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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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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Implementation of Cloud Retrievals for Tropospheric Emission Spectrometer (TES) Atmospheric Retrievals: Part 1. Description and Characterization of Errors on Trace Gas Retrievals

We develop an approach to estimate and characterize trace gas retrievals in the presence of clouds in high spectral measurements of upwelling radiance in the infrared spectral region (650-2260/cm). The radiance contribution of clouds is parameterized in terms of a set of frequency-dependent nonscattering optical depths and a cloud height. These cloud parameters are retrieved jointly with surface temperature, emissivity, atmospheric temperature, and trace gases such as ozone from spectral data. We demonstrate the application of this approach using data from the Tropospheric Emission Spectrometer (TES) and test data simulated with a scattering radiative transfer model. We show the value of this approach in that it results in accurate estimates of errors for trace gas retrievals, and the retrieved values improve over the initial guess for a wide range of cloud conditions. Comparisons are made between TES retrievals of ozone, temperature, and water to model fields from the Global Modeling and Assimilation Office (GMAO), temperature retrievals from the Atmospheric Infrared Sounder (AIRS), tropospheric ozone columns from the Goddard Earth Observing System (GEOS) GEOS-Chem, and ozone retrievals from the Total Ozone Mapping Spectrometer (TOMS). In each of these cases, this cloud retrieval approach does not introduce observable biases into TES retrievals.

aerosols↗
NASA NTRS2009

Distributions and Seasonal Variations of Tropospheric Ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) Solar Occultation Spectra

This work reports the first measurements of ethene (C2H4) distributions in the upper troposphere. These are obtained by retrieving vertical profiles from 5 to 20 km from infrared solar occultation spectra recorded in 2005 and 2006 by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS). Background volume mixin^ ratios (vmrs) ranging from a few to about 50 pptv (10(exp -1) are measured at the different altitudes, while for certain occultations, vmrs as high as 200 pptv are observed. Zonal distributions and vertically resolved latitudinal distributions are derived for the two year period analyzed, highlighting spatial - including a North-South gradient - as well as seasonal variations. We show the latter to be more pronounced at the highest latitudes, presumably as a result of less active photochemistry during winter. The observation of C2H4 enhancements in remote Arctic regions at high latitudes is consistent with the occurrence of fast transport processes of gaseous pollution from the continents leading to Arctic haze. Citation: Herbin, H., D. Hurtmans, L. Clarisse, S. Turquety, C. Clerbaux, C. P. Rinsland, C. Boone, P. F. Bernath, and P.-F. Colieur (2009), Distributions and seasonal variations of tropospheric ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) solar occultation spectra,

Herbin, H.↗
DOE OSTI2024

Finite-frequency modeling of regional tropospheric infrasound using realistic atmospheres and terrain

Infrasonic waves have been observed to propagate to regional (greater than 15 km) distances through the troposphere. Infrasound propagation in the geometric acoustics approximation has shown that realistic terrain can scatter acoustic energy from tropospheric ducts; however, ray methods cannot intrinsically capture finite-frequency behavior such as diffraction. A two-dimensional finite-difference time-domain (FDTD) method has been developed to solve linearized equations for infrasound propagation with realistic terrain. Acoustic wave propagation over 100 km with both flat terrain and a Gaussian hill was first simulated in order to compare finite-frequency propagation with ray predictions. The effects of realistic terrain and atmospheres on infrasound signals from a 2012 surface explosion at the Utah Testing and Training Range are then investigated. Propagation through the troposphere is suggested by array processing results, but eigenrays are not predicted due to weak to nonexistent ducting conditions. FDTD modeling suggests that the inclusion of terrain and finite frequency effects helps explain much of the observed signal in a realistic scenario. Furthermore, these results suggest that geometric acoustics may underestimate propagation through the troposphere, and that recorded waveforms at regional distances may be noticeably affected by terrain.

58 GEOSCIENCES↗
NASA NTRS1986

Estimating Microwave Delay by Atmospheric Water

Tropospheric path delays for microwave very-long-baseline interferometry (VLBI) estimated with algorithm that determines and explicitly integrates simple water-vapor distribution based on temperature data from water-vapor radiometer (WVR) and emission model. Although computationally complex, method readily accommodates even dramatic changes in observation conditions, emission model, and WVR equipment. Algorithm accommodates changes in observation conditions, emission model, and radiometer hardware.

