Desert dust transported over Europe: Lidar observations and model evaluation of the radiative impact

Pitari, Giovanni; Genova, Glauco Di; Coppari, Eleonora; Luca, Natalia De; Carlo, Piero Di; Iarlori, M.; Rizi, V.

doi:10.1002/2014jd022875

Cited by 12 publications

(14 citation statements)

References 73 publications

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“…In addition, a companion broadband, k-distribution longwave radiative module is used to compute radiative transfer and heating rates in the planetary infrared spectrum [54].…”

Section: Methodsmentioning

confidence: 99%

“…These are actually effective flux changes, because model predictions include the dynamical responses. The ULAQ-CCM radiative transfer module [46,54] was set up to compute the tropopause-adjusted RF time series for each eruption considered in this study, both in clear and all sky conditions. Sulfate aerosol Mie scattering data have been computed using refractive properties for a 75% concentration by weight of sulfuric acid derived from the OPAC database.…”

Section: Aerosol Radiative Flux Changesmentioning

confidence: 99%

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Stratospheric Aerosols from Major Volcanic Eruptions: A Composition-Climate Model Study of the Aerosol Cloud Dispersal and e-folding Time

et al. 2016

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Large explosive volcanic eruptions are capable of injecting considerable amounts of particles and sulfur gases above the tropopause, causing large increases in stratospheric aerosols. Five major volcanic eruptions after 1960 (i.e., Agung, St. Helens, El Chichón, Nevado del Ruiz and Pinatubo) have been considered in a numerical study conducted with a composition-climate coupled model including an aerosol microphysics code for aerosol formation and growth. Model results are compared between an ensemble of numerical simulations including volcanic aerosols and their radiative effects (VE) and a reference simulations ensemble (REF) with no radiative impact of the volcanic aerosols. Differences of VE-REF show enhanced diabatic heating rates; increased stratospheric temperatures and mean zonal westerly winds; increased planetary wave amplitude; and tropical upwelling. The impact on stratospheric upwelling is found to be larger when the volcanically perturbed stratospheric aerosol is confined to the tropics, as tends to be the case for eruptions which were followed by several months with easterly shear of the quasi-biennial oscillation (QBO), e.g., the Pinatubo case. Compared to an eruption followed by a period of westerly QBO, such easterly QBO eruptions are quite different, with meridional transport to mid-and high-latitudes occurring later, and at higher altitude, with a consequent decrease in cross-tropopause removal from the stratosphere, and therefore longer decay timescale. Comparing the model-calculated e-folding time of the volcanic aerosol mass during the first year after the eruptions, an increase is found from 8.1 and 10.3 months for El Chichón and Agung (QBO westerly shear), to 14.6 and 30.7 months for Pinatubo and Ruiz (QBO easterly shear). The corresponding e-folding time of the global-mean radiative flux changes goes from 9.1 and 8.0 months for El Chichón and Agung, to 28.7 and 24.5 months for Pinatubo and Ruiz.

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“…In addition, a companion broadband, k-distribution longwave radiative module is used to compute radiative transfer and heating rates in the planetary infrared spectrum [54].…”

Section: Methodsmentioning

confidence: 99%

Section: Aerosol Radiative Flux Changesmentioning

confidence: 99%

Stratospheric Aerosols from Major Volcanic Eruptions: A Composition-Climate Model Study of the Aerosol Cloud Dispersal and e-folding Time

et al. 2016

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“…A companion broadband, k-distribution longwave radiative module is used to compute radiative transfer and heating rates in the planetary infrared spectrum [31,32].…”

Section: Ulaq-ccmmentioning

confidence: 99%

“…The ULAQ-RTM uses a Mie scattering program to process aerosol optical properties from the OPAC database and size distributions from the ULAQ-CCM to compute the relevant wavelength-dependent aerosol optical properties (extinction, absorption and asymmetry parameter at all vertical layers of the model) [30,32]. All-sky cloud coverage is computed using a maximum-random overlapping scheme from MODIS Terra and Aqua Level 3 data, while surface albedo is derived from MERRA 2D data.…”

