scholarly journals Global sensitivity analysis of GEOS-Chem modeled ozone and hydrogen oxides during the INTEX campaigns

2017 ◽  
Author(s):  
Kenneth E. Christian ◽  
William H. Brune ◽  
Jingqiu Mao ◽  
Xinrong Ren
Keyword(s):  
Transport Model ◽  
Specific Model ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Global Sensitivity ◽  
Mixing Ratios ◽  
Making Sense ◽  
Sensitivity Method ◽  
Lightning Nox

Abstract. Making sense of modeled atmospheric composition requires not just comparison to in situ measurements, but also knowing and quantifying the sensitivity of the model to its input factors. Using a global sensitivity method involving the simultaneous perturbation of many chemical transport model input factors, we find the model uncertainty for ozone (O3), hydroxyl radical (OH), and hydroperoxyl radical (HO2) mixing ratios and apportion this uncertainty to specific model inputs for the DC-8 flight tracks corresponding to the NASA INTEX campaigns of 2004 and 2006. In general, when uncertainties in modeled and measured quantities are accounted for, we find agreement between modeled and measured oxidant mixing ratios with the exception of ozone during the Houston flights of the INTEX-B campaign and HO2 for the flights over the northernmost Pacific Ocean during INTEX-B. For ozone and OH, modeled mixing ratios were most sensitive to a bevy of emissions, notably lightning NOx, various surface NOx sources, and isoprene. HO2 mixing ratios were most sensitive to CO and isoprene emissions as well as the aerosol uptake of HO2. With ozone and OH being generally over predicted by the model, we find better agreement between modeled and measured vertical profiles when reducing NOx emissions from surface as well as lightning sources.

scholarly journals Global sensitivity analysis of GEOS-Chem modeled ozone and hydrogen oxides during the INTEX campaigns

2018 ◽  
Vol 18 (4) ◽  
pp. 2443-2460 ◽  
Author(s):  
Kenneth E. Christian ◽  
William H. Brune ◽  
Jingqiu Mao ◽  
Xinrong Ren
Keyword(s):  
Transport Model ◽  
Chemical Transport ◽  
Specific Model ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Global Sensitivity ◽  
Mixing Ratios ◽  
Making Sense ◽  
Transport Experiment ◽  
Sensitivity Method

Abstract. Making sense of modeled atmospheric composition requires not only comparison to in situ measurements but also knowing and quantifying the sensitivity of the model to its input factors. Using a global sensitivity method involving the simultaneous perturbation of many chemical transport model input factors, we find the model uncertainty for ozone (O3), hydroxyl radical (OH), and hydroperoxyl radical (HO2) mixing ratios, and apportion this uncertainty to specific model inputs for the DC-8 flight tracks corresponding to the NASA Intercontinental Chemical Transport Experiment (INTEX) campaigns of 2004 and 2006. In general, when uncertainties in modeled and measured quantities are accounted for, we find agreement between modeled and measured oxidant mixing ratios with the exception of ozone during the Houston flights of the INTEX-B campaign and HO2 for the flights over the northernmost Pacific Ocean during INTEX-B. For ozone and OH, modeled mixing ratios were most sensitive to a bevy of emissions, notably lightning NOx, various surface NOx sources, and isoprene. HO2 mixing ratios were most sensitive to CO and isoprene emissions as well as the aerosol uptake of HO2. With ozone and OH being generally overpredicted by the model, we find better agreement between modeled and measured vertical profiles when reducing NOx emissions from surface as well as lightning sources.

scholarly journals Ten years of atmospheric methane from ground-based NDACC FTIR observations

2016 ◽  
Author(s):  
Whitney Bader ◽  
Benoît Bovy ◽  
Stephanie Conway ◽  
Kimberly Strong ◽  
Dan Smale ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Composition ◽  
Atmospheric Methane ◽  
Chemical Transport Model ◽  
Oil Transport ◽  
Sigma Level ◽  
Solar Observations ◽  
Time Period ◽  
Emissions Inventories

