Characteristics of atmospheric boundary layer structure and its influencing factors under different sea and land positions in Europe

This study identifies quantitatively the dominant contributions of meteorological factors on the development of the boundary layer heights (BLH) in the European region, based on 32 years (1990−2021) of radiosonde observations. The spatial variability of the BLH is further discussed by location, by classifying recording stations as inland, coastal, or bay. We find that the BLH in Europe varies considerably from day to night and with the seasons. Nighttime BLH is higher in winter and lower in summer, with the highest BLH recorded at coastal stations. Daytime BLH at coastal stations shows a bimodal structure with peaks in spring and autumn; at inland and bay stations, daytime BLH is lower in winter and higher in summer. The daily amplitudes of BLH at the inland and bay stations are stronger than those at coastal stations. Based on our multiple linear regression analysis and our decoupling analysis of temperature and specific humidity, we report that the development of the nighttime BLH at all types of stations is strongly dominated by the variations of surface wind speed (and, at coastal stations, wind directions). The main contributors to daytime BLH are the near-surface temperature variability at most coastal and inland stations, and, at most bay stations, the variation of the near-surface specific humidity.