A Tsunami Simulator in Oceans and Coastal areas "T-STOC", which was developed by Port and Airport Research Institute, Japan, has been released as an open source computational code to simulate tsunami behavior from ocean to coastal area integrally. However, T-STOC does not support a storm surge simulation because wind speed and air pressure cannot be set on free surface boundary. In this study, we apply T-STOC to storm surge simulation by adding the input function of meteorological field and improving free surface condition. We calculated storm surges in Seto Inland Sea caused by two previous typhoons, Japan, which are Typhoon No. 16 in 2004 (T0416) and Typhoon No. 14 in 2005 (T0514), and compared the numerical results with the field observation ones in terms of storm surge deviation. As a result, the improved T-STOC considering meteorological field was confirmed to reproduce storm surge deviation appropriately. Furthermore, the influence of the number of vertical layers on storm surge analysis was also examined in this study.
Huge storm surge disasters have recently occurred in the world, such as Hurricane Katrina in 2005 which attacked Florida and Louisiana states in USA, Typhoon Haiyan in 2013 (Tajima et al., 2014) which hit the eastern part of the Philippines, and so forth. In Japan, Typhoon Vera (Isewan Typhoon) in 1959, which was the biggest storm surge disaster in Japan, struck the head regions of Ise Bay in Aichi Prefecture killing more than 5,000 people, and caused catastrophic human and property damages.
In storm surge simulations, a nesting method which connects multiple computational domains with different meshes is, in general, employed to appropriately represent sea bottom and land topographies from ocean (wide region) to coastal area (narrow region) integrally. A lot of numerical analysis models with the nesting method (e.g., Kawasaki et al., 2016; Kawasaki et al., 2016) have been developed recently, and STOC (Tomita and Kakinuma, 2005) (Storm surge and Tsunami Simulator in Oceans and Coastal areas), which is non-open source code for storm surge and tsunami simulations, has been provided by Port and Airport Research Institute, National Research and Development Agency, Japan, as one of the models. STOC consists of a quasi-three-dimensional multilevel model (STOC-ML) and a full three-dimensional model (STOC-IC) so as to be able to calculate three-dimensional fluid dynamic behaviors around structures with high accuracy. However, T-STOC, which is open source version of STOC, releases only the part of tsunami simulation model, and cannot analyze storm surge and it-induced inundation. There have been also few numerical investigations on storm surge using STOC as compared with tsunami studies.