Abstract. Changes of atmospheric methane (CH4) since 2005 have been evaluated using Fourier Transform Infrared (FTIR) solar observations performed at ten ground-based sites, all members of the Network for Detection of Atmospheric Composition Change (NDACC). From this, we find an increase of atmospheric methane total columns that amounts to 0.31 ± 0.03 % year−1 (2-sigma level of uncertainty) for the 2005–2014 period. Comparisons with in situ methane measurements at both local and global scales show good agreement. We used the GEOS-Chem Chemical Transport Model tagged simulation that accounts for the contribution of each emission source and one sink in the total methane, simulated over the 2005–2012 time period and based on emissions inventories and transport. After regridding according to NDACC vertical layering using a conservative regridding scheme and smoothing by convolving with respective FTIR seasonal averaging kernels, the GEOS-Chem simulation shows an increase of atmospheric methane of 0.35 ± 0.03 % year−1 between 2005 and 2012, which is in agreement with NDACC measurements over the same time period (0.30 ± 0.04 % year−1, averaged over ten stations). Analysis of the GEOS-Chem tagged simulation allows us to quantify the contribution of each tracer to the global methane change since 2005. We find that natural sources such as wetlands and biomass burning contribute to the inter-annual variability of methane. However, anthropogenic emissions such as coal mining, and gas and oil transport and exploration, which are mainly emitted in the Northern Hemisphere and act as secondary contributors to the global budget of methane, have played a major role in the increase of atmospheric methane observed since 2005. Based on the GEOS-Chem tagged simulation, we discuss possible cause(s) for the increase of methane since 2005, which is still unexplained.

scholarly journals Global sensitivity analysis of the GEOS-Chem chemical transport model: Ozone and hydrogen oxides during ARCTAS (2008)

2016 ◽  
Author(s):  
Kenneth E. Christian ◽  
William H. Brune ◽  
Jingqiu Mao
Keyword(s):  
Aerosol Particle ◽  
Transport Model ◽  
Chemical Transport ◽  
Sensitivity Analyses ◽  
Chemical Transport Model ◽  
Global Sensitivity ◽  
Particle Uptake ◽  
Mixing Ratios ◽  
The North ◽  
Input Variables

Abstract. Developing predictive capability for future atmospheric oxidation capability requires a detailed analysis of model uncertainties and sensitivity of the modeled oxidation capacity to model input variables. Using oxidant mixing ratios modeled by the GEOS-Chem chemical transport model and measured on the NASA DC8 aircraft, uncertainty and global sensitivity analyses were performed on the GEOS-Chem chemical transport model for the modeled oxidants hydroxyl (OH), hydroperoxyl (HO2), and ozone (O3). The sensitivity of modeled OH, HO2, and ozone to modeled inputs perturbed simultaneously within their respective uncertainties were found for the period of NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) A &amp; B campaigns (2008) in the North American Arctic. For the spring deployment (ARCTAS-A), ozone is most sensitive to the photolysis rate of NO2, the NO2 + OH reaction rate, and various emissions, including methyl bromoform (CHBr3). OH and HO2 were overwhelmingly sensitive to aerosol particle uptake of HO2 with this one factor contributing upwards of 75 % of the uncertainty in HO2. For the summer deployment (ARCTAS-B), ozone was most sensitive to emissions factors, such as soil NOx and isoprene. OH and HO2 were most sensitive to biomass emissions and aerosol particle uptake of HO2. With modeled HO2 showing a factor of 2 underestimation compared to measurements in the lowest 2 kilometers of the troposphere, lower uptake rates (γHO2 < 0.04), regardless of whether or not the product of the uptake is H2O or H2O2, produced better agreement between modeled and measured HO2.

scholarly journals Intercomparison methods for satellite measurements of atmospheric composition: application to tropospheric ozone from TES and OMI

2010 ◽  
Vol 10 (1) ◽  
pp. 1417-1456 ◽  
Author(s):  
L. Zhang ◽  
D. J. Jacob ◽  
X. Liu ◽  
J. A. Logan ◽  
K. Chance ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Kernel Smoothing ◽  
Transport Model ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Ozone Monitoring Instrument ◽  
Satellite Measurements ◽  
In Situ Data ◽  
In Situ Method

Abstract. We analyze three different methods to validate and intercompare satellite measurements of atmospheric composition, and apply them to tropospheric ozone retrievals from the Tropospheric Emission Spectrometer (TES) and the Ozone Monitoring Instrument (OMI). The first method (in situ method) uses in situ vertical profiles for absolute instrument validation; it is limited by the sparseness of in situ data. The second method (CTM method) uses a chemical transport model (CTM) as an intercomparison platform; it provides a globally complete intercomparison with relatively small noise added by model error. The third method (averaging kernel smoothing method) involves smoothing the retrieved profile from one instrument with the averaging kernel matrix of the other; it also provides a global intercomparison but dampens the actual difference between instruments and adds noise from the a priori. Application to a full year (2006) of TES and OMI data shows mean positive biases of 5.3 parts per billion volume (ppbv) (10%) for TES and 2.8 ppbv (5%) for OMI at 500 hPa relative to in situ data from ozonesondes. We show that the CTM method (using the GEOS-Chem CTM) closely approximates results from the in situ method while providing global coverage. It reveals that differences between TES and OMI are generally less than 10 ppbv (18%), except at northern mid-latitudes in summer and over tropical continents. The CTM method allows for well-constrained CTM evaluation in places where the satellite observations are consistent. We thus find that GEOS-Chem underestimates tropospheric ozone in the tropics, reflecting a combination of possible factors, and overestimates ozone in the northern subtropics and southern mid-latitudes, likely because of excessive stratospheric influx.

