Response of sea and land breeze characteristics to urban heat island over the west coast of Bohai Bay

By using observation data from 14 automatic weather stations in Tianjin and conventional data from every 6 h surface meteorological stations,the effect of urban heat island( UHI) on sea-land breeze(SLB) over the west coast of Bohai Bay during 2008 is analyzed with statistical analysis method.The result shows that the frequency of SLB is very low in both weak and strong UHI conditions,reason is that the strong UHI blocks the penetration of the sea breeze. Among all ground stations,the highest frequency of maximum wind speed of sea breeze appears in Jinnan station,the probability of which is higher in weak heat island intensity. UHI delays the starting time of sea breeze appearance and shortens the duration. A negative correlation. exists between the UHI and sea breeze speed. When the heat island intensity is less than 2. 6 ℃,the decrease of UHI intensity leads to the increase of land-breeze speed,and vice versa in urban station like Tianjin. Furthermore,when the sea breeze extends inland,the heat island intensity increases during the period of prevalent sea breeze and is overlaid with sea breeze ctrculation here,which leads to the increase of surface-layer wind flow and its westward spreading to the center of the city.