First estimate of NO2 in the upper troposphere from TROPOMI

Commercial Aircraft ◽

Upper Troposphere ◽

Aircraft Observations ◽

Research Aircraft ◽

Ozone Monitoring ◽

Sky Conditions

Nitrogen oxides (NO x = NO + NO2) in the upper troposphere (~10-12 km) are effective at producing ozone in the upper troposphere where ozone is a potent greenhouse gas. Observations of NOx in the upper troposphere are limited in time to a few intensive research aircraft campaigns and in space to commercial aircraft campaigns. There are satellite-derived observations of NO2 in the upper troposphere from the Ozone Monitoring Instrument (OMI), but these are at very coarse resolutions (seasonal, > 2,000 km). The high-resolution Sentinel-5P/TROPOMI instrument offers higher spatial resolution and better cloud-resolving capability than OMI. Here we use synthetic columns of NO2 from the GEOS-Chem chemical transport model to assess feasibility of deriving NO2 in the upper troposphere using partial columns of NO2 above cloudy scenes (the so-called cloud-slicing technique). The model is also used to quantify errors induced by uncertainties in cloud-top height and to determine whether NO2 over cloudy scenes is representative of all-sky conditions (the "truth"). We find that the cloud-slicing approach is spatially consistent (R =0.5) with the "truth", but with a small (10 pptv) bias in background NO2. Cloud-slicing is then applied to TROPOMI total columns of NO2 to derive near-global observations of NO2 in the upper troposphere and assessed against the existing OMI products and aircraft observations from NASA DC8 aircraft campaigns.

Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model

10.5194/acpd-13-21455-2013 ◽

2013 ◽

Vol 13 (8) ◽

pp. 21455-21505

Author(s):

E. Emili ◽

B. Barret ◽

S. Massart ◽

E. Le Flochmoen ◽

A. Piacentini ◽

...

Keyword(s):

Tropospheric Ozone ◽

Radiative Forcing ◽

Transport Model ◽

Stratospheric Ozone ◽

Chemical Transport ◽

Free Troposphere ◽

Global Chemical Transport Model ◽

The Impact

Abstract. Accurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. In this study we examine the impact of assimilating ozone observations from the Microwave Limb Sounder (MLS) and the Infrared Atmospheric Sounding Interferometer (IASI) in a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE). The assimilation of the two instruments is performed by means of a variational algorithm (4-D-VAR) and allows to constrain stratospheric and tropospheric ozone simultaneously. The analysis is first computed for the months of August and November 2008 and validated against ozone-sondes measurements to verify the presence of observations and model biases. It is found that the IASI Tropospheric Ozone Column (TOC, 1000–225 hPa) should be bias-corrected prior to assimilation and MLS lowermost level (215 hPa) excluded from the analysis. Furthermore, a longer analysis of 6 months (July–August 2008) showed that the combined assimilation of MLS and IASI is able to globally reduce the uncertainty (Root Mean Square Error, RMSE) of the modeled ozone columns from 30% to 15% in the Upper-Troposphere/Lower-Stratosphere (UTLS, 70–225 hPa) and from 25% to 20% in the free troposphere. The positive effect of assimilating IASI tropospheric observations is very significant at low latitudes (30° S–30° N), whereas it is not demonstrated at higher latitudes. Results are confirmed by a comparison with additional ozone datasets like the Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC) data, the Ozone Monitoring Instrument (OMI) total ozone columns and several high-altitude surface measurements. Finally, the analysis is found to be little sensitive to the assimilation parameters and the model chemical scheme, due to the high frequency of satellite observations compared to the average life-time of free-troposphere/low-stratosphere ozone.

The MOPITT Version 6 product: algorithm enhancements and validation

Atmospheric Measurement Techniques ◽

10.5194/amt-7-3623-2014 ◽

2014 ◽

Vol 7 (11) ◽

pp. 3623-3632 ◽

Cited By ~ 60

Author(s):

M. N. Deeter ◽

S. Martínez-Alonso ◽

D. P. Edwards ◽

L. K. Emmons ◽

J. C. Gille ◽

...

