Recent Science Highlights
Enormous breadth to Atmospheric Infrared Sounder (AIRS) research. Reflected in the approximately 400 publications mainly in Weather, Climate and Atmospheric Composition.
Atmospheric Infrared Sounder (AIRS)↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Spectroscopy of Exoplanet Atmospheres with the FINESSE Explorer
FINESSE (Fast INfrared Exoplanet Spectroscopic Survey Explorer) will provide uniquely detailed information on the growing number of newly discovered planets by characterizing their atmospheric composition and temperature structure. This NASA Explorer mission, selected for a competitive Phase A study, is unique in its breath and scope thanks to broad instantaneous spectroscopy from the optical to the mid-IR (0.7 - 5 micron), with a survey of exoplanets measured in a consistent, uniform way. For 200 transiting exoplanets ranging from Terrestrial to Jovians, FINESSE will measure the chemical composition and temperature structure of their atmospheres and trace changes over time with exoplanet longitude. The mission will do so by measuring the spectroscopic time series for a primary and secondary eclipse over the exoplanet orbital phase curve. With spectrophotometric precision being a key enabling aspect for combined light exoplanet characterization, FINESSE is designed to produce spectrophotometric precision of better than 100 parts-per-million per spectral channel without the need for decorrelation. The exceptional stability of FINESSE will even allow the mission to characterize non-transiting planets, potentially as part of FINESSE's Participating Scientist Program. In this paper, we discuss the flow down from the target availability to observations and scheduling to the analysis and calibration of the data and how it enables FINESSE to be the mission that will truly expand the new field of comparative exoplanetology.
chemical abundance↗
Thermosphere conditions deduced from satellite observations.
Atmospheric composition data from Explorer XVII SATELLITE, obtaining expression for thermal diffusion factor of He
EXPLORER XVII SATELLITE↗
Assessing the Ability of Instantaneous Aircraft and Sonde Measurements to Characterize Climatological Means and Long-Term Trends in Tropospheric Composition
Over four decades of measurements exist that sample the 3-D composition of reactive trace gases in the troposphere from approximately weekly ozone sondes, instrumentation on civil aircraft, and individual comprehensive aircraft field campaigns. An obstacle to using these data to evaluate coupled chemistry-climate models (CCMs)the models used to project future changes in atmospheric composition and climateis that exact space-time matching between model fields and observations cannot be done, as CCMs generate their own meteorology. Evaluation typically involves averaging over large spatiotemporal regions, which may not reflect a true average due to limited or biased sampling. This averaging approach generally loses information regarding specific processes. Here we aim to identify where discrete sampling may be indicative of long-term mean conditions, using the GEOS-Chem global chemical-transport model (CTM) driven by the MERRA reanalysis to reflect historical meteorology from 2003 to 2012 at 2o by 2.5o resolution. The model has been sampled at the time and location of every ozone sonde profile available from the Would Ozone and Ultraviolet Radiation Data Centre (WOUDC), along the flight tracks of the IAGOSMOZAICCARABIC civil aircraft campaigns, as well as those from over 20 individual field campaigns performed by NASA, NOAA, DOE, NSF, NERC (UK), and DLR (Germany) during the simulation period. Focusing on ozone, carbon monoxide and reactive nitrogen species, we assess where aggregates of the in situ data are representative of the decadal mean vertical, spatial and temporal distributions that would be appropriate for evaluating CCMs. Next, we identically sample a series of parallel sensitivity simulations in which individual emission sources (e.g., lightning, biogenic VOCs, wildfires, US anthropogenic) have been removed one by one, to assess where and when the aggregated observations may offer constraints on these processes within CCMs. Lastly, we show results of an additional 31-year simulation from 1980-2010 of GEOS-Chem driven by the MACCity emissions inventory and MERRA reanalysis at 4o by 5o. We sample the model at every WOUDC sonde and flight track from MOZAIC and NASA field campaigns to evaluate which aggregate observations are statistically reflective of long-term trends over the period.
Atmospheric composition↗
Local time variation of equatorial thermospheric composition determined by the San Marco 3 Nace
The results of the Neutral Atmospheric Composition Experiment (Nace) on the Italian San Marco 3 satellite are analyzed. The analysis provides a comprehensive description of the daily variations in the densities of O, N2, Ar, and He in composition of the lower thermosphere, and also indicates that transport processes (possibly occurring elsewhere in the atmosphere) play an important part in the daily variation of the thermospheric composition at altitudes between 220 and 250 km.
Newton, G. P.↗
Neutral composition in the thermosphere.
Data obtained from the Ogo 6 neutral atmospheric composition (NAC) experiment for a period of more than 1 year are used to compare the average constituent composition at an altitude of 400 km with that predicted by the Jacchia 1971 and 1965 models. The comparison shows that the Jacchia 1971 model underestimates the molecular nitrogen densities at 400 km by a factor of 2. An atmosphere is constructed down to 120 km by means of the Stein and Walker technique. A fit is made with (1) the 400-km total densities from drag measurements and the composition from Ogo 6 NAC, (2) the 250-km measured molecular nitrogen densities, and (3) the 150-km total densities from drag. This fit shows that the Jacchia 1971 model overestimates the atomic oxygen content at 150 km.
