< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> Atmospheric Chemistry Modeling Group, Harvard University

CURRENT RESEARCH PROJECTS

Last Updated: November 6, 2018

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Our research focuses on better understanding the chemical composition of the atmosphere, its perturbation by human activity, and the implications for life on Earth. We use advanced global models of atmospheric composition to interpret observations from satellites, aircraft, ground networks, and other platforms. We view our models as part of an integrated observing system bridging the information from different data sets to increase fundamental knowledge and address pressing environmental issues.

GLOBAL MODELS. A central tool in our research is the GEOS-Chem global 3-D model of atmospheric composition, developed by a large grass-roots research community at Harvard and elsewhere. See the GEOS-Chem web site for more details. We apply the model to a wide range of atmospheric chemistry problems and lead its development on both scientific and software engingeering fronts. GEOS-Chem provides a cutting-edge tool for modeling atmospheric composition and at the same time a powerful chemical module for Earth System Models to be used in study of chemistry-climate interactions and for chemical data assimilation.

AIRCRAFT MISSIONS. Aircraft enable detailed chemical characterization of atmospheric composition from the surface to the stratosphere. We have been involved over the years in many aircraft missions in different regions of the world. Our roles include mission design, flight planning, near-real-time model simulations, and post-mission data analysis. We use the GEOS-Chem model to integrate and interpret observations taken from different instruments and from different platforms.

SATELLITE OBSERVATIONS. Satellites are revolutionizing atmospheric chemistry research by providing global continuous data to inform emission inventories, air quality, climate forcing, and other issues. The data require advanced models for interpretation and we lead the development and application of these models. Our activities include retrievals of satellite spectra using radiative transfer models, inverse model analyses, chemical data assimilation, and Observing System Simulation Experiments (OSSEs) for future satellite missions.

model ITCT satellite

CURRENT PROJECTS

Air quality | Methane | Chemistry-climate | Fires and aerosols | Chemistry | Model development

AIR QUALITY (subgroup leader: Lu Shen) METHANE (subgroup leader: Yuzhong Zhang) CHEMISTRY-CLIMATE INTERACTIONS
FIRES AND AEROSOLS (subgroup leader: Yang Li)
  • See Loretta Mickley's research page. Students/postdocs working on chemistry/climate interactions, effects of fires on air quality, and connections to public health generally have Loretta Mickley as primary research advisor.

CHEMISTRY (subgroup leader: Kelvin Bates) MODEL DEVELOPMENT (subgroup leader: Sebastian Eastham)

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Project Descriptions



nigeria TROPOSPHERIC OXIDANTS

BACKGROUND:

Tropospheric oxidants (ozone and OH) are of central importance for global atmospheric chemistry. The hydroxyl radical (OH) is the main atmospheric oxidant responsible for removal of atmospheric gases, yet we have little understanding of its variability. Ozone is a major greenhouse gas in the middle/upper troposphere, a toxic gas at the surface, and the primary source of OH, but the factors controlling its global trend are poorly understood. Chemical production and loss of ozone and OH involve complex nonlinear mechanisms coupled to transport on all scales. Better understanding this chemistry holds the key to quantifying human influence.

OBJECTIVES:

  • Develop a new method for monitoring global OH;
  • Better understand nonlinearity in global ozone chemistry and its implications for ozone sources.

APPROACH:

  • Explore the potential to monitor tropospheric OH and its trend using satellite observations of atmospheric methane;
  • Develop a new conceptual model for the budget of tropospheric ozone.

PEOPLE: , Yuzhong Zhang, Kelvin Bates

REFERENCES:

  • Zhang, Y., D.J. Jacob, J.D. Maasakkers, M.P. Sulprizio, J. Sheng, R. Gautam, and J. Worden, Monitoring global OH concentrations using satellite observations of atmospheric methane , Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-467, in review, 2018. [PDF]

SUPPORT: NASA ACMAP, NASA IDS, HUCE Fellowship to Kelvin Bates

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nigeria TROPOSPHERIC HALOGEN CHEMISTRY

BACKGROUND:

Recent observations indicate high tropospheric concentrations of halogen radicals, leading to oxidant chains and catalytic cycles that have important implications for the global budgets of the main tropospheric oxidants (ozone and OH), the oxidation of mercury, and aerosol formation. Halogen chemistry has in general not been included in global models of tropospheric chemistry because the underlying processes are not well understood.

