Abstract: Based on hindcast simulation of a fine resolution ocean-sea ice model (NAPA1/12), the seasonal variations of the Pacific Summer Water (PSW) over the northwestern Chukchi shelf, the eastern Chukchi slope and the Canadian Basin are evaluated. The path of PSW in the Arctic Ocean is also analyzed. Results indicate that: 1) Over the northwestern shelf and the eastern slope of the Chukchi Sea, late August temperatures in the upper layer are higher than those at the bottom due to the influence of solar radiation following complete melting of the sea ice. With the reinitiation of freezing in October, a warm water mass is maintained below 20m. This warm water is related to the advection of PSW. Over the northwestern shelf, PSW is mainly derived from the summer Bering Sea Water (sBSW). Over the eastern slope, PSW is composed of the Alaska Coastal Water (ACW) and sBSW, in which ACW plays a dominant role early in the water mass’s development. 2) Barrow Canyon is the main oceanic gateway for PSW into the Arctic Ocean. After exiting Barrow Canyon, PSW first intrudes eastward onto the Beaufort Sea shelf west of 144°W in mid-July. In early August, the majority of PSW is transported westward along the Chukchi Sea slope, thereby entering the Canadian Basin in a clockwise direction. 3) PSW in the Canadian Basin is maintained between the depths of 50 and 100 m. In the western basin, PSW exists year round, while in the eastern basin, PSW exists low temperature.

Key words: Pacific Summer Water, seasonal variation, Arctic Ocean