Taeusch, D. R.↗
Data from Explorer 17 on composition of the upper atmosphere
Explorer XVII data on neutral particle concentrations in upper atmosphere
ATMOSPHERIC COMPOSITION↗
Uranus
Observations and theoretical investigations of the Uranus (U) system from the period 1983-1986 are reviewed, with an emphasis on the Voyager 2 encounter with U on January 26, 1986. Topics addressed include the bulk U composition, structure, and heat flux; the U atmospheric composition, structure, and circulation; the U rings; the major and minor U satellites; the U magnetosphere; and the Lyman-alpha 'electroglow' observed on the sunlit hemisphere of U.
Bergstralh, Jay T.↗
Tropospheric chemical models
The differences in atmospheric composition over the globe and the short- and long-term variations in this composition are the net effect of several atmospheric and biospheric processes: biospheric emissions, atmospheric circulation, atmospheric chemical transformations and finally deposition back to the surface. Accurate and realistic atmospheric chemistry and circulation models are essential to interpret the observed global distributions and trends of atmospheric species in terms of these underlying processes. Comparisons between model predictions and observations test current understanding of these processes and models used in conjunction with inverse methods allow deductions of the rates of these processes from the observations. With the planned inclusion of at least CO and CH4 observations on the Earth Observing System (EOS) satellites, together with the large global data set expected from in situ observations under the International Global Atmospheric Chemistry (IGAC) Project, the further development of global three-dimensional high-resolution atmospheric chemistry and circulation models in order to interpret this new data is a high-priority endeavor.
Prinn, R. G.↗
Observation of Chorus Waves by the Van Allen Probes: Dependence on Solar Wind Parameters and Scale Size
Highly energetic electrons in the Earths Van Allen radiation belts can cause serious damage to spacecraft electronic systems and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are nonspecific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity, respectively. Results show that the average scale size of chorus wave packets is approximately 13002300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.
Aryan, Homayon↗
Research Scanning Polarimeter (RSP): Retrievals from PODEX and SEAC4RS
We illustrate our methods on examples from the recent NASA's field campaigns POlarimeter Definition EXperiment (PODEX, based in Palmdale, California, January - February 2013) and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, based in Houston, Texas in August - September 2013). During these campaigns the RSP was onboard the NASA's long-range high-altitude ER-2 aircraft together with an array of other remote sensing instrumentation. Correlative sampling measurements from another aircraft were also available. The data obtained during these campaigns provides an excellent opportunity to study cloud properties in variety of locations and atmospheric conditions. We present examples of boundary layer cumulus and stratocumulus clouds, liquid altostratus clouds, and fogs. In the latter two cases the droplet size distribution derived from RFT analysis exhibited multiple modes corresponding to different cloud layers, as supported by the correlative lidar atmospheric profiles.
climate↗
Exploration Spacecraft and Space Suit Internal Atmosphere Pressure and Composition
The design of habitat atmospheres for future space missions is heavily driven by physiological and safety requirements. Lower EVA prebreathe time and reduced risk of decompression sickness must be balanced against the increased risk of fire and higher cost and mass of materials associated with higher oxygen concentrations. Any proposed increase in space suit pressure must consider impacts on space suit mass and mobility. Future spacecraft designs will likely incorporate more composite and polymeric materials both to reduce structural mass and to optimize crew radiation protection. Narrowed atmosphere design spaces have been identified that can be used as starting points for more detailed design studies and risk assessments.
Lange, Kevin↗
The Role of Temporal Evolution in Modeling Atmospheric Emissions from Tropical Fires
Fire emissions associated with tropical land use change and maintenance influence atmospheric composition, air quality, and climate. In this study, we explore the effects of representing fire emissions at daily versus monthly resolution in a global composition-climate model. We find that simulations of aerosols are impacted more by the temporal resolution of fire emissions than trace gases such as carbon monoxide or ozone. Daily-resolved datasets concentrate emissions from fire events over shorter time periods and allow them to more realistically interact with model meteorology, reducing how often emissions are concurrently released with precipitation events and in turn increasing peak aerosol concentrations. The magnitude of this effect varies across tropical ecosystem types, ranging from smaller changes in modeling the low intensity, frequent burning typical of savanna ecosystems to larger differences when modeling the short-term, intense fires that characterize deforestation events. The utility of modeling fire emissions at a daily resolution also depends on the application, such as modeling exceedances of particulate matter concentrations over air quality guidelines or simulating regional atmospheric heating patterns.
aerosols↗
Directly Imaged Giant Planets: What Do We Hope to Learn?
