Rectification of surface chlorophyll (Chl) concentration by the atmospheric intraseasonal variability is detected in a numerical biophysical ocean model when it is forced by composite Madden-Julian Oscillation (MJO) events. In addition to the shoaled mixed layer depth (MLD) previously reported, it is found that increased mean Chl by MJO forcing mostly co-occurs with shoaled isothermal depth (ITD) / nutrient isopleths and reduced barrier layer thickness (BLT).