On the origin of equatorial Atlantic biases in coupled general circulation models

Richter, Ingo; Xie, Shang‐Ping

doi:10.1007/s00382-008-0364-z

Cited by 270 publications

(272 citation statements)

References 38 publications

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“…The sign of SST gradient is surprisingly well simulated by UTCM_Kuo, even if the east-west SST difference is only about one half of that in the observation. This situation is in contrast with the CMIP3 models [Richter and Xie, 2008], UTCM_Emanuel, and UTCM_Tiedtke, where the annual mean SST is warmer in the east. The annual mean zonal wind stress is also best simulated by UTCM_ Kuo, whereas that in others is weaker than the observed ( Figure 1b).…”

Section: Simulated Zonal Sst Gradient In the Equatorial Atlanticmentioning

confidence: 62%

“…This favors the southeasterly trade winds near the equator in UTCM_Kuo (Figure 6b) and thus the development of the cold tongue [Richter and Xie, 2008]. However, several CMIP3 models fail to reproduce the zonal SST gradient even though the meridional location of the ITCZ is in agreement with the observation [Doi et al, 2010].…”

Section: Simulated Zonal Sst Gradient In the Equatorial Atlanticmentioning

confidence: 76%

“…[9] Since the cold tongue starts to develop in boreal spring [Richter and Xie, 2008], we focus on this key season. Two main features stand out from a comparison of precipitation patterns in boreal spring (March-May; Figure 2).…”

Section: Simulated Zonal Sst Gradient In the Equatorial Atlanticmentioning

confidence: 99%

“…Biasutti et al [2006] examined the Intertropical Convergence Zone (ITCZ) in atmospheric general circulation models (AGCMs) and found that the ITCZ in the Atlantic shifts too far south in boreal spring and leads to excessive precipitation in the Southern Hemisphere. Using outputs from CGCMs, Richter and Xie [2008] showed that the westerly wind bias in boreal spring, which also exists in uncoupled AGCMs, deepens the thermocline in the east and hampers the seasonal development of the cold tongue in boreal summer. This zonal wind bias is suggested to be linked with the erroneous zonal precipitation distribution [Chang et al, 2007;Richter and Xie, 2008;Wahl et al, 2010].…”

Section: Introductionmentioning

confidence: 99%

“…Using outputs from CGCMs, Richter and Xie [2008] showed that the westerly wind bias in boreal spring, which also exists in uncoupled AGCMs, deepens the thermocline in the east and hampers the seasonal development of the cold tongue in boreal summer. This zonal wind bias is suggested to be linked with the erroneous zonal precipitation distribution [Chang et al, 2007;Richter and Xie, 2008;Wahl et al, 2010]. Also, Breugem et al [2008] pointed out that most Coupled Model Intercomparison Project phase 3 (CMIP3) models simulate a spurious barrier layer in the southeastern tropical Atlantic due to excessive rainfall there.…”

Section: Introductionmentioning

confidence: 99%

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Key factors in simulating the equatorial Atlantic zonal sea surface temperature gradient in a coupled general circulation model

Tozuka¹,

Doi²,

Miyasaka³

et al. 2011

J. Geophys. Res.

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[1] Causes of the coupled model bias in simulating the zonal sea surface temperature (SST) gradient in the equatorial Atlantic are examined in three versions of the same coupled general circulation model (CGCM) differing only in the cumulus convection scheme. One version of the CGCM successfully simulates the mean zonal SST gradient of the equatorial Atlantic, in contrast to the failure of the Coupled Model Intercomparison Project phase 3 models. The present analysis shows that key factors to be successful are high skills in simulating the meridional location of the Intertropical Convergence Zone, the precipitation over northern South America, and the southerly winds along the west coast of Africa associated with the West African monsoon in boreal spring. Model biases in the Pacific contribute to the weaker precipitation over northern South America. Uncoupled experiments with the atmospheric component further confirm the importance of remote influences on the development of the equatorial Atlantic bias.

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Section: Simulated Zonal Sst Gradient In the Equatorial Atlanticmentioning

confidence: 62%

Section: Simulated Zonal Sst Gradient In the Equatorial Atlanticmentioning

confidence: 76%

Section: Simulated Zonal Sst Gradient In the Equatorial Atlanticmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Key factors in simulating the equatorial Atlantic zonal sea surface temperature gradient in a coupled general circulation model

Tozuka¹,

Doi²,

Miyasaka³

et al. 2011

J. Geophys. Res.

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The impact of mean state errors on equatorial Atlantic interannual variability in a climate model

et al. 2015

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Observations show that the Equatorial Atlantic Zonal Mode (ZM) obeys similar physics to the El Niño Southern Oscillation (ENSO): positive Bjerknes and delayed negative feedbacks. This implies the ZM may be predictable on seasonal timescales, but models demonstrate little prediction skill in this region. In this study using different configurations of the Kiel Climate Model (KCM) exhibiting different levels of systematic error, we show that a reasonable simulation of the ZM depends on realistic representation of the mean state, i.e., surface easterlies along the equator, upward sloping thermocline to the east, with an equatorial SST cold tongue in the east. We further attribute the differences in interannual variability among the simulations to the individual components of the positive Bjerknes and delayed negative feedbacks. Differences in the seasonality of the variability are similarly related to the impact of seasonal biases on the Bjerknes feedback. Our results suggest that model physics must be enhanced to enable skillful seasonal predictions in the Tropical Atlantic Sector, although some improvement with regard to the simulation of Equatorial Atlantic interannual variability may be achieved by momentum flux correction. This pertains especially to the seasonal phase locking of interannual SST variability.

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A new synoptic scale resolving global climate simulation using the Community Earth System Model

Small

Bacmeister

Bailey

et al. 2014

J Adv Model Earth Syst

288

329

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High-resolution global climate modeling holds the promise of capturing planetary-scale climate modes and small-scale (regional and sometimes extreme) features simultaneously, including their mutual interaction. This paper discusses a new state-of-the-art high-resolution Community Earth System Model (CESM) simulation that was performed with these goals in mind. The atmospheric component was at 0.25 grid spacing, and ocean component at 0.1 . One hundred years of ''present-day'' simulation were completed. Major results were that annual mean sea surface temperature (SST) in the equatorial Pacific and ElNiño Southern Oscillation variability were well simulated compared to standard resolution models. Tropical and southern Atlantic SST also had much reduced bias compared to previous versions of the model. In addition, the high resolution of the model enabled small-scale features of the climate system to be represented, such as air-sea interaction over ocean frontal zones, mesoscale systems generated by the Rockies, and Tropical Cyclones. Associated single component runs and standard resolution coupled runs are used to help attribute the strengths and weaknesses of the fully coupled run. The high-resolution run employed 23,404 cores, costing 250 thousand processor-hours per simulated year and made about two simulated years per day on the NCAR-Wyoming supercomputer ''Yellowstone.''

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On the origin of equatorial Atlantic biases in coupled general circulation models

Cited by 270 publications

References 38 publications

Key factors in simulating the equatorial Atlantic zonal sea surface temperature gradient in a coupled general circulation model

Key factors in simulating the equatorial Atlantic zonal sea surface temperature gradient in a coupled general circulation model

The impact of mean state errors on equatorial Atlantic interannual variability in a climate model

A new synoptic scale resolving global climate simulation using the Community Earth System Model

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