Scale Heights of Water Vapor and Sulfur Compounds in the Lower Troposphere.

A global analysis of geographical features of vertical profiles of specific air humidity and concentrations of sulfur dioxide and sulfate aerosols is carried out based on the CAMS reanalysis data, as well as the height of the planetary boundary layer (PBL) based on the ERA5 reanalysis data for 2003–2020. The scale height H_Y, i.e., the height at which the concentration of the substance Y decreases by a factor of e, is used as a characteristic of the aforesaid profiles. The maximal heights of the upper PBL boundary are observed in regions of the prevailing cyclonic gyre—in storm tracks and in regions of monsoonal circulation in summer. For the vertical scale of the specific humidity profile, minima are identified in the regions of the subtropical gyre with prevailing large-scale subsidence of air masses. The scale height of SO₂ is characterized by spatial minima associated with oxidation of this substance. For , a spatial minimum over the ocean near southeast Asia is found. A statistically significant negative correlation between the PBL thickness and the vertical scale of the specific humidity profile in humid regions of the tropics is revealed, as well as a positive correlation between scale heights of sulfur dioxide and sulfates, most significantly manifested in regions with acute pollution of the lower troposphere by these substances. [ABSTRACT FROM AUTHOR]