Tropical Intraseasonal Variability in 14 IPCC AR4 Climate Models. Part I: Convective Signals

Abstract This study evaluates the tropical intraseasonal variability, especially the fidelity of Madden–Julian oscillation (MJO) simulations, in 14 coupled general circulation models (GCMs) participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). Eight years of daily precipitation from each model’s twentieth-century climate simulation are analyzed and compared with daily satellite-retrieved precipitation. Space–time spectral analysis is used to obtain the variance and phase speed of dominant convectively coupled equatorial waves, including the MJO, Kelvin, equatorial Rossby (ER), mixed Rossby–gravity (MRG), and eastward inertio–gravity (EIG) and westward…

• NS
  National Science Foundation
• UD
  U.S. Department of Energy

  Awards: W-7405, 7405-Eng-48
• NA
  National Aeronautics and Space Administration
• NO
  National Oceanic and Atmospheric Administration
• OO
  Office of Science
• LL
  Lawrence Livermore National Laboratory

  Awards: -7405-Eng-48, W-7405-Eng-48