Impact of IASI thermal infrared measurements on global ozone reanalyses

Infrared Measurements ◽

Tropospheric O3 ◽

The Tropics ◽

Abstract. The information content of thermal infrared measurements for tropospheric O3 estimation has already been well demonstrated. However, the impact of such measurements to constrain modelled ozone distributions within global assimilation systems is not yet unequivocal. A new tropospheric O3 reanalysis is computed for the year 2010 by means of assimilating measurements from the Infrared Atmospheric Sounding Interferometer (IASI) within the MOCAGE chemical transport model. The objective is to evaluate the impact of recent methodological improvements of the data assimilation scheme on the O3 distribution. The new O3 reanalysis (named IASI-r) and its precursor (IASI-a) have been validated against ozonesondes, compared to independent estimations of tropospheric O3 and to results from two state-of-the-art models based on detailed tropospheric chemistry (GEOS-CCM and C-IFS). The main difference between IASI-r and the former IASI-a concerns the treatment of IASI observations, with radiances being assimilated directly in IASI-r instead of intermediate Level 2 O3 retrievals. IASI-r is found to correct major issues of IASI-a, i.e. the neutral or negative impact of IASI assimilation in the extra-tropics and the presence of residual biases in the tropics. IASI-r compares also relatively well to the C-IFS reanalysis, which is based on more comprehensive chemical mechanism and the assimilation of several UV and microwave measurements.

Impact of the new HNO3-forming channel of the HO2+NO reaction on tropospheric HNO3, NOx, HOx and ozone

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-4061-2008 ◽

2008 ◽

Vol 8 (14) ◽

pp. 4061-4068 ◽

Cited By ~ 25

Author(s):

D. Cariolle ◽

M. J. Evans ◽

M. P. Chipperfield ◽

N. Butkovskaya ◽

A. Kukui ◽

...

Keyword(s):

Southern Hemisphere ◽

Atmospheric Chemistry ◽

Tropospheric Ozone ◽

Transport Model ◽

Temperature Dependent ◽

Upper Troposphere ◽

The Mean ◽

The Tropics ◽

Abstract. We have studied the impact of the recently observed reaction NO+HO2→HNO3 on atmospheric chemistry. A pressure and temperature-dependent parameterisation of this minor channel of the NO+HO2→NO2+OH reaction has been included in both a 2-D stratosphere-troposphere model and a 3-D tropospheric chemical transport model (CTM). Significant effects on the nitrogen species and hydroxyl radical concentrations are found throughout the troposphere, with the largest percentage changes occurring in the tropical upper troposphere (UT). Including the reaction leads to a reduction in NOx everywhere in the troposphere, with the largest decrease of 25% in the tropical and Southern Hemisphere UT. The tropical UT also has a corresponding large increase in HNO3 of 25%. OH decreases throughout the troposphere with the largest reduction of over 20% in the tropical UT. The mean global decrease in OH is around 13%, which is very large compared to the impact that typical photochemical revisions have on this modelled quantity. This OH decrease leads to an increase in CH4 lifetime of 5%. Due to the impact of decreased NOx on the OH:HO2 partitioning, modelled HO2 actually increases in the tropical UT on including the new reaction. The impact on tropospheric ozone is a decrease in the range 5 to 12%, with the largest impact in the tropics and Southern Hemisphere. Comparison with observations shows that in the region of largest changes, i.e. the tropical UT, the inclusion of the new reaction tends to degrade the model agreement. Elsewhere the model comparisons are not able to critically assess the impact of including this reaction. Only small changes are calculated in the minor species distributions in the stratosphere.

