Effect of forest canopy on the flow and dispersion characteristics over the Kaiga complex terrain region

Kaiga Nuclear Power Plants (NPPs) are located in the Western Ghats ~45 km away from the Arabian Sea. NPPs are situated in the valley region formed by the hills of Western Ghats. The hills are mainly covered by dense evergreen broadleaf forest. The landscape features such as hill-valleys and dense vegetation can offer significant surface roughness and cause drag to the air flow leading to wind speed as well as wind direction changes. Also, regional/local factors such as the land use/land cover, soil types and land surface physics influences the numerical simulation of the boundary layer flow characteristics. In this study, surface roughness length is estimated using the sonic anemometer and Mini Boundary Layer Mast (MBLM) data employing the logarithmic profile relationships under neutral stability conditions. With the updated roughness length, numerical simulations are attempted using the Weather Research and Forecast (WRF) model. Also, to study the effect of land surface physics on the simulated sea breeze characteristics numerical simulations are carried out with two Land Surface Model, Noah and Noah-Multi Physics (Noah-MP). It has been found that Noah-MP better represented the sea breeze characteristics such as the onset time, inland extent, intensity and duration of the sea breeze. (author)