Seasonal cycle of the Antarctic coastal ocean

• Main Authors: Kay I. Ohshima, Takatoshi Takizawa, Shuki Ushio, Toshiyuki Kawamura
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Institute of Polar Research 1997
• Subjects: geo; envir; Antarctic; Austral; The Antarctic; Antarc*
• Online Access: https://doi.org/10.15094/00008978; https://doaj.org/article/54074bd8c6e44d27b601f329139a662f

Under the Japanese Antarctic Climate Research (ACR) program, year-round oceanographic observations were conducted in the vicinity of Lutzow-Holm Bay, during 1990-1992. It was found that the thickness of the Winter Water (WW) layer, characterized by a cold fresh oxygen-rich water, exhibits its maximum in the austral fall (typically 500m) and its minimum in the austral summer (typically 350-400m). The associated density variation of the water column explains only about one third of the seasonal variations in sea level at the coast, which suggests a large seasonal variation in barotropic coastal flow. Prominent freshening occurs in the WW layer during fall. This appears to be caused by the accumulation of WW, whose upper portion is freshened in the preceding summer. We think that this accumulation of the freshened (accordingly less dense) water is a possible reason why bottom water formation can not occur in this area. We propose that the seasonal variation in the WW layer is mainly caused by the seasonal variation in the wind over the coastal ocean. In fall the prevailing easterly wind intensifies, which increases the Ekman convergence of WW in the coastal ocean, while in summer the opposite occurs.