Attributing the decadal variations in springtime East Asian and North American dust emission to regime shifts in extratropical cyclone

Abstract

Dust activities across East Asia and North America have shown decadal variations, mediating radiation budget, air quality, and human health, especially during their peak months of April and May. Using satellite and ground measurements, as along with simulations from a dust emission model, we demonstrate an increase of 12.7 % and 23.4 % in April dust emissions across East Asia and North America, respectively, during the past four decades, in contrast to a 16.5 % and 2.5 % decrease during the last two decades. Meanwhile, both regions show a steady increase in May dust emissions by 5.7 % and 16.3 %, respectively, since the 1980s. Sensitivity experiments attribute both regions' decadal variations in dust emission primarily to surface wind speed changes; whereas vegetation exerts minimum influence on the regional dust emission variations. Furthermore, these decadal variations in dust initiating wind could largely be attributed to regime shifts in extratropical cyclone (EC), including their duration and intensity. Specifically, ECs are responsible for 60 %–70 % of the April–May total dust emissions in East Asia and 30 %–40 % of that in North America; meanwhile, ECs explain a larger portion of the decadal variations in April dust emission from East Asia (up to ∼80 %), compared with May and from North America. These results highlight the changing frequency and duration of strong winds, especially those associated with EC, and their role in shaping the decadal variations of mid-latitude dust emissions.