Relationships between Temperature at Surface Level and in the Troposphere over the Northern Hemisphere

Abstract

The thermal structure of the troposphere remains a hot topic, including modelling issues as well as temperature field simulations. This study evaluates the relationship between the air temperature at the Earth’s surface and the temperature of various layers of the troposphere over the Northern Hemisphere, as well as attempts to identify determinants of its variability. Vertical differentiation has been analyzed from the layer σ = 0.995 representing the surface (surface air temperature, SAT), up to an isobaric level of 300 hPa with a focus on the main pressure levels, i.e., 925 hPa, 850 hPa, 700 hPa, 500 hPa. The data were obtained from an NCEP/NCAR reanalysis with a resolution of 2.5 degrees latitude and longitude for the period 1961–2020. The relationship between the SAT and the temperature at each level was expressed using a simple but effective correlation coefficient by Pearson (PCC). These relationships obviously, according to Tobler’s law, weaken with an increasing altitude. However, the distribution of PCC (both horizontal and vertical) proves the impact of geographic factors associated with the relief and also with the surface itself (e.g., land cover). These factors are the main drivers of inversion layers and significantly disturb the straight vertical structure of the atmosphere. The research has shown a significant interannual differentiation of these interactions, as well as their spatial diversity in geographic space. The altitude–temperature relationship becomes weaker in all seasons, but much faster during summer and winter, relative to both spring and autumn.