D. R. Marsh

National Center for Atmospheric Research, Boulder, Colorado, United States

Are you D. R. Marsh?

Claim your profile

Publications (154)222.49 Total impact

  • Journal of Advances in Modeling Earth Systems 05/2015; DOI:10.1002/2014MS000387
  • Journal of Geophysical Research: Space Physics 05/2015; DOI:10.1002/2015JA021196
  • [Show abstract] [Hide abstract]
    ABSTRACT: Measurements of the diurnal cycle of potassium (K) atoms between 80 and 110 km have been made during October (for the years 2004-2011) using a Doppler lidar at Kühlungsborn, Germany (54.1°N, 11.7°E). A pronounced diurnal variation is observed in the K number density, which is explored by using a detailed description of the neutral and ionized chemistry of K in a three dimensional chemistry climate model. The model captures both the amplitude and phase of the diurnal and semi-diurnal variability of the layer, although the peak diurnal amplitude around 90 km is overestimated. The model shows that the total potassium density (≈ K + K+ + KHCO3) exhibits little diurnal variation at each altitude, and the diurnal variations are largely driven by photochemical conversion between these reservoir species. In contrast, tidally-driven vertical transport has a small effect at this mid-latitude location, and diurnal fluctuations in temperature are of little significance because they are small and the chemistry of K is relatively temperature-independent.
    04/2015; 42(9). DOI:10.1002/2015GL063718
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a comparison of the temperature and sodium layer properties observed by the ALOMAR Na lidar (69.3°N, 16.0°E) and simulated by the Whole Atmosphere Community Climate Model with specified dynamics and implemented sodium chemistry (WACCM-Na). To constrain the meteorological fields below 60 km, we use MERRA and GEOS-5. For the years 2008 to 2012, we analyze daily averages of temperature between 80.5 km and 101.5 km altitude, and of the Na layer's peak height, peak density, and centroid height. Both model runs are able to reproduce the pronounced seasonal cycle of Na number density and temperature at high latitudes very well. Especially between 86.5 km and 95.5 km, the measured and simulated temperatures agree very well. The lidar measurements confirm the model predictions that the January 2012 stratospheric warming led to large variation in temperature and Na density. The correlation coefficient between Na number density and temperature is positive for almost all altitudes in the lidar data, but not in the simulations. On average, the centroid height and peak height measured by lidar is about 2 km to 3 km higher than simulated by WACCM-Na.
    Journal of Atmospheric and Solar-Terrestrial Physics 01/2015; 44. DOI:10.1016/j.jastp.2015.01.003
  • [Show abstract] [Hide abstract]
    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.
    12/2014; 41(23). DOI:10.1002/2014GL061627
  • Source
    [Show abstract] [Hide abstract]
    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 09/2014; 119(9). DOI:10.1002/2014JA020383
  • Jeffrey M. Forbes, Xiaoli Zhang, Daniel R. Marsh
    [Show abstract] [Hide abstract]
    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.
    08/2014; 119(16). DOI:10.1002/2014JD021484
  • Source
    [Show abstract] [Hide abstract]
    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; 6(3). DOI:10.1002/2014MS000346
  • Source
    [Show abstract] [Hide abstract]
    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.
    07/2014; 119(13):n/a-n/a. DOI:10.1002/2013JD021403
  • [Show abstract] [Hide abstract]
    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). DOI:10.1002/2014GL060334
  • Source
    [Show abstract] [Hide abstract]
    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. DOI:10.5194/acp-14-5251-2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: For atmospheric tides driven by solar heating, the database of climate model output used in the most recent assessment report of the Intergovernmental Panel on Climate Change (IPCC) confirms and extends the authors' earlier results based on the previous generation of models. Both the present study and the earlier one examine the surface pressure signature of the tides, but the new database removes a shortcoming of the earlier study in which model simulations were not strictly comparable to observations. The present study confirms an approximate consistency among observations and all model simulations, despite variation of model tops from 31 to 144 km. On its face, this result is surprising because the dominant (semidiurnal) component of the tides is forced mostly by ozone heating around 30-70-km altitude. Classical linear tide calculations and occasional numerical experimentation have long suggested that models with low tops achieve some consistency with observations by means of compensating errors, with wave reflection from the model top making up for reduced ozone forcing. Future work with the new database may confirm this hypothesis by additional classical calculations and analyses of the ozone heating profiles and wave reflection in Coupled Model Intercomparison Project (CMIP) models. The new generation of models also extends CMIP's purview to free-atmosphere fields including the middle atmosphere and above.
    Journal of the Atmospheric Sciences 06/2014; 71(6):1905-1913. DOI:10.1175/JAS-D-13-0358.1
  • Source
  • [Show abstract] [Hide abstract]
    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.
  • [Show abstract] [Hide abstract]
    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.
    Atmospheric Chemistry and Physics 12/2013; 14(2). DOI:10.5194/acpd-14-1971-2014
  • [Show abstract] [Hide abstract]
    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.
    10/2013; 118(20). DOI:10.1002/2013JD020294
  • Source
    [Show abstract] [Hide abstract]
    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.
    10/2013; 118(19). DOI:10.1002/jgrd.50868
  • [Show abstract] [Hide abstract]
    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.
    10/2013; 118(19). DOI:10.1002/jgrd.50870
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Community Earth System Model (CESM) is a flexible and extensible community tool used to investigate a diverse set of Earth system interactions across multiple time and space scales. This global coupled model significantly extends its predecessor, the Community Climate System Model, by incorporating new Earth system simulation capabilities. These comprise the ability to simulate biogeochemical cycles, including those of carbon and nitrogen, a variety of atmospheric chemistry options, the Greenland Ice Sheet, and an atmosphere that extends to the lower thermosphere. These and other new model capabilities are enabling investigations into a wide range of pressing scientific questions, providing new foresight into possible future climates and increasing our collective knowledge about the behavior and interactions of the Earth system. Simulations with numerous configurations of the CESM have been provided to phase 5 of the Coupled Model Intercomparison Project (CMIP5) and are being analyzed by the broad community of scientists. Additionally, the model source code and associated documentation are freely available to the scientific community to use for Earth system studies, making it a true community tool. This article describes this Earth system model and its various possible configurations, and highlights a number of its scientific capabilities.
    Bulletin of the American Meteorological Society 09/2013; 94(9):1339-1360. DOI:10.1175/BAMS-D-12-00121.1
  • Source
    [Show abstract] [Hide abstract]
    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.
    08/2013; 118(16). DOI:10.1002/jgrd.50708

Publication Stats

2k Citations
222.49 Total Impact Points

Institutions

  • 2000–2015
    • National Center for Atmospheric Research
      • • Division of Atmospheric Chemistry
      • • High Altitude Observatory
      Boulder, Colorado, United States
  • 2014
    • Columbia University
      • Department of Applied Physics and Applied Mathematics
      New York, New York, United States
  • 2009–2014
    • National Research Center (CO, USA)
      Boulder, Colorado, United States
  • 2007
    • University of Colorado at Boulder
      Boulder, Colorado, United States
  • 1999
    • University of Michigan
      • Department of Atmospheric, Oceanic and Space Sciences
      Ann Arbor, MI, United States