scholarly journals Global sensitivity analysis of the GEOS-Chem chemical transport model: ozone and hydrogen oxides during ARCTAS (2008)

2017 ◽  
Vol 17 (5) ◽  
pp. 3769-3784 ◽  
Author(s):  
Kenneth E. Christian ◽  
William H. Brune ◽  
Jingqiu Mao
Keyword(s):  
Aerosol Particle ◽  
Transport Model ◽  
Chemical Transport ◽  
Sensitivity Analyses ◽  
Chemical Transport Model ◽  
Oxidation Capacity ◽  
Global Sensitivity ◽  
Particle Uptake ◽  
Mixing Ratios ◽  
The North

Abstract. Developing predictive capability for future atmospheric oxidation capacity requires a detailed analysis of model uncertainties and sensitivity of the modeled oxidation capacity to model input variables. Using oxidant mixing ratios modeled by the GEOS-Chem chemical transport model and measured on the NASA DC-8 aircraft, uncertainty and global sensitivity analyses were performed on the GEOS-Chem chemical transport model for the modeled oxidants hydroxyl (OH), hydroperoxyl (HO2), and ozone (O3). The sensitivity of modeled OH, HO2, and ozone to model inputs perturbed simultaneously within their respective uncertainties were found for the flight tracks of NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) A and B campaigns (2008) in the North American Arctic. For the spring deployment (ARCTAS-A), ozone was most sensitive to the photolysis rate of NO2, the NO2 + OH reaction rate, and various emissions, including methyl bromoform (CHBr3). OH and HO2 were overwhelmingly sensitive to aerosol particle uptake of HO2 with this one factor contributing upwards of 75 % of the uncertainty in HO2. For the summer deployment (ARCTAS-B), ozone was most sensitive to emission factors, such as soil NOx and isoprene. OH and HO2 were most sensitive to biomass emissions and aerosol particle uptake of HO2. With modeled HO2 showing a factor of 2 underestimation compared to measurements in the lowest 2 km of the troposphere, lower uptake rates (γHO2 < 0. 055), regardless of whether or not the product of the uptake is H2O or H2O2, produced better agreement between modeled and measured HO2.

scholarly journals The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005

2017 ◽  
Vol 17 (3) ◽  
pp. 2255-2277 ◽  
Author(s):  
Whitney Bader ◽  
Benoît Bovy ◽  
Stephanie Conway ◽  
Kimberly Strong ◽  
Dan Smale ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Composition ◽  
Atmospheric Methane ◽  
Chemical Transport Model ◽  
Oil Transport ◽  
Solar Observations ◽  
Time Period ◽  
Possible Cause ◽  
Good Agreement

Abstract. Changes of atmospheric methane total columns (CH4) since 2005 have been evaluated using Fourier transform infrared (FTIR) solar observations carried out at 10 ground-based sites, affiliated to the Network for Detection of Atmospheric Composition Change (NDACC). From this, we find an increase of atmospheric methane total columns of 0.31 ± 0.03 % year−1 (2σ level of uncertainty) for the 2005–2014 period. Comparisons with in situ methane measurements at both local and global scales show good agreement. We used the GEOS-Chem chemical transport model tagged simulation, which accounts for the contribution of each emission source and one sink in the total methane, simulated over 2005–2012. After regridding according to NDACC vertical layering using a conservative regridding scheme and smoothing by convolving with respective FTIR seasonal averaging kernels, the GEOS-Chem simulation shows an increase of atmospheric methane total columns of 0.35 ± 0.03 % year−1 between 2005 and 2012, which is in agreement with NDACC measurements over the same time period (0.30 ± 0.04 % year−1, averaged over 10 stations). Analysis of the GEOS-Chem-tagged simulation allows us to quantify the contribution of each tracer to the global methane change since 2005. We find that natural sources such as wetlands and biomass burning contribute to the interannual variability of methane. However, anthropogenic emissions, such as coal mining, and gas and oil transport and exploration, which are mainly emitted in the Northern Hemisphere and act as secondary contributors to the global budget of methane, have played a major role in the increase of atmospheric methane observed since 2005. Based on the GEOS-Chem-tagged simulation, we discuss possible cause(s) for the increase of methane since 2005, which is still unexplained.

