How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Westerly Biases Over the Equatorial Atlantic
Zermeņo-Diaz, D.M. and Zhang, C. 2013. Possible root causes of surface westerly biases over the equatorial Atlantic in global climate models. Journal of Climate 26: 8154-8168.

The authors write that "most global climate models (GCMs) suffer from biases of a reversed zonal gradient in sea surface temperature (SST) and weak surface easterlies (the westerly bias) in the equatorial Atlantic during boreal spring." And they say that "these biases exist in the atmospheric GCMs (AGCMs) and are amplified by air-sea interactions in atmospheric-oceanic GCMs," noting that "this problem has persisted despite considerable model improvements in other aspects."

What was done
Zermeņo-Diaz and Zhang, as they describe it, "used a simple model for a well-mixed boundary layer over the tropical oceans and simulations from eight AGCMs to diagnose possible root causes of the surface westerly bias over the Atlantic during boreal spring," examining "the possible roles of the vertical structure of diabatic heating and zonal momentum entrainment across the top of the boundary layer."

What was learned
Apparently not very much of significance, as the two researchers say that their work merely lays the foundation for a mere hypothesis.

What it means
And what are the implications of these "results"? Quoting the two researchers themselves, "the implication of our results is that there might be no simple or single remedy for the westerly bias in GCMs." And they say that "this may be why this problem has been so stubborn and persistent up to the new generation of CMIP5 models." And, we might add, why the problem still remains ... unresolved!

Reviewed 8 January 2014