Atmospheric fronts and their association with day-to-day temperature differences

Advancements in computer technology have facilitated the objective analysis of atmospheric fronts. With objectively defined fronts at hand, it was a relatively short step to producing the climatology of their occurrence. Recent studies have focused on delineating the spatial distribution of fronts across various spatial scales and on elucidating the relationship between fronts and precipitation patterns.

Despite the considerable attention given to the link between fronts and precipitation, little emphasis has been placed on exploring their influence on surface temperature dynamics over consecutive days. Traditionally, fronts have been associated with temperature gradients aloft rather than at the surface. However, a number of small-scale (regional and local) processes play an important role in surface temperature dynamics. Surface temperature is modified by a variety of boundary-layer and surface processes, that make its dynamics in the vicinity of fronts and during their passage very complex, and therefore worth investigating. Examining the impact of fronts on surface temperature variability is important task, given their potential contribution to asymmetries in distributions of day-to-day temperature differences – a key indicator of weather variability.

This study presents a comprehensive climatological analysis of cold and warm fronts in the Euro-Atlantic region, utilizing the ERA-5 reanalysis dataset spanning from 1961 to 2020. To objectively identify fronts, we utilize the temperature frontal parameter defined as the second derivative of temperature in the direction perpendicular to the front. The change in temperature over a 24-hour period centered on the passage of a front is retained for each gridpoint over which the front passes. Through this approach, we derive the climatology of day-to-day temperature differences associated with the passage of cold and warm fronts, and we compare these results with temperature patterns in the absence of any frontal activity.

We found that strong day-to-day cooling events are significantly more likely to be associated with the passage of cold fronts in summer across most of the European continent. However, the passage of a warm front in summer leads, on average, to warming only over approximately one half of the continent, while the opposite effect can be seen for the other half. We will further analyse the whole day-to-day temperature difference distribution and its regional specifics during frontal passages, and investigate links between day-to-day temperature differences and various properties of cloud cover.