We performed a a month-long sensitivity study of obs-nudging on meteorology and ozone chemistry. Notable increases in temperature and wind performance were observed after obs-nudging with hourly nudging files. PBL height also matched better in the sensitivity case. The model ozone improved at ground level and aloft but to a lesser degree. An examination of a high ozone episode showed that the current nudging process does not perform consistently – quite well at times while poor at other times.