scholarly journals HCOOH distributions from IASI for 2008–2014: comparison with ground-based FTIR measurements and a global chemistry-transport model

2016 ◽  
Author(s):  
M. Pommier ◽  
C. Clerbaux ◽  
P.-F. Coheur ◽  
E. Mahieu ◽  
J.-F. Müller ◽  
...  
Keyword(s):  
Transport Model ◽  
Positive Trend ◽  
Good Representation ◽  
La Réunion ◽  
Transport Models ◽  
Chemistry Transport Model ◽  
Biogenic Emission ◽  
Annual Cycles ◽  
Sources And Sinks ◽  
Mountainous Regions

Abstract. Formic acid (HCOOH) is one of the most abundant volatile organic compounds in the atmosphere. It is a major contributor to rain acidity in remote areas. There are however large uncertainties on its sources and sinks, and HCOOH is misrepresented by global chemistry-transport models. This work presents global distributions from 2008 to 2014 as derived from the measurements of the Infrared Atmospheric Sounding Interferometer (IASI), based on conversion factors between brightness temperature differences and representative retrieved total columns over seven regions: Africa N, Africa S, Amazonia, Atlantic, Australia, Pacific and Russia. The dependence of the thermal contrast is taking account in the conversion method. This conversion presents errors lower than 20 % for total columns ranging between 0.5 and 1 × 1016 molec/cm2 but reaches higher values, up to 78 %, for columns lower than 0.3 × 1016 molec/cm2. Signatures from biomass burning events are highlighted, such as in the Southern Hemisphere and in Russia, as well as biogenic emission sources, e.g. over Eastern US. A comparison between 2008 and 2014 with ground-based FTIR measurements obtained at 4 locations (Maido and Saint-Denis at La Réunion, Jungfraujoch and Wollongong) is shown. Although IASI columns are found to correlate well with FTIR data, a large bias (> 100 %) is found over the two sites at La Réunion. A better agreement is found at Wollongong with a negligible bias. The comparison also highlights the difficulty for IASI to retrieve the total columns over mountainous regions such as Jungfraujoch. A comparison of the retrieved columns with the global chemistry-transport model IMAGESv2 is also presented, showing the good representation of the seasonal and inter-annual cycles over America, Australia, Asia and Siberia. A global model underestimation of the distribution and a misrepresentation of the seasonal cycle over India are also noted. A small positive trend in the IASI columns is also observed over Australia, Amazonia and India over 2008–2014 (from 0.7 to 1.5 %/year), while a decrease of ~ 0.8 %/year is measured over Siberia.

scholarly journals HCOOH distributions from IASI for 2008–2014: comparison with ground-based FTIR measurements and a global chemistry-transport model

2016 ◽  
Vol 16 (14) ◽  
pp. 8963-8981 ◽  
Author(s):  
Matthieu Pommier ◽  
Cathy Clerbaux ◽  
Pierre-François Coheur ◽  
Emmanuel Mahieu ◽  
Jean-François Müller ◽  
...  
Keyword(s):  
Transport Model ◽  
Positive Trend ◽  
Good Representation ◽  
La Réunion ◽  
Transport Models ◽  
Chemistry Transport Model ◽  
Biogenic Emission ◽  
Sources And Sinks ◽  
Mountainous Regions ◽  
Eastern Usa

Abstract. Formic acid (HCOOH) is one of the most abundant volatile organic compounds in the atmosphere. It is a major contributor to rain acidity in remote areas. There are, however, large uncertainties on the sources and sinks of HCOOH and therefore HCOOH is misrepresented by global chemistry-transport models. This work presents global distributions from 2008 to 2014 as derived from the measurements of the Infrared Atmospheric Sounding Interferometer (IASI), based on conversion factors between brightness temperature differences and representative retrieved total columns over seven regions: Northern Africa, southern Africa, Amazonia, Atlantic, Australia, Pacific, and Russia. The dependence of the measured HCOOH signal on the thermal contrast is taken into account in the conversion method. This conversion presents errors lower than 20 % for total columns ranging between 0.5 and 1 × 1016 molec cm−2 but reaches higher values, up to 78 %, for columns that are lower than 0.3 × 1016 molec cm−2. Signatures from biomass burning events are highlighted, such as in the Southern Hemisphere and in Russia, as well as biogenic emission sources, e.g., over the eastern USA. A comparison between 2008 and 2014 with ground-based Fourier transform infrared spectroscopy (FTIR) measurements obtained at four locations (Maido and Saint-Denis at La Réunion, Jungfraujoch, and Wollongong) is shown. Although IASI columns are found to correlate well with FTIR data, a large bias (> 100 %) is found over the two sites at La Réunion. A better agreement is found at Wollongong with a negligible bias. The comparison also highlights the difficulty of retrieving total columns from IASI measurements over mountainous regions such as Jungfraujoch. A comparison of the retrieved columns with the global chemistry-transport model IMAGESv2 is also presented, showing good representation of the seasonal and interannual cycles over America, Australia, Asia, and Siberia. A global model underestimation of the distribution and a misrepresentation of the seasonal cycle over India are also found. A small positive trend in the IASI columns is observed over Australia, Amazonia, and India over the 2008–2014 period (from 0.7 to 1.5 % year−1), while a decrease of ∼ 0.8 % year−1 is measured over Siberia.