OBJECTIVES:

  • Develop a comprehensive understanding of stratospheric-tropospheric Cl-Br-I chemistry for implementation in global models;
  • Examine the general implications for tropospheric chemistry.

APPROACH:

  • Implement a comprehensive representation of halogen chemistry in the GEOS-Chem global model;
  • Evaluate it with observations for halogen radicals and their reservoirs;
  • Quantify the effects on tropospheric ozone, OH, and related species, and the consistency with atmospheric observations of these species.

PEOPLE: Lei Zhu, Xuan Wang

COLLABORATORS: Sebastian Eastham (MIT), Mat Evans and Tomas Sherwen (U. York)

REFERENCES:

  • Wang, X., D.J. Jacob, M.P. Sulprizio, S.D. Eastham, L. Zhu, Q. Chen, B. Alexander, T. Sherwen, M.J. Evans, B.H. Lee, J.D. Haskins, F.D. Lopez-Hilfike, J.A. Thornton, G.L. Huey, and H. Liao, The role of chlorine in tropospheric chemistry , Atmos. Chem. Phys. Disc., https://doi.org/10.5194/acp-2018-1088, in review, 2018.[PDF]

SUPPORT: National Science Foundation, JLAQC

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fires AIR QUALITY IN CHINA

BACKGROUND:

Air quality in China is among the worst in the world and there is strong public pressure to improve it. Newly installed surface air quality networks together with satellite observations can lead to a better understanding of air quality problems, better choices for emission control strategies, and understanding of the effects of future climate change. Unusual air chemistry is taking place over China that needs to be better understood.

OBJECTIVES:

  • Understand the effects of anthropogenic emissions, chemical processes, and other factors in determining ozone and particulate matter (PM) air quality in China;
  • Make recommendations for improving air quality;
  • Project the effects of future climate change.

APPROACH:

  • Interpret interannual variability and trends in satellite observations of ozone, formaldehyde, and NO2 over China;
  • Better understand ozone and PM chemistry over China;
  • Analyze and model surface network data for ozone and PM to determine the dominant sources and the expected responses to emission controls;
  • Use observed relationships of air quality and meteorological variables, and extreme value theory, to project the effects of climate change on Beijing air quality.

PEOPLE: Ke Li, Lu Shen, Xuan Wang, Viral Shah, Jonathan Moch, Shixian Zhai, Drew Pendergrass

REFERENCES:

  • Uncertainties in aerosol chemistry and links to the gas phase , keynote presentation by Daniel Jacob at the AGU JING meeting, Xi'an, October 19, 2018. [PPT]

  • Shen, L., D.J. Jacob, L.J. Mickley, Y. Wang, and Q. Zhang, Effect of climate change on winter haze pollution in Beijing: uncertain and likely small , Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-932, in review, 2018. [PDF]

  • Pendergrass, D.C., L. Shen, D.J. Jacob, and L.J. Mickley, Predicting the impact of climate change on severe winter haze pollution events in Beijing using extreme value theory, submitted to Geophys. Res. Lett., 2018. [PDF]

  • Moch, J.M., E. Dovrou, L.J. Mickley, F.N. Keutsch, Y. Cheng, D.J. Jacob, J. Jiang, M. Li, J.W. Munger, X. Qiao, and Q. Zhang, Contribution of hydroxymethane sulfonate to ambient particulate matter: A potential explanation for high particulate sulfur during severe winter haze in Beijing, Geophys. Res. Lett., 2018. [PDF, Supplement]

SUPPORT: JLAQC, NASA Aura, Harvard Global Institute, CSC Fellowship to Shixian Zhai

COLLABORATORS: Hong Liao (NUIST)

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PRB AIR QUALITY IN THE UNITED STATES

BACKGROUND:

Air quality in the US has been steadily improving but surface concentrations of ozone and particulate matter (PM) still exceed air quality standards. Emission control strategies that have been successful in the past may not be as successful in the future as chemical regimes change and as natural emissions and international transport of pollution become more important. There is also large uncertainty surrounding emissions and trends of nitrogen oxides (NOx), which are key precursors for ozone and PM. We need to better understand what controls ozone and PM in the present day and the implications for meeting the standards.

OBJECTIVES:

  • Better understand the factors controlling surface ozone in the eastern US;
  • Better understand the factors controlling nitrogen oxide emissions.

