D. R. Marsh

National Research Center (CO, USA), Boulder, Colorado, United States

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Publications (147)181.64 Total impact

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    ABSTRACT: Global climate models that do not include interactive middle atmosphere chemistry, such as most of those contributing to the Coupled Model Intercomparison Project Phase 5, typically specify stratospheric ozone using monthly-mean, zonal-mean values, and linearly interpolate to the time resolution of the model. We show that this method leads to significant biases in the simulated climate of the Southern Hemisphere (SH) over the late 20th Century. Previous studies have attributed similar biases in simulated SH climate change to the effect of the spatial smoothing of the specified ozone, i.e., to using zonal-mean concentrations. We here show that the bias in climate trends due to undersampling of the rapid temporal changes in ozone during the seasonal evolution of the Antarctic ozone hole is considerable and reaches all the way into the troposphere. Our results suggest the bias can be substantially reduced by specifying daily ozone concentrations.
    Geophysical Research Letters. 10/2014;
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    ABSTRACT: We here present, document and validate a new atmospheric component of the Community Earth System Model (CESM1): the Specified Chemistry Whole Atmosphere Community Climate Model (SC-WACCM). As the name implies, SC-WACCM is a middle atmosphere-resolving model with prescribed, rather than interactive chemistry. Ozone concentrations are specified throughout the atmosphere, using zonal and monthly mean climatologies computed by a companion integration with the Whole Atmosphere Community Climate Model (WACCM). Above 65 km, in addition, the climatological chemical and shortwave heating, nitrogen oxide, atomic and molecular oxygen and carbon dioxide are also prescribed from the companion WACCM integrations.We carefully compare the climatology and the climate variability of pre-industrial integrations of SC-WACCM and WACCM each coupled with active land, ocean and sea-ice components. We note some differences in upper stratospheric and lower mesospheric temperature, just below the 65 km transition level, due to the diurnal ozone cycle that is not captured when monthly mean ozone is used. Nonetheless, we find that the climatology and variability of the stratosphere, the troposphere and surface climate are nearly identical in SC-WACCM and WACCM. Notably, the frequency and amplitude of Northern Hemisphere stratospheric sudden warmings in the two integrations are not significantly different. Also, we compare WACCM and SC-WACCM to CCSM4, the “low-top” version of CESM1, and we find very significant differences in the stratospheric climatology and variability.The removal of the chemistry reduces the computational cost of SC-WACCM to approximately one half of WACCM: in fact, SC-WACCM is only 2.5 times more expensive than CCSM4 at the same horizontal resolution. This considerable reduction in computational cost makes the new SC-WACCM component of CESM1 ideally suited for studies of stratosphere-troposphere dynamical coupling and, more generally, the role of the stratosphere in the climate system.
    Journal of Advances in Modeling Earth Systems 08/2014; · 4.11 Impact Factor
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    ABSTRACT: Estimates of the global influx of cosmic dust are highly uncertain, ranging from 0.4-110 t/d. All meteoric debris that enters the Earth's atmosphere is eventually transported to the surface. The downward fluxes of meteoric metals like mesospheric Na and Fe, in the region below where they are vaporized and where the majority of these species are still in atomic form, are equal to their meteoric ablation influxes, which in turn, are proportional to the total cosmic dust influx. Doppler lidar measurements of mesospheric Na fluxes made throughout the year at the Starfire Optical Range, NM (35°N) are combined with the Whole Atmosphere Community Climate Model (WACCM) predictions of the relative geographic variations of the key wave-induced vertical transport processes, to infer the global influxes of Na vapor and cosmic dust. The global mean vertical Na flux is estimated to be -16,100 ± 3,200 atoms/cm2/s at 87.5 km altitude, which corresponds to 278 ± 54 kg/d for the global input of Na vapor and 60 ± 16 t/d for the global influx of cosmic dust.
