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O3 concentration has many zero values

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New member
Hello all,
I am running the WRF-Chem with hourly wrfchemi* emission files made by myself.
I compared the O3 values of my wrfout files with the observation data. The trendency of O3 values are consistent with observed values, but there were many zero values and they are mainly existed when the observed values are lower.
The line plot is showed below and the red line represents simulated value while the blue one represents observed value.


I would really appreciate your help. Thank you.
I do see strong reductions in ozone mixing ratios close to pollution sources during the night in a similar (though maybe not as drastic) manner as this.

Ozone is a secondary pollutant - it's loss / gain rates will depend on the other emitted pollutants (principally NOx and NMVOCs). Its production is very dependent on photochemistry (hence the high mixing ratios during the day, and low mixing ratios at night). It might be that your general pollution emission rates are too high - have you checked your NOx and NMVOC mixing ratios? Also, are you making sure to use chemical boundary conditions? Downward transport of ozone from the free troposphere is an important source of ozone in the boundary layer - if it isn't available then that would lead to very low mixing ratios at night.