Robinson, S. E.↗
NASA NTRS2010

Ice Crystal Growth Rates Under Upper Troposphere Conditions

Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

Peterson, Harold S.↗
NASA NTRS2010

Ice Particle Growth Rates Under Upper Troposphere Conditions

Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

Peterson, Harold↗
NASA NTRS1988

Comparison of SAGE II solar extinction data with airborne measurements of atmospheric backscattering in the troposphere and lower stratosphere

In April 1986, during passage of the SAGE I satellite, the first simultaneous measurements of the atmospheric backscattering coefficient beta (pi, 10.6 microns) were made with an airborne CO2 lidar. Individual ratios of beta and the SAGE II extinction sigma (1.02 micron) are in reasonable accord with previously calculated values. The trend with height shows a distinctly nonlinear relation, which is probably attributable to steadily changing size distributions of aerosols.

Vaughn, J. M.↗
NASA NTRS1998

Fiber-Optic Coupled Lidar Receiver System to Measure Stratospheric Ozone

The measurement of ozone in the atmosphere has become increasingly important over the past two decades. Significant increases of ozone concentrations in the lower atmosphere, or troposphere, and decreases in the upper atmosphere, or stratosphere, have been attributed to man-made causes. High ozone concentrations in the troposphere pose a health hazard to plants and animals and can add to global warming. On the other hand, ozone in the stratosphere serves as a protective barrier against strong ultraviolet (UV) radiation from the sun. Man-made CFC's (chlorofluorocarbons) act as a catalyst with a free oxygen atom and an ozone molecule to produce two oxygen molecules therefore depleting the protective layer of ozone in the stratosphere. The beneficial and harmful effects of ozone require the study of ozone creation and destruction processes in the atmosphere. Therefore, to provide an accurate model of these processes, an ozone lidar system must be able to be used frequently with as large a measurement range as possible. Various methods can be used to measure atmospheric ozone concentrations. These include different airborne and balloon measurements, solar occulation satellite techniques, and the use of lasers in lidar (high detection and ranging,) systems to probe the atmosphere. Typical devices such as weather balloons can only measure within the direct vicinity of the instrument and are therefore used infrequently. Satellites use solar occulation techniques that yield low horizontal and vertical resolution column densities of ozone.

Harper, David Brent↗
NASA NTRSDate not supplied

Current and Future ESPO Supported Missions

The Earth Science Project Office (ESPO) at NASA Ames Research Center is a group of success-oriented individuals providing project management for NASA's Science Mission Directorate, Earth Science Division. We provide planning, implementation, and post-mission support for large, complex, multi-agency, domestic and international field campaigns. ESPO has led over 60 successful field campaigns, dating back to 1987. ESPO supports several of NASA's Earth Science Division’s programs, including Upper Atmosphere Research, Tropospheric Chemistry, Radiation Sciences, Weather and Atmospheric Dynamics, Ocean Biology and Biochemistry, Airborne Science, and the Earth System Science Pathfinder Program.

Erin Czech↗
NASA NTRS2010

Seven Years of Observations of Mid-Tropospheric CO2 from the Atmospheric Infrared Sounder

The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. AIRS acquires hyperspectral infrared radiances in the 3.7-15.4 um spectral region with spectral resolution of better than 1200. The AIRS was designed to measure temperature and water vapor profiles and cloud properties for improvement in weather forecast and improved parameterization of climate processes. Currently the AIRS Level 1B Radiance Products are assimilated by NWP centers and have shown considerable forecast improvement. Scientists have also demonstrated accurate retrievals of minor gases from AIRS including Carbon Monoxide, Methane, and Ozone. The excellent sensitivity and stability of the AIRS instrument has recently allowed the AIRS team to successfully retrieve Carbon Dioxide (CO2) concentrations in the mid-troposphere (8-10 km) with a horizontal resolution of 100 km and accuracy of 1-2 ppm. The AIRS retrieves over 15,000 measurements per day and can achieve full global coverage in 30 days. The AIRS CO2 accuracy has been validated against a variety of aircraft measurements in the mid-troposphere and upward looking interferometers. Findings from the AIRS data include higher than expected variability in the mid-troposphere, the presence of a belt of CO2 in the southern hemisphere, and numerous observations of atmospheric circulation including the effects of El Nino/La Nina on the CO2 concentrations in the mid-troposphere. The full mid-tropospheric AIRS CO2 data set is now available at the NASA GES/DISC for almost eight years since AIRS has been operational.