    Journal of Geophysical Research: Space Physics 08/2014; · 3.44 Impact Factor
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    ABSTRACT: Future changes in the stratospheric circulation could have an important impact on Northern winter tropospheric climate change, given that sea level pressure (SLP) responds not only to tropospheric circulation variations but also to vertically coherent variations in troposphere-stratosphere circulation. Here we assess Northern winter stratospheric change and its potential to influence surface climate change in the Coupled Model Intercomparison Project – phase 5 (CMIP5) multi-model ensemble. In the stratosphere at high latitudes, an easterly change in zonally averaged zonal wind is found for the majority of the CMIP5 models, under the Representative Concentration Pathway 8.5 scenario. Comparable results are also found in the 1% CO2 increase per year projections, indicating that the stratospheric easterly change is common feature in future climate projections. This stratospheric wind change, however, shows a significant spread among the models. By using linear regression, we quantify the impact of tropical upper troposphere warming, polar amplification and the stratospheric wind change on SLP. We find that the inter-model spread in stratospheric wind change contributes substantially to the inter-model spread in Arctic SLP change. The role of the stratosphere in determining part of the spread in SLP change is supported by the fact that the SLP change lags the stratospheric zonally averaged wind change. Taken together, these findings provide further support for the importance of simulating the coupling between the stratosphere and the troposphere, to narrow the uncertainty in the future projection of tropospheric circulation changes.
    Journal of Geophysical Research: Atmospheres. 07/2014;
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    ABSTRACT: It has been known since the 1960s that the layers of Na and K atoms, which occur between 80 and 105 km in the Earth's atmosphere as a result of meteoric ablation, exhibit completely different seasonal behavior. In the extratropics Na varies annually, with a pronounced wintertime maximum and summertime minimum. However, K varies semiannually with a small summertime maximum and minima at the equinoxes. This contrasting behavior has never been satisfactorily explained. Here we use a combination of electronic structure and chemical kinetic rate theory to determine two key differences in the chemistries of K and Na. First, the neutralization of K+ ions is only favored at low temperatures during summer. Second, cycling between K and its major neutral reservoir KHCO3 is essentially temperature independent. A whole atmosphere model incorporating this new chemistry, together with a meteor input function, now correctly predicts the seasonal behavior of the K layer.
    Geophysical Research Letters 07/2014; 41(13). · 3.98 Impact Factor
  • Jeffrey M. Forbes, Xiaoli Zhang, Daniel R. Marsh
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    ABSTRACT: Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature data during 2002 through 2013, and covering 20-110 km altitude between ±83° latitude are analyzed to determine the dependence of middle atmosphere temperatureson solar flux, as parameterized by a linear relation with 81-day mean values of the 10.7-cm solar radio flux, F10.7a. The basic data analyzed are 60-day mean values, which represent zonal- and local-time-means. Analysis is conducted on bothfixed altitude and fixed pressure levels. Below 70 km, the sensitivity of SABER annual-mean temperatures is of order 1-2 K per 100 solar flux units (100sfu) when data are analyzed on fixed altitude levels. At 85 km this increases to 3-6 K/100sfu between ±60° latitude. At 95 km, values of order 4-6 K/100sfu are found over the latitude range ±50° with values of order 10-14 K/100sfu at higher latitudes in both hemispheres; these values increase to 5-11 K/100sfu and 13-29 K/100sfu, respectively, at 105 km. Comparisons are made with similarly-analyzed temperatures from the NCAR Whole Atmosphere Community Climate Model (WACCM). At 85 km, the WACCM response is similar to observed but above that level WACCM predicts a lower response by a factor of about 2 at 95 km. On the other hand, below 70 km, the sensitivity of WACCM annual-mean temperatures is stronger than SABER (~3 K/100sfu). When analysis is instead performed on pressure levels, the response in the lower thermosphere increases, especially at 105 km where changes of 29 to 51 K/100sfu are seen in SABER annual-mean temperatures.
