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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 NTRS1978

Transformation of surface albedo to surface: Atmosphere surface and irradiance, and their spectral and temporal averages

The dependence of the albedo at the top of a realistic atmosphere upon the surface albedo, solar zenith angle, and cloud optical thickness is examined for the cases of clear sky, total cloud cover, and fractional cloud cover. The radiative transfer calculations of Dave and Braslau (1975) for particular values of surface albedo and solar zenith angle, and a single value of cloud optical thickness are used as the basis of a parametric albedo model. The question of spectral and temporal averages of albedos and reflected irradiances is addressed, and unique weighting functions for the spectral and temporal albedo averages are developed.

Nack, M. L.↗
NASA NTRSDate not supplied

Calculation of top-of-atmosphere, surface and atmospheric cloud radiative kernels and feedbacks based on ISCCP-H datasets

This study aims to create observation-based cloud radiative kernel (CRK) datasets and evaluate them by direct comparison of CRK and the CRK-derived cloud feedback datasets. Based on the International Satellite Cloud Climatology Project (ISCCP) H datasets, we calculate CRKs (called FH CRKs) as 2D joint function/histogram of cloud optical depth and cloud top pressure for shortwave, longwave, and their sum, Net, at the top of atmosphere (TOA), as well as, for the first time, at the surface (SFC) and in the atmosphere (ATM). The direct comparison shows that FH agrees reasonably well with three other TOA CRK datasets. With cloud fraction change (CFC) datasets of the same histogram for doubled-CO2 simulation from 10 CFMIP1 models, we derive all the TOA, SFC and ATM cloud feedback using the FH CRKs. Our TOA cloud feedback is highly similar to the previous counterparts. Based on the comparison for the 4 CRK datasets and the 10 CFC datasets, we estimate the uncertainty budget for the CRK-derived cloud feedback and show that the CFC-associated uncertainty contributes > 98.5% of the total cloud feedback uncertainty while CRK’s is very small. Our preliminary evaluation shows that some near-zero/small cloud feedback in the TOA-alone feedback indeed results from the compensation of sizable cloud feedback of the SFC and ATM feedback, demonstrating that they help reveal some significant surface and atmospheric cloud feedback whose sum appears insignificant in TOA-alone feedback

cloud radiative kernel (CRK) datasets↗
NASA NTRS2021

The Top-of-Atmosphere, Surface and Atmospheric Cloud Radiative Kernels Based on ISCCP-H Datasets: Method and Evaluation

This study aims to create observation-based cloud radiative kernel (CRK) datasets and evaluate them by direct comparison of CRK and the CRK-derived cloud feedback datasets. Based on the International Satellite Cloud Climatology Project (ISCCP) H datasets, we calculate CRKs (called ISCCP-FH or FH CRKs) as 2D joint function/histogram of cloud optical depth and cloud top pressure for shortwave (SW), longwave (LW), and their sum, Net, at the top of atmosphere (TOA), as well as, for the first time, at the surface (SFC) and in the atmosphere (ATM). With cloud fraction change (CFC) datasets from doubled-CO2 simulation and short-term observational anomalies, we derive all the TOA, SFC and ATM cloud feedback for SW, LW and Net using our CRKs.The direct comparison with modeled and observed CRKs (or cloud radiative effects), cloud feedback from previous model results and the Clouds and the Earth's Radiant Energy System products show that our CRKs and CRK-derived cloud feedback are reasonably well validated. We estimate the uncertainty for the CRK-derived cloud feedback and show that the CFC-associated uncertainty contributes >98.5% of the total cloud feedback uncertainty while CRK's is very small. Our preliminary evaluation also shows that some near-zero/small cloud feedback in the TOA-alone feedback indeed results from the compensation of sizable cloud feedback of the SFC and ATM feedback and reveals some significant surface and atmospheric cloud feedback whose sum appears insignificant in TOA-alone feedback. In addition, the atmospheric longwave cloud feedback seems to play a role in enhancing meridional atmospheric energy transport.

cloud radiative kernel↗
NASA NTRS2022

Constraining Arctic Climate Projections of Wintertime Warming With Surface Turbulent Flux Observations and Representation of Surface-Atmosphere Coupling

