West African monsoon.
Atmos Sci Lett 12(1):24–30. https://doi.org/10.1002/asl.287
Brandt P, Funk A, Hormann V et al (2011b) Interannual atmospheric
variability forced by the deep equatorial Atlantic ocean. Nature
473(7348):497–500. https://doi.org/10.1038/nature10013
Burls NJ, Reason CJC, Penven P et al (2011) Similarities between
the tropical Atlantic seasonal cycle and ENSO: an energetics perspective. J Geophys Res Oceans 116(C11):C11010. https://doi.
org/10.1029/2011JC007164
Burls NJ, Reason CJC, Penven P et al (2012) Energetics of the tropical Atlantic zonal mode. J Clim 25(21):7442–7466. https://doi.
org/10.1175/JCLI-D-11-00602.1
Caniaux G, Giordani H, Redelsperger JL et al (2011) Coupling between
the Atlantic cold tongue and the West African monsoon in boreal
spring and summer. J Geophys Res Oceans 116(4):C04003. https://
doi.org/10.1029/2010JC006570
Chang P, Saravanan R, Wang F et al (2004) Predictability of linear coupled systems. Part II: an application to a simple model of
tropical Atlantic variability. J Clim 17(7):1487–1503. https://doi.
org/10.1175/1520-0442(2004)017<1487:POLCSP>2.0.CO;2
Chang CY, Carton JA, Grodsky SA et al (2007) Seasonal climate of
the tropical Atlantic sector in the NCAR community climate system model 3: error structure and probable causes of errors. J Clim
20(6):1053–1070. https://doi.org/10.1175/JCLI4047.1
Cromwell T (1953) Circulation in a meridional plane in the central
equatorial Pacific. J Mar Res 23:196–213
Cromwell T, Montgomery RB, Stroup ED (1954) Equatorial undercurrent in Pacific ocean revealed by new methods. Science
119(3097):648–649. https://doi.org/10.1126/science.119.3097.648
Davey M, Huddleston M, Sperber K et al (2002) STOIC: a study
of coupled model climatology and variability in tropical ocean
regions. Clim Dyn 18(5):403–420. https://doi.org/10.1007/
s00382-001-0188-6
Deppenmeier AL, Haarsma RJ, Hazeleger W (2016) The Bjerknes
feedback in the tropical Atlantic in CMIP5 models. Clim Dyn 47(7–
8):2691–2707. https://doi.org/10.1007/s00382-016-2992-z
DeWitt DG (2005) Diagnosis of the tropical Atlantic near-equatorial
SST bias in a directly coupled atmosphere-ocean general circulation model. Geophys Res Lett 32(1):L01703. https://doi.
org/10.1029/2004GL021707
Ding H, Greatbatch RJ, Latif M et al (2015) The impact of sea surface temperature bias on equatorial Atlantic interannual variability in partially coupled model experiments. Geophys Res Lett
42(13):5540–5546. https://doi.org/10.1002/2015GL064799
Dippe T, Greatbatch RJ, Ding H (2017) On the relationship between
Atlantic Niño variability and ocean dynamics. Clim Dyn. https://
doi.org/10.1007/s00382-017-3943-z
Doi T, Vecchi GA, Rosati AJ et al (2012) Biases in the Atlantic ITCZ in
seasonal-interannual variations for a coarse- and a high- resolution
coupled climate model. J Clim 25(16):5494–5511. https://doi.
org/10.1175/JCLI-D-11-00360.1
Foltz GR, McPhaden MJ (2010) Interaction between the Atlantic
meridional and Niño modes. Geophys Res Lett 37:L18604. https://
doi.org/10.1029/2010GL044001
Can Climate Models Simulate the Observed Strong Summer Surface Cooling in the Equatorial Atlantic?
In the equatorial Atlantic, the entire coupled system is offkey in coupled global climate models due to the misrepresentation of crucial physical processes. However, alternative
ways exist to study the tropical Atlantic with the help of
models. Akin to early modeling studies of the El NiñoSouthern Oscillation, statistical models can provide some
insight into the equatorial Atlantic (e.g., Wang and Chang
2008; Chang et al. 2004). Simulations with ocean-only
GCMs help to understand the oceanic response to atmospheric processes (e.g., Lübbecke et al. 2010). Additionally,
regional climate models of the equatorial Atlantic have been
employed successfully to study different aspects of the
region (e.g., Seo et al. 2006; Burls et al. 2011, 2012). Lastly,
computational power continues to increase and allows for
higher spatial resolution. If the equatorial Atlantic contains
predictive potential, future generations of improved CGCMs
are likely to unlock it at some point.
The research into various biases, their origins, their
dynamics, and, most importantly, possible ways to reduce
them, remains a core challenge of the global climate modeling community.
Acknowledgements We would like to thank Richard Greatbatch, Peter
Brandt, Mojib Latif, Rebecca Hummels, and Martin Claus for discussing the manuscript with us at an early stage and contributing valuable
ideas.
While we finished work on the first submitted draft of the manuscript, our colleague and friend Martin Krebs passed away. We hope
this study will serve as a reminder of Martin’s outstanding scientific
work. TD will fondly remember how she discussed first ideas for the
manuscript with Martin and how they came up with a rather wayward
way to illustrate how much energy was lost from the Atl3 region during
the formation of the cold tongue. Turns out that 2.6 times the total
global energy consumption of 2011 is enough to power roughly 70 billion generic 600 W fridges for 4 months.
