A space-time correlation study of oxidant and carbon monoxide in the Los Angeles basin

Autocorrelations of oxidant and carbon-monoxide between different sites and at different times and time intervals (within ± 5 h) in the Los Angeles Basin were studied to establish the transport length scale of the pollutants.Consideration of several ground-based station pairs suggests that oxidant has a transport scale on the order of 55 km along the San Gabriel Valley, east of Los Angeles, in the afternoon, when wind transport is most effective. However, the transport scale appears to be short to the north because of the mountain range, and to the south because of high local NO sources and the Palos Verdes convergence. The transport scale for CO on the other hand is short since local emissions can easily dominate the transported portion.In the afternoon, the lack of surface wind dependence in the oxidant correlations between Los Angeles and Pasadena, and between Los Angeles and Azusa may indicate the importance of high altitude transport.