Radiative Impacts of the 2011 Abrupt Drops in Water Vapor and Ozone in the Tropical Tropopause Layer

Gilford, Daniel; Solomon, Susan; Portmann, R. W.

doi:10.1175/jcli-d-15-0167.1

Cited by 34 publications

(41 citation statements)

References 64 publications

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“…MLS data stretches from the upper troposphere to the stratosphere, with 31 recommended useful vertical levels for water vapor observations (316 to 1 hPa) and 29 recommended useful vertical levels for ozone and temperature observations (261 to 1 hPa). Aura MLS measurements of water vapor and ozone compare well with multiinstrument means in the tropical lower stratosphere (see Tegtmeier et al 2013;Hegglin et al 2013), and they can resolve horizontal structures that were not available with previous satellite instruments [such as the Halogen Occultation Experiment (HALOE); see Gilford et al (2016)]. The ;300-km native horizontal resolution in the tropical tropopause region is fine enough to explore the latitudinal structure of the ozone seasonal cycle and its radiative effects (see section 3b).…”

Section: A Observationsmentioning

confidence: 91%

“…PORT is an offline broadband radiative transfer configuration of the Community Atmosphere Model, version 4 (CAM4), in the Community Earth System Model (CESM). Gilford et al (2016) compared PORT with a line-by-line radiative transfer model and found good agreement for both water vapor and ozone perturbations. PORT's background heating rates are similar to those of previous studies (e.g., Gettelman et al 2004;Fueglistaler and Fu 2006;Abalos et al 2012), though there are some differences likely associated with radiative code and constituent backgrounds (see supplemental Fig.…”

Section: B Radiative Transfer Calculationsmentioning

confidence: 99%

“…Because water vapor and ozone radiative impacts can depend on the location of the tropopause (Forster et al 1997;Solomon et al 2010), we use a methodology similar to that in Gilford et al (2016) to preserve the distribution of water vapor and ozone seasonal cycles relative to the tropopause. We convert Aura MLS pressure coordinates to a vertical grid of log-pressure height relative to the Aura MLS cold-point tropopause, and then interpolate constituent concentrations onto a PORT vertical grid of log-pressure height relative to its tropopause (white dashed curves in Figs.…”

Section: B Radiative Transfer Calculationsmentioning

confidence: 99%

“…These temperature changes are referred to as ''temperature adjustments.'' The fixed-dynamical heating approach has been commonly used in studies of lower-stratospheric radiative temperature adjustments and radiative forcing (e.g., Forster et al 2007;Maycock et al 2014;Grise et al 2009;Solomon et al 2010;Gilford et al 2016). Dynamical forcing is the leading cause of composition and temperature seasonal cycles in the tropical lower stratosphere (see section 1), and SEFDH assumes that the temperature seasonal cycle is primarily driven by dynamics with a fixed seasonal cycle (Forster et al 1997).…”

Section: B Radiative Transfer Calculationsmentioning

confidence: 99%

“…A portion of the tropical lowerstratospheric temperature seasonal cycle is likely related to the dynamically driven ozone seasonal cycle through radiative amplification (Chae and Sherwood 2007;Fueglistaler et al 2011). Water vapor and ozone are strong radiatively active constituents in the tropical lower stratosphere, having both local radiative impacts on temperature and long-term implications for radiative forcing of climate change (Forster et al 1997;Forster and Shine 1999;Stuber et al 2001;Gettelman et al 2004;Randel et al 2006;Solomon et al 2010;Maycock et al 2011Maycock et al , 2014Dessler et al 2013;Gilford et al 2016;Wang et al 2016). In this study we investigate the radiative effects of water vapor and ozone seasonal cycles in the tropical lower stratosphere in detail.…”

Section: Introductionmentioning

confidence: 99%

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Radiative Effects of Stratospheric Seasonal Cycles in the Tropical Upper Troposphere and Lower Stratosphere