APPROACH:

  • Use a high-resolution version of the GEOS-Chem model to interpret air quality observations in the eastern US from surface networks and aircraft;
  • Use a large ensemble of satellite, surface, and wet deposition data as constraints on NOx emissions and their trends.

PEOPLE: Rachel Silvern, Katherine Travis (now at MIT)

REFERENCES:

  • Decadal trends in US OMI NO2 observations and the role of the upper troposphere, presented by Rachel Silvern at the 6th TEMPO^M Science Team Meeting, June 7, 2018. [PDF]

  • Modeling decadal trends in continental US air pollution, with a focus on NOx , presented by Rachel Silvern at the Harvard/MIT ACE Center Science Advisory Committee Meeting, May 30, 2018. [PDF]

  • Travis, K.R., and D.J. Jacob,Bias in evaluating chemical transport models with maximum daily 8-hour average 1 (MDA8) surface ozone for air quality applications, submitted to Geophys. Res. Lett., 2018. [PDF]

  • Silvern, R.F., D.J. Jacob, K.R. Travis, T. Sherwen, M.J. Evans, R.C. Cohen, J.L. Laughner, S.R. Hall, K. Ullmann, J.D. Crounse, P.O. Wennberg, J. Peischl, and I.B. Pollack, Observed NO-NO2 ratios in the upper troposphere imply errors in NO-NO2-O3 cycling kinetics or an unaccounted NOx reservoir, Geophys. Res. Lett., 45, https://doi.org/10.1029/2018GL077728, 2018. [PDF]

SUPPORT: NASA Aura, EPA

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PRB ORGANIC CHEMISTRY

BACKGROUND:

The atmospheric chemistry of volatile organic compounds (VOCs) has major implications for oxidant concentrations and for formation of organic aerosol. VOCs are emitted from a range of biogenic and anthropogenic sources. They undergo various oxidation cascades in the atmosphere, producing increasingly substituted and cleaved compounds, terminating eventually in the formation of CO2 or the removal by deposition. Most of the species and reactions involved have never been measured and must be inferred indirectly. Multigenerational products of VOC oxidation may be responsible for an "organic soup" in the remote troposphere that is suggested by observations but not understood at all. Representing organic chemistry in models is a major challenge.

OBJECTIVES:

  • Understand fully the chemical mechanism for isoprene oxidation and its implications for ozone, OH, aerosols;
  • Improve understanding of the budgets of oxygenated organics.

APPROACH:

  • Develop VOC oxidation mechanisms from first principles and test them in box models and in GEOS-Chem;
  • Interpret observations of oxygenated organics in the remote troposphere from the ATom aircraft campaign.

PEOPLE: Kelvin Bates

REFERENCES:

SUPPORT: NASA ACMAP, HUCE fellowship to Kelvin Bates

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PRB MERCURY CHEMISTRY

BACKGROUND:

Mercury deposition to ecosystems results in accumulation of toxic forms of mercury up the food chain. Mercury is emitted to the atmosphere mostly as Hg(0), and is oxidized in the atmosphere to Hg(II) which can be rapidly deposited but also reduced back to Hg(0). Understanding atmospheric Hg(0)/Hg(II) redox chemistry is crucial to predicting the patterns of mercury deposition and the subsequent biogeochemical cycling.

OBJECTIVES:

  • Better understand the atmospheric redox chemistry of mercury;
  • Determine the implications for mercury deposition to ecosystems and subsequent biogeochemical cycling.

APPROACH:

  • Simulate detailed mercury chemistry in the GEOS-Chem atmospheric model coupled to ocean and terrestrial mercury reservoirs;
  • Use this model to interpret global atmospheric observations of mercury.

PEOPLE: Colin Thackray

COLLABORATORS: Elsie Sunderland (Harvard), Alfonso Saiz-Lopez (CSIC)

REFERENCES:

  • Saiz-Lopez, A., S.P. Sitkiewicz, D. Roca-Sanjuan, J.M. Oliva-Enrich, J.Z. Davalos, R. Notario, M. Jiskra, Y. Xu, F. Wang, C.P. Thackray, E.M. Sunderland, D.J. Jacob, O. Tratnikov, C.A. Cuevas, A.U. Acuna, D. Rivero, J.M.C. Plane, D.E. Kinnison, and J.E. Sonke, Atmospheric photoreduction of gaseous oxidized mercury requires a rethink of the global mercury cycle Nature Comm., in press, 2018.

