Quentin Errera

• PhD
• Researcher at Royal Belgian Institute for Space Aeronomy

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 Reanal...

This paper presents a reanalysis of the atmospheric chemical composition from the upper troposphere to the lower mesosphere from August 2004 to December 2017. This reanalysis is produced by the Belgian Assimilation System for Chemical ObsErvations (BASCOE) constrained by the chemical observations from the Microwave Limb Sounder (MLS) on board the A...

The Brewer–Dobson circulation (BDC) is a stratospheric circulation characterized by upwelling of tropospheric air in the tropics, poleward flow in the stratosphere, and downwelling at mid and high latitudes, with important implications for chemical tracer distributions, stratospheric heat and momentum budgets, and mass exchange with the troposphere...

ALTIUS (Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere) is the upcoming stratospheric ozone monitoring limb sounder from ESA's Earth Watch programme. Measuring in the ultraviolet–visible–near-infrared (UV–VIS–NIR) spectral regions, ALTIUS will retrieve vertical profiles of ozone, aerosol extinction coefficients, nitroge...

The Copernicus Atmosphere Monitoring Service (CAMS) is operationally providing forecast and reanalysis products of air quality and atmospheric composition. In this article, we present an extended evaluation of the CAMS global reanalysis data set of four reactive gases, namely, ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and formaldehy...

The daily analyses and forecasts of atmospheric composition delivered by the Copernicus Atmosphere Monitoring Service (CAMS) are produced by the ECMWF Integrated Forecasting System configured for COMPOsition (IFS-COMPO). In 2023 this system was upgraded to Cy48R1 which solves explicitly for stratospheric chemistry through a module extracted from th...

The Copernicus Atmosphere Monitoring Service (CAMS) provides daily analyses and forecasts of the composition of the atmosphere, including the reactive gases such as O3, CO, NO2, HCHO and SO2; aerosol species; and greenhouse gases. The global CAMS analysis system (IFS-COMPO) is based on the ECMWF Integrated Forecasting System (IFS) for numerical wea...

The Copernicus Atmosphere Monitoring Service (CAMS) is providing daily analyses and forecasts of the composition of the atmosphere, including the reactive gases such as O3, CO, NO2, HCHO, SO2, aerosol species and greenhouse gases. The global CAMS analysis system (IFS-COMPO) is based on the ECMWF Integrated Forecast System (IFS) for numerical weathe...

In Switzerland, two ground-based ozone microwave radiometers are operated in the vicinity of each other (ca. 40 km): the GROund-based Millimeter-wave Ozone Spectrometer (GROMOS) in Bern (Institute of Applied Physics) and the Stratospheric Ozone MOnitoring RAdiometer (SOMORA) in Payerne (MeteoSwiss). Recently, their calibration and retrieval algorit...

In Switzerland, two ground-based ozone microwave radiometers are operated in the vicinity of each other (ca. 40 km): GROMOS in Bern (Institute of Applied Physics) and SOMORA in Payerne (MeteoSwiss). Recently, their calibration and retrieval algorithms have been fully harmonized and updated time series are now available since 2009. Using these harmo...

We study potential advantages coming from the exploitation of the synergy between limb and nadir measurements from Imaging Fourier Transform Spectrometers with the rigorous approach of the two-dimensional complete data fusion.

The Brewer‐Dobson Circulation (BDC) determines the distribution of long‐lived tracers in the stratosphere; therefore, their changes can be used to diagnose changes in the BDC. We evaluate decadal (2005–2018) trends of nitrous oxide (N2O) in two versions of the Whole Atmosphere Chemistry‐Climate Model (WACCM) by comparing them with measurements from...

We present a new tropospheric ozone dataset based on TROPOspheric Monitoring Instrument (TROPOMI)/Sentinel-5 Precursor (S5P) total ozone measurements combined with stratospheric ozone data from the Belgian Assimilation System for Chemical ObsErvations (BASCOE) constrained by assimilating ozone observations from the Microwave Limb Sounder (MLS). The...

In this paper, we report on the first implementation of atmospheric chemistry and aerosol as part of the European Centre for Medium-Range Weather Forecasts (ECMWF) OpenIFS model. OpenIFS is a portable version of ECMWF's global numerical weather prediction model. Modules and input data for model cycle CY43R3, which have been developed as part of the...

A long-term tropospheric ozone time series has been generated for the tropical band (20°S to 20°N) based on convective cloud differential algorithm (CCD). Tropical tropospheric ozone columns were retrieved from several European sensors starting with observations by GOME in 1995 and including data from SCIAMACHY, OMI, GOME-2A and GOME-2B. It has now...

