Abstract
A bottom cold water mass (BCWM) is a widespread physical oceanographic phenomenon in coastal seas, and its temperature variability has an important effect on the marine ecological environment. In this study, the interannual variation of the BCWM in Iyo-Nada (INCWM), a semi-enclosed bay in the Seto Inland Sea, Japan, from 1994 to 2015 and its influencing factors were investigated using monthly observational data and a hydrodynamic model. The interannual variation in water temperature inside the INCWM showed a negative correlation with the area of the INCWM, and positive correlations with the local water temperature from April to July and with remote water temperature below 10 m in an adjacent strait in July. Differing from previously studied BCWMs, which had interannual variations depending closely on the water temperature before the warming season, the interannual variation of INCWM depends strongly on the air-sea heat flux during the warming season via local vertical heat transport and lateral heat advection. Further, by comparing several BCWMs, we found that the BCWM size is a key factor in understanding the mechanisms responsible for the interannual variation of BCWMs in coastal seas. These findings will help to predict bottom water temperatures and improve the current understanding of ecosystem changes in shelf seas under global climate change.
Highlights
With global climate change, interannual variations in water temperature in coastal oceans are attracting significant attention 25 (Lin et al, 2005; Park et al, 2015; Chen et al, 2020)
We investigated the interannual variation of the INCWM from 1994 to 2015 using observational data along a transect across the INCWM
The interannual variation of water temperature inside the 370 INCWM depends on both the water temperature in April and the heat transport into the INCWM during the warming season
Summary
Interannual variations in water temperature in coastal oceans are attracting significant attention 25 (Lin et al, 2005; Park et al, 2015; Chen et al, 2020). The lack of long-term observations limits the studies on the bottom water temperature, even though its interannual variations are important for understanding how coastal oceans respond to atmospheric changes (Simpson et al, 2011; Turner et al, 2017). A bottom cold water mass (BCWM), called “cold pool”, is the water trapped on the bottom layer as a result of seasonal thermoclines during stratified seasons It is characterized by lower temperatures than the surrounding waters and has been 30 reported to occur in many shelf seas, such as the Yellow Sea (Wei et al, 2010), Irish Sea (Hill et al, 1994), Middle Atlantic Bight (Lentz, 2017), North Sea (Brown et al, 1999), Bering Sea (Zhang et al, 2012) and Seto Inland Sea
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
