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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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NASA NTRS1990

Atmospheric peroxyacetyl nitrate measurements over the Brazilian Amazon Basin during the wet season - Relationships with nitrogen oxides and ozone

An analysis is presented on the distribution and variability of PAN as well as its relationship with measured chemical and meteorological parameters. The chemicals of most interest for which measurements were available are PAN, NO(x), O3, CO, and C2Cl4. PAN was measured by the electron capture gas chromatographic technique, and the technique for calibrations and measurements are detailed. Data show that significant concentrations of PAN (5-125 ppt) are present during the wet season and this PAN is 1-5 times more abundant than NO(x). PAN levels at different atmospheric locations are discussed, and it is noted that PAN shows evidence of a possible latitudinal gradient in the free troposphere, with values falling rapidly from the northern midlatitudes toward the equator. High correlations between O3 and PAN levels suggest that nonmethane hydrocarbons may contribute significantly to high O3 in the free troposphere. Evidence indicates that virtually all of the NO(x) above 4 km could result from PAN decomposition.

Singh, H. B.↗
NASA NTRS1991

What maintains the zonal circulation in planetary atmospheres?

The latest Voyager observations have shown large zonal velocities in Neptune's atmosphere, with some indication of alternating jets. Similar wind velocities have also been observed on Venus and are characteristic of planetary atmospheres in general, which is remarkable considering that the available solar or internal heating varies by more than a factor of 1000. A simplified model of the planetary circulation which provides some qualitative understanding is discussed. The basic assumption is that the source driving the circulation is also generating the dissipating eddies which are simulated by diffusion. Thus, the magnitude and structure of the zonal circulation are independent both of the source and the dissipation rate. The zonal velocities are related to the speed of sound and are of comparable magnitude in different atmospheres; although the available heating varies by a large factor, and the planetary parameters vary over a wide range. The alternating jets are described by a convective eigenmode which develops when energy transport out of the planetary interior is important, as is the case on Jupiter, Neptune, and Saturn.

Mayr, H. G.↗
NASA NTRS1993

Calculation of the angular radiance distribution for a coupled atmosphere and canopy

The radiative transfer equations for a coupled atmosphere and canopy are solved numerically by an improved Gauss-Seidel iteration algorithm. The radiation field is decomposed into three components: unscattered sunlight, single scattering, and multiple scattering radiance for which the corresponding equations and boundary conditions are set up and their analytical or iterational solutions are explicitly derived. The classic Gauss-Seidel algorithm has been widely applied in atmospheric research. This is its first application for calculating the multiple scattering radiance of a coupled atmosphere and canopy. This algorithm enables us to obtain the internal radiation field as well as radiances at boundaries. Any form of bidirectional reflectance distribution function (BRDF) as a boundary condition can be easily incorporated into the iteration procedure. The hotspot effect of the canopy is accommodated by means of the modification of the extinction coefficients of upward single scattering radiation and unscattered sunlight using the formulation of Nilson and Kuusk. To reduce the computation for the case of large optical thickness, an improved iteration formula is derived to speed convergence. The upwelling radiances have been evaluated for different atmospheric conditions, leaf area index (LAI), leaf angle distribution (LAD), leaf size and so on. The formulation presented in this paper is also well suited to analyze the relative magnitude of multiple scattering radiance and single scattering radiance in both the visible and near infrared regions.

Liang, Shunlin↗
NASA NTRS2020

Constraining the Twomey effect from satellite observations: Issues and perspectives

