The Pivotal Role\nof Heavy Terpenes and Anthropogenic\nInteractions in New Particle Formation on the Southeastern Qinghai-Tibet\nPlateau

Aerosol particles originating from the Qinghai-Tibet\nPlateau (QTP)\nreadily reach the free troposphere, potentially affecting global radiation\nand climate. Although new particle formation (NPF) is frequently observed\nat such high altitudes, its precursors and their underlying chemistry\nremain poorly understood. This study presents direct observational\nevidence of anthropogenic influences on biogenic NPF on the southeastern\nQTP, near the Himalayas. The mean particle nucleation rate (<i>J</i><sub>1.7</sub>) is 2.6 cm<sup>–3</sup> s<sup>–1</sup>, exceeding the kinetic limit of sulfuric acid (SA) nucleation (mean\nSA: 2.4 × 10<sup>5</sup> cm<sup>–3</sup>). NPF is predominantly\ndriven by highly oxygenated organic molecules (HOMs), possibly facilitated\nby low SA levels. We identified 1538 ultralow-volatility HOMs driving\nparticle nucleation and 764 extremely low-volatility HOMs powering\ninitial particle growth, with mean total concentrations of 1.5 ×\n10<sup>6</sup> and 3.7 × 10<sup>6</sup> cm<sup>–3</sup>, respectively. These HOMs are formed by atmospheric oxidation of\nbiogenic precursors, unexpectedly including sesquiterpenes and diterpenes\nalongside the commonly recognized monoterpenes. Counterintuitively,\nover half of HOMs are organic nitrates, mainly produced by interacting\nwith anthropogenic NO<sub><i>x</i></sub> via RO<sub>2</sub>+NO terminations or NO<sub>3</sub>-initiated oxidations. These findings\nadvance our understanding of NPF mechanisms in this climate-sensitive\nregion and underscore the importance of heavy terpene and NO<sub><i>x</i></sub>-influenced chemistry in assessing anthropogenic-biogenic\ninteractions with climate feedbacks.