Keyword(s):

Transport Model ◽

A Priori ◽

Chemical Transport ◽

Upper Troposphere ◽

Community Atmosphere Model ◽

Model Community ◽

Modern Era ◽

Retrieval Bias ◽

Co Concentrations

Abstract. The Measurements of Pollution in the Troposphere (MOPITT) Version 6 (V6) product for carbon monoxide (CO) incorporates several enhancements which will benefit many users of MOPITT data. V6 algorithm improvements are described in detail, and V6 validation results are presented. First, a geolocation bias related to the orientation of the MOPITT instrument relative to the TERRA platform was characterized and eliminated. Second, the variable a priori for CO concentrations for V6 is based on simulations performed with the chemical transport model Community Atmosphere Model with Chemistry (CAM-chem) for the years 2000–2009 instead of the model-derived climatology for 1997–2004 used for V5. Third, meteorological fields required for V6 retrieval processing are extracted from the MERRA (Modern-Era Retrospective Analysis For Research And Applications) reanalysis. Finally, a significant latitude-dependent retrieval bias in the upper troposphere in Version 5 products has been substantially reduced.

Characteristics of intercontinental transport of tropospheric ozone from Africa to Asia

10.5194/acp-2017-728 ◽

2017 ◽

Author(s):

Han Han ◽

Jane Liu ◽

Huiling Yuan ◽

Ye Zhu ◽

Yue Wu ◽

...

Keyword(s):

Tropospheric Ozone ◽

Transport Model ◽

Chemical Transport ◽

Early Spring ◽

Boreal Summer ◽

Boreal Winter ◽

Upper Troposphere ◽

Intercontinental Transport ◽

Global Chemical Transport Model

Abstract. Based on 20-year simulations using a global chemical transport model, GEOS-Chem, and a trajectory model, HYSPLIT, the transport of ozone produced in the African troposphere to Asia is investigated. The study shows that the influence of African ozone on Asia varies largely in time and space. In the middle and upper troposphere, the inflow of African ozone to Asia peaks around 25° N, being the largest in boreal winter and early spring (> 10 ppbv) and the lowest in boreal summer (

Global and regional effects of the photochemistry of CH3O2NO2: evidence from ARCTAS

10.5194/acpd-11-2233-2011 ◽

2011 ◽

Vol 11 (1) ◽

pp. 2233-2262

Author(s):

E. C. Browne ◽

A. E. Perring ◽

P. J. Wooldridge ◽

E. Apel ◽

S. R. Hall ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Biomass Burning ◽

Low Temperatures ◽

Transport Model ◽

Chemical Transport ◽

Upper Troposphere ◽

Regional Effects ◽

Global Chemical Transport Model ◽

Lightning Nox

Abstract. Using measurements from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment, we show that methyl peroxy nitrate (CH3O2NO2) is present in concentrations of ~5–15 pptv in the springtime arctic upper troposphere. We investigate the regional and global effects of CH3O2NO2 by including its chemistry in the GEOS-CHEM 3-D global chemical transport model. We find that at temperatures below 240 K inclusion of CH3O2NO2 chemistry results in decreases of up to ~20% in NOx, ~20% in N2O5, ~5% in HNO3, ~2% in ozone, and increases in methyl hydrogen peroxide of up to ~14%. Larger changes are observed in biomass burning plumes lofted to high altitude. Additionally, by sequestering NOx at low temperatures, CH3O2NO2 decreases the cycling of HO2 to OH, resulting in a larger upper tropospheric HO2 to OH ratio. These results may impact some estimates of lightning NOx sources as well as help explain differences between models and measurements of upper tropospheric composition.

Validation of TES methane with HIPPO aircraft observations: implications for inverse modeling of methane sources

10.5194/acpd-11-27887-2011 ◽

2011 ◽

Vol 11 (10) ◽

pp. 27887-27911

Author(s):

K. J. Wecht ◽

D. J. Jacob ◽

S. C. Wofsy ◽

E. A. Kort ◽

J. R. Worden ◽

...