Section: Tropopause Radiative Flux Changesmentioning

confidence: 99%

Sulfate Aerosols from Non-Explosive Volcanoes: Chemical-Radiative Effects in the Troposphere and Lower Stratosphere

et al. 2016

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SO 2 and H 2 S are the two most important gas-phase sulfur species emitted by volcanoes, with a global amount from non-explosive emissions of the order 10 Tg-S/yr. These gases are readily oxidized forming SO 4 2´a erosols, which effectively scatter the incoming solar radiation and cool the surface. They also perturb atmospheric chemistry by enhancing the NO x to HNO 3 heterogeneous conversion via hydrolysis on the aerosol surface of N 2 O 5 and Br-Cl nitrates. This reduces formation of tropospheric O 3 and the OH to HO 2 ratio, thus limiting the oxidation of CH 4 and increasing its lifetime. In addition to this tropospheric chemistry perturbation, there is also an impact on the NO x heterogeneous chemistry in the lower stratosphere, due to vertical transport of volcanic SO 2 up to the tropical tropopause layer. Furthermore, the stratospheric O 3 formation and loss, as well as the NO x budget, may be slightly affected by the additional amount of upward diffused solar radiation and consequent increase of photolysis rates. Two multi-decadal time-slice runs of a climate-chemistry-aerosol model have been designed for studying these chemical-radiative effects. A tropopause mean global net radiative flux change (RF) of´0.23 W¨m´2 is calculated (including direct and indirect aerosol effects) with a 14% increase of the global mean sulfate aerosol optical depth. A 5-15 ppt NO x decrease is found in the mid-troposphere subtropics and mid-latitudes and also from pole to pole in the lower stratosphere. The tropospheric NO x perturbation triggers a column O 3 decrease of 0.5-1.5 DU and a 1.1% increase of the CH 4 lifetime. The surface cooling induced by solar radiation scattering by the volcanic aerosols induces a tropospheric stabilization with reduced updraft velocities that produce ice supersaturation conditions in the upper troposphere. A global mean 0.9% decrease of the cirrus ice optical depth is calculated with an indirect RF of´0.08 W¨m´2.

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“…This is a two-stream δ-Eddington approximation operating online in the ULAQ-CCM, used for photolysis rate calculation at UV-visible (Vis) wavelengths, solar heating rates, and radiative forcing at UV-Vis-NIR (near-infrared) bands (Randles et al, 2013;Pitari et al, 2015b). In addition, a companion broadband, kdistribution longwave radiation module is used to compute radiative transfer and heating rates in the planetary infrared spectrum (Chou et al, 2001;Pitari et al, 2015c). Calculations of photolysis rates and radiative fluxes have been evaluated in the framework of CCMVal (SPARC, 2010) and AeroCom inter-comparison campaigns (Randles et al, 2013).…”

Section: A16 Ulaq-ccmmentioning

confidence: 99%

Review of the global models used within phase 1 of the Chemistry–Climate Model Initiative (CCMI)

et al. 2017

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Abstract. We present an overview of state-of-the-art chemistry-climate and chemistry transport models that are used within phase 1 of the Chemistry-Climate Model Initiative (CCMI-1). The CCMI aims to conduct a detailed evaluation of participating models using process-oriented diagnostics derived from observations in order to gain confidence in the models' projections of the stratospheric ozone layer, tropospheric composition, air quality, where applicable global climate change, and the interactions between them. Interpretation of these diagnostics requires detailed knowledge of the radiative, chemical, dynamical, and physical processes incorporated in the models. Also an understanding of the degree to which CCMI-1 recommendations for simulations have been followed is necessary to understand model responses to anthropogenic and natural forcing and also to explain intermodel differences. This becomes even more important given the ongoing development and the ever-growing complexity of these models. This paper also provides an overview of the available CCMI-1 simulations with the aim of informing CCMI data users.

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Desert dust transported over Europe: Lidar observations and model evaluation of the radiative impact

Cited by 12 publications

References 73 publications

Stratospheric Aerosols from Major Volcanic Eruptions: A Composition-Climate Model Study of the Aerosol Cloud Dispersal and e-folding Time

Stratospheric Aerosols from Major Volcanic Eruptions: A Composition-Climate Model Study of the Aerosol Cloud Dispersal and e-folding Time

Sulfate Aerosols from Non-Explosive Volcanoes: Chemical-Radiative Effects in the Troposphere and Lower Stratosphere

Review of the global models used within phase 1 of the Chemistry–Climate Model Initiative (CCMI)

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