The Twomey effect describes the radiative forcing associated with a change in cloud albedo due to an increase in anthropogenic aerosol emissions. It is driven by the perturbation in cloud droplet number concentration (ΔNd,ant) in liquid-water clouds and is currently understood to exert a cooling effect on climate. The Twomey effect is the key driver in the effective radiative forcing due to aerosol–cloud interactions which also comprises rapid adjustments. These adjustments are essentially the responses of cloud fraction and liquid water path to ΔNd,ant and thus scale approximately with it. While the fundamental physics of the influence of added aerosol particles on the droplet concentration (Nd) is well described by established theory at the particle scale (micrometres), how this relationship is expressed at the large scale (hundreds of kilometres) ΔNd,ant remains uncertain. The discrepancy between process understanding at particle scale and insufficient quantification at the climate-relevant large scale is caused by co-variability of aerosol particles and vertical wind and by droplet sink processes. These operate at scales on the order of 10s of metres at which only localized observations are available and at which no approach exists yet to quantify the anthropogenic perturbation. Different atmospheric models suggest diverse magnitudes of the Twomey effect even when applying the same anthropogenic aerosol emission perturbation. Thus, observational data are needed to quantify and constrain the Twomey effect. At the global scale, this means satellite data. There are three key uncertainties in determining ΔNd,ant, namely the quantification (i) of the cloud-active aerosol – the cloud condensation nuclei concentrations (CCN) at or above cloud base –, (ii) of Nd, as well as (iii) the statistical approach for inferring the sensitivity of Nd to aerosol particles from the satellite data. A fourth uncertainty, the anthropogenic perturbation to CCN concentrations, is also not easily accessible from observational data. This review discusses deficiencies of current approaches for the different aspects of the problem and proposes several ways forward: In terms of CCN, retrievals of optical quantities such as aerosol optical depth suffer from a lack of vertical resolution, size and hygroscopicity information, the non-direct relation to the concentration of aerosols, the impossibility to quantify it within or below clouds, and the problem of insufficient sensitivity at low concentrations, in addition to retrieval errors. A future path forward can include utilizing colocated polarimeter and lidar instruments, ideally including high spectral resolution lidar capability at two wavelengths to maximize vertically resolved size distribution information content. In terms of Nd, a key problem is the lack of operational retrievals of this quantity, and the inaccuracy of the retrieval especially in broken-cloud regimes. As for the Nd – to – CCN sensitivity, key issues are the updraught distributions and the role of Nd sink processes, for which empirical assessments for specific cloud regimes are currently the best solutions. These considerations point to the conclusion that past studies using existing approaches have likely underestimated the true sensitivity and, thus, the radiative forcing due to the Twomey effect.

Twomey effect↗
NASA NTRSDate not supplied

Surface and Atmospheric Shortwave Radiative Fluxes From ISCCP Data and Fu-Liou Algorithm at Higher Spatial and Vertical Resolution

NASA/GEWEX Surface Radiation Budget (SRB) has provided surface and TOA shortwave and longwave radiative fluxes using International Satellite Cloud Climatology data as the primary input. Release 4.0 came out in 2019, with data from July 1983 through June 2017, and improved validation stats relative to Release 3.0 (Stackhouse et al., 2012). Release 4.0 used the newly reprocessed ISCCP H data set. The shortwave algorithm for versions 3 and 4 has been based on the Pinker and Laszlo (1992) algorithm, which relies on the satellite-measured shortwave radiance to produce a TOA albedo. This background TOA albedo is made utilizing the background clear-sky visible radiance (called clear-sky composite radiance in the ISCCP data) and applying narrowband-to-broadband angular distribution models. Using a climatological aerosol assumption, the surface albedo is estimated using radiative transfer based (i.e., Fu/Liou radiative transfer model; Fu and Liou, 1993) look-up tables. Using this surface albedo and an instantaneous TOA albedo, the look-up tables are used to adjust both the aerosol optical depth (for clear sky) and cloud optical depth (for cloudy sky) for each scene. These properties and look up tables are then used to generate surface fluxes. While this has worked well to provide useful fluxes, it has occasionally resulted in inaccurate direct and diffuse surface SW fluxes due to the overreliance on aerosol optical depth. With increased computational power and storage now available, a more direct approach is now possible. Here we present a different approach for a future high resolution SRB Release 5.0. We replace the Pinker-Laszlo lookup table approach with a forward call to the Fu-Liou radiative transfer model as modified by the CERES team (Rose et al., 2006). In addition to being a proven radiation code, Fu-Liou allows the calculation of fluxes at different atmospheric levels and spectral bands, which will provide more insight into the surface radiation budget, its variability and attribution. It is expected that horizontal resolution will increase to at least 0.5°x0.5° from the current 1°x1°. Here we demonstrate a preliminary look at the next SRB, and show comparisons with the current release.

Earth Radiation Budget↗
NASA NTRS1972

Description of solar structure and processes.