Keyword(s):

Simulation Experiment ◽

Transport Model ◽

Observation System ◽

Surface Type ◽

Upper Troposphere ◽

The Pacific ◽

Standard Product ◽

Aircraft Observations ◽

Better Than

Abstract. We validate satellite methane observations from the Tropospheric Emission Spectrometer (TES) with 151 aircraft vertical profiles over the Pacific from the HIAPER Pole-to-Pole Observation (HIPPO) program. We find that a collocation window of ±750 km and ±24 h does not introduce significant error in comparing TES and aircraft profiles. We validate both the TES standard product (V004) and an experimental product with two pieces of information in the vertical (V005). We determine a V004 mean bias of 65.7 ppb with residual standard deviation of 44.2 ppb. For V005 we determine mean biases (residual standard deviations) in the lower and upper troposphere of 18.2 (31.1) and 49.4 (33.2) ppb, respectively. TES errors show no significant dependence on latitude or surface type. Even when V005 cannot retrieve two pieces of information it still performs better than V004. An observation system simulation experiment (OSSE) with the GEOS-Chem chemical transport model (CTM) and its adjoint shows that TES V004 has only limited value for constraining methane sources. Our successful validation of V005 encourages its production as a standard retrieval to replace V004.

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations

10.5194/acpd-10-26361-2010 ◽

2010 ◽

Vol 10 (11) ◽

pp. 26361-26410 ◽

Cited By ~ 4

Author(s):

H. Sodemann ◽

M. Pommier ◽

S. R. Arnold ◽

S. A. Monks ◽

K. Stebel ◽

...

Keyword(s):

Transport Model ◽

Chemical Transport ◽

The Arctic ◽

Actual State ◽

Horizontal Structure ◽

Model Simulations ◽

Aircraft Observations ◽

Total Column ◽

Aircraft Data

Abstract. During the POLARCAT summer campaign in 2008, two episodes (2–5 July and 7–10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport models in the Arctic, which is a challenging model domain due to numerical and other complications. Here we compare transport simulations of carbon monoxide (CO) from the Lagrangian transport model FLEXPART, the Eulerian chemical transport model TOMCAT, and for numerical aspects the limited-area chemical transport model WRF-Chem. Retrievals of total column CO from the IASI passive infrared sensor onboard the MetOp-A satellite are used as a total column CO reference for the two simulations. Main aspect of the comparison is how realistic horizontal and vertical structures are represented in the model simulations. Analysis of CALIPSO lidar curtains and in situ aircraft measurements provide further independent reference points to assess how reliable the model simulations are and what the main limitations are. The horizontal structure of mid-latitude pollution plumes agrees well between the IASI total column CO and the model simulations. However, finer-scale structures are too quickly diffused in the Eulerian models. Aircraft data suggest that the satellite data are biased high, while TOMCAT and WRF-Chem are biased low. FLEXPART fits the aircraft data rather well, but due to added background concentrations the simulation is not independent from observations. The multi-data, multi-model approach allows separating the influences of meteorological fields, model realisation, and grid type on the plume structure. In addition to the very good agreement between simulated and observed total column CO fields, the results also highlight the difficulty to identify a data set that most realistically represents the actual state of the atmosphere.

Trends in Global Tropospheric Ozone Inferred from a Composite Record of TOMS/OMI/MLS/OMPS Satellite Measurements and the MERRA-2 GMI Simulation

10.5194/acp-2018-716 ◽

2018 ◽

Cited By ~ 1

Author(s):

Jerry R. Ziemke ◽

Luke D. Oman ◽

Sarah A. Strode ◽

Anne R. Douglass ◽

Mark A. Olsen ◽

...

