Temperature regulates dust activities over the Tibetan Plateau

Introduction

The environmental changes of the Tibetan Plateau (TP) are highly sensitive to global climate change and can be considered an early warning signal for global warming. Since the 1950s, the TP has undergone accelerated warming, leading to profound changes in its hydrological and ecological systems as well as regional dust activities. Currently, over 60% of the TP is classified as arid or semiarid. This harsh environment, characterized by loose surface sediments, sparse vegetation, and strong winds, makes the TP a major contributor to the global dust cycle. Dust emitted from the TP not only impacts local societies and economies but also exerts complex feedbacks on climates, including influences on nutrient cycling, surface albedo, radiative forcing, and cloud formation.1 Meanwhile, dust plays a key role in maintaining soil fertility and buffering capacity, forming the foundation for alpine ecosystems.2 Given these significant interactions, understanding the variability of dust activity over the TP and its driving mechanisms is both critical and urgent.

Temperature regulates dust activities over the TP on multiple timescales

Modern observations indicate that dust activity in the arid or semiarid regions primarily occurs during cold seasons, such as winter and spring, and is closely linked to near-surface wind patterns. During winter, air temperature over the TP drops more significantly than in surrounding areas at similar altitudes. This creates descending air masses over the TP, driving cool, dry air flows outward from the plateau. Modern near-surface (10 m) wind field observations from 1979 and 1998 support this phenomenon.3 These temperature-induced gradient winds are a primary driver of dust activity on the TP. Since the 1970s, dust activity on the TP has declined in response to the increasingly positive phase of the winter Arctic oscillation (AO) or North Atlantic oscillation (NAO), reflecting that the decadal-timescale (101 years) variability of dust activity is related to these climatic indices. When the AO/NAO is in a negative phase, the Azores high decreases, while the Icelandic low increases, leading to lower atmospheric pressure in middle latitudes and higher pressure in high latitudes. This pattern facilitates the transport of cold air from high to middle latitudes via the Westerlies, causing air temperatures to drop across most middle latitudes. The resulting air temperature drop intensifies near-surface winds, amplifying dust activity over the TP.