Three-Dimensional Structure of Low-Frequency Pressure Variations in the Tropical Atmosphere

Abstract

Results of a recent study show eastward propagation of information in the low-frequency variations of the tropical sea-level pressure (SLP) field. The current work extends that analysis to investigate the vertical structure of this signal. It is found that the propagating signal exists to a height of at least 850 mb. At 500 mb the signal is not so clear, while at 200 mb there is little evidence of propagation of information. Instead, the low-frequency variations in 200 rnb height appear coherent for the tropical belt around the entire globe. The analysis suggests that the anomalies discussed here appear first at the surface and later at higher levels in the atmosphere.