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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Daily Global Mapping of Mars Ozone Column Abundances with MARCI UV Band Imaging

Since November of 2006, The Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) has obtained multiple-filter daily global images of Mars centered upon a local time (LT) of 3 pm. Ultraviolet imaging bands placed within (260 nm) and longward (320 nm) of Hartley band (240-300 nm) ozone (O3) absorption support retrievals of atmospheric ozone columns, with detection limits (approximately 1 micrometer-atm) appropriate to mapping elevated O3 abundances at low latitudes around Mars aphelion, and over mid-to-high latitudes during fall/winter/spring seasons. MARCI O3 maps for these regions reveal the detailed spatial (approximately 1 deg lat/long, for 8 x 8 pixel binned resolution) and temporal (daily, with substantial LT coverage at pole) behaviors of water vapor saturation conditions that force large variations in water vapor photolysis products (HOx-OH, HO2, and H) responsible for the catalytic destruction of O3 in the Mars atmosphere. A detailed description of the MARCI O3 data set, including measurement and retrieval characteristics, is provided in conjunction with comparisons to Mars Express SPICAM ozone measurements (Perrier, S. et al. [2006]. J. Geophys. Res. (Planets) 111) and LMD GCM simulated O3 abundances (Lefevre, F. [2004]. J. Geophys. Res. (Planets) 109). Presented aspects of the MARCI ozone mapping data set include aphelion increases in low latitude O3, dynamically evolving high latitude O3 maxima associated with planetary waves and weather fronts during northern early spring, and distinctive winter/spring O3 and CO increases within the Hellas Basin associated with transport of condensation enhanced south polar air mass. Comparisons of coincident MARCI measurements and LMD simulations for ice cloud and O3 columns are considered in the context of potential heterogeneous photochemical processes (Lefevre, F. [2008]. Nature 454, 971-975), which are not strongly evidenced in the MARCI observations. Modest interannual variations are exhibited, most notably a 20% reduction in aphelion low latitude O3 columns following the 2007 perihelic global dust storm.

Clancy, R. Todd↗
NASA NTRS1991

A dynamical explanation for the asymmetry in zonally averaged column abundances of ozone between northern and southern springs

The observed zonally averaged column ozone shows a maximum at 90 deg N during the northern winter and spring and at 60 deg S throughout the southern winter and spring. This asymmetry is explained in the context of a zonally averaged model with coupled radiation, dynamics, and chemistry, together with consistently parameterized planetary wave driving and wave transport. It is shown that in the presence of weak wave driving, the penetration of the tropospheric circulation into the lower stratosphere and the characteristics of ozone chemistry are such that they produce a column ozone maximum at subpolar latitudes. The effect of increased wave driving is to intensify the residual circulation and extend it farther poleward, resulting in an ozone maximum at the pole. The role of the mesospheric drag is to further enhance these column ozone maxima. Model calculations show that the positions of the observed column ozone maxima are consistent with intensities of wave driving in the two hemispheres derived from data.

Hou, Arthur Y.↗
NASA NTRS1978

Tropospheric ozone distributions measured with an airborne laser absorption spectrometer

Measurements of tropospheric ozone have been made in the southern and middle California regions and over the Pacific Ocean during two series of flights in February and May 1977. The data were obtained by using a laser absorption spectrometer, a nadir-viewing instrument which remotely measures the ozone column abundance between ground level and aircraft altitude by interacting with ozone at specific wavelengths near 9.5 microns. The measurements indicate significantly lower ozone abundances above the Mojave Desert region as compared with farm, forest, and urban areas. The average tropospheric column density was found to be 0.0027 atm cm/km over the California region and 0.0035 atm cm/km over the Pacific Ocean region 1000-2000 km west of the coast of Mexico.

