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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 37 records · Page 2
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NASA NTRS1981

A diurnal resonance in the ocean tide and in the earth's load response due to the resonant free 'core nutation'

The effects of the oceans, which are subject to a resonance due to a free rotational eigenmode of an elliptical, rotating earth with a fluid outer core having an eigenfrequency of (1 + 1/460) cycle/day, on the body tide and nutational response of the earth to the diurnal luni-tidal force are computed. The response of an elastic, rotating, elliptical, oceanless earth with a fluid outer core to a given load distribution on its surface is first considered, and the tidal sea level height for equilibrium and nonequilibrium oceans is examined. Computations of the effects of equilibrium and nonequilibrium oceans on the nutational and deformational responses of the earth are then presented which show small but significant perturbations to the retrograde 18.6-year and prograde six-month nutations, and more important effects on the earth body tide, which is also resonant at the free core notation eigenfrequency.

Wahr, J. M.↗
NASA NTRS2000

Resonant Third-Degree Diurnal Tides in the Seas Off Western Europe

Third-degree diurnal tides are estimated from long time series of sea level measurements at three North Atlantic tide gauges. Although their amplitudes are only a few mm or less, their admittances are far larger than those of second-degree diurnal tides, just as Cartwright discovered for the M(sub 1) constituent. The tides are evidently resonantly enhanced owing to high spatial correlation between the third-degree spherical harmonic of the tidal potential and a near-diurnal oceanic normal mode that is most pronounced in the North Atlantic. By estimating the ocean tidal response across the diurnal band (5 tidal constituents plus nodal modulations), the period and Q of this mode and one nearby mode are estimated.

Ray, Richard D.↗
NASA NTRSDate not supplied

TPSAS-NF1676L-17931-DND

Many geophysical variables including temperature, clouds, and precipitation exhibit robust diurnal cycles in response to the daily cycle of solar insolation. Due to the fundamental nature of this variability, it is critical that weather and climate models accurately represent the diurnal cycle. Numerical model, however, have difficulty reproducing this observed diurnal cycle behavior, which leads to systematic errors in model representation of earth energy budget terms: including TOA and surface radiation, precipitation, and surface latent and sensible heat fluxes. This study evaluates the regional diurnal cycle in the Tropics within reanalysis models (ERA-Interim and MERRA) and quantifies systematic errors in the simulated TOA flux and precipitation due to biases in the diurnal cycle representation. The focus of this study is to quantify the importance of diurnal cycle simulation to systematic bias in reanalysis data set climatologies.

Patrick C Taylor↗
NASA NTRSDate not supplied

A Network of Surface Pressure Observations to Constrain Aerosol Forcing in Mars Climate Models

The evolving distribution of radiatively active dust and water ice clouds plays a major role in modulating the seasonal and interannual variation in the thermal forcing of the Martian atmosphere. Thermal tides are the global-scale atmospheric response to the diurnally varying thermal forcing due to aerosol heating within the atmosphere and radiative and convective heat transfer from the surface. The tide includes westward propagating (sun-synchronous) waves driven in response to solar heating, as well as nonmigrating waves that result from zonal variations in the thermotidal forcing caused by variations in topography and surface thermal properties and in the distribution of aerosols (dust and water ice clouds).

R. J. Wilson↗
NASA NTRS1985

Comparative study of the phase of diurnal anisotropy on quiet and disturbed days on a long term basis up to recent period

The data from the world wide grid of neutron monitoring stations was analyzed for a comparative study of the phase of diurnal anisotropy on quiet and disturbed days on a long term basis up to recent period. It has been observed that the phase of the diurnal anisotropy on disturbed days where the value of the Ap-index is higher, is found to shift towards earlier hours in comparison to the phase of the diurnal anisotropy on quiet days where the value of Ap-index is lower on all the stations from 1965 to 71. Such a trend is not observable for the later period. This affect is found to be more pronounced on equatorial stations, in particular, in comparison to high latitude stations. It was derived from these observational facts that the relationship between Ap-index and the phase of the diurnal anisotropy is not invariant throughout the period of consideration. Furthermore, the exact cause of such a drastic change is not known, but it demonstrates very clearly that the interplanetary conditions which are responsible for both, diurnal anisotropy of cosmic ray intensity and the geomagnetic Ap-index variation, have drastically changed during the period 1971 and onwards.

