Characterizing global air pollution seasonality and trends through integrated satellite and meteorological analytics.

Air pollution remains a major global health and climate challenge, contributing to 6.7-8 million premature deaths annually. Using six years (2019-2024) of monthly Sentinel-5P (NO 2, SO 2, CO, O 3, and HCHO) and ERA5-Land meteorological data, this study quantified the seasonal variability, spatial regimes, and temporal evolution of global atmospheric composition. Strong and statistically significant seasonality was confirmed (ANOVA p < 0.001), with NO2 increasing by up to 40 % in winter over South and East Asia and O3 increasing by 35 % in summer across the mid-latitudes. Seasonal Mann-Kendall trends revealed significant global increases in NO2 (τ = 0.50), HCHO (τ = 0.71), O3 (τ = 0.59), and temperature, while CO and SO2 displayed regionally mixed responses. Temperature was strongly correlated with O3 (r = 0.52) and NO2 (r = 0.68), whereas precipitation, humidity, and wind predominantly suppressed the accumulation of primary pollutants, highlighting the dominant influence of climate forcing. Biomass-burning regions in Africa and South America exhibited CO peaks exceeding two-fold background levels, whereas emission controls contributed to regional SO2 and NO2 reductions elsewhere. In particular, statistically significant declines in NO2 and SO2 across Europe and parts of East Asia are consistent with the effectiveness of emission control policies targeting the power generation, industrial activity, and transportation sectors. Despite providing globally consistent coverage, TROPOMI retrieval uncertainties and the absence of universal in situ validation introduce residual observational uncertainty. These insights into pollutant seasonality and short-term directional trends provide actionable information for air quality management, enabling improved seasonal forecasting, early warning assessments, and more targeted mitigation strategies at regional to global scales.