This study is aiming to provide an updated summertime (JJA) ozone climatology by combining all available ozone data in California from 2004 to 2014. Data used for this study include ozonesonde launches from the Trinidad Head site and the CalNex 2010 experiment, CARB and EPA ozone ground monitoring stations across the state, as well as satellite observations. Summer trends and the inter-annual variability of tropospheric and surface baseline ozone affecting California from long-range Pacific Ocean transport will be evaluated. Detailed comparisons of the ozonesondes and the ground ozone station data will be performed and analyzed to distinguish baseline ozone from inland anthropogenic sources. Additionally, a summertime climatology of back-trajectory analyses will be performed for the Trinidad Head ozonesonde location.