Source and Transport of Dust to the North Pacific: Observations and Analysis From a High Mountain

Abstract

Dust transported to the North Pacific originates not only from East Asian sources but also from non-East Asian sources, providing important marine nutrients to the open ocean. This study analyzes the sources, transport routes, and dust concentrations during 13 North Pacific events in 2010 observed at Mt. Lulin on the Northwest Pacific margin. In addition to aerosol measurements, surface weather data, space lidar observations, MERRA-2 reanalysis data, and trajectory simulations were used. The results show that, during transport to the Pacific, dust from North Africa and the Middle East first moves northeast to Central Asia (30-55 degrees N) and ascends to 200-400 hPa before crossing East Asia. In contrast, dust from the Taklamakan Desert in East Asia rises to 300-400 hPa before being transported eastward. As these dust sources descend into East Asia, they often mix with dust from the Gobi Desert. Indian dust travels zonally eastward at altitudes of 600-800 hPa over Southeast Asia without mixing. In the northwest Pacific, reanalysis data show that while dust is concentrated near the surface, maximum outflow to the Pacific occurs at 400 hPa in the mid-latitudes due to strong westerlies. Trajectory analysis combined with observations suggests that this high-altitude transport includes dust from the Sahara, Arabia, and Taklamakan deserts. At Mt. Lulin along the subtropical coast of East Asia, measured dust concentrations during dust events range from 15 to 39 mu g m-3, while the annual average is close to 5 mu g m-3, accounting for 42% of the aerosol concentration over the high mountain.