Surface wind climates in the North China Plain: Implications for air quality

Abstract

AbstractWind climatology is significant for applications from weather forecasting to air pollution control. Investigation of wind climates in the North China Plain (NCP) region is insufficient yet. Based on hourly observational data at 94 surface weather stations from 2014 to 2020, wind climatic features in the NCP region were examined using statistical and clustering methods. The seasonal average wind speed over this region is the highest in spring (2.7 m·s−1), followed by winter (2.5 m·s−1), and weakest in summer and autumn (2.0 and 1.9 m·s−1). The annual mean wind speed is higher in the mountainous and coastal areas (2.0–2.5 m·s−1) but lower in the plains (1.5–2.0 m·s−1). Mountain–plain/valley winds and sea–land breezes are important in the associated areas. Wind fields in the plains are variable, possibly due to the coexistence of multiple synoptic winds and regional thermal circulations. Monthly mean background wind fields display that northwesterly and southeasterly winds prevail over this region in winter and summer, respectively. Local winds, that is, mountain–plain winds and sea–land breezes, vary diurnally, but a time lag of about 3 hr exists between them. Synoptic winds act as a mediate wind system between local and background winds, being identified into eight patterns using a hierarchical clustering method. Among them, two patterns featuring a weak wind convergence zone along the mountains (36%) and three patterns featuring southerlies (55%) are major synoptic winds in this region.