scholarly journals The importance of transport model uncertainties for the estimation of CO<sub>2</sub> sources and sinks using satellite measurements

2010 ◽  
Vol 10 (20) ◽  
pp. 9981-9992 ◽  
Author(s):  
S. Houweling ◽  
I. Aben ◽  
F.-M. Breon ◽  
F. Chevallier ◽  
N. Deutscher ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
A Priori ◽  
Model Errors ◽  
Tracer Transport ◽  
Satellite Measurements ◽  
Transport Models ◽  
Sources And Sinks ◽  
The Impact ◽  
Ppm Level

Abstract. This study presents a synthetic model intercomparison to investigate the importance of transport model errors for estimating the sources and sinks of CO2 using satellite measurements. The experiments were designed for testing the potential performance of the proposed CO2 lidar A-SCOPE, but also apply to other space borne missions that monitor total column CO2. The participating transport models IFS, LMDZ, TM3, and TM5 were run in forward and inverse mode using common a priori CO2 fluxes and initial concentrations. Forward simulations of column averaged CO2 (xCO2) mixing ratios vary between the models by σ=0.5 ppm over the continents and σ=0.27 ppm over the oceans. Despite the fact that the models agree on average on the sub-ppm level, these modest differences nevertheless lead to significant discrepancies in the inverted fluxes of 0.1 PgC/yr per 106 km2 over land and 0.03 PgC/yr per 106 km2 over the ocean. These transport model induced flux uncertainties exceed the target requirement that was formulated for the A-SCOPE mission of 0.02 PgC/yr per 106 km2, and could also limit the overall performance of other CO2 missions such as GOSAT. A variable, but overall encouraging agreement is found in comparison with FTS measurements at Park Falls, Darwin, Spitsbergen, and Bremen, although systematic differences are found exceeding the 0.5 ppm level. Because of this, our estimate of the impact of transport model uncerainty is likely to be conservative. It is concluded that to make use of the remote sensing technique for quantifying the sources and sinks of CO2 not only requires highly accurate satellite instruments, but also puts stringent requirements on the performance of atmospheric transport models. Improving the accuracy of these models should receive high priority, which calls for a closer collaboration between experts in atmospheric dynamics and tracer transport.

scholarly journals Representing the effects of stratosphere–troposphere exchange on 3-D O<sub>3</sub> distributions in chemistry transport models using a potential vorticity-based parameterization

2016 ◽  
Vol 16 (17) ◽  
pp. 10865-10877 ◽  
Author(s):  
Jia Xing ◽  
Rohit Mathur ◽  
Jonathan Pleim ◽  
Christian Hogrefe ◽  
Jiandong Wang ◽  
...  
Keyword(s):  
Potential Vorticity ◽  
Transport Model ◽  
Model Performance ◽  
Surface Concentration ◽  
Weather Research And Forecasting ◽  
Regional Models ◽  
Transport Models ◽  
Reference Case ◽  
Chemistry Transport Model ◽  
Spatially Varying

Abstract. Downward transport of ozone (O3) from the stratosphere can be a significant contributor to tropospheric O3 background levels. However, this process often is not well represented in current regional models. In this study, we develop a seasonally and spatially varying potential vorticity (PV)-based function to parameterize upper tropospheric and/or lower stratospheric (UTLS) O3 in a chemistry transport model. This dynamic O3–PV function is developed based on 21-year ozonesonde records from World Ozone and Ultraviolet Radiation Data Centre (WOUDC) with corresponding PV values from a 21-year Weather Research and Forecasting (WRF) simulation across the Northern Hemisphere from 1990 to 2010. The result suggests strong spatial and seasonal variations of O3 ∕ PV ratios which exhibits large values in the upper layers and in high-latitude regions, with highest values in spring and the lowest values in autumn over an annual cycle. The newly developed O3 ∕ PV function was then applied in the Community Multiscale Air Quality (CMAQ) model for an annual simulation of the year 2006. The simulated UTLS O3 agrees much better with observations in both magnitude and seasonality after the implementation of the new parameterization. Considerable impacts on surface O3 model performance were found in the comparison with observations from three observational networks, i.e., EMEP, CASTNET and WDCGG. With the new parameterization, the negative bias in spring is reduced from −20 to −15 % in the reference case to −9 to −1 %, while the positive bias in autumn is increased from 1 to 15 % in the reference case to 5 to 22 %. Therefore, the downward transport of O3 from upper layers has large impacts on surface concentration and needs to be properly represented in regional models.