Keyword(s):

East Asia ◽

Tropospheric Ozone ◽

Transport Model ◽

Central Africa ◽

Chemical Transport ◽

Satellite Measurements ◽

Ozone Trends ◽

Ne Pacific

Abstract. Past studies have suggested that ozone in the troposphere has increased globally throughout much of the 20th century due to increases in anthropogenic emissions and transport. We show by combining satellite measurements with a chemical transport model that during the last four decades tropospheric ozone does indeed indicate increases that are global in nature, yet still highly regional. Satellite ozone measurements from Nimbus-7 and Earth Probe Total Ozone Mapping Spectrometer (TOMS) are merged with ozone measurements from Aura Ozone Monitoring Instrument/Microwave Limb Sounder (OMI/MLS) to determine trends in tropospheric ozone for 1979–2016. Both TOMS (1979–2005) and OMI/MLS (2005–2016) depict large increases in tropospheric ozone from the Near East to India/East Asia and further eastward over the Pacific Ocean. The 38-year merged satellite record shows total net change over this region of about +6 to +7 Dobson Units (DU) (i.e., ~ 15–20 % of average background ozone), with the largest increase (~ 4 DU) occurring during the 2005–2016 Aura period. The Global Modeling Initiative (GMI) chemical transport model with time-varying emissions is included to evaluate tropospheric ozone trends for 1980–2016. The GMI simulation for the combined record also depicts greatest increases of +6 to +7 DU over India/east Asia, identical to the satellite measurements. In regions of significant increases in TCO the trends are a factor of 2–2.5 larger for the Aura record when compared to the earlier TOMS record; for India/east Asia the trends in TCO for both GMI and satellite measurements are ~ +3 DU-decade−1 or greater during 2005–2016 compared to about +1.2 to +1.4 DU-decade−1 for 1979–2016. The GMI simulation and satellite data also reveal a tropospheric ozone increase of ~ +4 to +5 DU for the 38-year record over central Africa and the tropical Atlantic Ocean. Both the GMI simulation and satellite-measured tropospheric ozone during the latter Aura time period show increases of ~ +3 DU-decade−1 over the NH Atlantic and NE Pacific.

Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-177-2014 ◽

2014 ◽

Vol 14 (1) ◽

pp. 177-198 ◽

Cited By ~ 18

Author(s):

E. Emili ◽

B. Barret ◽

S. Massart ◽

E. Le Flochmoen ◽

A. Piacentini ◽

...

Keyword(s):

Tropospheric Ozone ◽

Radiative Forcing ◽

Transport Model ◽

Stratospheric Ozone ◽

Chemical Transport ◽

Intercontinental Transport ◽

Global Chemical Transport Model ◽

The Impact

Abstract. Accurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. We consider a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE) in combination with a linear ozone chemistry scheme to examine the impact of assimilating observations from the Microwave Limb Sounder (MLS) and the Infrared Atmospheric Sounding Interferometer (IASI). The assimilation of the two instruments is performed by means of a variational algorithm (4D-VAR) and allows to constrain stratospheric and tropospheric ozone simultaneously. The analysis is first computed for the months of August and November 2008 and validated against ozonesonde measurements to verify the presence of observations and model biases. Furthermore, a longer analysis of 6 months (July–December 2008) showed that the combined assimilation of MLS and IASI is able to globally reduce the uncertainty (root mean square error, RMSE) of the modeled ozone columns from 30 to 15% in the upper troposphere/lower stratosphere (UTLS, 70–225 hPa). The assimilation of IASI tropospheric ozone observations (1000–225 hPa columns, TOC – tropospheric O3 column) decreases the RMSE of the model from 40 to 20% in the tropics (30° S–30° N), whereas it is not effective at higher latitudes. Results are confirmed by a comparison with additional ozone data sets like the Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC) data, the Ozone Monitoring Instrument (OMI) total ozone columns and several high-altitude surface measurements. Finally, the analysis is found to be insensitive to the assimilation parameters. We conclude that the combination of a simplified ozone chemistry scheme with frequent satellite observations is a valuable tool for the long-term analysis of stratospheric and free-tropospheric ozone.

Trends in global tropospheric ozone inferred from a composite record of TOMS/OMI/MLS/OMPS satellite measurements and the MERRA-2 GMI simulation

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-3257-2019 ◽

2019 ◽

Vol 19 (5) ◽

pp. 3257-3269 ◽

Cited By ~ 24

Author(s):

Jerry R. Ziemke ◽

Luke D. Oman ◽

Sarah A. Strode ◽

Anne R. Douglass ◽

Mark A. Olsen ◽

...