carbon dioxide↗
NASA NTRS2010

Increasing Springtime Ozone Mixing Ratios in the Free Troposphere Over Western North America

In the lowermost layer of the atmosphere - the troposphere - ozone is an important source of the hydroxyl radical, an oxidant that breaks down most pollutants and some greenhouse gases. High concentrations of tropospheric ozone are toxic, however, and have a detrimental effect on human health and ecosystem productivity1. Moreover, tropospheric ozone itself acts as an effective greenhouse gas. Much of the present tropospheric ozone burden is a consequence of anthropogenic emissions of ozone precursors resulting in widespread increases in ozone concentrations since the late 1800s. At present, east Asia has the fastest-growing ozone precursor emissions. Much of the springtime east Asian pollution is exported eastwards towards western North America. Despite evidence that the exported Asian pollution produces ozone, no previous study has found a significant increase in free tropospheric ozone concentrations above the western USA since measurements began in the late 1970s. Here we compile springtime ozone measurements from many different platforms across western North America. We show a strong increase in springtime ozone mixing ratios during 1995-2008 and we have some additional evidence that a similar rate of increase in ozone mixing ratio has occurred since 1984. We find that the rate of increase in ozone mixing ratio is greatest when measurements are more heavily influenced by direct transport from Asia. Our result agrees with previous modelling studies, which indicate that global ozone concentrations should be increasing during the early part of the twenty-first century as a result of increasing precursor emissions, especially at northern mid-latitudes, with western North America being particularly sensitive to rising Asian emissions. We suggest that the observed increase in springtime background ozone mixing ratio may hinder the USA s compliance with its ozone air quality standard.

Cooper, O. R.↗
NASA NTRS1979

Heterogeneous atmospheric reactions - Sulfuric acid aerosols as tropospheric sinks

The reaction probabilities of various atmospheric species incident on a bulk sulfuric acid surface are measured in order to determine the role of sulfuric acid aerosols as pollutant sinks. Reaction products and unreacted starting materials leaving a Knudsen cell flow reactor after collision at 300 K with a H2SO4 surface or a soot surface were detected by mass spectrometry. Significant collision reaction probabilities are observed on a H2SO4 surface for H2O2, HNO3, HO2NO2, ClONO2, N2O5, H2O and NH3, and on soot for NH3. Estimates of the contribution of heterogeneous reactions to pollutant removal under atmospheric conditions indicate that while aerosol removal in the stratosphere is insignificant (loss rate constants approximately 10 to the -10th/sec), heterogeneous reactions may be the dominant loss process for several tropospheric species (loss rate constant approximately 10 to the -5th/sec, comparable to photolysis rate constants).

Baldwin, A. C.↗
DOE OSTI2022

Particle phase-state variability in the North Atlantic free troposphere during summertime is determined by atmospheric transport patterns and sources