Menzies, R. T.↗
NASA NTRS1991

Ground based infrared measurements of the global distribution of ozone in the atmosphere of Mars

The global distribution of ozone in the atmosphere of Mars was determined from Doppler-limited infrared heterodyne spectroscopy measurements at the NASA Infrared Telescope Facility (IRTF) facility during June 3-7, 1988. Mars spectra near two O3 lines arising from the v sub 3 band near 1031.45 cm (-1) were used. The lines were Doppler shifted out of the strong terrestrial ozone absorption spectrum and its effect was removed. Ozone measurements were obtained at eight beam positions over a range of latitudes and local solar zenith angles. The beam size of the planet was 1.4 arcsec. A Martian CO2 line appeared in the spectra and was inverted to retrieve local temperature profiles. Using these temperature profiles, the total ozone column abundance at each position was retrieved by fitting the measured line with synthetic spectra generated by a radiative transfer program. The only previous measurement of ozone at this season was made above the South polar cap by Mariner 7 and revealed an abundance of 10 micron-atm. However, the retrieved O3 column abundances from this investigation are less than 2.2 micron-atm at all positions sampled. These results are consistent with mid-spring abundances predicted by photochemical models of Liu and Donahue, and Shimazaki and Shimizu.

Kostiuk, Theodor↗
NASA NTRS1977

Ozone abundances in the lower mesosphere deduced from backscattered solar radiances

Backscatter ultraviolet data obtained by the Explorer E satellite imply very large ozone column abundances above 56 km in the tropics during mid-day. The number of molecules in a vertical column decays by a factor of 2-3 after the solar zenith angle exceeds 75 deg in the evening. An increase of similar magnitude occurs after sunrise. Such behavior implies the presence of a greater source of odd oxygen than is included in current photochemical theories. Ozone profiles deduced between altitudes of 50 and 62 km when the solar zenith angle exceeds 80 deg are in reasonable agreement with past rocket results.

Frederick, J. E.↗
DOE OSTI2015

mfrsr (00)

The visible multifilter rotating shadowband radiometer (MFRSR) is a passive instrument that measures global and diffuse components of solar irradiance at six narrowband channels and one open, or broadband, channel. Direct irradiance is not a primary measurement, but is calculated using diffuse and global measurements. To collect one data record, the MFRSR takes measurements at four different shadowband positions. The first measurement is taken with the shadowband in the nadir (home) position. The next three measurements are, in order, the first side-band, sun-blocked, and second side-band. The side-band measurements are used to correct for the portion of the sky obscured by the shadowband. The nominal wavelengths of the narrowband channels are 415, 500, 615, 673, 870, and 940 nm. From such measurements, the atmosphere’s aerosol optical depth at each wavelength can be inferred. In turn, these optical depths may be used to derive information about the column abundances of ozone and water vapor, as well as aerosol and other atmospheric constituents.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1993

The Earth Observing System

The idea that the climate of Earth has changed is not new. Much evidence has been collected from the sedimentary record indicating periodic as well as secular changes in climate parameters such as surface temperature, precipitation amount, and ice extent and abundance, on many time scales. But in the last quarter of the twentieth century, there are several new elements in the way climate change is perceived. One is the view that human activity is having an impact on climatic conditions, on a global scale. The conclusion of recent studies indicating that anthropogenic chlorofluorocarbons are the root cause of a measured secular decrease in atmospheric ozone column abundance over the Antarctic in spring, illustrates this point (e.g., Solomon 1990).

Wenkert, D.↗
NASA NTRS1988

Visible and near-ultraviolet spectroscopy at Thule AFB (76.5 N) from January 28 - February 15, 1988