SUPPORT: NSF

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CH4 UNDERSTANDING METHANE EMISSIONS

BACKGROUND:

Methane is the second most important anthropogenic greenhouse gas after CO2. It is particularly important for near-term (~20 years) climate change. Methane is emitted by a wide range of processes including oil/gas systems, livestock, landfills, wastewater, rice cultivation, and wetlands. The magnitudes of these sources, their spatial distributions, and their temporal trends are poorly understood. Improving methane emission inventories is imperative for climate policy.

OBJECTIVES:

  • Develop a high-resolution global methane emission inventory from the oil and gas industry;
  • Develop global methane emission inventories from aquatic systems including hydroelectric and other reservoirs, and coastal environments including estuaries;
  • Construct gridded policy-relevant anthropogenic emission inventories for Canada and Mexico to be evaluated with atmospheric observations.

APPROACH:

  • Estimate emissions and their distributions using best available data for activities and emission factors;
  • Use ancillary data as from satellites to inform the distribution of emissions;
  • Work with climate agencies in Canada and Mexico to construct gridded versions of their national inventories.

PEOPLE:   Bram Maasakkers (now at SRON), Tia Scarpelli, Melissa Sulprizio, Kyle Delwiche, Yuzhong Zhang

COLLABORATORS: Ritesh Gautam (EDF), Elsie Sunderland (Harvard)

REFERENCES:

  • Methane in the climate system: monitoring emissions from space , VIP talk by Daniel Jacob as part of the JPL Distinguished Climate Lecture Series, JPL, Pasadena, September 4, 2018. [PPT]

SUPPORT: NASA CMS, NASA IDS, Harvard Climate Initiative, NDSEG fellowship to Tia Scarpelli

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CH4 INFERRING GLOBAL METHANE EMISSIONS FROM ATMOSPHERIC OBSERVATIONS

BACKGROUND:

Satellite observations of atmospheric methane can test emission inventories and diagnose the causes of concentration trends. This involves statistical inversion of chemical transport models that relate emissions to concentrations. Satellites are now providing global continuous observations of methane that deliver powerful constraints on methane emissions worldwide. This information can be exploited to improve national emission inventories reported in international climate policy agreements and to identify targets for reducing methane emissions. The TROPOMI instrument launched in October 2017 promises to revolutionize our ability to map methane emissions from space by provding daily global coverage of methane concentrations. New satellite observations available in the thermal IR may improve our ability to constrain trends in emissions and OH (the main methane sink).

OBJECTIVES:

  • Infer global methane emissions and trends using satellite observations.

APPROACH:

  • Use GOSAT satellite observations for 2009-present to constrain methane emissions, their trends, and OH concentrations (the main methane sink);
  • Use results for the US to improve the national emission inventory compiled by EPA;
  • Develop new inverse methods to exploit the high density of observations from TROPOMI;

  • Determine the complementary information from satellite observations in the thermal IR (AIRS, CrIS).

PEOPLE: Bram Maasakkers (now at SRON), Melissa Sulprizio, Yuzhong Zhang, Hannah Nesser, Elise Penn

COLLABORATORS: Melissa Weitz (EPA), Tom Wirth (EPA), Anthony Bloom (JPL), John Worden (JPL), Ilse Aben (SRON)

REFERENCES:

  • Methane in the climate system: monitoring emissions from space , VIP talk by Daniel Jacob as part of the JPL Distinguished Climate Lecture Series, JPL, Pasadena, September 4, 2018. [PPT]

  • Sheng, J.-X., D.J. Jacob, A.J. Turner, J.D. Maasakkers, M.P. Sulprizio, A.A. Bloom, A.E. Andrews, and D. Wunch, High-resolution inversion of methane emissions in the Southeast US using SEAC4RS aircraft observations of atmospheric methane: anthropogenic and wetland sources, Atmos. Chem. Phys., 18, 6483-6491, 2018. [PDF]

SUPPORT: NASA CMS, NASA IDS, NSF fellowship to Hannah Nesser, NSF fellowship to Elise Penn

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CH4 DETECTING METHANE POINT SOURCES FROM SPACE

BACKGROUND:

Anthropogenic emissions of methane come from a very large number of relatively small point sources including coal mine vents, oil/gas processing facilities, stockyards, landfills, etc. These sources have highly variable emissions, and can spike under abnormal conditions. Satellites provide a vantage point for continuous monitoring of these point sources and detecting emission spikes. Pixel resolution, precision, and return time can however limit the information from a satellite instrument. Quantitative interpretation of the observed turbulent plume in terms of a point emission rate is not a trivial problem.