The drivers of rapid Arctic climate change—record sea ice loss, warming SSTs, and a lengthening of the sea ice melt season—compel us to understand how this complex system operates and use this knowledge to enhance Arctic predictability. Changing energy flows sparked by sea ice decline, spotlight atmosphere-surface coupling processes as central to Arctic system function and its climate change response. Despite this, the representation of surface turbulent flux parameterizations in models has not kept pace with our understanding. The large uncertainty in Arctic climate change projections, the central role of atmosphere-surface coupling, and the large discrepancy in model representation of surface turbulent fluxes indicates that these processes may serve as useful observational constraints on projected Arctic climate change. This possibility requires an evaluation of surface turbulent fluxes and their sensitivity to controlling factors (surface-air temperature and moisture differences, sea ice, and winds) within contemporary climate models (here Coupled Model Intercomparison Project 6). The influence of individual controlling factors and their interactions is diagnosed using a multi-linear regression approach. This evaluation is done for four sea ice loss regimes, determined from observational sea ice loss trends, to control for the confounding effects of natural variability between models and observations. The comparisons between satellite- and model-derived surface turbulent fluxes illustrate that while models capture the general sensitivity of surface turbulent fluxes to declining sea ice and to surface-air gradients of temperature and moisture, substantial mean state biases exist. Specifically, the central Arctic is too weak of a heat sink to the winter atmosphere compared to observations, with implications to the simulated atmospheric circulation variability and thermodynamic profiles. Models were found to be about 50% more efficient at turning an air-sea temperature gradient anomaly into a sensible heat flux anomaly relative to observations. Further, the influence of sea ice concentration on the sensible heat flux is underestimated in models compared to observations. The opposite is found for the latent heat flux variability in models; where the latent heat flux is too sensitive to a sea ice concentration anomaly. Lastly, the results suggest that present-day trends in sea ice retreat regions may serve as suitable observational constraints of projected Arctic warming.

turbulent fluxes↗
NASA NTRS1992

Atmosphere-surface interactions and atmospheric evolution on Mars

A knowledge of the original volatile endowment of Mars is essential for any discussion of atmospheric loss on this planet. Cosmochemical models which postulate that planetary bulk compositions and volatile contents were controlled by the radial temperature profile in the solar nebula, and estimated bulk compositions based on the assumption that Mars is the parent body for the SNC meteorites predicts that Mars is volatile-rich. However, contrary views can also be found. For illustrative purposes, it is assumed that Mars was volatile-rich initially like the Earth. Taking terrestrial volatiles as the sum of the atmospheric, crustal, and oceanic volatiles and assuming that Mars accreted with the same volatile content on a g/g basis, the volatile endowments for an Earth-like Mars correspond to approximately 14 bars CO2, 800 mbars N2, and 1.2 km H2O. Subsequent topics discussed are: composition of outgassing volatiles; rates of present day atmospheric-surface reactions; constraints on CO2 loss via carbonate formation; constraints on H2O loss; and loss of other volatiles.

Fegley, Bruce, Jr.↗
NASA NTRS1983

Optimizing a remote sensing instrument to measure atmospheric surface pressure

Atmospheric surface pressure can be remotely sensed from a satellite by an active instrument which measures return echoes from the ocean at frequencies near the 60 GHz oxygen absorption band. The instrument is optimized by selecting its frequencies of operation, transmitter powers and antenna size through a new procedure baesd on numerical simulation which maximizes the retrieval accuracy. The predicted standard deviation error in the retrieved surface pressure is 1 mb. In addition the measurements can be used to retrieve water vapor, cloud liquid water and sea state, which is related to wind speed.

Peckham, G. E.↗
NASA NTRS2001

Airborne spectral Measurements of Surface-Atmosphere Anisotropy for Several Surfaces and Ecosystem over Southern Africa

The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair CV-580 research aircraft and took measurements on 23 flights between August 15 and September 16. On 12 of those flights, BRF measurements were obtained over different natural surfaces and ecosystem in southern Africa. The BRF measurements were done to characterize surface anisotropy in support of SAFARI 2000 science objectives principally to validate products from NASA's EOS satellites, and to parameterize and validate BRF models. In this paper we present results of BRFs taken over two EOS validation sites: Skukuza tower, South Africa (25.0 deg S, 31.5 deg E) and Mongu tower, Zambia (15.4 deg S, 23.3 deg E). Additional sites are also considered and include, Maun tower, Botswana (20.0 deg S, 23.5 deg E), Sowa Pan, Botswana (20.6 deg S, 26.2 deg E) and Etosha Pan, Namibia (19.0 deg S, 16.0 deg E). The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 micrometers), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 micrometers). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to bank at a comfortable roll angle of approximately 20 degrees and fly in a circle about 3 km in diameter above the surface for roughly two minutes. Replicated observations (multiple circular orbits) were acquired over selected surfaces so that average BRF smooth out small-scale surface and atmospheric inhomogeneities. At an altitude of 600 m above the targeted surface area and with a 1 deg IFOV, the pixel resolution is about 10 m at nadir and about 270 m at an 80 deg viewing angle from the CAR.