Keyword(s):

East Asia ◽

Tropospheric Ozone ◽

Transport Model ◽

Central Africa ◽

Chemical Transport ◽

Satellite Measurements ◽

Ozone Trends ◽

Ne Pacific

Abstract. Past studies have suggested that ozone in the troposphere has increased globally throughout much of the 20th century due to increases in anthropogenic emissions and transport. We show, by combining satellite measurements with a chemical transport model, that during the last four decades tropospheric ozone does indeed indicate increases that are global in nature, yet still highly regional. Satellite ozone measurements from Nimbus-7 and Earth Probe Total Ozone Mapping Spectrometer (TOMS) are merged with ozone measurements from the Aura Ozone Monitoring Instrument/Microwave Limb Sounder (OMI/MLS) to determine trends in tropospheric ozone for 1979–2016. Both TOMS (1979–2005) and OMI/MLS (2005–2016) depict large increases in tropospheric ozone from the Near East to India and East Asia and further eastward over the Pacific Ocean. The 38-year merged satellite record shows total net change over this region of about +6 to +7 Dobson units (DU) (i.e., ∼15 %–20 % of average background ozone), with the largest increase (∼4 DU) occurring during the 2005–2016 Aura period. The Global Modeling Initiative (GMI) chemical transport model with time-varying emissions is used to aid in the interpretation of tropospheric ozone trends for 1980–2016. The GMI simulation for the combined record also depicts the greatest increases of +6 to +7 DU over India and East Asia, very similar to the satellite measurements. In regions of significant increases in tropospheric column ozone (TCO) the trends are a factor of 2–2.5 larger for the Aura record when compared to the earlier TOMS record; for India and East Asia the trends in TCO for both GMI and satellite measurements are ∼+3 DU decade−1 or greater during 2005–2016 compared to about +1.2 to +1.4 DU decade−1 for 1979–2005. The GMI simulation and satellite data also reveal a tropospheric ozone increases in ∼+4 to +5 DU for the 38-year record over central Africa and the tropical Atlantic Ocean. Both the GMI simulation and satellite-measured tropospheric ozone during the latter Aura time period show increases of ∼+3 DU decade−1 over the N Atlantic and NE Pacific.

Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC4RS aircraft observations over the southeast US

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-13477-2016 ◽

2016 ◽

Vol 16 (21) ◽

pp. 13477-13490 ◽

Cited By ~ 57

Author(s):

Lei Zhu ◽

Daniel J. Jacob ◽

Patrick S. Kim ◽

Jenny A. Fisher ◽

Karen Yu ◽

...

Keyword(s):

Transport Model ◽

Chemical Transport ◽

Atmospheric Composition ◽

Research Groups ◽

Aircraft Observations ◽

Volatile Organic ◽

Mass Factor ◽

The Mean ◽

Southeast Us

Abstract. Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs), but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) campaign over the southeast US in August–September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS; for clarification of these and other abbreviations used in the paper, please refer to Appendix A) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. All retrievals feature a HCHO maximum over Arkansas and Louisiana, consistent with the aircraft observations and reflecting high emissions of biogenic isoprene. The retrievals are also interconsistent in their spatial variability over the southeast US (r  =  0.4–0.8 on a 0.5°  ×  0.5°  grid) and in their day-to-day variability (r  =  0.5–0.8). However, all retrievals are biased low in the mean by 20–51 %, which would lead to corresponding bias in estimates of isoprene emissions from the satellite data. The smallest bias is for OMI-BIRA, which has high corrected slant columns relative to the other retrievals and low scattering weights in its air mass factor (AMF) calculation. OMI-BIRA has systematic error in its assumed vertical HCHO shape profiles for the AMF calculation, and correcting this would eliminate its bias relative to the SEAC4RS data. Our results support the use of satellite HCHO data as a quantitative proxy for isoprene emission after correction of the low mean bias. There is no evident pattern in the bias, suggesting that a uniform correction factor may be applied to the data until better understanding is achieved.