Wind dynamics drives the changes of the 2001–2023 grass pollen seasons in Córdoba (southern Spain)

Abstract

Aerobiological studies have reported an increasing severity of pollen seasons, both in terms of duration and total pollen amount. Climate change has also influenced global terrestrial near-surface wind speeds, yet its connection to pollen dynamics remains underexplored in southern Europe. This study analyzes long-term trends in grass (Poaceae) pollen season parameters in Córdoba, Spain (2001–2023), with a particular focus on wind dynamics—including air mass trajectories and wind speed—as well as other meteorological variables such as temperature and rainfall. By examining surface wind patterns in detail, the analysis also allows identification of potential pollen sources during different phases of the pollen season (pre- and post-peak). The results reveal a significant positive trend in pollen season duration (+3.7 days year⁻¹), associated with an earlier onset (–0.8 days year⁻¹) and a delayed end (+1.3 days year⁻¹). Temporal variations in air mass arrivals significantly influence grass pollen concentrations, with distinct patterns observed between pre- and post-peak periods. The pre-peak period is characterized by lower wind speeds (average 1.53 ± 0.05 m/s, with a negative trend of –0.007 m/s year⁻¹) and slow-moving air masses, favoring local sources and atmospheric accumulation processes that lead to progressively increasing concentrations. In contrast, the post-peak period is marked by higher wind speeds (average 1.82 ± 0.05 m/s, with a positive trend of +0.004 m/s year⁻¹) and the dominance of faster northerly and north-westerly flows, indicating a greater influence of distant sources. Additionally, the study identifies a positive contribution of precipitation during the season to the extension of the pollen season with an earlier onset and delayed end. These findings provide a comprehensive understanding of how meteorological factors, especially wind dynamics, shape temporal and spatial patterns in grass pollen seasons in southern Spain.