Erythemal Radiation, Column Ozone, and the North American Monsoon

Schoeberl, M. R.; Pfister, Leonhard; Wang, Tao; Kummer, J. R.; Dessler, A. E.; Yu, Wandi

doi:10.1029/2019jd032283

Cited by 8 publications

(10 citation statements)

References 54 publications

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“…However, a potential ozone destruction in the midlatitude lowermost stratosphere due to heterogeneous chlorine activation was discussed in previous studies (e.g. Keim et al, 1996;Anderson et al, 2012Anderson et al, , 2017Anderson and Clapp, 2018;Schwartz et al, 2013;Berthet et al, 2017;Robrecht et al, 2019;Clapp and Anderson, 2019;Schoeberl et al, 2020). This chlorine-driven ozone loss process could occur today above central North America in relation to stratospheric moistening through convective overshooting events during the North American Summer Monsoon (NAM).…”

Section: Discussionmentioning

confidence: 90%

“…In comparison, Schwartz et al (2013) argue that conditions cold and moist enough for chlorine activation are very rare and are usually associated with low HCl and ozone amounts. Schoeberl et al (2020) found that lowermoststratospheric H 2 O is increased during the NAM caused by enhanced convection followed by advection in the monsoon circulation.…”

Section: Discussionmentioning

confidence: 99%

“…S. Robrecht et al: Potential of future stratospheric ozone loss in the midlatitudes in summer, which would cause a catalytic ozone destruction, has been discussed in previous studies (Anderson et al, 2012(Anderson et al, , 2017Clapp and Anderson, 2019;Schwartz et al, 2013;Robrecht et al, 2019;Schoeberl et al, 2020). Here, we analyse the likelihood of the occurrence of a heterogeneous chlorine activation and its impact on ozone in the lowermost stratosphere in a future climate including the hypothetical application of sulfur injections into the stratosphere.…”

mentioning

confidence: 94%

“…Müller, 2009). In recent years, furthermore, the impact of heterogeneous chlorine activation caused by an enhancement of stratospheric water vapour (in the following referred to as H 2 O) through convective overshooting has been discussed (Anderson et al, 2012(Anderson et al, , 2017Clapp and Anderson, 2019;Schwartz et al, 2013;Robrecht et al, 2019;Schoeberl et al, 2020).…”

mentioning

confidence: 99%

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Potential of future stratospheric ozone loss in the mid-latitudes under climate change and sulfate geoengineering

Robrecht

Vogel

Tilmes

et al. 2020

Preprint

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Abstract. The potential of heterogeneous chlorine activation in the mid-latitude lowermost stratosphere during summer is a matter of debate. The occurrence of heterogeneous chlorine activation through the presence of aerosol particles could cause ozone destruction. This chemical process requires low temperatures and is accelerated by an enhancement of the stratospheric water vapour and sulfate amount. In particular, the conditions present in the lowermost stratosphere during the North American Summer Monsoon season (NAM) are expected to be cold and moist enough for causing the occurrence of heterogeneous chlorine activation. Furthermore, the temperatures, the water vapour mixing ratio and the sulfate aerosol abundance are affected by future climate change and by the potential application of sulfate geoengineering. Hence, both future scenarios could promote this ozone destruction process. We investigate the likelihood for the occurrence of heterogeneous chlorine activation and its impact on ozone in the lowermost stratospheric mixing layer between tropospheric and stratospheric air above central North America (30.6–49.6° N, 72.25–124.75° W) in summer for conditions today, at the mid and at the end of the 21st century. Therefore, the results of the Geoengineering Large Ensemble Simulations (GLENS) for the lowermost stratospheric mixing layer between tropospheric and stratospheric air are considered together with 10 day box-model simulations performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS). In GLENS two future scenarios are simulated: the RCP8.5 climate change scenario and a geoengineering scenario, where sulfur is additionally injected in the stratosphere to keep the global mean surface temperature from changing. In the GLENS simulations, the mixing layer will warm and moisten in both future scenarios with a larger effect in the geoengineering scenario. The likelihood for chlorine activation to occur in the mixing layer is highest in the years 2040–2050 if geoengineering is applied, accounting for 3.3 %. In comparison, the likelihood for conditions today is 1.0 %. At the end of the 21st century, the likelihood of this ozone destruction process to occur decreases. We found that 0.1 % of the ozone mixing ratios in the mixing layer above central North America is destroyed for conditions today. A maximum ozone destruction of 0.3 % in the mixing layer occurs in the years 2040–2050 if geoengineering is applied. Comparing the southernmost latitude band (30–35° N) and the northernmost latitude band (44–49° N) of the considered region, we found a higher likelihood for the occurrence of heterogeneous chlorine activation in the southernmost latitude band, causing a higher impact on ozone as well. However, the ozone loss process is found to have a minor impact on the mid-latitude ozone column with not more than 0.1 DU today or in the future scenarios.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 94%

mentioning

confidence: 99%

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Potential of future stratospheric ozone loss in the mid-latitudes under climate change and sulfate geoengineering