High-resolution model data are used to estimate the statistically typical mixing ratio variabilities of trace species as a function of distance and time separation. These estimates can be used to explain the fact that some of the differences between observations made with different observing systems are due to the less-than-perfect co-location of t...

In this paper, we report on the first implementation of atmospheric chemistry and aerosol as part of the European Centre for Medium-Range Weather Forecasts (ECMWF) OpenIFS model. For this, modules and input data for model cycle CY43R3, which have been developed as part of the Copernicus Atmosphere Monitoring Service (CAMS), have been ported to Open...

We present a new tropospheric ozone data set based on TROMOMI/Sentinel-5 Precursor (S5P) total ozone mea- surements combined stratospheric ozone data from the Belgian Assimilation System for Chemical ObsErvations (BASCOE). BASCOE is constrained by assimilating ozone observations from the microwave limb sounder (MLS). The tropospheric ozone algorith...

High-resolution model data are used to estimate typical variabilities of mixing ratios of trace species as a function of spatial and temporal distance. These estimates can be used to explain that part of the differences between observations made with different observing systems that are due to less than perfect collocation of the measurements. The...

ALTIUS (Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere) is the upcoming stratospheric ozone monitoring limb sounder from ESA's Earth Watch programme. Measuring in the ultraviolet-visible-near infrared spectral regions, ALTIUS will retrieve vertical profiles of ozone, aerosol extinction coefficients, nitrogen dioxide and...

CAIRT, a candidate for ESA’s Earth Explorer 11 mission, will observe the Earth’s limb with an imaging Fourier-transform spectrometer. It will provide global observations of ozone, temperature, water vapour and key halogen and nitrogen compounds.

Abstract. The Brewer–Dobson Circulation (BDC) transports chemical tracers from the well-mixed tropical troposphere to the polar stratosphere, with many important implications for climate, chemistry, ozone distribution and recovery. Since the photochemical losses of nitrous oxide (N₂O) are well-known, model differences in its rate of chan...

Understanding variations in atmospheric ozone in the Arctic is difficult because there are only a few long-term records of vertical ozone profiles in this region. We present 12 years of ozone profiles from February 2005 to February 2017 at four sites: Summit Station, Greenland; Ny-Ålesund, Svalbard, Norway; and Alert and Eureka, Nunavut, Canada. Th...

This paper presents a reanalysis of the atmospheric chemical composition from the upper troposphere to the lower mesosphere from August 2004 to December 2017. This reanalysis is produced by the Belgian Assimilation System for Chemical ObsErvations (BASCOE) constrained by the chemical observations from the Microwave Limb Sounder (MLS) onboard the Au...

This article describes the objectives, concept and expected performance of the ALTIUS (Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere) mission in view of the continuation of earth limb measurements for atmospheric science. The instrument, consisting of three independent spectral imagers in the UV–vis–NIR range, will be...

Understanding the drivers of atmospheric ozone variations in the Arctic is difficult because there are few long-term records of vertical ozone profiles in this region. We present 12 years of ozone profiles over Summit Station, Greenland (72.6 N, 38.4 W; 3200 meters) that were measured from 2005 to 2016. These profiles are subjected to data screenin...

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 Reanal...

The Belgian Assimilation System for Chemical ObsErvations (BASCOE) has been used to reanalyse Aura MLS observations. The system is based on the Ensemble Kalman Filter (EnKF) and a Chemistry Transport Model (CTM) involving 58 chemical species focusing on the stratosphere. The CTM accounts for the advection, the chemistry (gas phase, photolysis and h...

The Belgian Assimilation System for Chemical ObsErvations (BASCOE) has been used to reanalyse Aura MLS observations. The system is based on the Ensemble Kalman Filter (EnKF) and a Chemistry Transport Model (CTM) involving 58 chemical species focusing on the stratosphere. The CTM accounts for the advection, the chemistry (gas phase, photolysis and h...

BRAM is a reanalysis of Aura MLS observations produced by the Belgian Assimilation System of Chemical ObsErvations (BASCOE). BASCOE is based on a chemistry transport model (CTM) for the stratosphere involving 58 species. All species are advected by the Flux Form Semi-Lagrangian (FFSL) scheme (i.e. Lin and Rood, 1996). The CTM account for gas phase,...

This is the powerpoint of the Errera et al’s presentation given at EGU 2017 during the session AS3.14 (Atmospheric composition variability and trends)

This paper discusses assimilation experiments of methane (CH4) and nitrous oxide (N2O) profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Here we focus on data versions 6 and 7 provided by the ESA processor. These data sets have been assimilated by the Belgian Assimilation System for Chemical ObsErvations...