Comparison of tropospheric gas-phase chemistry schemes for use within global models

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-1831-2009 ◽

2009 ◽

Vol 9 (5) ◽

pp. 1831-1845 ◽

Cited By ~ 108

Author(s):

K. M. Emmerson ◽

M. J. Evans

Keyword(s):

Gas Phase ◽

Transport Model ◽

Regional Scale ◽

Tropospheric Chemistry ◽

Chemical Mechanism ◽

Model Framework ◽

Transport Models ◽

Global Models ◽

Calculated Concentration ◽

Abstract. Methane and ozone are two important climate gases with significant tropospheric chemistry. Within chemistry-climate and transport models this chemistry is simplified for computational expediency. We compare the state of the art Master Chemical Mechanism (MCM) with six tropospheric chemistry schemes (CRI-reduced, GEOS-CHEM and a GEOS-CHEM adduct, MOZART-2, TOMCAT and CBM-IV) that could be used within composition transport models. We test the schemes within a box model framework under conditions derived from a composition transport model and from field observations from a regional scale pollution event. We find that CRI-reduced provides much skill in simulating the full chemistry, yet with greatly reduced complexity. We find significant variations between the other chemical schemes, and reach the following conclusions. 1) The inclusion of a gas phase N2O5+H2O reaction in one scheme and not others is a large source of uncertainty in the inorganic chemistry. 2) There are significant variations in the calculated concentration of PAN between the schemes, which will affect the long range transport of reactive nitrogen in global models. 3) The representation of isoprene chemistry differs hugely between the schemes, leading to significant uncertainties on the impact of isoprene on composition. 4) Differences are found in NO3 concentrations in the nighttime chemistry. Resolving these four issues through further investigative laboratory studies will reduce the uncertainties within the chemical schemes of global tropospheric models.

Impact of the new HNO3-forming channel of the HO2+NO reaction on tropospheric HNO3, NOx, HOx and ozone

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-2695-2008 ◽

2008 ◽

Vol 8 (1) ◽

pp. 2695-2713 ◽

Cited By ~ 2

Author(s):

D. Cariolle ◽

M. J. Evans ◽

M. P. Chipperfield ◽

N. Butkovskaya ◽

A. Kukui ◽

...

Keyword(s):

Southern Hemisphere ◽

Atmospheric Chemistry ◽

Tropospheric Ozone ◽

Transport Model ◽

Temperature Dependent ◽

Upper Troposphere ◽

The Tropics ◽

The Impact ◽

Model Agreement

Abstract. We have studied the impact of the recently established reaction NO+HO2→HNO3 on atmospheric chemistry. A pressure and temperature-dependent parameterisation of this minor channel of the NO+HO2→NO2+OH reaction has been included in both a 2-D stratosphere-troposphere model and a 3-D tropospheric chemical transport model (CTM). Significant effects on the nitrogen species and hydroxyl radical concentrations are found throughout the troposphere, with the largest percentage changes occurring in the tropical upper troposphere (UT). Including the reaction leads to a reduction in NOx everywhere in the troposphere, with the largest decrease of 25% in the tropical and southern hemisphere UT. The tropical UT also has a corresponding large increase in HNO3 of 25%. OH decreases throughout the troposphere with the largest reduction of over 20% in the tropical UT. Mean global decreases in OH are around 13% which leads to a increase in CH4 lifetime of 5%. Due to the impact of decreased NOx on the OH:HO2 partitioning, modelled HO2 actually increases in the tropical UT on including the new reaction. The impact on tropospheric ozone is a decrease in the range 5 to 12%, with the largest impact in the tropics and southern hemisphere. Comparison with observations shows that in the region of largest changes, i.e. the tropical UT, the inclusion of the new reaction tends to degrade the model agreement. Elsewhere the model comparisons are not able to critically assess the impact of including this reaction. Only small changes are calculated in the minor species distributions in the stratosphere.

Atmospheric ethanol in London and the potential impacts of future fuel formulations

Faraday Discussions ◽

10.1039/c5fd00190k ◽

2016 ◽

Vol 189 ◽

pp. 105-120 ◽

Cited By ~ 9

Author(s):

Rachel E. Dunmore ◽

Lisa K. Whalley ◽

Tomás Sherwen ◽

Mathew J. Evans ◽

Dwayne E. Heard ◽

...

