Abstract
Abstract Recent observational analyses have indicated that tropospheric quasi-biennial oscillations (QBs) may play a fundamental role in regulating the timing and strength of El Nino and the Southern Oscillation. The biennial variability is examined in the tropical troposphere of a 35-year general circulation model (GCM) simulation forced by observed sea surface temperatures (SSTs). The results of spectral analyses and temporal filtering applied to the SST boundary conditions and the simulated lower- and upper-tropospheric zonal winds, precipitation, and sea level pressure anomalies are compared with observations and used to investigate the relationship between variables. The GCM obtains regions of coherent biennial variability over the tropical Indian and Pacific Oceans in close correspondence with observations. In addition, the evolution of the stronger QBs and the physical relationship between variables are fairly well simulated. Zonal wind anomalies, with a simple baroclinic structure, tend to propaga...
Published Version
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