Water Properties and Diffusive Convection in the Canada Basin

• Published in: Journal of Marine Science and Engineering
• Main Authors: Ling Qu, Shuangxi Guo, Shengqi Zhou, Yuanzheng Lu, Mingquan Zhu, Xianrong Cen, Di Li, Wei Zhou, Tao Xu, Miao Sun, Rui Zeng
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2024
• Subjects: Canada Basin; double diffusion convection; vertical heat transport; Naval architecture. Shipbuilding. Marine engineering; VM1-989; Oceanography; GC1-1581; canada basin; Sea ice
• Online Access: https://doi.org/10.3390/jmse12020290; https://doaj.org/article/66998c7558874f24a3827ca3289d54ec

The aim of this study is to better understand diffusive convection (DC) and its role in the upper ocean dynamic environment and sea ice melting in the Canada Basin. Based on a moored dataset with 6737 profiles collected from August 2003 to August 2011 in the upper layer of the Canada Basin, DC between the warm and salty Atlantic Water (AW) and the colder and less salty Lower Halocline Water (LHW) were investigated. The moorings were designated at four stations: A, B, C, and D, located at the southwestern, southeastern, northeastern, and northwestern parts of the basin, respectively. During the observation period, the temperature, salinity, and depth of the AW and LHW exhibited unique temporal variations. The temperature and salinity of the AW varied among stations, with a decreasing trend from northwest to southeast, consistent with the propagation path of the AW in the Canada Basin. The temperature and salinity of the LHW were similar at all stations. The AW and LHW cores were located between depths of 320–500 m and 160–300 m, respectively, and both gradually deepened over time. Distinct DC staircase structures were observed between the AW and LHW, more pronounced at stations C and D than at stations A and B, which is speculated to be related to eddies at stations A and B during the observation period. The vertical heat fluxes through the DC staircase layer at stations C and D ( F Hc_C and F Hc_D ) were estimated using an empirical formula. F Hc_C ranged from 0.05 to 0.94 W/m 2 , and F Hc_D ranged from 0.05 to 0.6 W/m 2 , with the maximum probability value for both at approximately 0.2 W/m 2 . The effective diffusivities at these two stations ( K T_C and K T_D ) are similar, ranging from 2 × 10 −6 to 3 × 10 −5 m 2 /s, with the highest probability occurring at 6 × 10 −6 m 2 /s. Both the probability density function of the heat flux and the effective diffusivity skewed towards larger values and obey a lognormal distribution, indicating turbulence intermittency of the DC staircase in the Canada Basin. These ...