Abstract. Free tropospheric aerosol particles have important but poorly constrained climate effects due to transformations of their physicochemical properties during long-range transport. In this study, we investigate the chemical composition and provide an overview of the phase states of individual particles that have undergone long-range transport over the North Atlantic Ocean in June and July 2014, 2015, and 2017 to the Observatory of Mount Pico (OMP) in the Azores. The OMP is an ideal site for studying long-range-transported free tropospheric particles because local emissions have a negligible influence and contributions from the boundary layer are rare. We used the FLEXible PARTicle Lagrangian particle dispersion model (FLEXPART) to determine the origins and transport trajectories of sampled air masses and found that most of them originated from North America and recirculated over the North Atlantic Ocean. The FLEXPART analysis showed that the sampled air masses were highly aged (average plume age >10 d). Size-resolved chemical compositions of individual particles were probed using computer-controlled scanning electron microscopy with an energy-dispersive X-ray spectrometer (CCSEM-EDX) and scanning transmission X-ray microscopy with near-edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS). CCSEM-EDX results showed that the most abundant particle types were carbonaceous (∼ 29.9 % to 82.0 %), sea salt (∼ 0.3 % to 31.6 %), and sea salt with sulfate (∼ 2.4 % to 31.5 %). We used a tilted stage interfaced within an environmental scanning electron microscope (ESEM) to determine the phase states of individual submicron particles. We found that most particles (∼ 47 % to 99 %) were in the liquid state at the time of collection due to inorganic inclusions. Moreover, we also observed substantial fractions of solid and semisolid particles (∼ 0 % to 30 % and ∼ 1 % to 42 %, respectively) during different transport patterns and events, reflecting the particles' phase-state variability for different atmospheric transport events and sources. Combining phase state measurements with FLEXPART CO tracer analysis, we found that wildfire-influenced plumes can result in particles with a wide range of viscosities after long-range transport in the free troposphere. We also used temperature and RH values extracted from the Global Forecast System (GFS) along the FLEXPART-simulated path to predict the phase state of the particles during transport and found that neglecting internal mixing with inorganics would lead to an overestimation of the viscosity of free tropospheric particles. Our findings warrant future investigation aiming at the quantitative assessment of the influence of internal mixing on the phase states of the individual particles. This study also provides insights into the chemical composition and phase state of free tropospheric particles, which can help models to reduce uncertainties about the effects of ambient aerosol particles on climate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1984

Signatures of troposphere-stratosphere momentum coupling Implications for global atmospheric angular momentum and earth rotation budgets

During January-August 1978, the global atmospheric angular momentum (M) exhibits distinct patterns of short term momentum interchange across latitudes. In the Northern Hemisphere winter-spring season, 30-50 day modulations of M are present in which momentum enhancements at mid-latitudes (20-30 deg) are closely matched by momentum depressions at high latitudes (50-60 deg). During the same interval there are no corresponding variations in M evident in the Southern Hemisphere. Conversely, during Southern Hemisphere fall-winter, similar anti-correlations in monthly scale momentum excursions are evident between mid and high latitudes. In the Northern Hemisphere, the winter-spring momentum signatures are detected throughout the atmosphere, from the lower troposphere to the stratosphere. During the Southern Hemisphere fall-winter, the modulation patterns are not evident at the higher altitudes. Structural details of the momentum signatures indicate that the coupling is sometimes effective on very short time scales, e.g., 1-2 days, or less. The evidence of distinct anti-correlation between large regions has interesting implications for studies of global atmospheric circulation, and also for studies of the excitation of variations in earth rotation in response to short term modulations of M.

Taylor, H. A.↗
NASA NTRS1995

Global tropospheric experiment at the Hong Kong Atmosphere Chemistry Measurement Station

The major activities of the Global Tropospheric Experiment at the Hong Kong Atmospheric Chemistry Measurement Station are presented for the period 1 January - 31 December 1995. Activities included data analysis, reduction, and archiving of atmospheric measurements and sampling. Sampling included O3, CO, SO2, NO, TSP, RSP, and ozone column density. A data archive was created for the surface meteorological data. Exploratory data analysis was performed, including examination of time series, frequency distributions, diurnal variations and correlation. The major results have been or will be published in scientific journals as well as presented at conferences/workshops. Abstracts are attached.

Carroll, Mary Ann↗
NASA NTRS2015

Improving the Accessibility and Use of NASA Earth Science Data

Many of the NASA Langley Atmospheric Science Data Center (ASDC) Distributed Active Archive Center (DAAC) multidimensional tropospheric and atmospheric chemistry data products are stored in HDF4, HDF5 or NetCDF format, which traditionally have been difficult to analyze and visualize with geospatial tools. With the rising demand from the diverse end‐user communities for geospatial tools to handle multidimensional products, several applications, such as ArcGIS, have refined their software. Many geospatial applications now have new functionalities that enable the end user to: Store, serve, and perform analysis on each individual variable, its time dimension, and vertical dimension. Use NetCDF, GRIB, and HDF raster data formats across applications directly. Publish output within REST image services or WMS for time and space enabled web application development. During this webinar, participants will learn how to leverage geospatial applications such as ArcGIS, OPeNDAP and ncWMS in the production of Earth science information, and in increasing data accessibility and usability.

Tisdale, Matthew↗