Gilford

Solomon

2017

J. Climate

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Water vapor and ozone are powerful radiative constituents in the tropical lower stratosphere, impacting the local heating budget and nonlocally forcing the troposphere below. Their near-tropopause seasonal cycle structures imply associated ''radiative seasonal cycles'' in heating rates that could affect the amplitude and phase of the local temperature seasonal cycle. Overlying stratospheric seasonal cycles of water vapor and ozone could also play a role in the lower stratosphere and upper troposphere heat budgets through nonlocal propagation of radiation. Previous studies suggest that the tropical lower stratospheric ozone seasonal cycle radiatively amplifies the local temperature seasonal cycle by up to 35%, while water vapor is thought to have a damping effect an order of magnitude smaller. This study uses Aura Microwave Limb Sounder observations and an offline radiative transfer model to examine ozone, water vapor, and temperature seasonal cycles and their radiative linkages in the lower stratosphere and upper troposphere. Radiative sensitivities to ozone and water vapor vertical structures are explicitly calculated, which has not been previously done in a seasonal cycle context. Results show that the water vapor radiative seasonal cycle in the lower stratosphere is not sensitive to the overlying water vapor structure. In contrast, about one-third of ozone's radiative seasonal cycle amplitude at 85 hPa is associated with longwave emission above 85 hPa. Ozone's radiative effects are not spatially homogenous: for example, the Northern Hemisphere tropics have a seasonal cycle of radiative temperature adjustments with an amplitude 0.8 K larger than the Southern Hemisphere tropics.

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Section: A Observationsmentioning

confidence: 91%

Section: B Radiative Transfer Calculationsmentioning

confidence: 99%

Section: B Radiative Transfer Calculationsmentioning

confidence: 99%

Section: B Radiative Transfer Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radiative Effects of Stratospheric Seasonal Cycles in the Tropical Upper Troposphere and Lower Stratosphere

Gilford

Solomon

2017

J. Climate

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Stratospheric ozone chemistry feedbacks are not critical for the determination of climate sensitivity in CESM1(WACCM)

Marsh

Lamarque

Conley

et al. 2016

Geophysical Research Letters

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The Community Earth System Model‐Whole Atmosphere Community Climate Model (CESM1‐WACCM) is used to assess the importance of including chemistry feedbacks in determining the equilibrium climate sensitivity (ECS). Two 4×CO2 model experiments were conducted: one with interactive chemistry and one with chemical constituents other than CO2 held fixed at their preindustrial values. The ECS determined from these two experiments agrees to within 0.01 K. Similarly, the net feedback parameter agrees to within 0.01 W m−2 K−1. This agreement occurs in spite of large changes in stratospheric ozone found in the simulation with interactive chemistry: a 30% decrease in the tropical lower stratosphere and a 40% increase in the upper stratosphere, broadly consistent with other published estimates. Off‐line radiative transfer calculations show that ozone changes alone account for the difference in radiative forcing. We conclude that at least for determining global climate sensitivity metrics, the exclusion of chemistry feedbacks is not a critical source of error in CESM.

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Improved aerosol radiative properties as a foundation for solar geoengineering risk assessment

Dykema

Keith

Keutsch

2016

Geophysical Research Letters

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Side effects resulting from the deliberate injection of sulfate aerosols intended to partially offset climate change have motivated the investigation of alternatives, including solid aerosol materials. Sulfate aerosols warm the tropical tropopause layer, increasing the flux of water vapor into the stratosphere, accelerating ozone loss, and increasing radiative forcing. The high refractive index of some solid materials may lead to reduction in these risks. We present a new analysis of the scattering efficiency and absorption of a range of candidate solid aerosols. We utilize a comprehensive radiative transfer model driven by updated, physically consistent estimates of optical properties. We compute the potential increase in stratospheric water vapor and associated longwave radiative forcing. We find that the stratospheric heating calculated in this analysis indicates some materials to be substantially riskier than previous work. We also find that there are Earth‐abundant materials that may reduce some principal known risks relative to sulfate aerosols.

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Radiative Impacts of the 2011 Abrupt Drops in Water Vapor and Ozone in the Tropical Tropopause Layer

Cited by 34 publications

References 64 publications

Radiative Effects of Stratospheric Seasonal Cycles in the Tropical Upper Troposphere and Lower Stratosphere

Radiative Effects of Stratospheric Seasonal Cycles in the Tropical Upper Troposphere and Lower Stratosphere

Stratospheric ozone chemistry feedbacks are not critical for the determination of climate sensitivity in CESM1(WACCM)

Improved aerosol radiative properties as a foundation for solar geoengineering risk assessment

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