Gatebe, Charles K.↗
NASA NTRS1992

MSATT Workshop on Innovative Instrumentation for the In Situ Study of Atmosphere-Surface Interactions on Mars

Papers accepted for the Mars Surface and Atmosphere Through Time (MSATT) Workshop on Innovative Instruments for the In Situ Study of Atmosphere-Surface Interaction of Mars, 8-9 Oct. 1992 in Mainz, Germany are included. Topics covered include: a backscatter Moessbauer spectrometer (BaMS) for use on Mars; database of proposed payloads and instruments for SEI missions; determination of martian soil mineralogy and water content using the Thermal Analyzer for Planetary Soils (TAPS); in situ identification of the martian surface material and its interaction with the martian atmosphere using DTA/GC; mass spectrometer-pyrolysis experiment for atmospheric and soil sample analysis on the surface of Mars; and optical luminescence spectroscopy as a probe of the surface mineralogy of Mars.

Fegley, Bruce, Jr.↗
NASA NTRS2018

Operational Testing of 4H-SiC JFET ICs for 60 Days Directly Exposed to Venus Surface Atmospheric Conditions

Prolonged Venus surface missions (lasting months instead of hours) have proven infeasible to date in the absence of a complete suite of electronics able to function for such durations without protection from the planet’s extreme conditions of ~460 °C, ~9.3 MPa (~ 92 Earth atmospheres) chemically reactive environment. Here we report testing data from a successful two-month (60-day) operational demonstration of two 175-transistor 4H-SiC junction field effect transistor (JFET) semiconductor integrated circuits (ICs) directly exposed (no cooling and no protective chip packaging) to a high-fidelity physical and chemical reproduction of Venus surface atmospheric conditions in a test chamber. These results extend the longest reported duration of electronics operation in Venus surface atmospheric conditions almost 3-fold and were accomplished using prototype SiC JFET chips of more than 7-fold increased complexity. The demonstrated advancement marks a significant step towards realization of electronics with sufficient complexity and durability for implementing robotic landers capable of returning months of scientific data from the surface of Venus.

Integrated Circuit↗
NASA NTRS1994

Impact of Clouds on the Shortwave Radiation Budget of the Surface: Atmosphere System for Snow Covered Surfaces

Recent data from the Earth Radiation Budget Experiment (ERBE) have raised the question as to whether or not the addition of clouds to the atmospheric column can decrease the top-of-the-atmosphere (TOA) albedo over bright snow-covered surfaces. To address this issue, ERBE shortwave pixel measurements have been collocated with surface insolation measurements made at two snow-covered locations: the South Pole and Saskatoon, Saskatchewan. Both collocated datasets show a negative correlation (with solar zenith angle variability removed) between TOA albedo and surface insolation. Because increased cloudiness acts to reduce surface insolation, these negative correlations demonstrate that clouds increase the TOA albedo at both snow-covered locations.

Nemesure, Seth↗
NASA NTRS1990

Characteristics of the Martian atmosphere surface layer

Elements of various terrestrial boundary layer models are extended to Mars in order to estimate sensible heat, latent heat, and momentum fluxes within the Martian atmospheric surface ('constant flux') layer. The atmospheric surface layer consists of an interfacial sublayer immediately adjacent to the ground and an overlying fully turbulent surface sublayer where wind-shear production of turbulence dominates buoyancy production. Within the interfacial sublayer, sensible and latent heat are transported by non-steady molecular diffusion into small-scale eddies which intermittently burst through this zone. Both the thickness of the interfacial sublayer and the characteristics of the turbulent eddies penetrating through it depend on whether airflow is aerodynamically smooth or aerodynamically rough, as determined by the Roughness Reynold's number. Within the overlying surface sublayer, similarity theory can be used to express the mean vertical windspeed, temperature, and water vapor profiles in terms of a single parameter, the Monin-Obukhov stability parameter. To estimate the molecular viscosity and thermal conductivity of a CO2-H2O gas mixture under Martian conditions, parameterizations were developed using data from the TPRC Data Series and the first-order Chapman-Cowling expressions; the required collision integrals were approximated using the Lenard-Jones potential. Parameterizations for specific heat and binary diffusivity were also determined. The Brutsart model for sensible and latent heat transport within the interfacial sublayer for both aerodynamically smooth and rough airflow was experimentally tested under similar conditions, validating its application to Martian conditions. For the surface sublayer, the definition of the Monin-Obukhov length was modified to properly account for the buoyancy forces arising from water vapor gradients in the Martian atmospheric boundary layer. It was found that under most Martian conditions, the interfacial and surface sublayers offer roughly comparable resistance to sensible heat and water vapor transport and are thus both important in determining the associated fluxes.