Kumar, S.↗
NASA NTRS1977

Diurnal rhythms of visual accommodation and blink responses - Implication for flight-deck visual standards

Possible 24-h variations in accommodation responses were investigated. A recently developed servo-controlled optometer and focus stimulator were used to obtain monocular accommodation response data on four college-age subjects. No 24-h rhythm in accommodation was shown. Heart rate and blink rate also were measured and periodicity analysis showed a mean 24-h rhythm for both; however, blink rate periodograms were significant for only two of the four subjects. Thus, with the qualifications that college students were tested instead of pilots and that they performed monocular laboratory tasks instead of binocular flight-deck tasks, it is concluded that 24-h rhythms in accommodation responses need not be considered in setting visual standards for flight-deck tasks.

Murphy, M. R.↗
NASA NTRS1979

Near-surface daytime thermal conductivity in the lunar regolith

If mass and heat transport properties in the top few cm of the lunar surface correspond, estimates of the daytime thermal conductivity based on the diffusivity calculated from in situ concentration gradients of low temperature volatile elements should be possible. Concentration gradients of Hg and Br in response to the diurnal heat pulse have been measured in samples from cores. The conductivity estimated is either approximately 10 to the -3rd or approximately 2 x 10 to the -4th W/cm-degrees K depending on the assumptions made. The latter value is in agreement with near-surface daytime thermal properties calculated by Keihm et al. (1973) to explain the mean surface temperature. An activation energy for diffusion of Hg in the top few cm of the lunar surface is estimated to be approximately 8 kcal/mole and suggests either vapor or surface migration. Fixation of the concentration gradient after the cores were extracted may be due to lack of a temperature gradient to act as a driving force or to disruption of grain contacts or their corrosion on exposure to air.

Reed, G. W., Jr.↗
NASA NTRS1985

Cosmic ray intensity variations observed at Matsushiro (220 M.W.E. in depth)

Cosmic ray data from Matsushiro underground station were analyzed for four years (1981 to 84). It is found that a marked semi-annual intensity variation has been observed in this period. Solar diurnal and semi-diurnal variations have also been observed. After correcting for the spurious sidereal diurnal variation arising from the anisotropy responsible for the solar semi-diurnal variation (Nagashima et al., 1983), it is found that the corrected sidereal diurnal variation is consistent with those so far reported.

Yasue, S.↗
NASA NTRS1985

The composition, structure, temperature and dynamics of the upper thermosphere in the polar regions during October to December 1981

Observational data obtained by the Dynamics Explorer-2 (DE-2) spacecraft were compared with global model simulations in order to study the composition, structure, temperature, and dynamics of the upper thermosphere in polar regions during the period October-December 1981. A UCL three-dimensional model was used to simulate the seasonal, diurnal, and geomagnetic response of the neutral thermosphere and to follow the major features of the solar and geomagnetic inputs during the late 1981 period. Overall agreement was obtained between the simulations and the DE-2 data for thermospheric wind structure at high latitudes, and for the combined thermal and compositional structure in both hemispheres. Computer-generated line drawings of the variations in thermospheric structure are given, as well as a series of color graphic illustrations of the DE-2 data.

