Annual amphidromes observed in the atmosphere with remote sensing data

[1] Annual cycle, one of the principle modes in the variability of the air-sea system, can be analyzed using tide analysis tools for extending the concept of oceanic tidal amphidromes to the atmosphere. In this paper, the annual phase-amplitude characteristics of two variables, sea-level pressure (SLP) and precipitation, were investigated to explore the annual atmospheric amphidromes on a global scale. For SLP, around a dozen annual amphidromic points were successfully identified. These points are distinguished by large-scale rotary phase propagations around them. For global precipitation, we identified a substantial amount of annual rainfall amphidromic points, with many of them appearing as pairs close to each other and less developed. Further examinations illustrate that these rainfall amphidromes tend to occur in narrow bands or small regions with low annual amplitudes and phase structures opposite to their surroundings. This suggests that precipitation amphidromes tend to appear as quasi-amphidromic lines or quasi-amphidromic zones. The occurrence of El Niño/La Niña events does not affect the formation and stability of SLP and precipitation amphidromes, although it can modify the annual variations in terms of amplitude and phase changes.