scholarly journals Sensitivity of chemistry-transport model simulations to the duration of chemical and transport operators: a case study with GEOS-Chem v10-01

2016 ◽  
Vol 9 (5) ◽  
pp. 1683-1695 ◽  
Author(s):  
Sajeev Philip ◽  
Randall V. Martin ◽  
Christoph A. Keller
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxides ◽  
Spatial Resolution ◽  
Transport Model ◽  
Transport Models ◽  
Chemistry Transport Model ◽  
Simulation Accuracy ◽  
Transport Operator ◽  
Computational Expense ◽  
Simulation Error

Abstract. Chemistry-transport models involve considerable computational expense. Fine temporal resolution offers accuracy at the expense of computation time. Assessment is needed of the sensitivity of simulation accuracy to the duration of chemical and transport operators. We conduct a series of simulations with the GEOS-Chem chemistry-transport model at different temporal and spatial resolutions to examine the sensitivity of simulated atmospheric composition to operator duration. Subsequently, we compare the species simulated with operator durations from 10 to 60 min as typically used by global chemistry-transport models, and identify the operator durations that optimize both computational expense and simulation accuracy. We find that longer continuous transport operator duration increases concentrations of emitted species such as nitrogen oxides and carbon monoxide since a more homogeneous distribution reduces loss through chemical reactions and dry deposition. The increased concentrations of ozone precursors increase ozone production with longer transport operator duration. Longer chemical operator duration decreases sulfate and ammonium but increases nitrate due to feedbacks with in-cloud sulfur dioxide oxidation and aerosol thermodynamics. The simulation duration decreases by up to a factor of 5 from fine (5 min) to coarse (60 min) operator duration. We assess the change in simulation accuracy with resolution by comparing the root mean square difference in ground-level concentrations of nitrogen oxides, secondary inorganic aerosols, ozone and carbon monoxide with a finer temporal or spatial resolution taken as “truth”. Relative simulation error for these species increases by more than a factor of 5 from the shortest (5 min) to longest (60 min) operator duration. Chemical operator duration twice that of the transport operator duration offers more simulation accuracy per unit computation. However, the relative simulation error from coarser spatial resolution generally exceeds that from longer operator duration; e.g., degrading from 2°  ×  2.5° to 4°  ×  5° increases error by an order of magnitude. We recommend prioritizing fine spatial resolution before considering different operator durations in offline chemistry-transport models. We encourage chemistry-transport model users to specify in publications the durations of operators due to their effects on simulation accuracy.

scholarly journals Interpreting the variability of space-borne CO<sub>2</sub> column-averaged volume mixing ratios over North America using a chemistry transport model

2008 ◽  
Vol 8 (19) ◽  
pp. 5855-5868 ◽  
Author(s):  
P. I. Palmer ◽  
M. P. Barkley ◽  
P. S. Monks
Keyword(s):  
North America ◽  
North American ◽  
Significant Contribution ◽  
Transport Model ◽  
Co2 Flux ◽  
Chemistry Transport Model ◽  
Sources And Sinks ◽  
Mixing Ratios ◽  
Non Local ◽  
Flux Estimation

Abstract. We use the GEOS-Chem chemistry transport model to interpret the sources and sinks of CO2 that determine variability of column-averaged volume mixing ratios (CVMRs), as observed by the SCIAMACHY satellite instrument, during the 2003 North American growing season. GEOS-Chem generally reproduces the magnitude and seasonal cycle of observed CO2 surface VMRs across North America and is quantitatively consistent with column VMRs in later years. However, it cannot reproduce the magnitude or variability of FSI-WFM-DOAS SCIAMACHY CVMRs. We use model tagged tracers to show that local fluxes largely determine CVMR variability over North America, with the largest individual CVMR contributions (1.1%) from the land biosphere. Fuel sources are relatively constant while biomass burning makes a significant contribution only during midsummer. We also show that non-local sources contribute significantly to total CVMRs over North America, with the boreal Asian land biosphere contributing close to 1% in midsummer at high latitudes. We used the monthly-mean Jacobian matrix for North America to illustrate that:~1) North American CVMRs represent a superposition of many weak flux signatures, but differences in flux distributions should permit independent flux estimation; and 2) the atmospheric e-folding lifetimes for many of these flux signatures are 3–4 months, beyond which time they are too well-mixed to interpret. These long lifetimes will improve the efficacy of observed CVMRs as surface CO2 flux constraints.