Abstract. We present a model description and benchmark evaluation of an extension of the tropospheric chemistry module in the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) with stratospheric chemistry, referred to as C-IFS-CB05-BASCOE (for brevity here referred to as C-IFS-TS). The stratospher...

We compare two optimized chemical data assimilation systems, one based on the ensemble Kalman filter (EnKF) and the other based on four-dimensional variational (4D-Var) data assimilation, using a comprehensive stratospheric chemistry transport model (CTM). This work is an extension of the Belgian Assimilation System for Chemical ObsErvations (BASCO...

This article outlines the objectives, concept and expected performance of the ALTIUS (Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere) mission in view of the continuation of earth limb measurements for atmospheric science. This type of measurement became rare with the failure of the European ENVISAT mission in 2012 and t...

This paper discusses assimilation experiments of methane (CH4) and nitrous oxide (N2O) profiles observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Here we focus on data versions 6 and 7 retrieved by the ESA processor. These datasets have been assimilated by the Belgian Assimilation System for Chemical ObsErvations (B...

We compare two optimized chemical data assimilation systems, one based on the ensemble Kalman filter (EnKF) and the other based on four-dimensional variational (4D-Var), using a comprehensive stratospheric chemistry transport model (CTM). The work is an extension of the Belgian Assimilation System for Chemical ObsErvations (BASCOE), initially desig...

We present a model description and benchmark evaluation of an extension of the tropospheric chemistry module in the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) with stratospheric chemistry, referred to as C-IFS-CB05-BASCOE (for brevity here referred to as C-IFS-TS). The stratospheric chemist...

BASCOE, operated by BIRA-IASB, is used for the MACC-III project to assimilate the offline observations of stratospheric composition by Aura-MLS. The system performance and operational implementation are described in the companion deliverable D20.2 and D21.1. Its results and usage are reported in the deliverables D19.2, D21.6 and D23.3. Here the qua...

Analysis of the chemical composition of the stratosphere on 1 May 2015, as generated by assimilation of Aura-MLS observations of O3, N2O, HNO3, HCl, CO and ClO into the Data Assimilation System BASCOE 4.3 . For more information, see the MACC stratospheric ozone service at www.copernicus-stratosphere.eu

This report compiles information about data assimilation features of BASCOE. BASCOE is operated by BIRA-IASB and delivers, principally, MLS ozone assimilated abundances with errors of less than 3% in the lower stratosphere and less than 5% at the middle stratosphere in its current 04 version. Such very good performance and the fact that the present...

Ground-based Fourier transform infrared (FTIR) measurements of solar absorption spectra can provide ozone total columns with a precision of 2%, but also independent partial column amounts in about four vertical layers, one in the troposphere and three in the stratosphere up to about 45 km, with a precision of 5–6%. We use eight of the Network for t...

This paper evaluates and discusses the quality of the stratospheric ozone analyses delivered in near real time by the MACC (Monitoring Atmospheric Composition and Climate) project during the 3-year period between September 2009 and September 2012. Ozone analyses produced by four different chemical data assimilation (CDA) systems are examined and co...

Ground-based Fourier transform infrared (FTIR) measurements of solar absorption spectra can provide ozone total columns with a precision of 2%, but also independent partial column amounts in about four vertical layers, one in the troposphere and three in the stratosphere up to about 45 km, with a precision of 5–6%. We use eight of the Network for t...

We investigate the role of the wind fields delivered by the dynamics component of MACC (IFS) as a cause for errors in modelling stratospheric composition, especially w.r.t. lower stratospheric ozone. This is done through the evaluation and intercomparison of three different analyses of wind fields to drive a CTM: ERA-Interim, the ECMWF Operational...

An ensemble Kalman filter (EnKF) assimilation method is applied to the tracer transport using the same stratospheric transport model as in the four-dimensional variational (4D-Var) assimilation system BASCOE (Belgian Assimilation System for Chemical ObsErvations). This EnKF version of BASCOE was built primarily to avoid the large costs associated w...

This paper evaluates the performance of the stratospheric ozone analyses delivered in near real time by the MACC (Monitoring Atmospheric Composition and Climate) project during the 3 year period between September 2009 and September 2012. Ozone analyses produced by four different chemistry transport models and data assimilation techniques are examin...

The Ensemble Kalman filter (EnKF) assimilation method is applied to the tracer transport using the same stratospheric transport model as in the 4D-Var assimilation system BASCOE. This EnKF version of BASCOE was built primarily to avoid the large costs associated with the maintenance of an adjoint model. The EnKF developed in BASCOE accounts for two...

