Dear teachers
I am investigating persistent discrepancies in CMAQv5.3 simulations of diurnal variation in NO2/NO concentration over Beijing urban area during January-March 2024 . The simulated NO₂ and NO consistently underestimate observations in the 00:00-08:00 BJT period, while showing a overestimation during early evening (17:00-22:00 BJT). Notably, simulated diurnal variation in Ox (NO₂ + O₃) maintains good agreement with observations throughout the day.