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Role of the boundary layer in the occurrence and termination of the tropospheric ozone depletion events in polar spring
Abstract Tropospheric ozone depletion events (ODEs) in the polar spring are frequently observed in a stable boundary layer condition, and the end of the events occurs when there is a breakup of the boundary layer. In order to improve the understanding of the role of the boundary layer in the ozone depletion event, a one-dimensional model is developed, focusing on the occurrence and the termination period of the ozone depletion episode. A module accounting for the vertical air transport is added to a previous box model, and a first-order parameterization is used for the estimation of the vertical distribution of the turbulent diffusivity. Simulations are performed for different strengths of temperature inversion as well as for different wind speeds. The simulation results suggest that the reactive bromine species released from the underlying surface into the lowest part of the troposphere initially stay in the boundary layer, leading to an increase of the bromine concentration. This bromine accumulation causes the ozone destruction below the top of the boundary layer. After the ozone is totally depleted, if the temperature inversion intensity decreases or the wind speed increases, the severe ozone depletion event tends to transit into a partial ozone depletion event or it recovers to the normal ozone background level of 30–40 ppb. This recovery process takes about 2 h. Due to the presence of high-level HBr left from the initial occurrence of ODEs, the complete removal of ozone in the boundary layer is achieved a few days after the first termination of ODE. The time required for the recurrence of the ozone depletion in a 1000 m boundary layer is approximately 5 days, while the initial occurrence of the complete ozone consumption takes 15 days. The present model is suitable to clarify the reason for both the start and the termination of the severe ozone depletion as well as the partial ozone depletion in the observations.
Highlights Bromine released from the underlying surface accumulates in the boundary layer, leading to the occurrence of ODEs. The quantitative information of the conditions under which ODEs occur, terminate and recur is given. The transitions between severe ODEs, partial ODEs, and the full recovery of ozone are captured. The present simulation results help to explain an unsolved finding in the observations of Bottenheim et al. (2009). The termination of ODEs is found after approximately 2 h.
Role of the boundary layer in the occurrence and termination of the tropospheric ozone depletion events in polar spring
Abstract Tropospheric ozone depletion events (ODEs) in the polar spring are frequently observed in a stable boundary layer condition, and the end of the events occurs when there is a breakup of the boundary layer. In order to improve the understanding of the role of the boundary layer in the ozone depletion event, a one-dimensional model is developed, focusing on the occurrence and the termination period of the ozone depletion episode. A module accounting for the vertical air transport is added to a previous box model, and a first-order parameterization is used for the estimation of the vertical distribution of the turbulent diffusivity. Simulations are performed for different strengths of temperature inversion as well as for different wind speeds. The simulation results suggest that the reactive bromine species released from the underlying surface into the lowest part of the troposphere initially stay in the boundary layer, leading to an increase of the bromine concentration. This bromine accumulation causes the ozone destruction below the top of the boundary layer. After the ozone is totally depleted, if the temperature inversion intensity decreases or the wind speed increases, the severe ozone depletion event tends to transit into a partial ozone depletion event or it recovers to the normal ozone background level of 30–40 ppb. This recovery process takes about 2 h. Due to the presence of high-level HBr left from the initial occurrence of ODEs, the complete removal of ozone in the boundary layer is achieved a few days after the first termination of ODE. The time required for the recurrence of the ozone depletion in a 1000 m boundary layer is approximately 5 days, while the initial occurrence of the complete ozone consumption takes 15 days. The present model is suitable to clarify the reason for both the start and the termination of the severe ozone depletion as well as the partial ozone depletion in the observations.
Highlights Bromine released from the underlying surface accumulates in the boundary layer, leading to the occurrence of ODEs. The quantitative information of the conditions under which ODEs occur, terminate and recur is given. The transitions between severe ODEs, partial ODEs, and the full recovery of ozone are captured. The present simulation results help to explain an unsolved finding in the observations of Bottenheim et al. (2009). The termination of ODEs is found after approximately 2 h.
Role of the boundary layer in the occurrence and termination of the tropospheric ozone depletion events in polar spring
Cao, Le (author) / Platt, Ulrich (author) / Gutheil, Eva (author)
Atmospheric Environment ; 132 ; 98-110
2016-02-19
13 pages
Article (Journal)
Electronic Resource
English