Atmospheric Teleconnection Patterns and Climate Anomalies Associated with the Variations of Mid-Oceanic Troughs in the Northern Hemisphere

The upper-tropospheric mid-oceanic troughs including the mid-Pacific trough (MPT) and the mid-Atlantic trough (MAT) are two major circulation systems over the northern hemisphere in summer. While the MPT acts as an atmospheric bridge connecting the climate over Asia and North America, and the MAT is linked to the climate over North America and the Eurasian continent. In this study, the multi-scale variations of the troughs, the associated atmospheric teleconnection patterns and surface climate anomalies, and their relationships with large-scale forcing including Arctic sea ice, tropical sea surface temperature (SST), and others are investigated.

The variations of MPT are significantly related to the tropical Pacific and Atlantic SSTs and the Arctic sea ice near the Bering Strait, and the variations of MAT are strongly associated with the North Atlantic Oscillation on interannual time scale and the Atlantic Multi-decadal Oscillation on interdecadal time scale. The physical processes and the responsible mechanisms for these relationships are depicted. The relationships between the trough variations and the anomalies of temperature and rainfall anomalies over East Asia, North America, and Europe are discussed. The relationship between the MPT and the genesis of Pacific tropical cyclones is also presented.