    Journal of Geophysical Research: Atmospheres. 07/2014;
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    ABSTRACT: We investigate the relative role of volcanic eruptions, El Niño–Southern Oscillation (ENSO), and the quasibiennial oscillation (QBO) in the quasi-decadal signal in the tropical stratosphere with regard to temperature and ozone commonly attributed to the 11 yr solar cycle. For this purpose, we perform transient simulations with the Whole Atmosphere Community Climate Model forced from 1960 to 2004 with an 11 yr solar cycle in irradiance and different combinations of other forcings. An improved multiple linear regression technique is used to diagnose the 11 yr solar signal in the simulations. One set of simulations includes all observed forcings, and is thereby aimed at closely reproducing observations. Three idealized sets exclude ENSO variability, volcanic aerosol forcing, and QBO in tropical stratospheric winds, respectively. Differences in the derived solar response in the tropical stratosphere in the four sets quantify the impact of ENSO, volcanic events and the QBO in attributing quasi-decadal changes to the solar cycle in the model simulations. The novel regression approach shows that most of the apparent solar-induced lower-stratospheric temperature and ozone increase diagnosed in the simulations with all observed forcings is due to two major volcanic eruptions (i.e., El Chichón in 1982 and Mt. Pinatubo in 1991). This is caused by the alignment of these eruptions with periods of high solar activity. While it is feasible to detect a robust solar signal in the middle and upper tropical stratosphere, this is not the case in the tropical lower stratosphere, at least in a 45 yr simulation. The present results suggest that in the tropical lower stratosphere, the portion of decadal variability that can be unambiguously linked to the solar cycle may be smaller than previously thought.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 06/2014; 14:5251–5269. · 5.51 Impact Factor
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    ABSTRACT: Production of neutral species such as NOx(N, NO, and NO2) during particle-induced ionization events plays an important role in the chemistry of the mesosphere and lower thermosphere (MLT) region, especially in high latitudes. The effective production rate of NOx is composed of the direct production in reactions associated with the ionization or dissociation process and of indirect production during subsequent ionic reactions and recombination. A state of the art ion chemistry model is used to study the dependence of the effective production rate of NOx on several atmospheric parameters such as density, temperature, and abundance of atmospheric constituents and trace gases. The resulting effective production rates vary significantly, depending on the atmospheric state, and reach values between 1.2 NOx per ion pair in the lower mesosphere and 1.9 NOx per ion pair in the lower thermosphere. In this paper, an alternative approach to obtain realistic NOx production rates without running a full ion chemistry model is discussed; a database setup and readout system is used to replace ion chemistry calculations. It is compared to the full ion chemistry model and to a thermospheric reduced ion chemistry model combined with constant rate estimation below the mesopause. Database readout performs better than the constant estimate at all altitudes, where above 100km reduced ion chemistry better reproduces full ion chemistry, but database readout performs better in terms of numerical cost.
    02/2014; 119(3).
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    ABSTRACT: Mg and Mg+ concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg+ dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly means of Mg and Mg+ for number density as well as vertical column density in different latitudinal regions are shown. Data from the limb mesosphere-thermosphere mode of SCIAMACHY/Envisat are used, which covers the 50 km to 150 km altitude region with a vertical sampling of 3.3 km and a highest latitude of 82°. The high latitudes are not covered in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm-3 and 2000 cm-3. Mg does not show strong seasonal variation at mid-latitudes. The Mg+ peak occurs 5-15 km above the neutral Mg peak at 95-105 km. Furthermore, the ions show a significant seasonal cycle with a summer maximum in both hemispheres at mid- and high-latitudes. The strongest seasonal variations of the ions are observed at mid-latitudes between 20-40° and densities at the peak altitude range from 500 cm-3 to 6000 cm-3. The peak altitude of the ions shows a latitudinal dependence with a maximum at mid-latitudes that is up to 10 km higher than the peak altitude at the equator. The SCIAMACHY measurements are compared to other measurements and WACCM model results. In contrast to the SCIAMACHY results, the WACCM results show a strong seasonal variability for Mg with a winter maximum, which is not observable by SCIAMACHY, and globally higher peak densities. Although the peak densities do not agree the vertical column densities agree, since SCIAMACHY results show a wider vertical profile. The agreement of SCIAMACHY and WACCM results is much better for Mg+, showing the same seasonality and similar peak densities. However, there are the following minor differences: there is no latitudinal dependence of the peak altitude for WACCM and the density maximum, passing the equatorial region during equinox conditions, is not reduced as for SCIAMACHY.
