The northern Antarctic Peninsula (NAP) is a highly productive ecosystem that supports a large marine food web, and is one of  the most rapidly warming areas in Antarctic. During the austral summer of 2006,  the NAP region had particularly high primary productivity, and chlorophyll-a (Chl-a) concentration was the highest during 2001-2011. The hydrographic and primary production data from the U.S. Antarctic Living Resources (AMLR) program and satellite observations were used to study the mechanisms of  the Chl-a anomalies. Mean sea level pressure (MSLP) was anomalously high over the Bellingshausen Sea west of the NAP in the summer of 2006, which induced anomalous southerly over the NAP and weakened the prevailing northwest wind. Such changes reduced the total cloud cover (TCC) and increased the photosynthetically available radiation (PAR). Significant positive correlation is detected between PAR and chlorophyll-a concentration. Hence, the improvement of light condition in 2006 summer directly promoted the phytoplankton production. Meanwhile, the enhancement of shortwave radiation also increased sea surface temperature (SST) and strengthened ocean stratification, which allowed phytoplankton to gather in the euphotic zone for photosynthesis. This work underlines the importance of physical processes for the occurrence of anomalous ecological states in the NAP region.