Keyword(s):

Transport Model ◽

Regional Scale ◽

Road Transport ◽

Emission Source ◽

Chemical Mechanism ◽

Scale Model ◽

Regional Modelling ◽

Primary Emissions ◽

There is growing global consumption of non-fossil fuels such as ethanol made from renewable biomass. Previous studies have shown that one of the main air quality disadvantages of using ethanol blended fuels is a significant increase in the production of acetaldehyde, an unregulated and toxic pollutant. Most studies on the impacts of ethanol blended gasoline have been carried out in the US and Brazil, with much less focus on the UK and Europe. We report time resolved measurements of ethanol in London during the winter and summer of 2012. In both seasons the mean mixing ratio of ethanol was around 5 ppb, with maximum values over 30 ppb, making ethanol currently the most abundant VOC in London air. We identify a road transport related source, with ‘rush-hour’ peaks observed. Ethanol is strongly correlated with other road transport-related emissions, such as small aromatics and light alkanes, and has no relationship to summer biogenic emissions. To determine the impact of road transport-related ethanol emission on secondary species (i.e. acetaldehyde and ozone), we use both a chemically detailed box model (incorporating the Master Chemical Mechanism, MCM) and a global and nested regional scale chemical transport model (GEOS-Chem), on various processing time scales. Using the MCM model, only 16% of the modelled acetaldehyde was formed from ethanol oxidation. However, the model significantly underpredicts the total levels of acetaldehyde, indicating a missing primary emission source, that appears to be traffic-related. Further support for a primary emission source comes from the regional scale model simulations, where the observed concentrations of ethanol and acetaldehyde can only be reconciled with the inclusion of large primary emissions. Although only constrained by one set of observations, the regional modelling suggests a European ethanol source similar in magnitude to that of ethane (∼60 Gg per year) and greater than that of acetaldehyde (∼10 Gg per year). The increased concentrations of ethanol and acetaldehyde from primary emissions impacts both radical and NOx cycling over Europe, resulting in significant regional impacts on NOy speciation and O3 concentrations, with potential changes to human exposure to air pollutants.

Tropospheric chemistry in the integrated forecasting system of ECMWF

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-7733-2014 ◽

2014 ◽

Vol 7 (6) ◽

pp. 7733-7803 ◽

Cited By ~ 6

Author(s):

J. Flemming ◽

V. Huijnen ◽

J. Arteta ◽

P. Bechtold ◽

A. Beljaars ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Transport Model ◽

Nitrogen Monoxide ◽

Coupled System ◽

Tropospheric Chemistry ◽

Chemical Mechanism ◽

Atmospheric Composition ◽

Data Set ◽

Forecasting System

Abstract. A representation of atmospheric chemistry has been included in the Integrated Forecasting System (IFS) of the European Centre for Medium-range Weather Forecasts (ECMWF). The new chemistry modules complement the aerosol modules of the IFS for atmospheric composition, which is named C-IFS. C-IFS for chemistry supersedes a coupled system, in which the Chemical Transport Model (CTM) Model for OZone and Related chemical Tracers 3 was two-way coupled to the IFS (IFS-MOZART). This paper contains a description of the new on-line implementation, an evaluation with observations and a comparison of the performance of C-IFS with MOZART and with a re-analysis of atmospheric composition produced by IFS-MOZART within the Monitoring Atmospheric Composition and Climate (MACC) project. The chemical mechanism of C-IFS is an extended version of the Carbon Bond 2005 (CB05) chemical mechanism as implemented in the CTM Transport Model 5 (TM5). CB05 describes tropospheric chemistry with 54 species and 126 reactions. Wet deposition and lightning nitrogen monoxide (NO) emissions are modelled in C-IFS using the detailed input of the IFS physics package. A one-year simulation by C-IFS, MOZART and the MACC re-analysis is evaluated against ozonesondes, carbon monoxide (CO) aircraft profiles, European surface observations of ozone (O3), CO, sulphur dioxide (SO2) and nitrogen dioxide (NO2) as well as satellite retrievals of CO, tropospheric NO2 and formaldehyde. Anthropogenic emissions from the MACC/CityZen (MACCity) inventory and biomass burning emissions from the Global Fire Assimilation System (GFAS) data set were used in the simulations by both C-IFS and MOZART. C-IFS (CB05) showed an improved performance with respect to MOZART for CO, upper tropospheric O3, winter time SO2 and was of a similar accuracy for other evaluated species. C-IFS (CB05) is about ten times more computationally efficient than IFS-MOZART.

