Temporal and spatial variability of surface‐based inversions over Europe based on ERA‐Interim reanalysis

ABSTRACT Tropospheric temperature inversions seem to be an important feature of climate, as well as a significant factor affecting air quality and fog formation. The aim of this article is to investigate the temporal and spatial variability of surface‐based inversions ( SBIs ) over Europe. It is based on data derived from the ERA ‐Interim reanalysis for the period 1981–2015. The study examines diurnal, seasonal and multiannual variability of temperature inversions based on their frequency, depth and strength. These three parameters are characterized by strong temporal variability – diurnal and seasonal, as well as strong spatial differentiation. It has been confirmed that the energy budget is the key factor responsible for diurnal, and partly seasonal variability of SBI occurrence. Its negative values lead to an intense cooling of active surface and initiate the formation of the radiative inversions, which are the most common type of inversion occurring over the mainland of Europe. Temperature inversions usually form shortly after dusk, increasing gradually their depth and strength until sunrise. At 0000 Universal Time Coordinated (UTC), SBI frequency attains higher values in the summer than in the winter over the predominant part of Europe. However, the inversion layers occurring then are noticeably shallower and weaker. Surface type strongly affects SBI properties. This is mostly marked in terms of the distinct differentiation between marine and land areas as well as the impact of vast glaciers located across Greenland and western part of Iceland. Moreover, the distribution of SBI depth and strength is shaped by atmospheric circulation. For instance, their higher values occur over Eastern Europe in the winter, which is associated with the influence of a seasonal high pressure system found over Russia. Taking into account multiannual variability, SBI parameters, primarily depth and strength, exhibit the most significant negative changes in the winter.