Search NASA⌕ Search

SEARCH · Search NASA

Results for “diurnal response”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

The Goddard Cumulus Ensemble Model (GCE): Improvements and Applications for Studying Precipitation Processes

Convection is the primary transport process in the Earth's atmosphere. About two-thirds of the Earth's rainfall and severe floods derive from convection. In addition, two-thirds of the global rain falls in the tropics, while the associated latent heat release accounts for three-fourths of the total heat energy for the Earth's atmosphere. Cloud-resolving models (CRMs) have been used to improve our understanding of cloud and precipitation processes and phenomena from micro-scale to cloud-scale and mesoscale as well as their interactions with radiation and surface processes. CRMs use sophisticated and realistic representations of cloud microphysical processes and can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems. CRMs also allow for explicit interaction between clouds, outgoing longwave (cooling) and incoming solar (heating) radiation, and ocean and land surface processes. Observations are required to initialize CRMs and to validate their results. The Goddard Cumulus Ensemble model (GCE) has been developed and improved at NASA/Goddard Space Flight Center over the past three decades. It is amulti-dimensional non-hydrostatic CRM that can simulate clouds and cloud systems in different environments. Early improvements and testing were presented in Tao and Simpson (1993) and Tao et al. (2003a). A review on the application of the GCE to the understanding of precipitation processes can be found in Simpson and Tao (1993) and Tao (2003). In this paper, recent model improvements (microphysics, radiation and land surface processes) are described along with their impact and performance on cloud and precipitation events in different geographic locations via comparisons with observations. In addition, recent advanced applications of the GCE are presented that include understanding the physical processes responsible for diurnal variation, examining the impact of aerosols (cloud condensation nuclei or CCN and ice nuclei or IN) on precipitation processes, utilizing a satellite simulator to improve the microphysics, providing better simulations for satellite-derived latent heating retrieval, and coupling with a general circulation model to improve the representation of precipitation processes.

GCE↗
NASA NTRS2020

Overview and Initial Results of SAND-E: Semi-Autonomous Navigation for Detrital Environments

Unmanned aerial systems (UAS) and automated terrain analysis for science and navigation are new technologies for planetary exploration. The Mars Helicopter will fly with the Mars2020 rover, the Dragonfly quadcopter will explore Titan, and Soil Properties and Object Classification (SPOC) software will be used for path planning and navigation on the Mars2020 rover. Using an Argo J5 rover instrumented with stereo cameras and Autonomous Soil Assessment System (ASAS) software, and an off the shelf quadcopter, SAND-E tested the use of automated terrain analysis and UAS data for science operations in a Mars-analog environment in Iceland during July of 2019. Scientifically, we sought to determine changes in the physical and chemical properties of sediments along a glacial-fluvial-aeolian transport pathway. Operationally, we tested rover mission-like scenarios that included UAS images and classified terrain images. Here, we present the initial results for both the operations and science elements of the study. Site Selection: A goal of SAND-E is examine sorting and alteration of sediments in fluvial and aeolian environments in both mineral-dominated and glass-dominated basaltic settings. During the first year of the project we focused on a mineral-dominated environment. Selection of the location was based on prior publications that indicated our selected region had a greater abundance of crystalline sediments than other areas fluvial-aeolian settings in Iceland. Other criteria included the presence of both fluvial and aeolian landforms along a transport pathway such that the sediments in transport could be linked to their source rocks. We chose the Skjaldbreidauhraun glacial outwash plain, which sits at the base of Thórisjökull glacier. The site is 30 km north of Thingvellir National Park and ~2 hours from Reykjavik. The outwash plain is fed by two small catchments that drain from the base of the glacier and cut through hyaloclastite and shield volcano bedrock. The drainage progresses from steep alluvial fans near the glacier into a low-sloping fluvial braidplain that becomes confined by the Skjaldbreidur shield volcano and creates a shallow canyon cut into lava bedrock. The fluvial system was a typical braided alluvial environment composed pebble- and cobble-bedded longitudinal bars and sandy channel beds. The river remained active and fluctuated in response to diurnal runoff cycles near the glacier before disappearing into the sandy substrate downstream. The high concentration of suspended sediment in the river was evident by the cloudy water and the silt and clay-sized sediments that draped the channel beds after abandonment and created playas in the lowest sloping areas of the catchment. The entire fluvial system was affected by the winds generated by frontal systems and katabatic flows descending the glacier. This resulted in the formation of aeolian lag deposits and a wind-deflation plain where the fluvial system was not active. Wind ripples and drifts formed in abandoned fluvial channels from aeolian reworking of the sand-sized fluvial sediments. The silt- and clay-sized sediments found in fluvial channels, bar tops, and playas generated dust plumes during high wind events. Our operation sought to capture the variability in this system by sampling from the range of fluvial and aeolian features 6.3 km (proximal), 11.3 km (medial), and 14.4 km (distal) along the river from its origin at the base of glacier.

