Time series analysis of wintertime O3 and NOx formation using vector autoregressions

Abstract

Concentrations of 11 species are reported from continuous measurements taken during a wintertime field study in Utah. Time series data for measured species generally displayed strong diurnal patterns. Six species show a diurnal pattern of daytime maximums (NO, NO y , O 3 , H 2 O 2 , CH 2 O 2 , and Cl 2), while five species show a diurnal pattern of night time maximums (NO 2 , HONO, ClNO 2 , HNO 3 , and N 2 O 5). Vector autoregression analyses were completed to better understand important species influencing the formation of O 3 and NO x. For the species studied, r 2 values of predicted versus measured concentrations ranged from 0.82-0.99. Fitting parameters for the autoregressive matrix, Π, indicated the importance of species precursors. In addition, values of fitting parameters for Π were relatively insensitive to data size, with variations generally <10%. Variable causation was quantified using the Granger causation method. Assuming O 3 and NO x behave as chemical products, reactants (in order of importance) are as follows:

A diurnal story of Δ17O($$\rm{NO}_{3}^{-}$$) in urban Nanjing and its implication for nitrate aerosol formation

“…In this case, the enriched NO 2 atmosphere and dark environment were responsible for generating NO 3 and N 2 O 5 at night without being photolysis 62,64 . This has been proved by some previous studies 65,66 . A recent observational study in Nanjing found that the high level of volatile organic components (VOCs) concentrations in January 2015, which were emitted by various industrial sources nearby 67 .…”