The effects of topography and urban agglomeration on the sea breeze evolution over the Pearl River Delta region

However, on the east coast, the topography promotes the sea breeze, resulting in an occurrence about 4 h earlier due to the heating effects. The depth and the speed of the sea breeze are increased by 466 m and 1.2 m/s, respectively. (2) Under the influence of Urban Heat Island Circulation (UHIC), the sea breezes reach cities near the coast an hour earlier and are later inhibited from propagating further inland.

Moreover, a wind convergence zone with a speed of 3-5 m/s and a width of about 25 km is formed along the boundary of suburbs and cities in the PRD region. As a result, two important convergence areas: Foshan-Guangzhou, and Dongguan-Shenzhen are formed. (3) Overall, the topography has a more remarkable impact on the mesoscale wind field especially in the mountain and bay areas, resulting in an average speed disturbance of 2.8 m/s.

The urban heat island effect is relatively small and on average it causes only +/- 0.9-1.8 m/s wind speed perturbations in the periphery of two convergence areas and over PRE.