Ewing, R. C.↗
NASA NTRS1970

Diurnal rhythm of the pituitary-adrenocortical response to stress: effect of constant light and constant darkness

The existence of a biological rhythm in the response of animals to noxious stimuli and drugs is well known. However, the mechanism of this response is not well understood. This study was undertaken to describe the existence of a diurnal rhythm in the hypothalamic-pituitary-adrenocortical system before and after stress in female rats kept in controlled environmental conditions in 12L:12D, 24L:OD, or OL:24D. Plasma ACTH and plasma corticosterone concentrations were compared in unstressed animals. The time pattern in the response to stress was determined at four hourly intervals during a 24 hr period in which plasma ACTH and plasma corticosterone were measured at different time intervals. The stress response varied considerably with time of day in both magnitude and duration. The adrenals of rats exposed to constant light for 45 days atrophied, whereas the adrenals of animals kept in constant dark for the same period did not differ significantly from those of controls kept in 12L:12D. The increase in plasma ACTH in response to stress was greater both in the animals maintained in constant light and in constant dark than in the 12L:12D controls. Homeostatic mechanisms involved in these changes are discussed.

Photoperiod↗
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.↗
DOE OSTI2025

The diurnal susceptibility of subtropical clouds to aerosols

The diurnal susceptibility of clouds and their radiative properties to aerosols is examined during their Lagrangian transition from subtropical stratocumulus to shallow cumulus regimes. Using large-eddy simulations, we analyze the six-day evolution of an air mass along a 3800 km observed trajectory from the coast of Peru toward the equator. Pristine and polluted scenarios are simulated with forcing imposed from weather reanalysis. The polluted scenario exhibits stronger diurnal variations in cloud water, cloud fraction, and albedo, with enhanced nighttime entrainment and suppressed precipitation. The overall response of cloud properties and outgoing shortwave radiation to droplet number concentration follows a distinct diurnal pattern: strong positive cloud adjustments dominate at night and in the morning, while weak negative adjustments prevail in the afternoon. This cycle is driven by the competition between precipitation suppression, which enhances cloud water and coverage, and entrainment drying, which depletes them. In polluted conditions, enhanced entrainment leads to a deeper and more decoupled boundary layer that cannot be sustained by surface fluxes in the afternoon, resulting in negative cloud adjustments. The enhanced entrainment rate under polluted conditions is caused by the reduced sedimentation of cloud and precipitation water from the entrainment zone. While the Twomey effect dominates the diurnal average albedo response, the diurnal variation in the competing cloud adjustments lead to a near-neutral net susceptibility in the afternoon, highlighting the critical role of diurnally varying processes in aerosol-cloud interactions.

Geosciences↗
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.↗
DOE OSTI2020

The influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting

Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as ‘true’ seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Short-term variation in leaf-level water use efficiency in a tropical forest

Here we report the representation of stomatal regulation of transpiration and CO 2 assimilation is key to forecasting terrestrial ecosystem responses to global change. Given its importance in determining the relationship between forest productivity and climate, accurate and mechanistic model representation of the relationship between stomatal conductance (g s ) and assimilation is crucial. We assess possible physiological and mechanistic controls on the estimation of the g 1 (stomatal slope, inversely proportional to water use efficiency) and g 0 (stomatal intercept) parameters, using diurnal gas exchange surveys and leaf level response curves of six tropical broadleaf evergreen tree species. g 1 estimated from ex-situ response curves averaged 50% less than g 1 estimated from survey data. While g 0 and g 1 varied between leaves of different phenological stages, the trend was not consistent among species. We identified a diurnal trend associated with g 1 and g 0 that significantly improved model projections of diurnal trends in transpiration. The accuracy of modelled g s can be improved by accounting for variation in stomatal behavior across diurnal periods, and between measurement approaches, rather than focusing on phenological variation in stomatal behavior. Additional investigation into the primary mechanisms responsible for diurnal variation in g 1 will be required to account for this phenomena in land surface models.

54 ENVIRONMENTAL SCIENCES↗