Ozone transport and thermodynamics during the passage of squall line in Central Amazon

Abstract

The main objective of this work is to better understand the increase of ozone (O3) in the surface by the influence of density currents formed by downdrafts from mesoscale convective systems, using as tool the JULES-CCATT-BRAMS model. Initially, the superficial increases of O3 were investigated with the ECMWF Era-Interim reanalysis that showed a plume rich in O3 located at middle troposphere along with the increase of this gas’ concentration in the surface during the rainy period in Central Amazon. GOES satellite images and surface synoptic charts showed the formation of a squall line (SL) in the interior of the Continent by the influence of a Frontal System that reached the southeast of South America in this period. The numerical simulation results provided an understanding of the three-dimensional structure of the chemistry and thermodynamics of the atmosphere during the passage of this SL at dawn on April 14, 2014. The downdrafts from SL bring cooler, drier, dense air to near the surface. This downdrafts air column passed by the O3 “plume” in the middle troposphere, formed rich gas density currents and low level jets were induced near the surface and spread the O3. Finally, this cleaner air column decreased the surface carbon monoxide (CO) levels, and as a result of the increase in O3 concentration resulted in an increase in surface nitrogen dioxide (NO2).