Clow, G. D.↗
NASA NTRS1994

Impact of clouds on the shortwave radiation budget of the surface-atmosphere system for snow-covered surfaces

Recent data from the Earth Radiation Budget Experiment (ERBE) have raised the question as to whether or not the addition of clouds to the atmospheric column can decrease the top-of-the atmosphere (TOA) albedo over bright snow-covered surface. To address this issue, ERBE shortwave pixel measurements have been collected with surface insolation measurements made at two snow-covered locations: the South Pole and Saskatoon, Saskatchewan. Both collected datasets show a negative correlation (with solar zenith angle variability removed) between TOA albedo and surfaces insolation. Because increased cloudiness acts to reduce surface insolation, these negative correlations demonstrate that clouds increase the TOA albedo at both snow-covered locations.

Nemesure, Seth↗
NASA NTRS1987

Enhancement of surface-atmosphere fluxes by desert-fringe vegetation through reduction of surface albedo and of soil heat flux

Under the arid conditions prevailing at the end of the dry season in the western Negev/northern Sinai region, vegetation causes a sharp increase relative to bare soil in the daytime sensible heat flux from the surface to the atmosphere. Two mechanisms are involved: the increase in the surface absorptivity and a decrease in the surface heat flux. By increasing the sensible heat flux to the atmosphere through the albedo and the soil heat flux reductions, the desert-fringe vegetation increases the daytime convection and the growth of the planetary boundary layer. Removal of vegetation by overgrazing, by reducing the sensible heat flux, tends to reduce daytime convective precipitation, producing higher probabilities of drought conditions. This assessment of overgrazing is based on observations in the Sinai/Negev, where the soil albedo is high and where overgrazing produces an essential bare soil. Even if the assessment for the Sinai/Negev does not quantitatively apply throughout Africa, the current practice in many African countries of maintaining a large population of grazing animals, can contribute through the mesoscale mechanisms described to reduce daytime convective precipitation, perpetuating higher probabilities of drought. Time-of-day analysis of precipitation in Africa appears worthwhile, to better assess the role of the surface conditions in contributing to drought.

Otterman, J.↗
NASA NTRS1992

Workshop on Innovative Instrumentation for the In Situ Study of Atmosphere-Surface Interactions on Mars

The speakers in the first session of the workshop addressed some of the continuing enigmas regarding the atmospheric composition, surface composition, and atmosphere-surface interactions on Mars; provided a description of a database of proposed payloads and instruments for SEI missions that is scheduled to be accessible in 1993; discussed potential uses of atmospheric imaging from landed stations on Mars; and advocated the collection and employment of high-spectral-resolution reflectance and emission data.

Fegley, Bruce, Jr.↗
NASA NTRS2000

Size Scales for Thermal Inhomogeneities in Mars' Atmosphere Surface Layer: Mars Pathfinder

Atmospheric temperature measurement at three heights with thin wire thermocouples on the 1.1 m Mars Pathfinder meteorology must allow estimates of the integral scale of the atmospheric thermal turbulence during an 83 sol period that begins in the summer. The integral scale is a measure for regions of perturbations. In turbulent media that roughly characterizes locations where the perturbations are correlated. Excluding some to intervals with violent excursions of the mean temperatures, integral scale values are found that increase relatively rapidly from a few tenths meters or less near down to several meters by mid-morning. During mid-morning, the diurnal and shorter time scale wind direction variations often place the meteorology mast in the thermal wake of the Lander.

Mihalov, John D.↗
NASA NTRS2001

Airborne Spectral Measurements of Surface-Atmosphere Anisotropy for Skukuza and Mongu Sites

The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair CV-580 research aircraft and took measurements on 23 flights between August 15 and September 16. On 12 of those flights, BRF (bidirectional reflection function) measurements were obtained over different natural surfaces and ecosystems in southern Africa. The BRF measurements were done to characterize surface anisotropy in support of SAFARI 2000 science objectives principally to validate products from NASA's EOS (Earth Observing System) satellites, and to parameterize and validate BRF models. In this paper we present results of BRFs taken over two EOS validation sites: Skukuza tower, South Africa (25.0 S, 31.5 E) and Mongu tower, Zambia (15.4 S, 23.3 E). The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 microns), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 microns). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to bank at a comfortable roll angle of approximately 20 degrees and fly in a circle about 3 km in diameter above the surface for roughly two minutes. Replicated observations (multiple circular orbits) were acquired over selected surfaces so that average BRF smooth out small-scale surface and atmospheric inhomogeneities. At an altitude of 600 m above the targeted surface area and with a 1 degree IFOV, the pixel resolution is about 10 m at nadir and about 270 m at an 80 degree viewing angle from the CAR.

Gatebe, C. K.↗