Comprehensive temporal analysis of temperature inversions across urban atmospheric boundary layer of Tehran within 2014–2018

• Published in: Modeling earth systems and environment 2020-06, Vol.6 (2), p.967-982
• Main Authors: Khalesi, Bahareh, Mansouri Daneshvar, Mohammad Reza
• Format: Article
• Language: English
• Subjects: Air masses; Air temperature; Atmospheric boundary layer; Boundary layers; Chemistry and Earth Sciences; Climate change; Computer Science; Confidence intervals; Diurnal; Earth and Environmental Science; Earth Sciences; Earth System Sciences; Ecosystems; Environment; Heat flux; Heat transfer; Inversion layers; Inversions; Land surface temperature; Lapse rate; Long wave radiation; Math. Appl. in Environmental Science; Mathematical Applications in the Physical Sciences; Nitrogen dioxide; Original Article; Physics; Radiation; Statistical analysis; Statistical methods; Statistics for Engineering; Subsidence; Surface temperature; Temperature gradients; Temperature inversion; Temperature inversions; Vertical motion
• ISSN: 2363-6203; 2363-6211
• DOI: 10.1007/s40808-020-00732-x

The present study attempted to assess the surface-based inversion characteristics in Tehran city, capital of Iran, using upper air sounding data, in different temporal scales during 2014–2018. Some characteristics such as the height and temperature of the inversion layers in addition to the environmental lapse rate and inversion intensity index were investigated in this study. From a total set of 1343 diurnal inversions within 2014–2018, the highest frequency of inversions was registered in 2017 by 317 days, and the lowest frequency was recorded in 2014 by 227 days. Averagely, radiation inversions with a frequency of 1030 (73% from total inversions) were estimated more than subsidence inversions with a frequency of 313 (23%). The higher values of temperature gradient of the inversion layer (D T INV ) coincided with the radiation inversions, depending on the most intensive inversions (0.1693) and the highest lapse rate (0.061). During the radiation inversion days, including intensive inversions in autumn and winter periods, the climatic variables of upward long-wave radiation, land surface temperature, surface sensible-heat flux, and vertical motion of air mass were in minimum levels across the atmospheric boundary layer, while the concentration of nitrogen dioxide was significantly in the highest value. All aforementioned climatic variables are reverted during the subsidence inversion days in the summer period with ticker but wicker inversion layers. Ultimately, the statistical analysis revealed the significant and positive correlation between nitrogen dioxide concentration and three characteristics of radiation inversion event, inversion intensity, and environmental lapse rate ( R from 0.735 to 0.859) at 75–85% of the confidence level based on monthly data.