Rees, D.↗
NASA NTRS1989

Ozone reference models for the middle atmosphere (new CIRA)

Models of ozone vertical structure were generated that were based on multiple data sets from satellites. The very good absolute accuracy of the individual data sets allowed the data to be directly combined to generate these models. The data used for generation of these models are from some of the most recent satellite measurements over the period 1978 to 1983. A discussion is provided of validation and error analyses of these data sets. Also, inconsistencies in data sets brought about by temporal variations or other factors are indicated. The models cover the pressure range from from 20 to 0.003 mb (25 to 90 km). The models for pressures less than 0.5 mb represent only the day side and are only provisional since there was limited longitudinal coverage at these levels. The models start near 25 km in accord with previous COSPAR international reference atmosphere (CIRA) models. Models are also provided of ozone mixing ratio as a function of height. The monthly standard deviation and interannual variations relative to zonal means are also provided. In addition to the models of monthly latitudinal variations in vertical structure based on satellite measurements, monthly models of total column ozone and its characteristic variability as a function of latitude based on four years of Nimbus 7 measurements, models of the relationship between vertical structure and total column ozone, and a midlatitude annual mean model are incorporated in this set of ozone reference atmospheres. Various systematic variations are discussed including the annual, semiannual, and quasibiennial oscillations, and diurnal, longitudinal, and response to solar activity variations.

Keating, G. M.↗
NASA NTRS1978

Observation of the nearly diurnal resonance of the earth using a laser strainmeter

The response of the Earth to the diurnal and semidiurnal tidal excitations was studied. Results show that there is significant structure in the response of the earth to tidal excitations near one cycle/sidereal day. This structure agrees with the resonance behavior predicted from the calculations of the forced elasticgravitational response of an elliptical, rotating earth with a liquid outer core. The data is used to test for possible preferred frames and spatial anisotropies. Upper bounds on the parameterized post-Newtonian (PPN) parameters were examined.

Levine, J.↗
NASA NTRS2017

Oculomotor Assessment of Diurnal Arousal Variations

Saccadic and pupillary responses are reliable indices of arousal decrement (e.g. fatigue), that might be exploited to improve work schedule guidelines. In this study, we tested the sensitivity of a short 30-s oculomotor test to detect diurnal arousal variations. Twelve participants (5 females, 7 males, 37.7+-11.9 years) volunteered to be assessed every hour (66+-20 min) for three consecutive working days, during their regular office-hours. We used a fully automated testing system, the FIT 2000 Fitness Impairment Tester (Pulse Medical Instruments Inc., Rockville, MD, USA), to measure and record saccadic peak velocity, pupil diameter, and latency and amplitude of the pupillary light reflex. In addition, we collected subjective levels of arousal using the Stanford Sleepiness Scale, and body core temperature. We analyzed the data using a linear mixed model approach for longitudinal data. Both saccadic velocity and subjective alertness decreased over the course of a day, while body core temperature increased (all p-values.05). The data also weakly suggested an increase of the pupil diameter (p 07). The findings support the use of oculomotor indices in the assessment of arousal and fatigue in applied settings.

saccadic velocity↗
NASA NTRS1977

Effect of haze absorption and scattering on radiative-convective-conductive heat flux divergence in Martian CO2 atmosphere and ground

The paper presents some guidelines of an improved numerical modeling effort developed to investigate the effect of an absorbing and scattering particulate phase on the temperature field of the Mars atmosphere and soil in its diurnal cycle and in response to a time-dependent convective heat transfer. Some guidelines are also formulated for the re-evaluation of Mariner 9 infrared radiometer or spectrometer inverted temperature measurements of the dust-laden atmosphere.

Pallmann, A. J.↗
NASA NTRS1993

Three-dimensional numerical simulation of near-surface flows over the Martian north polar cap

