Analysis of the effects of climate change on the gyre in Lake Biwa, Japan

The currents of gyre (circulation) flow play an important role in the transportation and mixing of dissolved or suspended nutrients and chemical substances. In recent years, the climate change has affected the flow field in Lake Biwa. However, how much the climate change can influence the flow field has not been clarified enough yet. In the present study, using a three-dimensional hydrodynamic model, we investigated the effect of changes in air temperature, wind speed, and precipitation on the change of the flow field in Lake Biwa. For sensitivity analysis, numerical simulations were performed for a baseline case using realistic meteorological data from 2007 to 2012, as well as hypothetical cases using meteorological data. The analysis revealed that the change in air temperature and precipitation changed stratification and vorticity in the surface layer in each season. The strength of the stratification affected the gyre strength in the surface layer. The change in wind speed, on the other hand, changed the wind stress acting on the lake's surface, influencing the strength of gyre significantly. Increased wind speed lengthened the radius of the gyre in Lake Biwa, while decreased wind speed made it weaker above and below the thermocline.

Automated summary

The currents of gyre flow have a significant impact on the transportation and mixing of nutrients and chemical substances in water bodies. This study aimed to investigate the effect of climate change on the flow field in Lake Biwa using a three-dimensional hydrodynamic model. Numerical simulations were conducted to analyze the sensitivity of air temperature, wind speed, and precipitation changes on the flow field. The results showed that changes in air temperature and precipitation affected the stratification and vorticity in each season, while wind speed changes significantly influenced the strength and radius of the gyre in Lake Biwa.