1:45 PM - 3:15 PM
[ACG30-P02] The role of Japan Sea Throughflow on the spatial variability of the SST warming trend in the Japan Sea
Keywords:SST, trend, Japan Sea
Sea surface temperature (SST) is an important physical parameter that can influence the atmosphere and ocean productivity. The state of the SST in the Japan Sea affects the amount of snowfall and rain along the coast of Honshu, Japan where it faces the Japan Sea (Takahashi et al. 2013, Takahashi and Idenaga 2013). The Japan Sea shows a larger SST warming trend than the surrounding oceans (Japan Meteorological Agency 2020). However, the SST trend in the Japan Sea does not occur uniformly in space. Weak trends are observed near the Tsushima Strait and strong trends are observed in the interior of the Japan Sea. The direct heat input from the atmosphere and Tsushima Current cannot explain this spatial distribution.
A numerical model was used to understand the mechanism that generates the spatial variability in the SST warming trend. The Japan Sea has two steady oceanic current pathways known as the Japan Sea Throughflow; a zonal flow along the coast of Honshu and 39N in the interior of the Japan Sea. This throughflow is responsible for exchanging the water mass of the Japan Sea with the external oceans. The existence of this current may shorten the residence time scale and reduce the amount of heat received from the atmosphere. The observed SST trend shows a weak trend along the pathway. We developed an idealized model reproducing the basic character of the ocean circulation field and the SST trend in the Japan Sea. We find weak trends along the oceanic current pathways and a strong trend in the interior. The heat budget analysis supports the role of the oceanic currents cooling the SST along its pathway while the interior is heated due to atmospheric forcing and long residence time. Model results suggest that the Japan Sea Throughflow is the primary mechanism that controls the spatial distribution of the SST warming trend in the Japan Sea.
A numerical model was used to understand the mechanism that generates the spatial variability in the SST warming trend. The Japan Sea has two steady oceanic current pathways known as the Japan Sea Throughflow; a zonal flow along the coast of Honshu and 39N in the interior of the Japan Sea. This throughflow is responsible for exchanging the water mass of the Japan Sea with the external oceans. The existence of this current may shorten the residence time scale and reduce the amount of heat received from the atmosphere. The observed SST trend shows a weak trend along the pathway. We developed an idealized model reproducing the basic character of the ocean circulation field and the SST trend in the Japan Sea. We find weak trends along the oceanic current pathways and a strong trend in the interior. The heat budget analysis supports the role of the oceanic currents cooling the SST along its pathway while the interior is heated due to atmospheric forcing and long residence time. Model results suggest that the Japan Sea Throughflow is the primary mechanism that controls the spatial distribution of the SST warming trend in the Japan Sea.