Measurements made by Viking Lander VL-2 (48 N) have shown that the near-surface wind and temperature regime on Mars displays striking similarities to terrestrial counterparts. The diurnal radiative cycle is responsible for establishment of a well-defined thermal circulation in which downslope (Katabatic) flows prevail during the nighttime hours and weak upslope (anabatic) conditions prevail during the daytime. Previous work has indicated that the slope flows are much like those found on Earth, particularly the Katabatic winds, which show striking similarities to drainage flows observed over Antarctica. The low-level wind regime appears to be an important factor in the scouring of the martian landscape. The north polar cap shows evidence of eolian features such as dunes, frost streaks, and grooves from Viking imagery. The direction of the prevailing wind can in cases be inferred from the eolian features. We examine the thermally induced flows that result from the radiative heating and cooling of the martian north polar region using a comprehensive three-dimensional atmospheric mesoscale numerical model. The same model has been used previously for simulation of Antarctic Katabatic winds. The model equations are written in terrain-following coordinates to allow for irregular terrain; prognostic equations include the flux forms of the horizontal momentum equations, temperature, continuity. A surface energy budget equation is also incorporated in which the surface temperature is determined. Explicit parameterization of both terrestrial (longwave) and solar (shortwave) radiation is included. Turbulent transfer of heat and momentum in the martian atmosphere is assumed to follow the similarity expressions in the surface boundary layer on Earth. The terrain heights for the martian north polar region have been obtained from the U.S. Geological Survey map and digitized onto a 57x57 grid with a spacing of 75 km. The resulting terrain map is shown in Fig. 1. The vertical grid consists of 15 levels (delta equals 0.998, 0.99, 0.98, 0.97, 0.96, 0.94, 0.92, 0.90, 0.85, 0.775, 0.70, 0.60, 0.50, 0.30, 0.10). The high resolution in the lower atmosphere is necessary to capture details of the boundary layer flows. The lowest level corresponds to a height of approximately 20 m above the ground, the seconds level 100 m.

Parish, Thomas R.↗
NASA NTRS1994

Galactic cosmic ray modulation and interplanetary medium perturbations due to a long-living active region during October 1989

During October 1989, three very energetic flares were ejected by the same active region at longitudes 9 deg E, 32 deg W, and 57 deg W, respectively. The shape of the galactic cosmic ray variations suggests the presence of large magnetic cloud structures (Nagashima et al., 1990) following the shock-associated perturbations. In spite of long data gaps the interplanetary observations at Interplanetary Monitoring Platform (IMP) 8 (near the Earth) and International Cometary Explorer (ICE)(approximately 1 AU, approximately 65 deg W) confirm this possibility for the event related to the 9 deg E flare; the principal axes analysis shows that the interplanetary magnetic field variations at both spacecraft locations are mainly confined on a meridian plane. This result suggests that the western longitudinal extension of this cloud is indeed very large (greater than or equal to 5 deg). The nonnegligible depression in the cosmic ray intensity observed inside the possible cloud related to the 57 deg W flare indicates that also the eastern extension could be very wide. The analysis of neutron monitor data shows clearly the cosmic ray trapping effect of magnetic clouds; this mechanism seems to be responsible for the enhanced diurnal effect often observed during the recovery phase of Forbush decreases. We give an interpretation for the anisotropic cosmic ray peak occurring in the third event, and, related to that, we suggest that the Forbush decrease modulated region at the Earth's orbit could be somewhat wider than the magnetic cloud, as already anticipated by Nagashima et al. (1990). By this analysis, based mainly on cosmic ray data, we show that it is possible to do reasonable inferences on the large-scale structure of flare-related interplanetary perturbations when interplanetary medium data are not completely present.

Bavassano, B.↗
NASA NTRS1991

Diurnal temperature fluctuation effects on potatoes grown with 12 hr photoperiods

This study was designed to characterize the growth responses of potato (Solanum tuberosum L.) to diurnal temperature fluctuations. Potato plants of two cultivars, Norland and Denali, were grown for 90 days under 12 hr photoperiod in walk-in growth rooms at the University of Wisconsin Biotron. The alternating temperature was 22 C light/14 C dark and compared to a constant 18 C as control. At all temperature regimes vapor pressure deficit was maintained at 0.62 kPa (70% relative humidity [correction of humdidity] at 18 C). Plant height, plant dry weight, tuber dry weight, and harvest index were overall greater under the warm light/cool dark alternating temperatures than under the constant temperature. The differences between temperature treatments were greater for Denali than for Norland. Alternating temperatures increased Denali tuber weights by 25%, but no significant increase was found with Norland. Also the total plant weight was increased over 20% with Denali, but increased with Norland in only one of the two replications of the experiment. This study documents that alternating temperatures are a benefit to some cultivars but may not be of benefit to all cultivars.

NASA Discipline Number 61-10↗