The Relation Between Aerosol Vertical Distribution and Temperature Inversions in the Arctic in Winter and Spring. Issue 5 (1st March 2019)

• Record Type: Journal Article
• Authors: Thomas, Manu Anna; Devasthale, Abhay; Tjernström, Michael; Ekman, Annica M. L.
• Is Part Of: Geophysical research letters. Volume 46:Issue 5(2019)
• Page Start: 2836
• Page End: 2845
• Publication Date: 2019-03-01
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2018GL081624
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Temperature inversions, being a common meteorological phenomenon in the Arctic, especially during winter and spring, play a special role in regulating the distribution of aerosols. Using 10 years of collocated satellite observations, we evaluate the covariability of the vertical distribution of aerosol extinction and different atmospheric stability regimes. It is observed that as the atmospheric stability increases, more aerosols are trapped below inversions over the majority of the Arctic (except in the Pacific sector) during winter, indicating low‐level transport from lower latitudes into the Arctic. In contrast, additional aerosol layers are accumulated above inversion layers during spring in the Eurasian and Pacific sectors as the stability increases, indicating long‐range transport at higher altitudes. In this study, satellite observations are, for the first time, used as sole evidence to support the hypothesis that low‐level transport dominates in winter and free tropospheric transport dominates in spring. Plain Language Summary: Both in situ measurements and satellite observations unequivocally show that temperature inversions are common phenomena in the Arctic during polar winter. This invisible barrier controls the atmosphere and surface interactions, including aerosol vertical distribution. Having knowledge about the relationship between aerosols and inversions is important as the radiative and dynamic impacts of aerosols in the Arctic are strongly dependent on how they are distributed in the atmosphere in the presence of inversions. However, there exists a key knowledge gap about this relationship. Here we use 10 years of observations from two satellite missions, one providing temperature and humidity profiles and the other providing aerosol vertical distribution, to quantify this relationship for the first time. We investigated aerosol vertical distribution under different stability regimes that are defined based on temperature inversion strength. We found that as the atmosphere becomes more stable, more aerosols are trapped below inversions over the majority of the Arctic (except in the Pacific sector) during winter. During spring, the accumulation of aerosols over the inversion layers is dominant, except in the Atlantic sector. We argue that different pollution pathways into the Arctic can explain the observed contrasting relationships. Key Points: Aerosol vertical distribution under different static stability regimes is investigated in the Arctic As atmospheric stability increases, more and thicker aerosol layers below inversions during winter and above during spring are observed For the first time, collocated satellite observations are used to quantify this relationship and to infer the role of long‐range transport