    12/2013; 14(2).
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    ABSTRACT: [1] We investigate the influence of major sudden stratospheric warming (SSW) and elevated stratopause (ES) events in the Northern Hemisphere winter on the transport of NOx produced by energetic particle precipitation (EPP) from the mesosphere–lower thermosphere to the stratosphere using the Whole Atmosphere Community Climate Model (WACCM). Increases in NOx following a major SSW and/or ES event are in excess of 100% compared to winters when no major SSW or ES event occurred. The increase in NOx is attributed to an increase in the descending branch of the residual circulation () following the event. The timing of the event strongly affects the amount of NOx that descends to the stratosphere: the earlier the event occurs, the more NOx descends to the stratosphere. We also quantify the amount of NOx produced by EPP descending to the stratosphere in each winter and find that the largest increases in NOx are in years that have a major SSW followed by an ES event early in the season (December or early January). The strength of following an event shows a very strong seasonal dependence and explains why the timing of the event affects the transport of NOx.
    Journal of Geophysical Research: Atmospheres. 10/2013; 118(20).
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    ABSTRACT: [1] A global model of sodium in the mesosphere and lower thermosphere has been developed within the framework of the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM). The standard fully interactive WACCM chemistry module has been augmented with a chemistry scheme that includes nine neutral and ionized sodium species. Meteoric ablation provides the source of sodium in the model and is represented as a combination of a meteoroid input function (MIF) and a parameterized ablation model. The MIF provides the seasonally and latitudinally varying meteoric flux which is modeled taking into consideration the astronomical origins of sporadic meteors and considers variations in particle entry angle, velocity, mass, and the differential ablation of the chemical constituents. WACCM simulations show large variations in the sodium constituents over time scales from days to months. Seasonality of sodium constituents is strongly affected by variations in the MIF and transport via the mean meridional wind. In particular, the summer to winter hemisphere flow leads to the highest sodium species concentrations and loss rates occurring over the winter pole. In the Northern Hemisphere, this winter maximum can be dramatically affected by stratospheric sudden warmings. Simulations of the January 2009 major warming event show that it caused a short-term decrease in the sodium column over the polar cap that was followed by a factor of 3 increase in the following weeks. Overall, the modeled distribution of atomic sodium in WACCM agrees well with both ground-based and satellite observations. Given the strong sensitivity of the sodium layer to dynamical motions, reproducing its variability provides a stringent test of global models and should help to constrain key atmospheric variables in this poorly sampled region of the atmosphere.
    Journal of Geophysical Research: Atmospheres. 10/2013; 118(19).
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    ABSTRACT: [1] The hydrological impact of enhancing Earth's albedo by solar radiation management is investigated using simulations from 12 Earth System models contributing to the Geoengineering Model Intercomparison Project (GeoMIP). We contrast an idealized experiment, G1, where the global mean radiative forcing is kept at preindustrial conditions by reducing insolation while the CO2 concentration is quadrupled to a 4×CO2 experiment. The reduction of evapotranspiration over land with instantaneously increasing CO2 concentrations in both experiments largely contributes to an initial reduction in evaporation. A warming surface associated with the transient adjustment in 4×CO2 generates an increase of global precipitation by around 6.9% with large zonal and regional changes in both directions, including a precipitation increase of 10% over Asia and a reduction of 7% for the North American summer monsoon. Reduced global evaporation persists in G1 with temperatures close to preindustrial conditions. Global precipitation is reduced by around 4.5%, and significant reductions occur over monsoonal land regions: East Asia (6%), South Africa (5%), North America (7%), and South America (6%). The general precipitation performance in models is discussed in comparison to observations. In contrast to the 4×CO2 experiment, where the frequency of months with heavy precipitation intensity is increased by over 50% in comparison to the control, a reduction of up to 20% is simulated in G1. These changes in precipitation in both total amount and frequency of extremes point to a considerable weakening of the hydrological cycle in a geoengineered world.