OBJECTIVES:

  • Infer point source emissions from plume observations with the GHGSat satellite instrument;
  • Determine the ability of different satellite observing configurations to detect and locate abnormally high emitters in a dense emission field;
  • Evaluate the potential of hyperspectral surface imagers for detecting methane point sources.

APPROACH:

  • Conduct large-eddy simulations of point sources to test different algorithms for retrieving emission rates from plume observations;
  • Use GHGSat observations to detect and quantify point sources;
  • Conduct observing system simulation experiments (OSSEs) to test the ability of different satellite systems for detecting abnormal emitters;
  • Evaluate the potential of the soon-to-be-launched EnMAP and PRISMA hyperspectral surface imagers to detect methane point sources.

PEOPLE: Daniel Varon, Dan Cusworth (now at JPL).

COLLABORATORS: Jason McKeever (GHGSat, Inc.), Cynthia Randles, Laurent White, Jeremry Boardman (Exxon Mobil)

REFERENCES:

  • Cusworth, D.H., D.J. Jacob, J.-X. Sheng, J. Benmergui, A.J. Turner, J. Brandman, L. White, and C.A. Randles, Detecting high-emitting methane sources in oil/gas fields using satellite observations, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-741, in review, 2018. [PDF]

  • Varon, D.J., D.J. Jacob, J. McKeever, D. Jervis, B.O.A. Durak, Y. Xia, and Y. Huang, Quantifying methane point sources from fine-scale (GHGSat) satellite observations of atmospheric methane plumes, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2018-171, in review, 2018. [PDF]

  • Methane in the climate system: monitoring emissions from spaceM , VIP talk by Daniel Jacob as part of the JPL Distinguished Climate Lecture Series, JPL, Pasadena, September 4, 2018. [PPT]

SUPPORT: GHGSat, Inc., Exxon Mobil

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ESMF GEOS-Chem AS CHEMICAL MODULE FOR EARTH SYSTEM MODELS AND MASSIVELY PARALLEL APPLICATIONS

BACKGROUND:

Earth System Models (ESMs) used for climate simulations, seasonal forecasting, and data assimilation do not include detailed atmospheric chemistry because of the perceived complexity and computational cost. Yet atmospheric chemistry is key to climate forcing and air quality forecasting, and is also needed for assimilation of chemical observations from satellites. The software architecture needed to couple chemical modules in ESMs also allows massively parallel chemical transport modeling using the Message Passing Interface (MPI) protocol. This provides the basis for the high-performance version of GEOS-Chem (GCHP).

OBJECTIVES:

  • Develop a capability for use of GEOS-Chem as chemical module in ESMs, using exactly the same code as in the off-line GEOS-Chem developed and supported by a large community of atmospheric chemistry users;
  • Demonstrate this capability in the NASA-Goddard Earth Observing System ESM (GEOS) and the NCAR ESM (CESM);
  • Use this on-line capability for seasonal forecasting of air quality, and for joint chemical and meteorological data assimilation;
  • Develop capability for massively parallel GEOS-Chem simulations through GCHP.

APPROACH:

  • Integrate GEOS-Chem into different ESM environments;
  • Develop a capability for chemical data assimilation within the NASA GEOS data assimilation system;
  • Develop GCHP as a powerful resource for high-resolution simulations of atmospheric chemistry.

PEOPLE:   Sebastian Eastham (now at MIT), Ada Shaw, GEOS-Chem Support Team

COLLABORATORS: Steven Pawson (NASA/GSFC), Christoph Keller (NASA/GSFC), Randall Martin (Dalhousie)

REFERENCES:

  • Eastham, S.D., M.S. Long, C.A. Keller, E. Lundgren, R.M. Yantosca, J. Zhuang, C. Li, C.J. Lee, M. Yannetti, B.M. Auer, T.L. Clune, J. Kouatchou, W.M. Putman, M.A. Thompson, A.L. Trayanov, A.M. Molod, R.V. Martin, and D.J. Jacob, GEOS-Chem High Performance (GCHP): A next-generation implementation of the GEOS-Chem chemical transport model for massively parallel applications, Geosci. Mod. Dev., 11, 2941-2953, 2018. [PDF].

