References of "Minganti, Daniele"
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See detailN2O-based climatology of the Brewer Dobson Circulation in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses
Minganti, Daniele ULiege; Chabrillat, Simon; Christophe, Yves et al

Conference (2020, May 05)

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See detailN2O-based climatology of the Brewer-Dobson Circulation in WACCM, a chemical renalysis and a CTM driven by four dynamical reanalyses
Minganti, Daniele ULiege; Chabrillat, Simon; Christophe, Yves et al

Poster (2019, December 11)

The Brewer-Dobson Circulation (BDC) plays a major role in the stratospheric dynamics in terms of tracer transport through the mean residual meridional advection and the isentropic two-way mixing. The ... [more ▼]

The Brewer-Dobson Circulation (BDC) plays a major role in the stratospheric dynamics in terms of tracer transport through the mean residual meridional advection and the isentropic two-way mixing. The climatological BDC in the Whole Atmosphere Community Climate Model (WACCM) is separated in those components and evaluated through a comparison with a chemical reanalysis of Aura MLS (BRAM2) and with a chemistry-transport model driven by four modern reanalyses (ERA-Interim, JRA-55, MERRA and MERRA2), using the Transformed Eulerian Mean (TEM) analysis of the long-lived tracer N2O and focusing on the vertical residual advection and the horizontal two-way mixing terms. In the wintertime Southern polar region the horizontal mixing term in WACCM shows near-zero values, while all the reanalyses show strong negative contributions. This disagreement is likely due to the different representation of the polar transport barrier, that affects the mixing inside the polar vortex. In this region the reanalyses are characterized by large uncertainties of the TEM analysis, i.e. the residual term of the budget is quite large (the N2O TEM budget is not fully closed). In the wintertime Northern polar latitudes WACCM shows smaller values of the horizontal mixing term compared to the reanalyses, which show lower uncertainties of the TEM budget. The agreement is improved in the middle and low latitudes, especially in the Northern Hemisphere: the differences are smaller and the residual term is lower compared to the polar latitudes. The inter-annual variability of the horizontal mixing term is large in the Southern polar latitudes during austral fall and in the Northern polar latitudes during boreal winter. [less ▲]

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See detailImproved FTIR retrieval strategy for HCFC-22 (CHClF2), comparisons with in situ and satellite datasets with the support of models, and determination of its long-term trend above Jungfraujoch
Prignon, Maxime ULiege; Chabrillat, Simon; Minganti, Daniele ULiege et al

in Atmospheric Chemistry and Physics (2019), 19(19), 1230912324

Hydrochlorofluorocarbons (HCFCs) are the first, but temporary, substitution products for the strong ozone-depleting chlorofluorocarbons (CFCs). In this work, we present and validate an improved method to ... [more ▼]

Hydrochlorofluorocarbons (HCFCs) are the first, but temporary, substitution products for the strong ozone-depleting chlorofluorocarbons (CFCs). In this work, we present and validate an improved method to retrieve the most abundant HCFC in the atmosphere, allowing its evolution to be monitored independently in the troposphere and stratosphere. These kinds of contributions are fundamental for scrutinizing the fulfilment of the Montreal Protocol on Substances that Deplete the Ozone Layer. [less ▲]

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See detailInvestigation of stratospheric circulation using long-lived tracers with WACCM, BASCOE CTM and a reanalysis of MLS observations
Minganti, Daniele ULiege; Chabrillat, Simon; Christophe, Yves et al

Poster (2019, April 12)

The stratospheric circulation is investigated using WACCM4 (Whole Atmosphere Community Climate Model version 4), together with BASCOE CTM (Belgian Assimilation System for Chemical Observations Chemistry ... [more ▼]

The stratospheric circulation is investigated using WACCM4 (Whole Atmosphere Community Climate Model version 4), together with BASCOE CTM (Belgian Assimilation System for Chemical Observations Chemistry-Transport Model) and a reanalysis of stratospheric composition observed by MLS: BRAM2 (BASCOE Reanalysis of AURA MLS release 2) over the period 2005-2015. Three different reanalyses of the wind fields (ERA-interim, JRA55 and MERRA2) are used to drive the CTM, providing an estimate of the uncertainties in our representation of the actual stratospheric circulation. We use a long-lived tracer (N2O), and the Transformed Eulerian Mean (TEM) framework to analyse the tracer budget. We focus on the residual advection (mainly vertical) and eddy mixing (mainly horizontal) contributions to the N2O variations, studying the mean annual cycle and variability in the higher stratosphere and how it is depicted in the different datasets. The BRAM2 mean annual cycle, for both the vertical and the horizontal terms, is nearly in the middle of the spread. WACCM is in good agreement concerning the vertical term but differs considerably from the other datasets in the horizontal (~mixing) term. WACCM present a smaller variability with respect to the reanalysis in the Tropical higher stratosphere, especially for the vertical term. The next step of our research is to perform such analysis with the newer version of WACCM (version 6) as well as new BASCOE CTM runs using other reanalysis products. Multi-decadal changes in the terms of the budget, and their space dependence, will be investigated as well. [less ▲]