    Journal of Geophysical Research: Atmospheres. 10/2013; 118(19).
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    Bulletin of the American Meteorological Society 09/2013; 94(9):1339-1360. · 11.57 Impact Factor
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    ABSTRACT: [1] We conducted model simulations to examine how changes in concentration of radiatively active trace gases in the middle atmosphere affect long-term changes in the upper atmosphere. We focused our model study on the impact of increases in carbon dioxide (CO2), methane (CH4), and water vapor (H2O), and decreases in ozone (O3) between 1983 and 2003. We used both the National Center for Atmospheric Research Whole Atmosphere Community Climate Model and the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model, global mean version, in this study. The model simulations indicate that CO2 is the main forcing mechanism of long-term changes in the thermsophere, with minor influences from O3, CH4, and H2O. At 400 km altitude, global mean thermospheric neutral density decreased by ~4.5% due to CO2 forcing alone, whereas it decreased by ~4.8% due to the combined forcing from all four gases. O3 depletion caused cooling in the stratosphere and mesosphere (maximum decrease of 0.5 K) due to reduced absorption of solar ultraviolet radiation, but had nearly no cooling effect in the thermosphere. However, due to thermal contraction in the stratosphere and mesosphere, O3 depletion caused a small decrease in thermospheric neutral density of ~0.25%. Increases in both CH4 and H2O may slightly warm the upper mesosphere and thermosphere due to increased chemical heating and absorption of solar ultraviolet radiation.
    Journal of Geophysical Research: Space Physics 06/2013; 118(6). · 3.44 Impact Factor
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    ABSTRACT: [1] Ozone changes and associated climate impacts in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations are analyzed over the historical (1960–2005) and future (2006–2100) period under four Representative Concentration Pathways (RCP). In contrast to CMIP3, where half of the models prescribed constant stratospheric ozone, CMIP5 models all consider past ozone depletion and future ozone recovery. Multimodel mean climatologies and long-term changes in total and tropospheric column ozone calculated from CMIP5 models with either interactive or prescribed ozone are in reasonable agreement with observations. However, some large deviations from observations exist for individual models with interactive chemistry, and these models are excluded in the projections. Stratospheric ozone projections forced with a single halogen, but four greenhouse gas (GHG) scenarios show largest differences in the northern midlatitudes and in the Arctic in spring (~20 and 40 Dobson units (DU) by 2100, respectively). By 2050, these differences are much smaller and negligible over Antarctica in austral spring. Differences in future tropospheric column ozone are mainly caused by differences in methane concentrations and stratospheric input, leading to ~10 DU increases compared to 2000 in RCP 8.5. Large variations in stratospheric ozone particularly in CMIP5 models with interactive chemistry drive correspondingly large variations in lower stratospheric temperature trends. The results also illustrate that future Southern Hemisphere summertime circulation changes are controlled by both the ozone recovery rate and the rate of GHG increases, emphasizing the importance of simulating and taking into account ozone forcings when examining future climate projections.
    Journal of Geophysical Research: Atmospheres. 05/2013; 118(10).
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    ABSTRACT: [1] A future Maunder Minimum type grand solar minimum, with total solar irradiance reduced by 0.25% over a 50 year period from 2020 to 2070, is imposed in a future climate change scenario experiment (RCP4.5) using, for the first time, a global coupled climate model that includes ozone chemistry and resolved stratospheric dynamics (Whole Atmosphere Community Climate Model). This model has been shown to simulate two amplifying mechanisms that produce regional signals of decadal climate variability comparable to observations, and thus is considered a credible tool to simulate the Sun's effects on Earth's climate. After the initial decrease of solar radiation in 2020, globally averaged surface air temperature cools relative to the reference simulation by up to several tenths of a degree Centigrade. By the end of the grand solar minimum in 2070, the warming nearly catches up to the reference simulation. Thus, a future grand solar minimum could slow down but not stop global warming.