scholarly journals Representing the effects of stratosphere-troposphere exchange on 3D O<sub>3</sub> distributions in chemistry transport models using a potential vorticity based parameterization

2016 ◽  
Author(s):  
Jia Xing ◽  
Rohit Mathur ◽  
Jonathan Pleim ◽  
Christian Hogrefe ◽  
Jiandong Wang ◽  
...  
Keyword(s):  
Potential Vorticity ◽  
Transport Model ◽  
Model Performance ◽  
Surface Concentration ◽  
Weather Research And Forecasting ◽  
Regional Models ◽  
Transport Models ◽  
Reference Case ◽  
Chemistry Transport Model ◽  
Spatially Varying

Abstract. Downward transport of ozone (O3) from the stratosphere can be a significant contributor to tropospheric O3 background levels. However, this process often is not well represented in current regional models. In this study, we develop a seasonally and spatially varying potential vorticity (PV)-based function to numerically assimilate upper tropospheric / lower stratospheric (UTLS) O3 in a chemistry transport model. This dynamic O3-PV function is parametrized based on 21-year ozonesonde records from World Ozone and Ultraviolet Radiation Data Centre (WOUDC) with corresponding PV values from a 21-year Weather Research and Forecasting (WRF) simulation across the northern hemisphere from 1990 to 2010. The result suggests strong spatial and seasonal variations of O3/PV ratios which exhibits large values in the upper layers and in high latitude regions, with highest values in spring and the lowest values in autumn over an annual cycle. The newly-developed O3/PV function was then applied in the Community Multiscale Air Quality (CMAQ) model for an annual simulation of the year 2006. The simulated UTLS O3 agrees much better with observations in both magnitude and seasonality after the implementation of the new function. Considerable impacts on surface O3 model performance were found in the comparison with observations from three observational networks, i.e., EMEP, CASTNET and WDCGG. With the new function, the negative bias in spring is reduced from −20 to −15 % in the reference case to −9 to −1 %, while the positive bias in autumn is increased from 1 to 15 % in the reference case to 5 to 22 %. Therefore, the downward transport of O3 from upper layers has large impacts on surface concentration and needs to be properly represented in regional models.

scholarly journals The importance of transport model uncertainties for the estimation of CO<sub>2</sub> sources and sinks using satellite measurements

2010 ◽  
Vol 10 (6) ◽  
pp. 14737-14769 ◽  
Author(s):  
S. Houweling ◽  
I. Aben ◽  
F.-M. Breon ◽  
F. Chevallier ◽  
N. Deutscher ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Model Errors ◽  
Satellite Measurements ◽  
Transport Models ◽  
Sources And Sinks ◽  
Remote Sensing Technique ◽  
Mixing Ratios ◽  
Further Development ◽  
Ppm Level

Abstract. This study presents a synthetic model intercomparison to investigate the importance of transport model errors for estimating the sources and sinks of CO2 using satellite measurements. The experiments were designed for testing the potential performance of the proposed CO2 lidar A-SCOPE, but also apply to other space borne missions that monitor total column CO2. The participating transport models IFS, LMDZ, TM3, and TM5 were run in forward and inverse mode using common CO2 fluxes and initial concentrations. Simulated column averaged CO2 (xCO2) mixing ratios vary between the models by σ=0.5 ppm over the continents and σ=0.27 ppm over sea. A variable, but overall quite encouraging agreement is found in comparison with FTS measurements at Park Falls, Darwin, Spitsbergen, and Bremen. Despite the fact that the models agree on average on the sub-ppm level, these modest differences nevertheless lead to significant discrepancies in the inverted fluxes of 0.1 Pg C/yr per 106 km2 over land and 0.03 Pg C/yr per 106 km2 over the ocean. These transport model induced flux uncertainties exceed the target requirement that was formulated for the A-SCOPE mission of 0.02 Pg C/yr per 106 km2, and could also limit the overall performance of other CO2 missions such as GOSAT. It is concluded that to make use of the remote sensing technique for quantifying the sources and sinks of CO2 not only requires highly accurate satellite instruments, but also puts stringent requirements on the performance of atmospheric transport models. Further development of these models should receive high priority.