Appendix
This article is related to the YOUMARES 8 conference session no. 3: “Physical Processes in the Tropical and Subtropical
Oceans: Variability, Impacts, and Connections to Other
Components of the Climate System”. The original Call for
Abstracts and the abstracts of the presentations within this
session can be found in the appendix “Conference Sessions
and Abstracts”, chapter “1 Physical Processes in the Tropical
and Subtropical Oceans: Variability, Impacts, and Connections
to Other Components of the Climate System”, of this book.
References
Banzon V, Smith TM, Chin TM et al (2016) A long-term record of
blended satellite and in situ sea-surface temperature for climate
monitoring, modeling and environmental studies. Earth Syst Sci
Data 8(1):165–176. https://doi.org/10.5194/essd-8-165-2016
Bjerknes J (1969) Atmospheric teleconnections from the equatorial
Pacific. Mon Weather Rev 97(3):163–172
Bourlès B, Lumpkin R, McPhaden MJ et al (2008) The Pirata program:
history, accomplishments, and future directions. Bull Am Meteorol
Soc 89(8):1111–1125. https://doi.org/10.1175/2008BAMS2462.1
Brandt P, Schott FA, Provost C et al (2006) Circulation in the
central equatorial Atlantic: mean and intraseasonal to seasonal variability. Geophys Res Lett 33(7):L07609. https://doi.
org/10.1029/2005GL025498
Brandt P, Hormann V, Bourlès B et al (2008) Oxygen tongues and
zonal currents in the equatorial Atlantic. J Geophys Res Oceans
113(4):C04012. https://doi.org/10.1029/2007JC004435
Brandt P, Caniaux G, Bourlès B et al (2011a) Equatorial upper-ocean
dynamics and their interaction with the West African monsoon.
Atmos Sci Lett 12(1):24–30. https://doi.org/10.1002/asl.287
Brandt P, Funk A, Hormann V et al (2011b) Interannual atmospheric
variability forced by the deep equatorial Atlantic ocean. Nature
473(7348):497–500. https://doi.org/10.1038/nature10013
Burls NJ, Reason CJC, Penven P et al (2011) Similarities between
the tropical Atlantic seasonal cycle and ENSO: an energetics perspective. J Geophys Res Oceans 116(C11):C11010. https://doi.
org/10.1029/2011JC007164
Burls NJ, Reason CJC, Penven P et al (2012) Energetics of the tropical Atlantic zonal mode. J Clim 25(21):7442–7466. https://doi.
org/10.1175/JCLI-D-11-00602.1
Caniaux G, Giordani H, Redelsperger JL et al (2011) Coupling between
the Atlantic cold tongue and the West African monsoon in boreal
spring and summer. J Geophys Res Oceans 116(4):C04003. https://
doi.org/10.1029/2010JC006570
Chang P, Saravanan R, Wang F et al (2004) Predictability of linear coupled systems. Part II: an application to a simple model of
tropical Atlantic variability. J Clim 17(7):1487–1503. https://doi.
org/10.1175/1520-0442(2004)017<1487:POLCSP>2.0.CO;2
Chang CY, Carton JA, Grodsky SA et al (2007) Seasonal climate of
the tropical Atlantic sector in the NCAR community climate system model 3: error structure and probable causes of errors. J Clim
20(6):1053–1070. https://doi.org/10.1175/JCLI4047.1
Cromwell T (1953) Circulation in a meridional plane in the central
equatorial Pacific. J Mar Res 23:196–213
Cromwell T, Montgomery RB, Stroup ED (1954) Equatorial undercurrent in Pacific ocean revealed by new methods. Science
119(3097):648–649. https://doi.org/10.1126/science.119.3097.648
Davey M, Huddleston M, Sperber K et al (2002) STOIC: a study
of coupled model climatology and variability in tropical ocean
regions. Clim Dyn 18(5):403–420. https://doi.org/10.1007/
s00382-001-0188-6
Deppenmeier AL, Haarsma RJ, Hazeleger W (2016) The Bjerknes
feedback in the tropical Atlantic in CMIP5 models. Clim Dyn 47(7–
8):2691–2707. https://doi.org/10.1007/s00382-016-2992-z
DeWitt DG (2005) Diagnosis of the tropical Atlantic near-equatorial
SST bias in a directly coupled atmosphere-ocean general circulation model. Geophys Res Lett 32(1):L01703. https://doi.
org/10.1029/2004GL021707
Ding H, Greatbatch RJ, Latif M et al (2015) The impact of sea surface temperature bias on equatorial Atlantic interannual variability in partially coupled model experiments. Geophys Res Lett
42(13):5540–5546. https://doi.org/10.1002/2015GL064799
Dippe T, Greatbatch RJ, Ding H (2017) On the relationship between
Atlantic Niño variability and ocean dynamics. Clim Dyn. https://
doi.org/10.1007/s00382-017-3943-z
Doi T, Vecchi GA, Rosati AJ et al (2012) Biases in the Atlantic ITCZ in
seasonal-interannual variations for a coarse- and a high- resolution
coupled climate model. J Clim 25(16):5494–5511. https://doi.
org/10.1175/JCLI-D-11-00360.1
Foltz GR, McPhaden MJ (2010) Interaction between the Atlantic
meridional and Niño modes. Geophys Res Lett 37:L18604. https://
doi.org/10.1029/2010GL044001
Can Climate Models Simulate the Observed Strong Summer Surface Cooling in the Equatorial Atlantic?