Monsoon circulations and tropical heterogeneous chlorine chemistry in the stratosphere

Solomon, Susan; Kinnison, Douglas E.; García, Rolando R.; Bandoro, Justin; Mills, Michael J.; Wilka, Catherine; Neely, Ryan R.; Schmidt, Anja; Barnes, John; Vernier, Jean‐Paul; Höpfner, Michael

doi:10.1002/2016gl071778

Cited by 36 publications

(41 citation statements)

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“…Both satellite and aircraft measurements show that tracer constituents exhibit localized extrema in the upper troposphere lower stratosphere (UTLS) over the Asian and North American monsoon regions during boreal summer, such as maxima of tropospheric species‐like methane (Park et al, ), carbon monoxide (CO; Garny & Randel, ; Li, Jacob, et al, ; Li, Jiang, et al, ; Pan et al, ), and stratospheric water vapor (Dessler & Sherwood, ; Gettelman et al, ; Milz et al, ; Park et al, ; Rosenlof et al, ; Randel et al, , ; Zhang et al, ), and minima of stratospheric species‐like ozone (Gettelman et al, ; Park et al, , ; Randel & Park, ; Randel et al, ). Among these chemical constituents in the UTLS, stratospheric water vapor (SWV) is important due to not only its radiative forcing on surface climate (Forster & Shine, ; Maycock et al, ; Solomon et al, ) but also its chemical effects on stratospheric ozone (Dvortsov & Solomon, ) and chlorine activation reactions (Anderson et al, ; Solomon et al, ). The importance of a realistic representation of the SWV over the Asian summer monsoon region in atmospheric models has been emphasized in simulating troposphere‐stratosphere exchange correctly (Bannister et al, ; Dethof et al, ; Ploeger et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Simulation of Stratospheric Water Vapor Over the Asian Summer Monsoon in CESM1(WACCM) Models

Wang

Tung

et al. 2018

JGR Atmospheres

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Previous observational studies have found a persistent maximum in stratospheric water vapor (SWV) in the upper troposphere lower stratosphere (UTLS) confined by the upper-level anticyclone over the Asian summer monsoon region. This study investigates the simulation of SWV in the Community Earth System Model, version 1 with the Whole Atmosphere Community Climate Model as its atmospheric component [CESM1(WACCM)]. CESM1(WACCM) generally tends to simulate a SWV maximum over the central Pacific Ocean, but this bias is largely improved in the high vertical resolution version. The high vertical resolution model with increased vertical layers in the UTLS is found to have a less stratified UTLS over the central Pacific Ocean compared with the low vertical resolution model. It therefore simulates a steepened potential vorticity gradient over the central Pacific Ocean that better closes the upper-level anticyclone and confines the SWV within the enhanced transport barrier. . The simulation of stratospheric water vapor over the Asian summer monsoon region in CESM1(WACCM) models.

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Section: Introductionmentioning

confidence: 99%

The Simulation of Stratospheric Water Vapor Over the Asian Summer Monsoon in CESM1(WACCM) Models

Wang

Tung

et al. 2018

JGR Atmospheres

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“…We note that previous multi-model comparisons of the residual circulation that use w * taken directly from models may have been subject to the same issue (e.g. Butchart et al, 2010;SPARC, 2010), though we cannot confirm this. To avoid this methodological inconsistency, Dietmüller et al (2018) recalculated w * from v * using the continuity equation, which requires a vertical integration and a derivative along the meridional direction.…”

Section: Model Namementioning

confidence: 62%

“…Unfortunately, heating rates were not available from all CCMI model simulations to perform the thermodynamic equation calculation. Nevertheless, we compute the direct and downward control principle diagnostics for the residual circulation in a self-consistent manner in the models and reanalyses to enable comparison with earlier multi-model studies (Butchart et al, 2006(Butchart et al, , 2010SPARC, 2010).…”