  • Hu, L., C.A. Keller, M.S. Long, T. Sherwen, B. Auer, A. Da Silva, J.E. Nielsen, S. Pawson, M.A. Thompson, A.L. Trayanov, K.R. Travis, S.K. Grange, M.J. Evans, and D.J. Jacob, Global simulation of tropospheric chemistry at 12.5 km resolution: performance and evaluation of the GEOS-Chem chemical module (v10-1) within the NASA GEOS Earth System Model (GEOS-5 ESM), Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2018-111, in review, 2018. [PDF]

SUPPORT: NASA MAP, NASA ACMAP, JLAQC

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Scale IMPROVING THE SIMULATION OF TRANSPORT

BACKGROUND:

Simulation of atmospheric transport in global models of atmospheric composition is a very difficult problem. Much of this transport takes place in concentrated layers that can preserve their integrity over thousands of km. Current models are completely incapable of resolving these layers. Emphasis in model development has been on increasing horizontal resolution but vertical resolution may in fact be the limiting factor. This has important implications for intercontinental air pollution influences and for describing non-linear processes in atmospheric chemistry.

OBJECTIVES:

  • Understand the sensitivity of model results to different simulation environments including spatial resolution, on-line vs. off-line, grid structure, etc.;
  • Better understand the model requirements needed for global-scale transport of chemical plumes.
  • Develop new, less dissipative algorithms for computing atmospheric transport.

APPROACH:

  • Study the role of numerical diffusion in realistic divergent atmospheric flows;
  • Use satellite observations to better understand the global-scale transport of chemical plumes;
  • Determine the model resolution needed to simulate global-scale transport.

PEOPLE: Sebastian Eastham (now at MIT), Jiawei Zhuang, Ada Shaw

COLLABORATORS: Andrea Molod (NASA/GSFC), Michael Brenner (Harvard)

REFERENCES:

  • Zhuang, J., D.J. Jacob, and S.D. Eastham, The importance of vertical resolution in the free troposphere for modeling intercontinental plumes, Atmos. Chem. Phys., 18, 6039-6055, 2018. [PDF]

  • Yu, K., C. A. Keller, D. J. Jacob, A. M. Molod, S. D. Eastham, and M. S. Long, Errors and improvements in the use of archived meteorological data for chemical transport modeling , Geosci. Model Dev., 11, 305-319, 2018. [PDF]

SUPPORT: NASA MAP, NASA fellowship to Jiawei Zhuang

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Scale GEOS-Chem ON THE CLOUD

BACKGROUND:

Cloud computing can allow GEOS-Chem users worldwide to run the model with no local hardware or systems support, and no installation or compilation of the code. Users can instead access the standard configuration of the model through the cloud and execute it for their application. They can also download the model and its environment from the cloud, ensuring compatibility with their local system. This has many advantages in terms of computing cost, model access, user support, reproducibility of results, and traceability of the standard model.

OBJECTIVES:

  • Develop capability to run GEOS-Chem and host its input databases on the cloud.

APPROACH:

  • Work with Amazon Web Services (AWS) and GEOS-Chem users to develop a successful business model.

PEOPLE: Jiawei Zhuang, Judit Flo-Gaya

COLLABORATORS: Amazon Web Services

REFERENCES:

SUPPORT: NASA ACMAP, NASA fellowship to Jiawei Zhuang

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Scale CHEMICAL SOLVERS

BACKGROUND:

Chemical mechanisms for atmospheric chemistry include hundreds of species interacting by kinetic equations on time scales ranging from less than a second to many years. Integration of these equations with numerical solvers is extremely expensive. This limits the level of chemical detail that can be afforded in atmospheric chemistry models, the spatial resolution of these models, and the inclusion of atmospheric chemistry in Earth System Models.

OBJECTIVE:

  • Speed up the chemical solvers in global atmospheric chemistry models.

APPROACH:

  • Use an adaptive method to reduce the mechanism locally while maintaining accuracy;
  • Use machine-learning algorithms to reduce computation cost by orders of magnitude.

PEOPLE: Lu Shen, Makoto Kelp

COLLABORATORS: Christoph Keller (NASA/GSFC), Nathan Kutz (U. Washington)

REFERENCES:

SUPPORT: NASA MAP

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