Comparison of tropospheric chemistry schemes for use within global models

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-19957-2008 ◽

2008 ◽

Vol 8 (6) ◽

pp. 19957-19987

Author(s):

K. M. Emmerson ◽

M. J. Evans

Keyword(s):

Transport Model ◽

Regional Scale ◽

Tropospheric Chemistry ◽

Chemical Mechanism ◽

Night Time ◽

Model Framework ◽

Transport Models ◽

Global Models ◽

Calculated Concentration ◽

Abstract. Methane and ozone are two important climate gases with significant tropospheric chemistry. Within chemistry-climate and transport models this chemistry is simplified for computational expediency. We compare the state of the art Master Chemical Mechanism (MCM) with six tropospheric chemistry schemes (CRI-reduced, GEOS-CHEM and a GEOS-CHEM adduct, MOZART, TOMCAT and CBM-IV) that could be used within composition transport models. We test the schemes within a box model framework under conditions derived from a composition transport model and from field observations from a regional scale pollution event. We find that CRI-reduced provides much skill in simulating the full chemistry, yet with greatly reduced complexity. We find significant variations between the other chemical schemes, and reach the following conclusions. 1) The inclusion of a gas phase N2O5+H2O reaction in some schemes and not others is a large source of uncertainty in the inorganic chemistry. 2) There are significant variations in the calculated concentration of PAN between the schemes, which will affect the long range transport of reactive nitrogen in global models. 3) The representation of isoprene chemistry differs hugely between the schemes, leading to significant uncertainties on the impact of isoprene on composition. 4) Night-time chemistry is badly represented with significant disagreements in the ratio of NO3 to NOx. Resolving these four issues through further investigative laboratory studies will reduce the uncertainties within the chemical schemes of global tropospheric models.

Comparison between the assimilation of IASI Level 2 retrievals and Level 1 radiances for ozone reanalyses

10.5194/amt-2018-426 ◽

2019 ◽

Author(s):

Emanuele Emili ◽

Brice Barret ◽

Eric Le Flochmoën ◽

Daniel Cariolle

Keyword(s):

Transport Model ◽

Atmospheric Composition ◽

Atmospheric Sounding ◽

Level 1 ◽

The Tropics ◽

L1 And L2 ◽

The Impact ◽

Level 2

Abstract. The prior information used for Level 2 (L2) retrievals in the thermal infrared can influence the quality of the retrievals themselves and, therefore, their further assimilation in atmospheric composition models. In this study we evaluate the differences between assimilating L2 ozone profiles and Level 1 (L1) radiances from the Infrared Atmospheric Sounding Interferometer (IASI). We minimized potential differences between the two approaches by employing the same radiative transfer code (RTTOV) and a very similar setup for both the L2 retrievals (1D-Var) and the L1 assimilation (3D-Var). We computed hourly 3D-Var reanalyses assimilating respectively L1 and L2 data in the chemical transport model MOCAGE and compared the resulting O3 fields among each other and against ozonesondes. We also evaluated the joint assimilation of limb measurements from the Microwave Limb Sounder (MLS) on top of IASI to assess the impact of stratospheric O3 on tropospheric reanalyses. Results indicate that significant differences can arise between L2 and L1 assimilation, especially in regions where the L2 prior is biased (at the tropics and in the southern hemisphere in this study). L1 and L2 assimilation give instead very similar results in the northern hemisphere, especially when MLS measurements are used to constrain the stratospheric O3 column. We conclude this study by listing remaining issues that are common to both the L1 and L2 approaches and that deserve further research.

