Relation of the double-ITCZ bias to the atmospheric energy budget in climate models
We examine how tropical zonal mean precipitation biases in current climate models relate to the atmospheric energy budget. Both hemispherically symmetric and antisymmetric tropical precipitation biases contribute to the well-known double-Intertropical Convergence Zone (ITCZ) bias; however, they have distinct signatures in the energy budget. Hemispherically symmetric biases in tropical precipitation are proportional to biases in the equatorial net energy input; hemispherically antisymmetric biases are proportional to the atmospheric energy transport across the equator. Both relations can be understood within the framework of recently developed theories. Atmospheric net energy input biases in the deep tropics shape both the symmetric and antisymmetric components of the double-ITCZ bias. Potential causes of these energetic biases and their variation across climate models are discussed.
© 2016 American Geophysical Union. Received 5 MAY 2016; Accepted 17 JUN 2016; Accepted article online 24 JUN 2016; Published online 18 JUL 2016. We thank Michael Byrne for his helpful comments. We thank the National Center for Atmospheric Research (NCAR) Climate and Global Dynamics Laboratory (CGD) for providing the ERA-Interim energy budget products. This research was supported by grants from the Swiss National Science Foundation and the U.S. National Science Foundation (grant AGS-1049201).
Published - Adam_etal-2016b.pdf
Supplemental Material - grl54642-sup-0001-supinfo.pdf
Supplemental Material - grl54642-sup-0002-FigureS1.ps
Supplemental Material - grl54642-sup-0003-FigureS2.ps
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