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See detailImpact of lower stratospheric dynamical variability on total inorganic fluorine derived from ground-based FTIR, satellite and model data
Prignon, Maxime ULiege; Bernath, P. F.; Chabrillat, S. et al

Poster (2019, April 12)

Long-lived tracer concentrations in the lower stratosphere are affected by short time scale circulation variability as highlighted by recent papers (e.g., Mahieu et al., 2014). Many tracers, such as ... [more ▼]

Long-lived tracer concentrations in the lower stratosphere are affected by short time scale circulation variability as highlighted by recent papers (e.g., Mahieu et al., 2014). Many tracers, such as hydrogen chloride (HCl) or hydrogen fluoride (HF) have now been successfully used to investigate or identify this variability (e.g., Harrison et al., 2016) In this work, the main reservoirs of inorganic fluorine [i.e., HF, carbonyl fluoride (COF2) and carbonyl chloride fluoride (COClF)] and their sum (total inorganic fluorine, Fy) are used to investigate the lower stratospheric circulation changes. We use Fourier Transform InfraRed (FTIR) ground-based observations conducted in the framework of the NDACC network (http://www.ndacc.org) to derive column abundances of HF and COF2, thus providing a good proxy for Fy. To support this research, we also include satellite observations from HALOE (HF available) and ACE-FTS (HF, COF2 and COClF available). Moreover, we use the Chemical-Transport Model (CTM) BASCOE (Belgian Assimilation System for Chemical ObsErvations; Chabrillat et al., 2018) to evaluate the representation of the investigated circulation changes in state-of-the-art meteorological reanalyses. We also evaluate if WACCM4 (Whole Atmosphere Community Climate Model version 4) is able to reproduce these changes through a free dynamics and free chemistry run. Finally, SLIMCAT CTM (Chipperfield et al., 2015) simulations are included to provide information on the partitioning between the main Fy reservoirs. [less ▲]

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See detailComparison of mean age of air in five reanalyses using the BASCOE transport model
Chabrillat, S.; Vigouroux, C.; Christophe, Y. et al

in Atmospheric Chemistry and Physics (2018), 18

We present a consistent intercomparison of the mean age of air (AoA) according to five modern reanalyses: the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), the ... [more ▼]

