Potential impacts of the wintertime Arctic Oscillation and North Atlantic Oscillation on spring dust activity over northern China: comparing and contrasting

Abstract:

Asian dust is a well-known spring season phenomenon originating from arid or semiarid highlands in northern China and Mongolia. Many previous studies suggested that the occurrence and transport of Asian dust (i.e. dust activity) are closely related to variations in large-scale climate variables and local to regional climate conditions, and demonstrated the physical and dynamic mechanisms behind these relationships. However, the physical mechanism involved in the link between wintertime climate variability and spring dust activity was not fully explored. In this work, we analyzed the impacts of the wintertime Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) on spring dust activity over northern China. After an extensive analysis for the effect of wintertime AO, we observed colder surface temperatures, stronger weather fluctuations, and frequent cold surges over northern China during the negative phase of AO, and thus found that AO can affect spring dust activity with time-lagged consistency. While there are many similarities between AO and NAO, on the other hand, previous studies suggested that they are significantly different in both their dynamical interpretation such as zonal-mean structure, and their spatial and temporal variability. In this study, AO is positively correlated with NAO with the correlation coefficient of +0.51, for the winter seasons of 1953-2007. In spite of high correlation with in-phase combinations, the enhancement of spring dust activity during the negative phase of NAO is higher than that during the negative phase of AO. Based on the superiority in dust activity, the possible differences in physical mechanism between AO and NAO will also be discussed.