Sources, Sinks, and the Distribution of OH in the Lower Stratosphere

Hanisco, T. F.; Lanzendorf, E. J.; Wennberg, P. O.; Perkins, Katherine K.; Stimpfle, R. M.; Voss, P. B.; Anderson, James G.; Cohen, R. C.; Fahey, D. W.; Gao, R. S.; Hintsa, E. J.; Salawitch, R. J.; Margitan, J. J.; McElroy, C. T.; Midwinter, C.

doi:10.1021/jp002334g

Cited by 42 publications

(49 citation statements)

References 21 publications

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“…Low NO further reduces OH concentrations due to Reaction (R3). OH concentrations in this air mass are up to a factor of four smaller than those observed in the compact OH vs. solar zenith angle relation reported by Hanisco et al (2001) for similar altitudes.…”

Section: Aircraft Measurements Of Ohcontrasting

confidence: 64%

“…This approach used with our data results in negative ozone values throughout much of the troposphere for most of our tropical soundings. Hanisco et al (2001). The red circle indicates air masses from the West Pacific with extremely low ozone and OH.…”

Section: Ozone Profile Measurementsmentioning

confidence: 99%

“…chapter 1.3.3). But the degree of temporal and spatial variability of tropospheric OH is the subject of ongoing debate (Hanisco et al, 2001;Lelieveld et al, 2004;Berglen et al, 2004;Manning et al, 2005;Rohrer and Berresheim, 2006;Montzka et al, 2011). There are still systematic discrepancies between models and observations for the spatial distribution of OH (Naik et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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A tropical West Pacific OH minimum and implications for stratospheric composition

et al. 2014

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Abstract. Most of the short-lived biogenic and anthropogenic chemical species that are emitted into the atmosphere break down efficiently by reaction with OH and do not reach the stratosphere. Here we show the existence of a pronounced minimum in the tropospheric column of ozone over the West Pacific, the main source region for stratospheric air, and suggest a corresponding minimum of the tropospheric column of OH. This has the potential to amplify the impact of surface emissions on the stratospheric composition compared to the impact when assuming globally uniform OH conditions. Specifically, the role of emissions of biogenic halogenated species for the stratospheric halogen budget and the role of increasing emissions of SO 2 in Southeast Asia or from minor volcanic eruptions for the increasing stratospheric aerosol loading need to be reassessed in light of these findings. This is also important since climate change will further modify OH abundances and emissions of halogenated species. Our study is based on ozone sonde measurements carried out during the TransBrom cruise with the RV Sonne roughly along 140-150 • E in October 2009 and corroborating ozone and OH measurements from satellites, aircraft campaigns and FTIR instruments. Model calculations with the GEOS-Chem Chemistry and Transport Model (CTM) and the ATLAS CTM are used to simulate the tropospheric OH distribution over the West Pacific and the transport pathways to the stratosphere. The potential effect of the OH minimum on species transported into the stratosphere is shown via modeling the transport and chemistry of CH 2 Br 2 and SO 2 .

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Section: Aircraft Measurements Of Ohcontrasting

confidence: 64%

Section: Ozone Profile Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A tropical West Pacific OH minimum and implications for stratospheric composition

et al. 2014

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“…The update includes a revised formulation of the system of differential equations, a new training method based on model results of the ATLAS Chemistry and Transport Model 1981, 1987, 1991, 2001, 2004, 201210 February 200915 February 20101 March 1984, 198910 March 1980, 200515 March 1983, 1986, 1988, 1998, 2000, 2002, 2003, 200824 March 201130 March 1982, 1990, 1992, 1993, 1994, 1995, 1996, 1997, 2014No stable vortex 1985, 1999 and an extension from a single level to the vertical range in which polar ozone depletion is observed.…”

Section: Discussionmentioning

confidence: 99%

“…The mixing ratio [OH] day is modeled by assuming Figure 4 shows that this is a sufficiently good assumption, partly due to the fact that the mixing ratios of OH are relatively similar in the Northern and Southern hemispheres. In conditions not disturbed by heterogenous chemistry on PSCs, it can be shown that the stratospheric OH abundance is in relatively good approximation a linear function of the solar zenith angle, mostly independent from the concentrations of other species (Hanisco et al, 2001). In addition, the average solar zenith angle in the vortex is in good approximation a linear function of FAS.…”

Section: Term Fmentioning

confidence: 99%

Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)

2017

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Abstract. The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O 3 , chemically active chlorine (ClO x ), HCl, ClONO 2 and HNO 3 . The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortexaveraged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO 3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect caused by the original training on satellite data. Hence, the new version allows for an implementation into climate models in combination with an existing stratospheric transport scheme. Finally, the model is now formulated on several vertical levels encompassing the vertical range in which polar ozone depletion is observed. The results of the Polar SWIFT model are validated with independent Microwave Limb Sounder (MLS) satellite observations and output from the original detailed chemistry model of ATLAS.

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A case study of convectively sourced water vapor observed in the overworld stratosphere over the United States

et al. 2017

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On 27 August 2013, during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys field mission, NASA's ER‐2 research aircraft encountered a region of enhanced water vapor, extending over a depth of approximately 2 km and a minimum areal extent of 20,000 km2 in the stratosphere (375 K to 415 K potential temperature), south of the Great Lakes (42°N, 90°W). Water vapor mixing ratios in this plume, measured by the Harvard Water Vapor instrument, constitute the highest values recorded in situ at these potential temperatures and latitudes. An analysis of geostationary satellite imagery in combination with trajectory calculations links this water vapor enhancement to its source, a deep tropopause‐penetrating convective storm system that developed over Minnesota 20 h prior to the aircraft plume encounter. High resolution, ground‐based radar data reveal that this system was composed of multiple individual storms, each with convective turrets that extended to a maximum of ~4 km above the tropopause level for several hours. In situ water vapor data show that this storm system irreversibly delivered between 6.6 kt and 13.5 kt of water to the stratosphere. This constitutes a 20–25% increase in water vapor abundance in a column extending from 115 hP to 70 hPa over the plume area. Both in situ and satellite climatologies show a high frequency of localized water vapor enhancements over the central U.S. in summer, suggesting that deep convection can contribute to the stratospheric water budget over this region and season.

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Sources, Sinks, and the Distribution of OH in the Lower Stratosphere

Cited by 42 publications

References 21 publications

A tropical West Pacific OH minimum and implications for stratospheric composition

A tropical West Pacific OH minimum and implications for stratospheric composition

Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)

A case study of convectively sourced water vapor observed in the overworld stratosphere over the United States

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