An integrated approach to the heat and water mass dynamics of a large bay: High-resolution simulations of Funka Bay, Japan

Abstract

[1] Heat and water mass transports tagged by water type in a bay were investigated using daily outputs from a high-resolution land-sea coupled model. The modeled circulation and water property distribution were similar to those reported by observations. In this paper, the heat angle is introduced to accurately define the roles of the lateral heat flux (LF) into the bay and the net surface heat flux on temperature changes in the bay water. As a result, ocean phenomena in the bay can be categorized by using the heat angle in an intensive LF regime on short-period timescales and a gradual LF regime on intraseasonal timescales. Our close examination revealed that the velocity fields can be classified into three flow patterns: a twin vortex accompanied by positive LF, a clockwise flow with negative LF, and an anticlockwise flow with both LFs. These patterns occur in both intensive and gradual LF regimes. Intensive wind-driven LF forced by atmospheric disturbances was often observed from summer to autumn in 2008, accompanying the intrusion of southern subtropical Tsugaru warm water that was colder than the deep bay water (LF < 0) and subarctic Oyashio water that was warmer than the surface bay water (LF > 0), but both were hardly found in 2009. This thermal contrast affects the interannual difference in the stratification inherent in the bay. Our integrated analysis method is useful for prompt and robust understanding of the thermal and dynamic states in a bay based on ocean simulation data.

Hyperspectral optical discrimination of phytoplankton community structure in Funka Bay and its implications for ocean color remote sensing of diatoms

“…Seasonal changes in seawater temperatures and salinities at the surface ( decreased in salinity due to the effects of melting snow (Nakada et al, 2013). In October 2010 and November of both years, the water mass was influenced by the intrusion of the Tsugaru Warm Water, high saline water (T N 6°C, salinity N 33.6), which originates from the Kuroshio (Kuroda et al, 2012).…”

Ocean Prediction for Aquaculture: An Interview-based system

“…To date, studies to predict water temperature and chlorophyll-a on the bay-scale have often been conducted and have gradually improved their predictability. In particular, the seasonal prediction of the vertical profile, water mass, and water temperature in Funka Bay has been in practical use [4,8]. In this study, focusing on the low-salinity nearshore water affecting scallop production, we propose the prediction and visualization of low-salinity nearshore water and analyze its spatiotemporal variation.…”

“…The objective of the present study is to answer the question: which prediction system and visualization are necessary to provide the information required by aquaculturists? To address this question, we attempted to interview aquaculturists using the Evaluation Grid Method (EGM) [7] and employed an ocean prediction system that can be used during various periods, from several days to interannual timescales [8].…”

Implications of marine environment change on Japanese scallop (Mizuhopecten yessoensis) aquaculture suitability: a comparative study in Funka and Mutsu Bays, Japan

“…Daily vertical water column of sea temperature distributions were extracted from model‐derived four dimensional‐variational (4D‐VAR) data assimilation system that was developed at Kyoto University (Nakada, Ishikawa, Awaji, In, Koyamada, Watanobe, Okumura, Nishida & Saitoh ). The vertical data derived corresponded to latitude and longitude positions of the study areas to ascertain the scallop ecological environment.…”