A general introduction to solar structure and processes is presented. The sun is first viewed as a spherically symmetric steady-state system, and the energy generated in the core is traced as it flows outward. The various forms and manifestations of this energy flow and the resulting uniquely defined characteristics of different atmospheric layers are described. The sources of solar activity are assumed to be differential rotation and solar magnetic fields. The interaction of these sources to produce the observed solar cycle, active regions, the active-sun corona, and solar flares is discussed. In describing solar structure and processes, only elementary physical concepts are utilized.

Gibson, E. G.↗
NASA NTRS1976

Measurement of transpiration in Pinus taeda L. and Liquidambar styraciflua L. in an environmental chamber using tritiated water

Transpiration rates of loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.) were measured at two different atmospheric water vapor pressure deficits (V.P.D.) in a controlled environment growth chamber using tritiated water as a tracer. The trees were maintained in a sealed plant bed containing a hydroponic nutrient solution into which labeled water (spike) was introduced. Samples of leaves, chamber air, spiked nutrient solution and control water were assayed for ratio-activity using liquid scintillation techniques to determine transpiration rates. The transpiration rate of sweetgum in ml./hr./gm. (4.95) was found to be 5 times greater than that of loblolly pine (1.03) at 1.84 V.P.D. and 8 times greater at 6.74 V.P.D. (15.99 for sweetgum vs. 2.19 for pine). Transpiration (based on measurements of leaf radioactivity) in both species rose with increasing deficit; however sweetgum increased its output by 3 times while pine only doubled its rate. Cyclical changes in transpiration rates were noted in both species; the sweetgum cycle required a 6 hour interval whereas the pine cycle required a 9 hour interval.

Levy, G. F.↗
NASA NTRS1976

Development of solar active regions

The birth, growth, and decay of solar active regions are described. The appearance of active regions in different atmospheric layers is examined, and the coronal extension of active regions is considered. The use of Skylab soft X-ray and extreme UV observations for studying the complex loop structure of active regions in the solar corona and the sensitive reactions of the upper atmospheric layers to newly emerging flux is explained. It was found that well developed active regions are much bigger in the corona than in the underlying sunspot groups and plages, and that many of the active regions are connected with others through systems of magnetic field lines, occasionally visible in soft X-rays. These interconnections, which may survive several solar rotations, indicate bigger complexes on the sun than one individual active region.

Svestka, Z.↗
NASA NTRS1980

Multispectral Resource Sampler (MRS): Proof of concept. Study on bidirectional reflectance. A simulation analysis of bidirectional reflectance properties and their effects on scene radiance. Implications for the MRS

A study was performed to evaluate the geometrical implication of a Multispectral Resource Sampler; a pointable sensor. Several vegetative targets representative of natural and agricultural canopies were considered in two wavelength bands. All combinations of Sun and view angles between 5 and 85 degrees zenith for a range of azimuths were simulated to examine geometrical dependance arising from seasonal as well as latitudinal variation. The effects of three different atmospheres corresponding to clear, medium and heavy haze conditions are included. An extensive model data base was generated to provide investigators with means for possible further study of atmospheric correction procedures and sensor design questions.

Smith, J. A.↗
NASA NTRS1982

The JPL millimeter, submillimeter and microwave line catalog

The catalog includes molecules of interest in the interstellar medium, in planetary atmospheres and in the Earth's atmosphere. Different units than those on the AFGL tape are used. For citing line frequencies in the microwave region. Either the experimental errors or the propagation of errors from the fit are included on the tape. This gives an estimate of how accurate the frequencies are. The intensity units are defined as follows: the logarithm of the intensity unit is the cross section times the frequency in MHz. This is essentially the same unit as on the AFGL tape, but contains fewer factors of the speed of light. The catalog is available to the scientific community either as a tape or on microfiche (filmed in frequency sorted and molecule sorted format).

Pickett, H.↗
NASA NTRS1983

A model of mean zonal flows in the major planets

The linear theory of deep zonal flows developed by Busse (1976) for the origins of deep motions of the atmospheres of Jupiter and Saturn is extended into the nonlinear regime. Relationships for the relative magnitudes of convective heat and momentum transports are formulated. A perturbation approach is taken to the problem, with the amplitude of the convection serving as the small parameter, and the basic equations being expanded in terms of the Prandtl number. The Boussinesq approximation is employed, together with an assumption of a low Rossby number for the Jovian and Saturn atmospheres. Differences in the amplitude of the Jovian equatorial jet relative to that of Saturn are explored in terms of a low equatorial convective heat flux on Jupiter.