scholarly journals Intercomparison methods for satellite measurements of atmospheric composition: application to tropospheric ozone from TES and OMI

2010 ◽  
Vol 10 (10) ◽  
pp. 4725-4739 ◽  
Author(s):  
L. Zhang ◽  
D. J. Jacob ◽  
X. Liu ◽  
J. A. Logan ◽  
K. Chance ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Kernel Smoothing ◽  
Transport Model ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Ozone Monitoring Instrument ◽  
Satellite Measurements ◽  
In Situ Data ◽  
In Situ Method

Abstract. We analyze the theoretical basis of three different methods to validate and intercompare satellite measurements of atmospheric composition, and apply them to tropospheric ozone retrievals from the Tropospheric Emission Spectrometer (TES) and the Ozone Monitoring Instrument (OMI). The first method (in situ method) uses in situ vertical profiles for absolute instrument validation; it is limited by the sparseness of in situ data. The second method (CTM method) uses a chemical transport model (CTM) as an intercomparison platform; it provides a globally complete intercomparison with relatively small noise from model error. The third method (averaging kernel smoothing method) involves smoothing the retrieved profile from one instrument with the averaging kernel matrix of the other; it also provides a global intercomparison but dampens the actual difference between instruments and adds noise from the a priori. We apply the three methods to a full year (2006) of TES and OMI data. Comparison with in situ data from ozonesondes shows mean positive biases of 5.3 parts per billion volume (ppbv) (10%) for TES and 2.8 ppbv (5%) for OMI at 500 hPa. We show that the CTM method (using the GEOS-Chem CTM) closely approximates results from the in situ method while providing global coverage. It reveals that differences between TES and OMI are generally less than 10 ppbv (18%), except at northern mid-latitudes in summer and over tropical continents. The CTM method further allows for CTM evaluation using both satellite observations. We thus find that GEOS-Chem underestimates tropospheric ozone in the tropics due to possible underestimates of biomass burning, soil, and lightning emissions. It overestimates ozone in the northern subtropics and southern mid-latitudes, likely because of excessive stratospheric influx of ozone.

scholarly journals In-Situ Chemical and Isotopic Measurements of the Atmosphere of Jupiter

1998 ◽  
Vol 11 (2) ◽  
pp. 1057-1064
Author(s):  
P.R. Mahaffy ◽  
S.K. Atreya ◽  
H.B. Niemann ◽  
T.C. Owen
Keyword(s):  
Mass Spectrometer ◽  
Atmospheric Composition ◽  
Mixing Ratios ◽  
Major Species ◽  
Lateral Mixing ◽  
Detailed Composition ◽  
Different Depths ◽  
Galileo Probe ◽  
Spectrometer Data

AbstractInsights into both the detailed composition of Jupiter’s atmosphere and unexpected local meteorological phenomena were revealed by in-situ measurements from the Galileo Probe Neutral Mass Spectrometer taken on December 7, 1995. Measurements of the neutral atmospheric composition from a pressure of 0.5 bar to approximately 21 bar revealed the mixing ratios of the major species helium and hydrogen as well as numerous minor constituents including methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. This instrument measured the isotope ratios3He/4He, D/H, and13C/12C as well as the isotopes of neon, argon, krypton, and xenon. A summary is given of progress that has been made in refining preliminary estimates of the abundances of condensable volatiles and noble gases as a result of an ongoing laboratory study using a nearly identical engineering unit. The depletion of simple condensable species to depths well below their expected condensation levels is explained by a local downdraft in the region of the probe entry. The mass spectrometer data suggests that different species may recover at different depths and this may be due to lateral mixing of Jovian air.

scholarly journals Extending methane profiles from aircraft into the stratosphere for satellite total column validation using the ECMWF C-IFS and TOMCAT/SLIMCAT 3-D model

2017 ◽  
Vol 17 (11) ◽  
pp. 6663-6678 ◽  
Author(s):  
Shreeya Verma ◽  
Julia Marshall ◽  
Mark Parrington ◽  
Anna Agustí-Panareda ◽  
Sebastien Massart ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Transport Model ◽  
A Priori ◽  
Atmospheric Composition ◽  
Random Errors ◽  
Chemical Transport Model ◽  
Spatial Coverage ◽  
Forecasting System ◽  
The Impact ◽  
Total Column