Near-ultraviolet and visible spectrographs identical to those employed at McMurdo Station, Antarctica (77.8 S) during the austral spring seasons of 1986 and 1987 were used to study the stratosphere above Thule, Greenland (76.5 N) during early spring, 1988. Observations were carried out both at night using the direct moon as a light source, and during the day by collecting the scattered light from the zenith sky when solar zenith angles were less than about 94.5 degrees. Excellent meteorological conditions prevailed in the troposphere and stratosphere at Thule. Surface weather was extremely clear over most of the period, facilitating measurements of the direct light from the moon. The lower stratospheric arctic polar vortex was located very near Thule throughout the observing period, and temperature at the 30 mbar level were typically below -80 C above Thule, according to the National Meteorological Center daily analyses. Thus conditions were favorable for polar stratospheric cloud formation above Thule. Total column ozone abundances were about 350 to 400 Dobson units, and did not suggest a clear temporal trend over the observing period. Stratospheric nitrogen dioxide measurements were complicated by the presence of a large component of tropospheric pollution on many occasions. Stratospheric nitrogen dioxide could be identified on most days using the absorption in the scattered light from the zenith sky, which greatly enhances the stratospheric airmass while suppressing the tropospheric contribution. These measurements suggest that the total vertical column abundance of nitrogen dioxide present over Thule in February was extremely low, sometimes as low as 3 x 10 to the 14th per sq cm. The abundance of nitrogen dioxide increased systemically from about 3 x 10 to the 14th in late January to 1.0 x 10 to the 15th per sq cm in mid-February, perhaps because of photolysis of N2O5 in the upper part of the stratosphere, near 25 to 35 km.

Mount, G. H.↗
NASA NTRS1991

The chemical composition of the dust-free Martian atmosphere - Preliminary results of a two-dimensional model

This paper describes a two-dimensional model of the Martian atmosphere, in which chemical, radiative and dynamical processes are treated interactively. The model is developed for a carbon dioxide-hydrogen-oxygen-nitrogen atmosphere and provides estimates of concentrations for 19 chemical species. The dynamical equations are expressed in the transformed Eulerian coordinates. The wave driving and eddy mixing coefficients resulting from gravity and Rossby wave absorption are computed consistently with the evolving distribution of the mean zonal wind. The net diabatic heating/cooling rate is derived from a detailed radiative scheme including the contributions of CO2, O3, H2O and O2, and is computed consistently with the calculated distribution of temperature and trace species quantities. The computed temperature field as well as the meridional and seasonal variations of ozone column abundance are in good agreement with the distributions observed by Mariner 9 and Viking spacecrafts and the results obtained by previous studies. The present version of the model does not include the effects of dust, clouds and polar hood and only the chemistry in a dust-free atmosphere is considered.

Moreau, D.↗
NASA NTRS1992

A contribution toward understanding the biospherical significance of Antarctic ozone depletion

The paper presents and compares measurements of biologically active UV radiation made by the NSF scanning spectroradiometer (UV-monitor) at Palmer Station, Antarctica, during the Austral springs of 1988, 1989, and 1990. Column ozone abundance above Palmer Station is computed from these measurements using a multiple wavelength algorithm. Two contrasting action spectra are employed to estimate the biologically relevant dose from the spectral measurements: a standard weighting function for damage to DNA, and a new action spectrum representing the potential for photosynthesis inhibition in Antarctic phytoplankton. The former weights only UV-B wavelengths (280-320 nm) and gives the most weight to wavelengths shorter than 300 nm, while the latter includes large contributions out to 355 nm. Ozone abundances and dose-weighted irradiances provided by the NSF UV-monitor are used to derive the radiation amplification factors for both DNA- and phytoplankton-effective irradiance.

Lubin, Dan↗
NASA NTRS1993

Fluctuations of total ozone and their relationship to stratospheric air motions

The origin of fluctuations of total ozone and the interactions that take place between the distribution of total ozone and the circulation of the troposphere are investigated on the basis of observations of total ozone from Nimbus 7 TOMS together with contemporaneous analyses of the circulation. It is shown that a sizable component of total ozone variability is explained by the quasi-columnar motion of air in the lower stratosphere. The development also suggests that in combination with isentropic analyses, total ozone measurements can provide a detailed picture of air motions in the lower stratosphere. Distributions of ozone column abundance and pressure on the 375-K isentropic surface for the Northern and Southern Hemispheres are illustrated.

