太平洋夏季水在北冰洋扩展路径的模拟分析

ANALYSIS ON THE SIMULATED PATHWAY OF PACIFIC SUMMER WATER IN THE ARCTIC OCEAN

基于高分辨率海洋-海冰模式(NAPA1/12)的模拟结果,分析了1996年太平洋夏季水(PacificSummer Water, PSW)在楚科奇海西北部陆架、东部陆坡和加拿大海盆区域的季节变化特征及其扩展路径。结果表明:1)在楚科奇海西北部陆架和东部陆坡处,8月底海冰完全融化后,受太阳辐射的影响,上层水温较高。10月起,海冰再次覆盖,上层(约20 m厚)水温接近冰点,其下层水温受PSW平流作用影响而呈现较高值,其中,西北部陆架处PSW主要为夏季白令海水(summer Bering Sea Water, sBSW),东部陆坡处PSW前期主要为阿拉斯加沿岸水(Alaska Coastal Water, ACW),后期为sBSW和ACW的混合。2)PSW主要通过巴罗峡谷进入北冰洋。在7月中旬PSW出巴罗峡谷后首先向东入侵至144°W以西的波弗特海陆架区;8月初,大部分向西沿楚科奇海陆坡输运,并以顺时针的方向进入深海盆。3)加拿大海盆区PSW维持在50-100m之间,海盆西部全年存在PSW,海盆东部PSW的高温特征不明显。

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 20 m. 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.