Prior biosphere model impact on global terrestrial CO2 fluxes estimated from OCO-2 retrievals

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-13267-2019 ◽

2019 ◽

Vol 19 (20) ◽

pp. 13267-13287 ◽

Cited By ~ 1

Author(s):

Sajeev Philip ◽

Matthew S. Johnson ◽

Christopher Potter ◽

Vanessa Genovesse ◽

David F. Baker ◽

...

Keyword(s):

Transport Model ◽

Net Ecosystem Exchange ◽

Co2 Flux ◽

Inverse Model ◽

Error Statistics ◽

Prior Model ◽

The Tropics ◽

Biosphere Model ◽

Abstract. This study assesses the impact of different state of the art global biospheric CO2 flux models, when applied as prior information, on inverse model “top-down” estimates of terrestrial CO2 fluxes obtained when assimilating Orbiting Carbon Observatory 2 (OCO-2) observations. This is done with a series of observing system simulation experiments (OSSEs) using synthetic CO2 column-average dry air mole fraction (XCO2) retrievals sampled at the OCO-2 satellite spatiotemporal frequency. The OSSEs utilized a 4-D variational (4D-Var) assimilation system with the GEOS-Chem global chemical transport model (CTM) to estimate CO2 net ecosystem exchange (NEE) fluxes using synthetic OCO-2 observations. The impact of biosphere models in inverse model estimates of NEE is quantified by conducting OSSEs using the NASA-CASA, CASA-GFED, SiB-4, and LPJ models as prior estimates and using NEE from the multi-model ensemble mean of the Multiscale Synthesis and Terrestrial Model Intercomparison Project as the “truth”. Results show that the assimilation of simulated XCO2 retrievals at OCO-2 observing modes over land results in posterior NEE estimates which generally reproduce “true” NEE globally and over terrestrial TransCom-3 regions that are well-sampled. However, we find larger spread among posterior NEE estimates, when using different prior NEE fluxes, in regions and seasons that have limited OCO-2 observational coverage and a large range in “bottom-up” NEE fluxes. Seasonally averaged posterior NEE estimates had standard deviations (SD) of ∼10 % to ∼50 % of the multi-model-mean NEE for different TransCom-3 land regions with significant NEE fluxes (regions/seasons with a NEE flux ≥0.5 PgC yr−1). On a global average, the seasonally averaged residual impact of the prior model NEE assumption on the posterior NEE spread is ∼10 %–20 % of the posterior NEE mean. Additional OCO-2 OSSE simulations demonstrate that posterior NEE estimates are also sensitive to the assumed prior NEE flux uncertainty statistics, with spread in posterior NEE estimates similar to those when using variable prior model NEE fluxes. In fact, the sensitivity of posterior NEE estimates to prior error statistics was larger than prior flux values in some regions/times in the tropics and Southern Hemisphere where sufficient OCO-2 data were available and large differences between the prior and truth were evident. Overall, even with the availability of spatiotemporally dense OCO-2 data, noticeable residual differences (up to ∼20 %–30 % globally and 50 % regionally) in posterior NEE flux estimates remain that were caused by the choice of prior model flux values and the specification of prior flux uncertainties.

Impact of ECMWF ERA-Interim and ERA5 reanalysis on the simulated tracer transport and polar ozone loss using a chemical transport model TOMCAT/SLIMCAT

10.5194/egusphere-egu2020-8918 ◽

2020 ◽

Author(s):

Wuhu Feng ◽

Martyn Chipperfield ◽

Sandip Dhmose ◽

Florence Goutail ◽

Michelle Santee ◽

...