Salby, Murry L.↗
NASA NTRS2001

Volcanoes, Polar Clouds and Arctic Ozone

Satellite observations and model calculations show 5 to 10% local column ozone loss in some tropical and mid latitude locations, following El Chichon and Mount Pinatubo eruptions. The rapid deepening of the Antarctic ozone hole in the early 1980s has also been partially attributed to chemistry on volcanic aerosols from a number of large eruptions. Here the effects of volcanoes on Arctic polar processes are explored. Large polar stratospheric cloud particles that cause denitrification cannot form in a volcanically perturbed environment. Denitrification can increase Arctic ozone loss by up to 30% in a future colder climate. However, we show that enhanced chemical processing on volcanic aerosols can increase Arctic ozone loss in a cold year by about 60% independent of denitrification. A coupled chemistry-microphysics model is used to show that widespread distribution of volcanic aerosols in 2000 could have caused severe springtime ozone depletion in the Arctic stratosphere. While, volcanic aerosols can strongly affect the current Arctic column ozone abundance in a cold year, denitrification effects on ozone can only become important in a much colder lower stratosphere.

Tabazadeh, Azadeh↗
NASA NTRS2004

Antarctic Ultraviolet Radiation Climatology from Total Ozone Mapping Spectrometer Data

This project has successfully produced a climatology of local noon spectral surface irradiance covering the Antarctic continent and the Southern Ocean, the spectral interval 290-700 nm (UV-A, UV-B, and photosynthetically active radiation, PAR), and the entire sunlit part of the year for November 1979-December 1999. Total Ozone Mapping Spectrometer (TOMS) data were used to specify column ozone abundance and UV-A (360- or 380-nm) reflectivity, and passive microwave (MW) sea ice concentrations were used to specify the surface albedo over the Southern Ocean. For this latter task, sea ice concentration retrievals from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and its successor, the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) were identified with ultraviolet/visible-wavelength albedos based on an empirical TOMS/MW parameterization developed for this purpose (Lubin and Morrow, 2001). The satellite retrievals of surface albedo and UV-A reflectivity were used in a delta-Eddington radiative transfer model to estimate cloud effective optical depth. These optical depth estimates were then used along with the total ozone and surface albedo to calculate the downwelling spectral UV and PAR irradiance at the surface. These spectral irradiance maps were produced for every usable day of TOMS data between 1979-1999 (every other day early in the TOMS program, daily later on).

Lubin, Dan↗
NASA NTRS1994

Climatic consequences of observed ozone loss in the 1980s: Relevance to the greenhouse problem

Recently published findings using satellite and ground-based observations indicate a large winter and summertime decrease in the column abundance of ozone at high and middle latitudes during the last decade. Using a simple ozone depletion profile reflecting the observed decrease in ozone column abundance, Ramaswamy et al. (1992) showed that the negative radiative forcing that results from the ozone decrease between 1979 and 1990 approximately balanced the greenhouse climate forcing due to the chlorofluorocarbons emitted during the same period. Here, we extend the forcing analyses by calculating the equilibrium surface temperature response explicitly, using an updated version of the Atmospheric and Environmental Research two-dimensional radiative-dynamical seasonal model. The calculated steady state responses suggest that the surface cooling due to the ozone depletion in the lower stratosphere offsets about 30% of the surface warming due to greenhouse gases emitted during the same decade. The temperature offset is roughly a factor of 2 larger than the corresponding offset obtained from forcing intercomparisons. This result appears to be related to the climate feedback mechanisms operating in the model troposphere, most notably that associated with atmospheric meridional heat transport. Thus a comprehensive assessment of ozone change effects on the predicted greenhouse warming cannot be accomplished based on forcing evaluations alone. Our results also show that calculations adopting a seasonally and latitudinally dependent ozone depletion profile produce a negative forcing about 50% smaller than that calculated for the depletion profile used by Ramaswamy et al. (1992).