Busse, F. H.↗
NASA NTRS1984

Air-sampling inlet contamination by aircraft emissions on the NASA CV-990 aircraft

Results of an experimental investigation of the contamination of air sampling inlets by aircraft emissions from the NASA CV-990 research aircraft are presented. This four-engine jet aircraft is a NASA facility used for many different atmospheric and meteorological experiments, as well as for developing spacecraft instrumentation for remote measurements. Our investigations were performed to provide information on which to base the selection of sampling locations for a series of multi-instrument missions for measuring tropospheric trace gases. The major source of contamination is the exhaust from the jet engines, which generate many of the same gases that are of interest in atmospheric chemistry, as well as other gases that may interfere with sampling measurements. The engine exhaust contains these gases in mixing ratios many orders of magnitude greater than those that occur in the clean atmosphere which the missions seek to quantify. Pressurized samples of air were collected simultaneously from a scoop located forward of the engines to represent clean air and from other multiport scoops at various aft positions on the aircraft. The air samples were analyzed in the laboratory by gas chromatography for carbon monoxide, an abundant combustion by-product. Data are presented for various scoop locations under various flight conditions.

Condon, E. P.↗
NASA NTRS1984

Airborne Doppler lidar wind field measurements

A coherent Doppler lidar has been used in an aircraft to measure the two-dimensional wind field in a number of different atmospheric situations. The lidar, a pulsed CO2 system, was installed in the NASA Convair 990, Galileo II, and flown in a summer field program that included flights in California, in Oklahoma at the National Severe Storms Laboratory, and in Montana at the Cooperative Convective Precipitation Experiment (CCOPE). This paper provides a brief description of the instrumentation and summarizes the research flights. Examples of some of the results are given along with plans for future use of the lidar.

Bilbro, J.↗
NASA NTRS1985

Sea surface temperature anomalies, planetary waves, and air-sea feedback in the middle latitudes

Current analytical models for large-scale air-sea interactions in the middle latitudes are reviewed in terms of known sea-surface temperature (SST) anomalies. The scales and strength of different atmospheric forcing mechanisms are discussed, along with the damping and feedback processes controlling the evolution of the SST. Difficulties with effective SST modeling are described in terms of the techniques and results of case studies, numerical simulations of mixed-layer variability and statistical modeling. The relationship between SST and diabatic heating anomalies is considered and a linear model is developed for the response of the stationary atmosphere to the air-sea feedback. The results obtained with linear wave models are compared with the linear model results. Finally, sample data are presented from experiments with general circulation models into which specific SST anomaly data for the middle latitudes were introduced.

Frankignoul, C.↗
NASA NTRS1986

Constraints on the NH3 and PH3 distributions in the Great Red Spot

Medium resolution (10 A) UV spectra were obtained for the Great Red Spot (GRS) and South Tropical Zone (STZ) of Jupiter using the low dispersion mode of the IUE spectrometers at wavelengths from 1900-2200 A. The scans were carried out to determine the coloring agent for the GRS to improve the database for developing photochemical models of the feature. The wavelengths were selected to cover the absorption features of NH3 and PH3. The resulting data were interpreted using a vertically inhomogeneous Rayleigh scattering radiative transfer model. Various NH3 concentrations were explored in an effort to fit the data, taking into account changes which would occur at different atmospheric pressure levels and due to the projected temperature fields. A forbidden NH3/forbidden H2 mixing ratio that was calculated at the 80-125 mbar pressure level in the GRS was enhanced by 3-10 percent relative to the STZ. An upper limit was obtained for the mixing ratio of PH3 in the GRS that is significantly lower than previously predicted concentrations, implying that vertical transport in the GRS is not much greater than in adjacent regions.

Wagener, R.↗
NASA NTRS1986

Quality indicators for trace gas concentrations determined from earthlimb emission spectra

Different techniques which can be used to indicate the quality of the mixing ratios retrieved from spectral radiance measurements made by the CLAES instrument for 11 different atmospheric gases are discussed. A key to retrieval from noisy data is the Singular Value Decomposition (SVD), which is described. The use of the SVD with simulated data and radiance measurements from a balloon floating at 30 km is discussed.

Uplinger, W. G.↗