Orbital Controls on North Pacific Dust Flux During the Late Quaternary

Abstract

Airborne mineral dust is sensitive to climatic changes, but its response to orbital forcing is still not fully understood. Here, we present a reconstruction of dust input to the Subarctic Pacific Ocean covering the past 190 kyr. The dust composition record is indicative of source moisture conditions, which were dominated by precessional variations. In contrast, the dust flux record is dominated by obliquity variations and displays an out‐of‐phase relationship with a dust record from the mid‐latitude North Pacific Ocean. Climate model simulations suggest precession likely drove changes in the aridity and extent of dust source regions. Additionally, the obliquity variations in dust flux can be explained by meridional shifts in the North Pacific westerly jet, driven by changes in the meridional atmospheric temperature gradient. Overall, our findings suggest that North Pacific dust input was primarily modulated by orbital‐controlled source aridity and the strength and position of the westerly winds.

Changes in Late Pleistocene Dust Activity in the Southern Tibetan Plateau in Response to Orbital Precession and Mountain Glaciers

“…During times of high obliquity, the midlatitudes at the top of the atmosphere receive relatively less radiation and poles at the top of the atmosphere receive more (Mohtadi et al, 2016), creating a weaker meridional insolation or high-level atmospheric temperature gradient (Cruz et al, 2006;Loutre et al, 2004) and furtherly weakening the high-level westerlies (Frisch et al, 2019). A strong obliquity signal has also been revealed in dust flux records from the subarctic Pacific Ocean (Zhong et al, 2024), where dust is transported by high-level westerlies. Although high dust activity occurred in the southern TP during ∼58-47 ka, the weak high-level westerlies could not have transported substantial dust to Greenland.…”