Abstract. Airborne observations of greenhouse gases are a very useful reference for validation of satellite-based column-averaged dry air mole fraction data. However, since the aircraft data are available only up to about 9–13 km altitude, these profiles do not fully represent the depth of the atmosphere observed by satellites and therefore need to be extended synthetically into the stratosphere. In the near future, observations of CO2 and CH4 made from passenger aircraft are expected to be available through the In-Service Aircraft for a Global Observing System (IAGOS) project. In this study, we analyse three different data sources that are available for the stratospheric extension of aircraft profiles by comparing the error introduced by each of them into the total column and provide recommendations regarding the best approach. First, we analyse CH4 fields from two different models of atmospheric composition – the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System for Composition (C-IFS) and the TOMCAT/SLIMCAT 3-D chemical transport model. Secondly, we consider scenarios that simulate the effect of using CH4 climatologies such as those based on balloons or satellite limb soundings. Thirdly, we assess the impact of using a priori profiles used in the satellite retrievals for the stratospheric part of the total column. We find that the models considered in this study have a better estimation of the stratospheric CH4 as compared to the climatology-based data and the satellite a priori profiles. Both the C-IFS and TOMCAT models have a bias of about −9 ppb at the locations where tropospheric vertical profiles will be measured by IAGOS. The C-IFS model, however, has a lower random error (6.5 ppb) than TOMCAT (12.8 ppb). These values are well within the minimum desired accuracy and precision of satellite total column XCH4 retrievals (10 and 34 ppb, respectively). In comparison, the a priori profile from the University of Leicester Greenhouse Gases Observing Satellite (GOSAT) Proxy XCH4 retrieval and climatology-based data introduce larger random errors in the total column, being limited in spatial coverage and temporal variability. Furthermore, we find that the bias in the models varies with latitude and season. Therefore, applying appropriate bias correction to the model fields before using them for profile extension is expected to further decrease the error contributed by the stratospheric part of the profile to the total column.

scholarly journals Contributions to local and regional-scale formaldehyde concentrations

2018 ◽  
Author(s):  
Lucas Bastien ◽  
Nancy Brown ◽  
Robert Harley
Keyword(s):  
Organic Compounds ◽  
San Francisco ◽  
Transport Model ◽  
Regional Scale ◽  
Air Pollutant ◽  
Chemical Transport Model ◽  
Adjoint Sensitivity ◽  
Voc Emissions ◽  
Mixing Ratios ◽  
Basin Scale

Abstract. Reducing ambient formaldehyde concentrations is a complex task because formaldehyde is both a primary and a secondary air pollutant, with significant anthropogenic and biogenic sources of volatile organic compounds (VOC) precursor emissions. This work uses adjoint sensitivity analysis in a chemical transport model to identify emission sources and chemical reactions that influence formaldehyde mixing ratios in the San Francisco Bay Area, and within three urbanized sub-areas. For each of these receptors, the use of the adjoint technique allows for efficient calculation of the sensitivity of formaldehyde to emissions of NOx, formaldehyde, and VOC precursors occurring at any location and time. Formaldehyde mixing ratios are found to be generally higher in summer than in winter. The opposite seasonal trend is observed for the sensitivities of these mixing ratios to formaldehyde emissions. In other words, even though formaldehyde is higher in summer, reducing formaldehyde emissions has a greater impact in winter. In winter, 85–90 % of the sensitivity to emissions is attributed to direct formaldehyde emissions. In summer, this contribution is smaller and more variable, ranging from 26 to 72 % among the receptor areas investigated in this study. Higher relative contributions of secondary formation versus direct emissions are associated with receptors located farther away from heavily urbanized and emission-rich areas. In particular, the relative contribution of biogenic VOC emissions (15–41 % in summer) is largest for these receptors. Ethene and other alkenes are the most influential anthropogenic precursors to secondary formaldehyde. Isoprene is the most influential biogenic precursor. Sensitivities of formaldehyde to NOx emissions are generally negative, but small in magnitude compared to sensitivities to VOC emissions. The magnitude of anthropogenic emissions of organic compounds other than formaldehyde is found to correlate reasonably well with their influence on population-weighted formaldehyde mixing ratios at the air basin scale. This correlation does not hold for ambient formaldehyde in smaller urbanized sub-areas. The magnitude of biogenic emissions does not correlate with their influence in either case.

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