scholarly journals Monitoring aerosols over Europe: an assessment of the potential benefit of assimilating the VIS04 measurements from the future MTG/FCI geostationary imager

2018 ◽  
Author(s):  
Maxence Descheemaecker ◽  
Matthieu Plu ◽  
Virginie Marécal ◽  
Marine Claeyman ◽  
Francis Olivier ◽  
...  
Keyword(s):  
Transport Model ◽  
Positive Impact ◽  
Added Value ◽  
Spatial And Temporal Patterns ◽  
Transport Models ◽  
Chemistry Transport Model ◽  
The Future ◽  
General Benefit ◽  
Pollution Event ◽  
Observing System Simulation Experiment

Abstract. The study assesses the possible benefit of assimilating Aerosol Optical Depth (AOD) from the future spaceborne sensor FCI (Flexible Combined Imager) for air quality monitoring in Europe. An Observing System Simulation Experiment (OSSE) was designed and applied over a 4-months period that includes a severe pollution episode. The study focuses on the FCI channel centred at 444 nm, which is the shortest wavelength of FCI. A Nature Run (NR) and four different Control Runs of the MOCAGE chemistry-transport model were designed and evaluated to guarantee the robustness of the OSSE results. The AOD synthetic observations from the NR were disturbed by errors that are typical of the FCI. The variance of the FCI AOD at 444 nm was deduced from a global sensitivity analysis that took into account the aerosol type, surface reflectance and different atmospheric optical properties. The experiments show a general benefit on all statistical indicators of the assimilation of the FCI AOD at 444 nm for aerosol concentrations at surface over Europe, and also a positive impact during the severe pollution event. The simulations with data assimilation reproduced spatial and temporal patterns of PM10 concentrations at surface better than without assimilation all along the simulations and especially during the pollution event. This work demonstrates the capability of data from the future FCI sensor to bring an added value to the MOCAGE aerosol simulations, and in general, to other chemistry transport models.

scholarly journals Variability of springtime transpacific pollution transport during 2000–2006: the INTEX-B mission in the context of previous years

2010 ◽  
Vol 10 (3) ◽  
pp. 1345-1359 ◽  
Author(s):  
G. G. Pfister ◽  
L. K. Emmons ◽  
D. P. Edwards ◽  
A. Arellano ◽  
T. Campos ◽  
...  
Keyword(s):  
Transport Model ◽  
Pollution Transport ◽  
Chemistry Transport Model ◽  
Pollution Levels ◽  
Annual Variability ◽  
Source Regions ◽  
Time Period ◽  
The Pacific ◽  
The Us ◽  
Transport Experiment

Abstract. We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.

scholarly journals The On-Line Integrated Mesoscale Chemistry Model BOLCHEM

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 192
Author(s):  
Rita Cesari ◽  
Tony Christian Landi ◽  
Massimo D’Isidoro ◽  
Mihaela Mircea ◽  
Felicita Russo ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Transport Model ◽  
Horizontal Resolution ◽  
Integration Step ◽  
Chemistry Transport Model ◽  
European Environmental Agency ◽  
On Line ◽  
One Year ◽  
Pm2.5 And Pm10 ◽  
Monitoring Service

This work presents the on-line coupled meteorology–chemistry transport model BOLCHEM, based on the hydrostatic meteorological BOLAM model, the gas chemistry module SAPRC90, and the aerosol dynamic module AERO3. It includes parameterizations to describe natural source emissions, dry and wet removal processes, as well as the transport and dispersion of air pollutants. The equations for different processes are solved on the same grid during the same integration step, by means of a time-split scheme. This paper describes the model and its performance at horizontal resolution of 0.2∘× 0.2∘ over Europe and 0.1∘× 0.1∘ in a nested configuration over Italy, for one year run (December 2009–November 2010). The model has been evaluated against the AIRBASE data of the European Environmental Agency. The basic statistics for higher resolution simulations of O3, NO2 and particulate matter concentrations (PM2.5 and PM10) have been compared with those from Copernicus Atmosphere Monitoring Service (CAMS) ensemble median. In summer, for O3 we found a correlation coefficient R of 0.72 and mean bias of 2.15 over European domain and a correlation coefficient R of 0.67 and mean bias of 2.36 over Italian domain. PM10 and PM2.5 are better reproduced in the winter, the latter with a correlation coefficient R of 0.66 and the mean bias MB of 0.35 over Italian domain.

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