Characteristics of sea breezes over the Jiangsu coastal area, China

The synoptic circulation patterns during sea breeze events for the period March 2010 to February 2011 in the coastal region of the Jiangsu Province are investigated using the Lamb-Jenkinson circulation classification method for National Centers for Environment Prediction (NCEP) reanalysis data. The results show that the undefined flow type (UD), the rotational flow types of anticyclones (A)/cyclones (C), the directional flow types of southeast (SE)/southwest (SW) and the hybrid flow type CSW (combining the C and SW patterns) are conducive to the development of sea breeze circulation in the coastal region of the Jiangsu Province and together account for 84.3% of the circulation types in the year 2010. The wind observation data collected at a height of 70m over the Nantong wind tower operated by the China Meteorological Administration (CMA) and located on the coast of Jiangsu are also analysed. The statistical characteristics of sea breeze circulation in the coastal area of Jiangsu are: (1) sea breeze circulation occurs most often in the summer (June-August) with a frequency of 52.8% and is rarely observed from November to January; (2) sea breeze circulation usually occurs 5-6 h after sunrise and lasts until 2-3 h after sunset, and the duration of sea breeze circulation has a maximum value of approximately 11 h in February; (3) the seasonal variation of sea breeze strength is small, with the monthly average wind speed about 3ms(-1); and (4) in 2010, the daily average hodograph in the Nantong station during the sea breeze days exhibits an expected clockwise rotation.