Section: Downward Control Principle Calculationsmentioning

confidence: 99%

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Chrysanthou¹

2019

Preprint

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We perform the first multi-model intercomparison of the impact of nudged meteorology on the stratospheric residual circulation using hindcast simulations from the Chemistry-Climate Model Initiative (CCMI). We examine simulations over the period 1980-2009 from seven models in which the meteorological fields are nudged towards a reanalysis dataset and compare these with their equivalent free-running simulations and the reanalyses themselves. We show that for the current implementations, nudging meteorology does not constrain the mean strength of the stratospheric residual circulation and that the inter-model spread is similar, or even larger, than in the free-running simulations. The nudged models generally show slightly stronger upwelling in the tropical lower stratosphere compared to the free-running versions and exhibit marked differences com-pared to the directly estimated residual circulation from the reanalysis dataset they are nudged towards. Downward control calculations applied to the nudged simulations reveal substantial differences between the climatological lowerstratospheric tropical upward mass flux (TUMF) computed from the modelled wave forcing and that calculated directly from the residual circulation. This explicitly shows that nudging decouples the wave forcing and the residual circulation so that the divergence of the angular momentum flux due to the mean motion is not balanced by eddy motions, as would typically be expected in the time mean. Overall, nudging meteorological fields leads to increased intermodel spread for most of the measures of the mean climatological stratospheric residual circulation assessed in this study. In contrast, the nudged simulations show a high degreePublished by Copernicus Publications on behalf of the European Geosciences Union. 11560A. Chrysanthou et al.: The effect of nudging on the stratospheric residual circulation of consistency in the inter-annual variability in the TUMF in the lower stratosphere, which is primarily related to the contribution to variability from the resolved wave forcing. The more consistent inter-annual variability in TUMF in the nudged models also compares more closely with the variability found in the reanalyses, particularly in boreal winter. We apply a multiple linear regression (MLR) model to separate the drivers of inter-annual and long-term variations in the simulated TUMF; this explains up to ∼ 75 % of the variance in TUMF in the nudged simulations. The MLR model reveals a statistically significant positive trend in TUMF for most models over the period 1980-2009. The TUMF trend magnitude is generally larger in the nudged models compared to their free-running counterparts, but the intermodel range of trends doubles from around a factor of 2 to a factor of 4 due to nudging. Furthermore, the nudged models generally do not match the TUMF trends in the reanalysis they are nudged towards for trends over different periods in the interval 1980-2009. Hence, we conclude that nudging does not strongly constrain long-term trends simulated by the...

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“…to temperatures below 195 K (Kawa et al, 1997). Solomon et al (2016) found chlorine activation on liquid sulfate aerosols near the northern monsoon regions in their model calculations.…”

Section: Clono 2 and Extra-polar Stratospheric Chlorine Chemistrymentioning

confidence: 94%

Chlorine Nitrate in the Atmosphere

Clarmann¹,

Johansson²

2018

Preprint

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This review article compiles the characteristics of the gas chlorine nitrate and discusses its role in atmospheric chemistry. Chlorine nitrate is a reservoir of both stratospheric chlorine and nitrogen. It is formed by a termolecular reaction of ClO and NO 2 . Sink processes include gas-phase chemistry, photo-dissociation, and heterogeneous chemistry on aerosols. The latter sink is particularly important in the context of polar spring stratospheric chlorine activation. ClONO 2 has vibrationalrotational bands in the infrared, notably at 779 cm −1 , 809 cm −1 , 1293 cm −1 , and 1735 cm −1 , which are used for remote 5 sensing of ClONO 2 in the atmosphere. Mid-infrared emission and absorption spectroscopy have long been the only concepts for atmospheric ClONO 2 measurements. More recently, fluorescence and mass spectroscopic in situ techniques have been developed. Global ClONO 2 distributions have a maximum at polar winter latitudes at about 20-30 km altitude, where mixing ratios can exceed 2 ppbv. The annual cycle is most pronounced in the polar stratosphere, where ClONO 2 concentrations are an indicator of chlorine activation and de-activation.10

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Monsoon circulations and tropical heterogeneous chlorine chemistry in the stratosphere

Cited by 36 publications

References 50 publications

The Simulation of Stratospheric Water Vapor Over the Asian Summer Monsoon in CESM1(WACCM) Models

The Simulation of Stratospheric Water Vapor Over the Asian Summer Monsoon in CESM1(WACCM) Models

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Chlorine Nitrate in the Atmosphere

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