As we move into an era when GPI and SPHERE are (hopefully) discovering and characterizing new young giant planets, it is worthwhile to step back and review our science goals for young giant planets. Of course for individual planets we ideally would hope to measure mass, radius, atmospheric composition, temperature, and cloud properties, but how do these characteristics fit into our broader understanding of planetary system origin and evolution theories? In my presentation I will review both the specifics of what we hope to learn from newly discovered young worlds as well as how these characteristics inform our broader understanding of giant planets and planetary systems. Finally I will consider the limitations realistic datasets will place on our ability to understand newly discovered planets, illustrating with data from any new such worlds that are available by the conference date.
temperature↗
Role of Clouds, Aerosols, and Aerosol-Cloud Interaction in 20th Century Simulations with GISS ModelE2
We use the new version of NASA Goddard Institute for Space Studies (GISS) climate model, modelE2 with 2º by 2.5º horizontal resolution and 40 vertical layers, with the model top at 0.1 hPa [Schmidt et al., 2014]. We use two different treatments of the atmospheric composition and aerosol indirect effect: (1) TCAD(I) version has fully interactive Tracers of Aerosols and Chemistry in both the troposphere and stratosphere. This model predicts total aerosol number and mass concentrations [Shindell et al., 2013]; (2) TCAM is the aerosol microphysics and chemistry model based on the quadrature methods of moments [Bauer et al., 2008]. Both TCADI and TCAM models include the first indirect effect of aerosols on clouds [Menon et al., 2010]; the TCAD model includes only the direct aerosol effect. We consider the results of the TCAD, TCADI and TCAM models coupled to "Russell ocean model" [Russell et al., 1995], E2-R. We examine the climate response for the "historical period" that include the natural and anthropogenic forcings for 1850 to 2012. The effect of clouds, their feedbacks, as well as the aerosol-cloud interactions are assessed for the transient climate change.
climate models↗
Multi-Model Simulations of Aerosol and Ozone Radiative Forcing Due to Anthropogenic Emission Changes During the Period 1990-2015
Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. 1 to 3 percent per year in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by 0.17 plus or minus 0.08 watts per square meter, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5 (Intergovernmental Panel on Climate Change Fifth Assessment Report). The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.
emissions↗
Observations of Greenhouse Gases as Climate Indicators
Humans have significantly altered the energy balance of the Earth’s climate system mainly not only by extracting and burning fossil fuels but also by altering the biosphere and using halocarbons. The 3rd US National Climate Assessment pointed to a need for a system of indicators of climate and global change based on long-term data that could be used to support assessments and this led to the development of the National Climate Indicators System (NCIS). Here we identify a representative set of key atmospheric indicators of changes in atmospheric radiative forcing due to greenhouse gases (GHGs), and we evaluate atmospheric composition measurements, including non-CO2GHGs for use as climate change indicators in support of the US National Climate Assessment. GHG abundances and their changes over time can provide valuable information on the success of climate mitigation policies, as well as insights into possible carbon-climate feedback processes that may ultimately affect the success of those policies. To ensure that reliable information for assessing GHG emission changes can be provided on policy-relevant scales, expanded observational efforts are needed. Furthermore, the ability to detect trends resulting from changing emissions requires a commitment to supporting long-term observations. Long-term measurements of greenhouse gases, aerosols, and clouds and related climate indicators used with a dimming/brightening index could provide a foundation for quantifying forcing and its attribution and reducing error in existing indicators that do not account for complicated cloud processes.
greenhouse gases↗
The Turning Point of the Aerosol Era
Over the CMIP6 historical period (1850–2014), aerosols provided the largest negative forcing compared to all other climate forcings via their ability to absorb or scatter solar radiation and alter clouds. Aerosols played an important role in counterbalancing warming by greenhouse gases (GHGs). Here we study aerosol forcing trends in the CMIP6 simulations of the NASA Goddard Institute for Space Studies (GISS) ocean-atmosphere ModelE version 2.1 (GISS-E2.1-G) using a fully coupled atmospheric composition configuration, including interactive gas-phase chemistry, and either an aerosol microphysical (MATRIX) or a mass-based aerosol (OMA) module. Simulations of the CMIP6 historical period are analyzed as well as four Shared Socioeconomic Pathway (SSP) future scenarios for 2015–2100: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. The main conclusion of this study is that aerosol forcing in the GISS model has reached its turning point, switching from globally increasing to a decreasing trend in the first decade of the 21st century. This result is robust, independent of which aerosol module or SSP scenario is used. Non-linear aerosol-cloud interactions dominate as a forcing agent over aerosol-radiation interactions. Aerosols' ability to counterbalance GHG forcing on the global scale is today at a level comparable to that at the beginning of the last century. In the 1980s, the decade of largest global aerosol loads, aerosols balanced up to 80% of GHG forcing. As a consequence, global warming of the last decades, which is primarily driven by greenhouse gases, has been augmented by the effect of decreasing aerosol cooling in our model. By the end of this century, following the SSP scenarios, aerosols will only counterbalance 0%–20% of GHG forcing, depending on model and on scenario.
Aerosol forcing↗