A 3-D Chemical Transport Model (CTM), with full stratospheric chemistry and driven by the ECMWF temperature and wind fields, has been coupled to a detailed PSC microphysical model to simulate polar winters. The formation and evolution of four types of PSC particles (STS, SAT, NAT, and ice) are described through relevant microphysical processes whic...

BIRA-IASB is planning a reanalysis of the stratospheric chemical composition for the period 2002-2012 using the Belgian Assimilation System for Chemical ObsErvations (BASCOE). BASCOE is a 4D-Var system based on a chemistry transport model that has 57 chemical species, 200 chemical reactions and a PSC parameterization. For this reanalysis, the model...

In this work, we present an ensemble Kalman filter (EnKF) assimilation method applied to the stratospheric chemical transport model of BASCOE (Belgian Assimilation System for Chemical ObsErvations). BASCOE was developed originally with a 4DVar assimilation method and is providing near-real-time analyses for the European project MACC-II. 4DVar metho...

An eight-year long reanalysis of atmospheric composition data covering the period 2003–2010 was constructed as part of the FP7-funded Monitoring Atmospheric Composition and Climate project by assimilating satellite data into a global model and data assimilation system. This reanalysis provides fields of chemically reactive gases, namely carbon mono...

The formulation of the background error covariances represented in the spectral space is discussed in the context of univariate assimilation relying on a grid point model, leaving out all the aspects of balances between the different control variables needed in meteorological assimilation. The spectral transform operations are discussed in the case...

The formulation of the background error covariances represented in the spectral space is discussed in the context of univariate assimilation relying on a grid point model, leaving out all the aspects of balances between the different control variables needed in meteorological assimilation. The spectral transform operations are discussed in the case...

Chemical transport models (CTM) are broadly used to forecast chemical species concentration or analyze the tropospheric pollution. As more chemical observations become available, the use of data assimilation methods, integrating observational data with model predictions to obtain an optimal state of the atmosphere, plays an essential role in air-qu...

One of the critical aspects of any assimilation system is the formulation of a background error covariance matrix (BECM) which is sufficiently compact to be implemented numerically and sufficiently complex to represent correctly the real error covariances of the first guess field. In the late nineties, meteorological centers have implemented relati...

A 3-D Chemical Transport Model (CTM), with full stratospheric chemistry and driven by the ECMWF temperature and wind fields, is coupled to the PSC microphysical model PSCBox. This interactively describes the formation and evolution of four types of PSC particles (STS, SAT, NAT, and ice) through relevant microphysical processes. The number density a...

We present observations of the 2010-2011 Arctic winter stratosphere from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT. We adopted a full 2D tomographic retrieval approach to account for the strong horizontal inhomogeneity of the atmosphere present under vortex conditions. A well isolated stratospheric vortex...

This report describes the non-operational validation activities performed within the GEMS GRG subproject w.r.t. stratospheric ozone, i.e. the validation of the GRG model and assimilation system for particular case studies defined at the start of MACC. While Task G-RG_1.5 covers the intercomparison of the different assimilation models BASCOE, SACADA...

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O₃ and NO₂ observations. Comparisons between the GOME-2 results and BrO vertical columns...

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and correlative data including ground-based Br...

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlat...

The record–breaking major stratospheric warming of northern winter 2009 (January–February) is studied using BASCOE (Belgian Assimilation System for Chemical ObsErvation) stratospheric water vapour analyses and MLS (Microwave Limb Sounder) water vapour observations, together with meteorological data from the European Centre for Medium-Range Weather...

We present the most recent work related to the development and use of the Model for STrato-spheric Aerosols (MOSTRA). This model is a 3D microphysical/transport model describing the evolution in time and space of the aerosol size distribution described using a set of particle bins. The microphysical module used in the model is based on the PSCBOX m...

We present the analyses of UARS MLS ozone data obtained by the Belgian Assimilation System for Chemical ObsErvations (BASCOE). This system, based on the 4D-var method, is dedicated to the assimilation of stratospheric chemistry observations. It uses a 3-D Chemical Transport Model (3D-CTM) including 57 chemical species with explicit calculation of s...

During the PROMOTE project (www.gse-promote.org), BIRA-IASB has assimilated UARS MLS chemical observations of O3, HNO3, H2O and ClO between 1992 and 1997 using the BASCOE 4D-Var system (Viscardy et al., accepted for publication in JSTARS). This system is based on a stratospheric chemistry transport model (CTM) where chemical reactions are calculate...

