Double Low-Level Jets Drive Vertical Folding and Suspension of Dust Layers over the Taklimakan Desert

Abstract. Dust-boundary layer interaction is critical for regulating regional climate and the global dust cycle, yet the lack of high-resolution vertical profiling has long hampered mechanistic understanding, especially over complex terrain. Here, ground-based lidar measurements collected in the hinterland of the Taklimakan Desert (TD) from 2023 to 2025 were analysed to reveal a previously overlooked coupling regime: a Double Low-Level Jet (DLLJ) structure. DLLJ comprises a nocturnal low-level jet (NLLJ) characterised by eastward winds near the surface and a synoptic-system-related low-level jet (SLLJ) associated with northwesterly winds at approximately 600 hPa. We demonstrate that their convergence dynamically facilitates the large-scale vertical folding of the dust layer (VFDL), effectively injecting coarse-mode desert dust from the surface directly into the residual layer and above. SLLJ was attributed to the convergence related to Central Asian cold air descent and ascending airflow at the terminal of NLLJ, which not only produces distinct optical stratifications and source but also sustains a dense dust reservoir aloft under high-topography forcing. Climatologically, DLLJs and VFDLs occur with frequencies of approximately 19 % and 36 % during warm season, respectively, with a co-existence frequency of 9 %. Notably, 47 % of VFDL events were associated with DLLJ-inducing northwestern low-pressure systems. These findings offer the first observation evidence of how DLLJ modulate the vertical distribution of dust over complex terrain, revealing that current reanalyses and climate models substantially underestimate elevated dust layers. Globally, similar datasets of vertical distribution can offer a stringent observational benchmark for improving dust-cycle representation in global climate projections.