Chemical Mechanisms and Their Applications in the Goddard Earth Observing System (GEOS) Earth System Model

Nielsen, J. E.; Pawson, Steven; Molod, Andrea; Auer, Benjamin M.; Silva, Arlindo da; Douglass, Anne R.; Duncan, B. N.; Liang, Qing; Manyin, Michael; Oman, Luke D.; Putman, William M.; Strahan, S. E.; Wargan, Krzysztof

doi:10.1002/2017ms001011

Cited by 65 publications

(65 citation statements)

References 131 publications

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“…The MERRA-2 Global Modeling Initiative (M2-GMI) is a GEOS simulation that is constrained with MERRA-2 meteorological fields (but not by MERRA-2 ozone) and uses the GMI chemical mechanism (Douglass et al, 2004;Nielsen et al, 2017). It uses the "replay" methodology, where increments are calculated from the assimilated horizontal winds, temperature, and pressure and applied as a forcing to the meteorology at every model time step (Bloom et al, 1996;Orbe et al, 2017).…”

Section: The Geos Productsmentioning

confidence: 99%

Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Wargan

Orbe

Pawson

et al. 2018

Geophysical Research Letters

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101

115

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The 1998–2016 ozone trends in the lower stratosphere are examined using the Modern‐Era Retrospective Analysis for Research and Applications Version 2 (MERRA‐2) and related National Aeronautics and Space Administration products. After removing biases resulting from step changes in the MERRA‐2 ozone observations, a discernible negative trend of −1.67 ± 0.54 Dobson units per decade (DU/decade) is found in the 10‐km layer above the tropopause between 20°N and 60°N. A weaker but statistically significant trend of −1.17 ± 0.33 DU/decade exists between 50°S and 20°S. In the Tropics, a positive trend is seen in a 5‐km layer above the tropopause. Analysis of an idealized tracer in a model simulation constrained by MERRA‐2 meteorological fields provides strong evidence that these trends are driven by enhanced isentropic transport between the tropical (20°S–20°N) and extratropical lower stratosphere in the past two decades. This is the first time that a reanalysis data set has been used to detect and attribute trends in lower stratospheric ozone.

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Section: The Geos Productsmentioning

confidence: 99%

Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Wargan

Orbe

Pawson

et al. 2018

Geophysical Research Letters

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101

115

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“…nasa.gov/Projects/GEOSCCM/MERRA2GMI/) of the Goddard Earth Observing System (GEOS) Chemistry Climate Model (GEOSCCM). The GEOSCCM (Nielsen et al, 2017;Oman et al, 2013) uses the GEOS version 5 global atmospheric general circulation model (Molod et al, 2015) with the Global Modeling Initiative (GMI) chemistry mechanism Strahan et al, 2007) for trace gas chemistry and the Goddard Chemistry Aerosol Radiation and Transport (GOCART) module (Chin et al, 2002;Colarco et al, 2010) for aerosols. The GMI chemistry mechanism includes both stratospheric and tropospheric chemistry, with over 120 species and over 400 reactions.…”

Section: Merra2-gmi Simulationmentioning

confidence: 99%

Global changes in the diurnal cycle of surface ozone

Strode

Ziemke

Oman

et al. 2019

Atmospheric Environment

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A B S T R A C TChanging emissions of NO x and other ozone precursors drive trends in both production and loss of surface ozone, leading to surface ozone trends that differ according to the time of day. Consequently, the magnitude of the diurnal cycle in surface ozone is changing in several regions of the world. Changes in the diurnal cycle of ozone have implications for the metrics used to assess the impact of ozone on human health and vegetation, since different metrics are sensitive to different portions of the diurnal cycle. We use a high resolution model simulation to examine global changes in the magnitude of the diurnal cycle of O 3 between 1980 and 2015. The simulation reproduces the negative trends in the tropospheric NO 2 column over the eastern United States and Europe, and the positive trends over East Asia, seen by the Ozone Monitoring Instrument (OMI). It also gives a reasonable reproduction of the change in the diurnal cycle of surface ozone seen at rural sites in the eastern United States between the 1990s and 2000s. The simulation shows that the magnitude of the surface O 3 diurnal cycle is increasing in regions with positive changes in NO x emissions, such as South and East Asia, and decreasing in regions with reductions in NO x emissions. It also shows changes in the diurnal cycle of the tropospheric ozone column, although these have fewer regions with statistically significant trends. These changes suggest that daily mean ozone is responding less than the mid-day ozone measured by the Total Ozone Mapping Spectrometer (TOMS) and OMI.

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“…Both of the models in this work are driven with the MERRA‐2 meteorological reanalysis, and both use versions of NASA's GMI chemical mechanism (Duncan et al, ; Nielsen et al, ). The first model (M2 GMI Replay; Orbe et al, ; Wargan et al, ) runs a previous version of the GMI mechanism, but uses the Replay technique (Orbe et al, ) to recalculate meteorological variables throughout the simulation.…”

Section: Data and Model Outputmentioning

confidence: 99%

The Effects of a 1998 Observing System Change on MERRA‐2‐Based Ozone Profile Simulations

Stauffer

Thompson²,

Oman³

et al. 2019

JGR Atmospheres

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Model simulations of ozone (O3) driven by meteorological reanalyses are useful for filling observational gaps and interpreting observed O3 variability and trends. However, the transport circulation of reanalysis products is impacted by changes to the observing system (the data assimilated into the reanalyses). We examine the impacts of these changes on simulated O3 from two models, Global Modeling Initiative (GMI) Chemistry Transport Model (GMI CTM) and Modern‐Era Retrospective Analysis for Research Applications version 2 (MERRA‐2) GMI Replay (M2 GMI Replay) simulation, using observations from global ozonesondes (>50,000 profiles) and satellites from 1980 to 2016. Both models are constrained by meteorology from the NASA MERRA‐2 reanalysis, and both use versions of NASA's GMI chemical mechanism. We focus on an observing system change affecting simulated O3 after 1998, associated with the assimilation of temperature and humidity data from new microwave profiling satellites. A large post‐1998 O3 increase, mainly confined to 15–20‐km altitude, of ~10 Dobson units (DU) in midlatitudes occurs in the GMI CTM, worsening the bias compared to observations. In contrast, an increase in M2 GMI Replay simulation O3 of ~10 DU is observed only near −60° latitude, reducing the bias compared to observations. The GMI CTM O3 high biases display a Quasi‐Biennial Oscillation (QBO)‐like periodicity that result from excessive transport from the tropical stratosphere to the midlatitude lower stratosphere during the QBO westerly phase. We quantify O3 discontinuities caused by MERRA‐2 observing system changes and demonstrate how the MERRA‐2 Global Modeling Initiative Replay simulation dampens the effects of these changes and QBO‐driven artifacts on simulated lower stratospheric and total O3. We caution against using simulations driven by a reanalysis to derive multidecadal O3 trends, especially prior to 1998.

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Chemical Mechanisms and Their Applications in the Goddard Earth Observing System (GEOS) Earth System Model

Cited by 65 publications

References 131 publications

Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Global changes in the diurnal cycle of surface ozone

The Effects of a 1998 Observing System Change on MERRA‐2‐Based Ozone Profile Simulations

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