We present a consistent intercomparison of the mean age of air (AoA) according to five modern reanalyses: the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), the Japanese Meteorological Agency's Japanese 55-year Reanalysis (JRA-55), the National Centers for Environmental Prediction Climate Forecast System Reanalysis (CFSR) and the National Aeronautics and Space Administration's Modern Era Retrospective analysis for Research and Applications version 1 (MERRA) and version 2 (MERRA-2). The modeling tool is a kinematic transport model driven only by the surface pressure and wind fields. It is validated for ERA-I through a comparison with the AoA computed by another transport model. The five reanalyses deliver AoA which differs in the worst case by 1 year in the tropical lower stratosphere and more than 2 years in the upper stratosphere. At all latitudes and altitudes, MERRA-2 and MERRA provide the oldest values ( ∼ 5–6 years in midstratosphere at midlatitudes), while JRA-55 and CFSR provide the youngest values ( ∼ 4 years) and ERA-I delivers intermediate results. The spread of AoA at 50hPa is as large as the spread obtained in a comparison of chemistry–climate models. The differences between tropical and midlatitude AoA are in better agreement except for MERRA-2. Compared with in situ observations, they indicate that the upwelling is too fast in the tropical lower stratosphere. The spread between the five simulations in the northern midlatitudes is as large as the observational uncertainties in a multidecadal time series of balloon observations, i.e., approximately 2 years. No global impact of the Pinatubo eruption can be found in our simulations of AoA, contrary to a recent study which used a diabatic transport model driven by ERA-I and JRA-55 winds and heating rates. The time variations are also analyzed through multiple linear regression analyses taking into account the seasonal cycles, the quasi-biennial oscillation and the linear trends over four time periods. The amplitudes of AoA seasonal variations in the lower stratosphere are significantly larger when using MERRA and MERRA-2 than with the other reanalyses. The linear trends of AoA using ERA-I confirm those found by earlier model studies, especially for the period 2002–2012, where the dipole structure of the latitude–height distribution (positive in the northern midstratosphere and negative in the southern midstratosphere) also matches trends derived from satellite observations of SF6. Yet the linear trends vary substantially depending on the considered period. Over 2002–2015, the ERA-I results still show a dipole structure with positive trends in the Northern Hemisphere reaching up to 0.3yrdec−1. No reanalysis other than ERA-I finds any dipole structure of AoA trends. The signs of the trends depend strongly on the input reanalysis and on the considered period, with values above 10hPa varying between approximately −0.4 and 0.4yrdec−1. Using ERA-I and CFSR, the 2002–2015 trends are negative above 10hPa, but using the three other reanalyses these trends are positive. Over the whole period (1989–2015) each reanalysis delivers opposite trends; i.e., AoA is mostly increasing with CFSR and ERA-I but mostly decreasing with MERRA, JRA-55 and MERRA-2. In view of this large disagreement, we urge great caution for studies aiming to assess AoA trends derived only from reanalysis winds. We briefly discuss some possible causes for the dependency of AoA on the input reanalysis and highlight the need for complementary intercomparisons using diabatic transport models. [less ▲]

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See detailPreliminary characterization of the stratospheric circulation using long-lived tracers with the WACCM chemistry-climate model and observations
Minganti, Daniele ULiege

Poster (2018, January 12)

The changes in stratospheric circulation are one of the major sources of uncertainty in climate projection, therefore they are a major area of research. The current work is part of the ACCROSS ... [more ▼]

The changes in stratospheric circulation are one of the major sources of uncertainty in climate projection, therefore they are a major area of research. The current work is part of the ACCROSS (Atmospheric Composition and Circulation investigated with meteorological Reanalyses, Observational datasets and models for the Study of the Stratosphere and its changes) project, which intends to improve our understanding of the circulation changes in the past years through an extensive use of observations and model simulations of selected long-lived tracers. Here we compare simulations of a state-of-the-art Chemistry Climate Model with satellite observations of HF and N2O from February 2004 to February 2013. To accomplish this task major modifications to the model chemistry scheme have been made. This early comparison shows poor agreement in the HF distribution in the middle stratosphere for all latitudes, while in the low stratosphere the agreement is better, especially in the tropics. Since good agreement is found in the N2O distribution, the residual circulation is well represented, e.g. the model reproduces well the position of the transport barriers in the SH, this suggests that the disagreement in the HF distributions is due to an incomplete chemical scheme. A comparison with chemistry-transport models using the same chemistry scheme and boundary conditions is needed to evaluate this point. [less ▲]

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See detailStratospheric circulation in the WACCM chemistry-climate model: mean age of air against observations and CTM
Minganti, Daniele ULiege

Poster (2017, October)

The mean age of air is a classical diagnostic of the transit time from the troposphere to the various regions of the stratosphere, providing insights on the strength and structure of the Brewer-Dobson ... [more ▼]

The mean age of air is a classical diagnostic of the transit time from the troposphere to the various regions of the stratosphere, providing insights on the strength and structure of the Brewer-Dobson Circulation (BDC), the polar vortex and the irreversible mixing in the mid-latitudes. We apply this diagnostic to the WACCM chemistry-climate model for the 1985-2014 period. A comparison is presented between unconstrained simulations (FR-WACCM) with and without the representation of the QBO, simulations nudged to the MERRA-2 reanalysis (SD-WACCM), in-situ measurements and a chemistry-transport model (CTM). The results are different depending on the simulation, with SD-WACCM resulting closer to the observations w.r.t. FR-WACCM. In the FR-WACCM the QBO plays a role leading to older age of air. The time evolution over the considered period is slightly decreasing, while observations show a positive (not significant) trend. Given those results, further studies have to be carried out investigating the multi-decadal trends of mean age of air and involving actual tracers. [less ▲]

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See detailStratospheric variability and its dynamical impact on the troposphere simulated by chemistry-climate models
Minganti, Daniele ULiege

Scientific conference (2017, February 10)

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