We present recent advances in the development of a microphysical/transport model for stratospheric aerosols, called MOdel for STRatospheric Aerosols (MOSTRA). MOSTRA is a D model describing the evolution in time and space of the stratospheric aerosol distribution described using a set of discrete size bins. The microphysical module used in this mod...

During the wintertime stratosphere, a strong cyclonic polar vortex is usually observed. However, during January-February 2009, an unprecedented major warming took place in the Arctic stratosphere, which involved a split of the vortex and disrupted the typical air circulation in this region. The purpose of this contribution is to study the dynamical...

Background. In the 1990s, following years of development of meteorological data assimilation by the Numerical Weather Prediction (NWP) community, the data assimilation methodology began to be applied to constituents, with a strong focus on stratospheric ozone (Rood 2005; Lahoz et al. 2007a). Because of its comparatively later application, constitue...

The record–breaking major stratospheric warming of northern winter 2009 (January–February) is studied using BASCOE (Belgian Assimilation System for Chemical ObsErvation) stratospheric water vapour analyses and MLS (Microwave Limb Sounder) water vapour observations, together with meteorological data from the European Centre for Medium-Range Weather...

This paper presents results from the first detailed intercomparison of stratosphere-lower mesosphere water vapour analyses; it builds on earlier results from the EU funded framework V "Assimilation of ENVISAT Data" (ASSET) project. Stratospheric water vapour plays an important role in many key atmospheric processes and therefore an improved underst...

A new climatology of stratospheric BrO profiles based on a parameterization using dynamical and chemical indicators has been developed, with the aim to apply it to the retrieval of tropospheric BrO columns from space nadir measurements. The adopted parameterization is based on three years of output data from the 3-D chemistry transport model BASCOE...

The PROMOTE Stratospheric Ozone Profile Record service has been setup to deliver 3D global re-analyses of ozone and other related trace gas (www.gse-promote.org). Provided by DLR and BIRA-IASB, re-analyses will cover the period from 1992 until now. Both institutions are running their own systems and deal with different datasets, thus different peri...

This poster presents actual research using the strato-spheric chemistry transport model and the 4D-Var assimila-tion system of stratospheric chemical data, both developed at BIRA-IASB.

A new climatology of stratospheric BrO profiles based on dynamical and chemical indicators has been developed, with the aim to apply it to the retrieval of tropospheric BrO columns from space nadir measurements. The suitability of the adopted parameterization is evaluated based on three years of output data from the 3-D chemistry transport model BA...

Data assimilation of atmospheric constituents is becoming more and more important as the number and quality of satellite observations increases. New assimilation methods allow us to derive continuous four-dimensional depictions of the atmos-phere’s chemical state. Within the European ESA/GMES project PROMOTE three CTM-based assimilation systems hav...

This paper discusses the global analyses of stratospheric ozone (O₃) and nitrogen dioxide (NO₂) obtained by the Belgian Assimilation System for Chemical Observations from Envisat (BASCOE). Based on a chemistry transport model (CTM) and the 4-dimensional variational (4D-Var) method, BASCOE has assimilated chemical observations...

This paper discusses the global analyses of stratospheric ozone (O3) and nitrogen dioxide (NO2) obtained by the Belgian Assimilation System for Chemical Observations from Envisat (BASCOE). Based on a chemistry transport model (CTM) and the 4-dimensional variational (4D-Var) method, BASCOE has assimilated chemical observations of O3, NO2, HNO3, N2O,...

A new climatology of stratospheric BrO profiles has been developed, with the aim to apply it to the retrieval of tropospheric BrO columns from space nadir measurements. The impact of the atmospheric dynamic on the stratospheric BrO distribution is treated by means of Br y /ozone correlations build from 3D-CTM model results, while photochemical effe...

The data assimilation of stratospheric constituents is reviewed. The data assimilation method is introduced, with particular consideration to its application to stratospheric constituent measurements. Differences from meteorological data assimilation are outlined. Historically, two approaches have been used to carry out constituent assimilation. On...

The service aims at providing a global reanalysis of ozone and related conservative and reactive species in the stratosphere by exploiting observations from ERS-2/GOME, ENVISAT/MIPAS, SCIAMACHY and GOMOS as well as UARS/MLS. The target period covers the years 1992 to present will be covered. In order to derive a global consistent record of stratosp...

MIPAS (v4.61) and GOMOS (v6.0a) observations of O 3 and NO 2 have been assimilated separately by the Belgian Assimilation System of Chemical Observations from En-visat (BASCOE). In the first experiment, MIPAS ob-servations have been assimilated from October 2002 to March 2004 (18 months) including also observations of HNO 3 , N 2 O, CH 4 and H 2 O...