Modification of the Gravity Wave Parameterization in the Whole Atmosphere Community Climate Model: Motivation and Results

García, Rolando R.; Smith, Anne K.; Kinnison, Douglas E.; Cámara, Álvaro de la; Murphy, D. J.

doi:10.1175/jas-d-16-0104.1

Cited by 228 publications

(307 citation statements)

References 46 publications

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“…This new development allows for the examination of the effects of SO 2 injections on the QBO, which are presented in Richter et al (), motivated in part by previous work that has suggested that stratospheric sulfate geoengineering could severely alter the QBO (Aquila et al, ). Additional tuning of the gravity wave parameterization in WACCM has significantly reduced the bias of the temperatures in the Antarctic polar vortex, which is critical to calculating ozone loss (Garcia et al, ).…”

Section: Methodsmentioning

confidence: 99%

Radiative and Chemical Response to Interactive Stratospheric Sulfate Aerosols in Fully Coupled CESM1(WACCM)

et al. 2017

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We present new insights into the evolution and interactions of stratospheric aerosol using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi‐biennial oscillation and significant improvements to stratospheric temperatures and ozone compared to observations. We present a validation of WACCM column ozone and climate calculations against observations. The prognostic treatment of stratospheric sulfate aerosols accurately represents the evolution of stratospheric aerosol optical depth and perturbations to solar and longwave radiation following the June 1991 eruption of Mount Pinatubo. We confirm the inclusion of interactive OH chemistry as an important factor in the formation and initial distribution of aerosol following large inputs of sulfur dioxide (SO2) to the stratosphere. We calculate that depletion of OH levels within the dense SO2 cloud in the first weeks following the Pinatubo eruption significantly prolonged the average initial e‐folding decay time for SO2 oxidation to 47 days. Previous observational and model studies showing a 30 day decay time have not accounted for the large (30–55%) losses of SO2 on ash and ice within 7–9 days posteruption and have not correctly accounted for OH depletion. We examine the variability of aerosol evolution in free‐running climate simulations due to meteorology, with comparison to simulations nudged with specified dynamics. We assess calculated impacts of volcanic aerosols on ozone loss with comparisons to observations. The completeness of the chemistry, dynamics, and aerosol microphysics in WACCM qualify it for studies of stratospheric sulfate aerosol geoengineering.

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Section: Methodsmentioning

confidence: 99%

Radiative and Chemical Response to Interactive Stratospheric Sulfate Aerosols in Fully Coupled CESM1(WACCM)

et al. 2017

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“…For instance, except for orography, even the coupling to physical GW source processes is missing in many models. Initial parameters of the GW parametrization schemes have to be chosen and the mean wind and temperature fields produced by the GCM are highly sensitive to this parameter choice at all altitudes (e.g., Sigmond and Scinocca, 2010;Garcia et al, 2017;Medvedev and Klaassen, 2000;Yigit et al, 2008). The T/I is a region where GWs are one of the main driving forces and sensitivity to uncertainties in the GW parametrizations is high.…”

Section: Q T Trinh Et Al: Satellite Observations Of Vertical Couplmentioning

confidence: 99%

Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

et al. 2018

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Abstract. Atmospheric gravity waves (GWs) are essential for the dynamics of the middle atmosphere. Recent studies have shown that these waves are also important for the thermosphere/ionosphere (T/I) system. Via vertical coupling, GWs can significantly influence the mean state of the T/I system. However, the penetration of GWs into the T/I system is not fully understood in modeling as well as observations. In the current study, we analyze the correlation between GW momentum fluxes observed in the middle atmosphere (30-90 km) and GW-induced perturbations in the T/I. In the middle atmosphere, GW momentum fluxes are derived from temperature observations of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instrument. In the T/I, GW-induced perturbations are derived from neutral density measured by instruments on the Gravity field and Ocean Circulation Explorer (GOCE) and CHAllenging Minisatellite Payload (CHAMP) satellites. We find generally positive correlations between horizontal distributions at low altitudes (i.e., below 90 km) and horizontal distributions of GW-induced density fluctuations in the T/I (at 200 km and above). Two coupling mechanisms are likely responsible for these positive correlations: (1) fast GWs generated in the troposphere and lower stratosphere can propagate directly to the T/I and (2) primary GWs with their origins in the lower atmosphere dissipate while propagating upwards and generate secondary GWs, which then penetrate up to the T/I and maintain the spatial patterns of GW distributions in the lower atmosphere. The mountain-wave related hotspot over the Andes and Antarctic Peninsula is found clearly in observations of all instruments used in our analysis. Latitude-longitude variations in the summer midlatitudes are also found in observations of all instruments. These variations and strong positive correlations in the summer midlatitudes suggest that GWs with origins related to convection also propagate up to the T/I. Different processes which likely influence the vertical coupling are GW dissipation, possible generation of secondary GWs, and horizontal propagation of GWs. Limitations of the observations as well as of our research approach are discussed.

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“…[] and Garcia et al . [] discuss in detail the sensitivity of these results to uncertainties in orographic gravity wave parameterizations.…”

Section: Data Sets and Model Simulationsmentioning

confidence: 99%

Mirrored changes in Antarctic ozone and stratospheric temperature in the late 20th versus early 21st centuries

et al. 2017

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Observed and modeled patterns of lower stratospheric seasonal trends in Antarctic ozone and temperature in the late 20th (1979–2000) and the early 21st (2000–2014) centuries are compared. Patterns of pre‐2000 observed Antarctic ozone decreases and stratospheric cooling as a function of month and pressure are followed by opposite‐signed (i.e., “mirrored”) patterns of ozone increases and warming post‐2000. An interactive chemistry‐climate model forced by changes in anthropogenic ozone depleting substances produces broadly similar mirrored features. Statistical analysis of unforced model simulations (from long‐term model control simulations of a few centuries up to 1000 years) suggests that internal and solar natural variability alone is unable to account for the pattern of observed ozone trend mirroring, implying that forcing is the dominant driver of this behavior. Radiative calculations indicate that ozone increases have contributed to Antarctic warming of the lower stratosphere over 2000–2014, but dynamical changes that are likely due to internal variability over this relatively short period also appear to be important. Overall, the results support the recent finding that the healing of the Antarctic ozone hole is underway and that coupling between dynamics, chemistry, and radiation is important for a full understanding of the causes of observed stratospheric temperature and ozone changes.

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Modification of the Gravity Wave Parameterization in the Whole Atmosphere Community Climate Model: Motivation and Results

Cited by 228 publications

References 46 publications

Radiative and Chemical Response to Interactive Stratospheric Sulfate Aerosols in Fully Coupled CESM1(WACCM)

Radiative and Chemical Response to Interactive Stratospheric Sulfate Aerosols in Fully Coupled CESM1(WACCM)

Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

Mirrored changes in Antarctic ozone and stratospheric temperature in the late 20th versus early 21st centuries

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