    Geophysical Research Letters. 05/2013; 40(9).
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    ABSTRACT: 1] Elevated stratopause (ES) events occurring during Northern Hemisphere winter are identified in four climate simulations of the period 1953–2005 made with the Whole Atmosphere Community Climate Model (WACCM). We find 68 ES events in 212 winters. These events are found in winters when the middle atmosphere is disturbed and there are zonal wind reversals in the stratosphere at high latitudes. These disturbances can be associated with both major and minor stratospheric sudden warming events (SSWs). The ES events occur under conditions where the stratospheric jet, the gravity wave forcing, and the residual circulation remain reversed longer than in those winters where an SSW occurs without an ES. We compare ES events with the type of SSW (vortex splitting and vortex displacement) and find that 68% of ES events form after vortex splitting events. We also present a climatology of ES events based on NASA's Modern-Era Retrospective Analysis for Research and Applications reanalysis data from 1979 to 2012 and compare it to the model results. WACCM composites of major SSW and ES also show enhanced Eliassen-Palm flux divergences in the upper mesosphere after the stratospheric warming, immediately before the formation of an ES. However, the formation of an ES in WACCM is due primarily to adiabatic heating from gravity wave-driven downwelling, which follows the reestablishment of the eastward jet in the upper stratosphere. We find nine winters where an ES forms in the absence of any significant planetary wave activity in the upper mesosphere and illustrate one such event., and L. de la Torre (2013), A climatology of elevated stratopause events in the whole atmosphere community climate model, J. Geophys. Res. Atmos., 118, 1234-1246, doi:10.1002/jgrd.50123.
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    ABSTRACT: We present a comparison of temperature trends using different satellite and radiosonde observations and climate (GCM) and chemistry-climate model (CCM) outputs, focusing on the role of photochemical ozone depletion in the Antarctic lower stratosphere during the second half of the twentieth century. Ozone-induced stratospheric cooling peaks during November at an altitude of approximately 100 hPa in radiosonde observations, with 1969 to 1998 trends in the range of -3.8 to -4.7 K/dec. This stratospheric cooling trend is more than 50% greater than the previously estimated value of -2.4 K/dec, which suggested that the CCMs were overestimating the stratospheric cooling, and that the less complex GCMs forced by prescribed ozone were matching observations better. Corresponding ensemble mean model trends are -3.8K/dec for the CCMs, -3.5K/dec for the CMIP5 GCMs, and -2.7K/dec for the CMIP3 GCMs. Accounting for various sources of uncertainty-including sampling uncertainty, measurement error, model spread, and trend confidence intervals-observations and CCM and GCM ensembles are consistent in this new analysis. This consistency does not apply to each individual that makes up the GCM and CCM ensembles, and some do not show significant ozone-induced cooling. Nonetheless, analysis of the joint ozone and temperature trends in the CCMs suggests that the modeled cooling/ozone-depletion relationship is within the range of observations. Overall, this study emphasizes the need to use a wide range of observations for model validation as well as sufficient accounting of uncertainty in both models and measurements.
    Journal of Geophysical Research-Atmospheres. 01/2013; 118(2):605-613.
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    ABSTRACT: The first global model of meteoric iron in the atmosphere (WACCM‐Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion‐molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion‐molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM‐Fe model has been evaluated against a number of available ground‐based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+concentration compared with the limited rocket‐borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe‐molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1‐D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.
    Journal of Geophysical Research: Atmospheres. 01/2013; 118(16).

Publication Stats

1k Citations
181.64 Total Impact Points

Institutions

  • 2014
    • National Research Center (CO, USA)
      Boulder, Colorado, United States
  • 2000–2014
    • National Center for Atmospheric Research
      • • Division of Atmospheric Chemistry
      • • High Altitude Observatory
      Boulder, Colorado, United States
  • 1999
    • University of Michigan
      • Department of Atmospheric, Oceanic and Space Sciences
      Ann Arbor, MI, United States