Robrecht

Vogel

Tilmes

et al. 2020

Preprint

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“…Briefly, the algorithm uses precipitation data together with infrared brightness temperature from geostationary satellites to determine the heights of convective clouds. This near-global cloud top product has been used to diagnose convective influence in a large number of trajectory studies (e.g., Bergman et al, 2012;Pfister et al, 2001;Schoeberl et al, 2019Schoeberl et al, , 2020Ueyama et al, 2014Ueyama et al, , 2018. Cloud top height data are made available every 3 h on a 0.25° longitude × 0.25° latitude grid in the 60°S-60°N domain.…”

Section: Satellite-based Convective Cloud Productmentioning

confidence: 99%

Diagnostics of Convective Transport Over the Tropical Western Pacific From Trajectory Analyses

et al. 2021

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This study characterizes the representation of convective transport by a Lagrangian trajectory model driven by kinematic (pressure tendency ω) vertical velocity. Four (re)analysis wind products are used in backward trajectory calculations with the TRAJ3D model, and their representations of convective transport are analyzed. Two observation‐based diagnostics are used for the evaluation: a database of observed convective cloud tops derived from satellite measurements and a set of transit time distributions (TTDs) derived from an airborne campaign during January–February 2014 in a domain over the Tropical Western Pacific (TWP). The analysis is designed to derive trajectory‐based TTDs that can be directly evaluated using the observation‐based TTDs. The results indicate a broad consistency between two independent TTD derivations characterizing vertical transport over the TWP, with a significant portion of convective transport processes represented in trajectory experiments driven by the selected (re)analysis wind products. The convective and boundary layer source regions of upper tropospheric air parcels are shown to be consistent with the climatological flow regime within the TWP. Furthermore, contributions of convection are identified in the ω fields of the (re)analysis wind data sets, as indicated by the spatiotemporal correlation of enhanced vertical velocity and observed convection. These results demonstrate the successful application of two observation‐based diagnostics and quantify the ability for kinematic trajectory models to represent convective transport processes.

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A 13‐year Trajectory‐Based Analysis of Convection‐Driven Changes in Upper Troposphere Lower Stratosphere Composition Over the United States

Tinney

Homeyer

2021

JGR Atmospheres

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Moist convection frequently reaches the tropopause and alters the distribution and concentration of radiatively important trace gases in the upper troposphere and lower stratosphere (UTLS), but the overall impact of convection on regional and global UTLS composition remains largely unknown. To improve understanding of convection‐driven changes in water vapor (H2O), ozone (O3), and carbon monoxide (CO) in the UTLS, this study utilizes 13 years of observations of satellite‐based trace gas profiles from the Microwave Limb Sounder (MLS) aboard the Aura satellite and convection from the operational network of ground‐based weather radars in the United States. Locations with and without convection identified via radar are matched with downstream MLS observations through three‐dimensional, kinematic forward trajectories, providing two populations of trace gas observations for analysis. These populations are further classified as belonging to extratropical or tropical environments based on the tropopause pressure at the MLS profile location. Extratropical regions are further separated by tropopause type (single or double), revealing differing impacts. Results show that convection typically moistens the UT by up to 300% and the LS by up to 100%, largely reduces O3 by up to 40%, and increases CO by up to 50%. Changes in H2O and O3 are robust, with LS O3 reduced more by convection within tropical environments, where the median concentration decrease is 34% at ∼2 km above tropopause, compared to 24% in extratropical environments. Quantification of CO changes from convection is less reliable due to differences being near the MLS measurement precision and accuracy.

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Erythemal Radiation, Column Ozone, and the North American Monsoon

Cited by 8 publications

References 54 publications

Potential of future stratospheric ozone loss in the mid-latitudes under climate change and sulfate geoengineering

Potential of future stratospheric ozone loss in the mid-latitudes under climate change and sulfate geoengineering

Diagnostics of Convective Transport Over the Tropical Western Pacific From Trajectory Analyses

A 13‐year Trajectory‐Based Analysis of Convection‐Driven Changes in Upper Troposphere Lower Stratosphere Composition Over the United States

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