Keyword(s):

Transport Model ◽

Three Dimensional ◽

Chemical Species ◽

Chemical Transport ◽

Tropospheric Chemistry ◽

Tracer Transport ◽

Ozone Loss ◽

The Impact ◽

Polar Ozone

<div> Three-dimensional chemical transport models (CTMs) have been widely used in a wide variety of scientific studies (e.g., to obtain a better understanding of tracer transport and to study the dynamical and chemical processes which control polar ozone losses etc). However, there are still some uncertainties in the model simulations and indeed in our understanding. For example, the accuracy of ozone simulations largely depends on the transport, chemistry and treatment of PSCs in the model as well as the forcing files.&#160; Here we have used a&#160; CTM model TOMCAT/SLIMCAT with a detailed description of stratospheric and tropospheric chemistry forced by differnt wind fields (ECMWF ERA-Interim and ERA5 reanalysis datasets) to investigate the different dynamical fields on the simulated tracer transport, ozone and other chemical species. Both simulations have been run from 1979 to 2018. First we will assess the impact of different reanalysis data on the idealised tracers when the model includes additional process of the gravitational separation of gases (e.g., Ar/N2) and compare the model results with dataset of gravitational fractionation of Ar/N2 and AoA observations made on flask samples from three airborne research projects. Modelled AoA will be also compared with MIPAS data.&#160; Then we will focus on the polar ozone loss from late 1990 to 2018 and quntify the amount of chemical ozone loss using both models and satellite observations as well as&#160; SAOZ measurements. The year-to-year variation of polar ozone depletion will also be discussed, in particular for the recent years of decreasing stratospheric chlorine loading.&#160; </div>

Tropospheric chemistry in the Integrated Forecasting System of ECMWF

Geoscientific Model Development ◽

10.5194/gmd-8-975-2015 ◽

2015 ◽

Vol 8 (4) ◽

pp. 975-1003 ◽

Cited By ~ 89

Author(s):

J. Flemming ◽

V. Huijnen ◽

J. Arteta ◽

P. Bechtold ◽

A. Beljaars ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Transport Model ◽

Nitrogen Monoxide ◽

Coupled System ◽

Tropospheric Chemistry ◽

Chemical Mechanism ◽

Atmospheric Composition ◽

Data Set ◽

Forecasting System

Abstract. A representation of atmospheric chemistry has been included in the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The new chemistry modules complement the aerosol modules of the IFS for atmospheric composition, which is named C-IFS. C-IFS for chemistry supersedes a coupled system in which chemical transport model (CTM) Model for OZone and Related chemical Tracers 3 was two-way coupled to the IFS (IFS-MOZART). This paper contains a description of the new on-line implementation, an evaluation with observations and a comparison of the performance of C-IFS with MOZART and with a re-analysis of atmospheric composition produced by IFS-MOZART within the Monitoring Atmospheric Composition and Climate (MACC) project. The chemical mechanism of C-IFS is an extended version of the Carbon Bond 2005 (CB05) chemical mechanism as implemented in CTM Transport Model 5 (TM5). CB05 describes tropospheric chemistry with 54 species and 126 reactions. Wet deposition and lightning nitrogen monoxide (NO) emissions are modelled in C-IFS using the detailed input of the IFS physics package. A 1 year simulation by C-IFS, MOZART and the MACC re-analysis is evaluated against ozonesondes, carbon monoxide (CO) aircraft profiles, European surface observations of ozone (O3), CO, sulfur dioxide (SO2) and nitrogen dioxide (NO2) as well as satellite retrievals of CO, tropospheric NO2 and formaldehyde. Anthropogenic emissions from the MACC/CityZen (MACCity) inventory and biomass burning emissions from the Global Fire Assimilation System (GFAS) data set were used in the simulations by both C-IFS and MOZART. C-IFS (CB05) showed an improved performance with respect to MOZART for CO, upper tropospheric O3, and wintertime SO2, and was of a similar accuracy for other evaluated species. C-IFS (CB05) is about 10 times more computationally efficient than IFS-MOZART.