Local versus non-local atmospheric weather noise and the North Pacific SST variability

Abstract

The interactive ensemble coupling strategy has been developed specifically to determine how noise impacts climate variability within context of coupled general circulation model (CGCM). This study examines the impacts of local versus non-local noise on the North Pacific sea surface temperature anomaly (SSTA) variability using three CGCM simulations. The control run uses the standard coupling strategy. In the first experiment, the interactive ensemble strategy is applied globally thereby reducing the noise at the air-sea interface at each grid point. In the second experiment, the interactive ensemble strategy is applied locally in the extra-tropics only. Perhaps as expected, our analysis indicates that the impact of local noise on the North Pacific SSTA variability is much larger than that of non-local noise. However, non-local noise can not be neglected; for example, non-local noise influences decadal SSTA variability in the central North Pacific. The hypothesis put forward here is that the noise due to enhanced tropical internal atmospheric variability causes the modulation of El Nino and Southern Oscillation, which in turn affects the North Pacific SSTA variability through the atmospheric bridge.