Molnar, G. I.↗
NASA NTRS1991

Predicted aircraft effects on stratospheric ozone

The possibility that the current fleet of subsonic aircraft may already have caused detectable changes in both the troposphere and stratosphere has raised concerns about the impact of such operations on stratospheric ozone and climate. Recent interest in the operation of supersonic aircraft in the lower stratosphere has heightened such concerns. Previous assessments of impacts from proposed supersonic aircraft were based mostly on one-dimensional model results although a limited number of multidimensional models were used. In the past 15 years, our understanding of the processes that control the atmospheric concentrations of trace gases has changed dramatically. This better understanding was achieved through accumulation of kinetic data and field observations as well as development of new models. It would be beneficial to start examining the impact of subsonic aircraft to identify opportunities to study and validate the mechanisms that were proposed to explain the ozone responses. The two major concerns are the potential for a decrease in the column abundance of ozone leading to an increase in ultraviolet radiation at the ground, and redistribution of ozone in the lower stratosphere and upper troposphere leading to changes in the Earth's climate. Two-dimensional models were used extensively for ozone assessment studies, with a focus on responses to chlorine perturbations. There are problems specific to the aircraft issues that are not adequately addressed by the current models. This chapter reviews the current status of the research on aircraft impact on ozone with emphasis on immediate model improvements necessary for extending our understanding. The discussion will be limited to current and projected commercial aircraft that are equipped with air-breathing engines using conventional jet fuel. The impacts are discussed in terms of the anticipated fuel use at cruise altitude.

Ko, Malcolm K. W.↗
NASA NTRS1988

Measurements of ozone in the Antarctic region during August and September of 1987

Mixing ratios are presented for ozone in the austral polar atmosphere during Aug. and Sept. of 1987. Since the mid-1970's, there has been a continuing decrease in the total column abundance of ozone over Antarctica during the late winter and early spring. This reduction now amounts to about one-half of the historical October mean. The results presented are derived from an ultraviolet ozone photometer. The ER-2 aircraft carrying 14 instruments participated in a major effort to penetrate the region of depletion. Data were gathered between altitudes of 53 deg and 72 deg S at pressure altitudes up to 21 km in a series of 12 flights. Additional data were obtained between latitudes of 37 deg N and 53 deg S on the 3 flight legs required to reach Punta Arenas from Moffett Field, CA, and on the same return legs to Moffett Field. The observed ozone mixing ratios indicate the effects of chemistry as well as the effects of the stratospheric polar vortex. Examples of the distributions of ozone mixing ratios as a function of altitude, latitude, or a time and the relationships to temperature and other trace gases are presented.

Starr, Walter L.↗
NASA NTRS1991

The potential for ozone depletion in the Arctic polar stratosphere

The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (CHl and ClONO2) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl2O2 thoroughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO3, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15 percent at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8 percent losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50 percent over the next two decades, ozone losses recognizable as an ozone hole may well appear.

Brune, W. H.↗
DOE OSTI2024

The Role and Lifetime of Dissociative Heterogeneous Processes in Improving Simulated Ozone on Mars

Abstract Ozone simulated in Mars Global Climate Models (MGCMs) is used to assess the underlying chemistry occurring in the atmosphere. Currently, ozone total column abundance (TCA) is under‐predicted in MGCMs by up to 120%, implying missing or inaccurate chemistry in models. Heterogeneous reactions of hydroxyl radicals (HO X ) have been offered as an explanation for some of this bias, because they cause ozone to increase at locations where it's currently under‐predicted. We use four simulations to compare modeled ozone TCA with observations from the UVIS spectrometer aboard the ExoMars Trace Gas Orbiter to improve the representation of heterogeneous processes and their impact on ozone. We use a gas‐phase only run, a dissociative scheme, an adsorbed HO X retention scheme, and a hybrid scheme that combines the dissociative mechanism with the retention of HO X on water ice. We find retention of HO X is dependent on water ice sublimation, and ozone abundance increases when water ice persists for longer periods (1–20 sols). Over time, the loss of HO X causes a depletion in H 2 O 2 concentration (HO X reservoir), and thus allows ozone concentration to increase. When adsorbed HO X are desorbed and dissociate into other by‐products, HO X are not immediately available to destroy ozone. This results in larger ozone concentrations than if desorbed HO X are released directly back into their gaseous states. When using the hybrid scheme, ozone TCA is increased up to 50% where the ozone deficit is greatest, demonstrating the best agreement with observations, and implying that HO X radicals are both retained when adsorbed and dissociate.

Brown, M. A. J.↗