Estimation of the effective zone of sea/land breeze in a coastal area

Sea/Land breezes that are generated by mesoscale–thermally induced winds due to the different heat capacities of the land and the sea water along coastal lines, have been important issues for coastal air environments due to their significant role for the transport and diffusion of air pollution. The meso–scale modeling tool, A2C flow/A2C t&d (A2C represents Atmospheric to Computational Fluid Dynamics and t&d represents transport and diffusion) was applied to simulate the pure Sea/Land breeze mechanism. Geographic data of resolution USGS 30” were used for setting the modeling domain with a size of 248 km × 224 km and it covers both sea and land area of the west coast of Korean peninsula. Modeling period was selected in late July for typical summer conditions. Then the initial and boundary conditions were set and the modeling was carried out.Strong land breeze was observed around 6 a.m., just before sunrise and it was neutralized between 9 a.m.–10 a.m. then the sea breeze started. The sea breeze achieved its maximum strength around 3 p.m. when the temperature difference between surface and air above 10 m was about 15 K. Subsequently, the energy of sea breeze decreased with the decrease of solar radiation with time and again reached to transition period between 8 p.m.–10 p.m. Then the vortex of breeze was generated again along the coastal line, and enlarged its buffer zone with the increase in temperature and pressure differences between the land and sea surfaces. The vortex depth of 350 m was obtained in the early morning and about 1 000 m around 3 p.m. for the modeling period. The maximum speeds of the sea and land breezes were approximately 2.5 m/s and 1.5 m/s, respectively along the coastal line. The penetration lengths of sea and land breezes were approximately 25–30 km and 15–20km, respectively. The suction lengths of sea and land breezes were about 15–20 km and 10–15 km, respectively.