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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Seasonal variation of the stratospheric circulation

An extensive analysis is made of the extratropical stratospheric circulation in terms of the seasonal variation of large-scale motion fields, with the aid of height and temperature data obtained from the TIROS satellite. Special attention is paid to a comparison of climatological aspects between the Northern Hemisphere (NH) and the Southern Hemisphere (SH). In order to see the general picture of the annual mach of the upper stratosphere, the zonal mean values of geopotential height of the 1 mb level at 70 deg N and 70 deg S were plotted on the daily basis throughout a year. It is observed that, during the winter, the zonal mean 1 mb height in the NH is much more variable than that in the SH. It is also notable that the SH height is rather oscillatory throughout the longer period from midwinter to early summer. Since the zonal mean height in the polar latitude is a rough measure of the mean zonal flow in extratropical latitudes, the difference of the seasonal variation between the two hemispheres mentioned above is considered to be due mainly to the planetary wave-mean flow interaction in the middle atmosphere. The wave activity in the middle atmosphere is represented more rigorously by the Eliassen-Palm flux associated with vertically propagating planetary waves forced from below. The day-to-day variation of the EP flux in the upper stratosphere shows that the wave activity varies intermittently with a characteristic time scale of about two weeks.

Hirota, I.↗
NASA NTRS2020

SEASONAL VARIATION IN THE MEASUREMENT OF GOES-16 ABI CHANNEL-TO-CHANNEL REGISTRATION

An Image Navigation and Registration (INR) Performance Assessment Tool Set (IPATS) was developed to assess the US Geostationary Operational Environmental Satellite R-series (GOES-R) Advanced Baseline Imager (ABI) and Geostationary Lighting Mapper (GLM) INR performance.Channel-to-channel registration (CCR) is one of the five INR performance metricsproduced by IPATS. A seasonal variationis observed in the CCR assessment in north-south direction when one or both channels are reflective. However, indirect CCR, calculated as the difference of NAV measurements between two channels, does not presentthe similar seasonal variation. The phenomenon of the seasonal variationcoincides with the annual change of the subsolar point location. The amplitude of the seasonal variation is related tothe length and the direction of the shadow. DirectCCR, measured by IPATSdirectly,performs better than indirect CCR when both channels are visible wavelengthsor emissivechannels. For all other channel paircombinations, the assessment of indirect CCR is more accurate.

Bin Tan↗
DOE OSTI2024

Measurement of seasonal variations of the NSLS-II circumference and energy

Routine beam-based characterization of the NSLS-II storage ring indicated probable seasonal variations of the ring circumference and energy. We arranged regular direct measurements of the ring circumference during 2023 and compared the results with the archived data of the magnet and undulator settings. A clear correlation between the ring circumference and energy was observed. These seasonal variations of the ring energy are found to be the main reason for regular lattice corrections required to keep the machine performance stable for user operations. Finally, the measurement techniques and results are discussed in this article.

36 MATERIALS SCIENCE↗
NASA NTRS2005

The Effects of Atmospheric Opacity on the Seasonal Variation of Martian Surface Temperature

The daily and seasonal variation of surface temperature is a central element in the description of martian climate. Surface thermal inertia and albedo are critical boundary inputs for simulating surface temperature in Mars general circulation models (MGCMs). Thermal inertia (TI) is also of intrinsic interest as it may be related to regolith properties such as particle size and surface character and so high spatial resolution is desirable. The recent mapping of TI at very high (0.25 deg) spatial resolution was achieved by fitting a thermal model to surface temperature observations obtained over a broad range of several martian years. However, varying atmospheric opacity (dust and water ice clouds) can significantly influence the estimated TI field and this effect was not fully compensated for. Opacity leads to an increase in morning temperature and a decrease in afternoon temperature, thus increasing the apparent thermal inertia.

Wilson, R. J.↗
NASA NTRS1988

Seasonal variation of the semiannual oscillation

Observations of zonally average temperature from the Nimbus-7 Stratospheric and Mesospheric Sounder in 1979-82 show the existence of a significant season variation in the equatorial semiannual oscillation. The first semiannual cycle, beginning in the Northern Hemisphere winter (December-May), is much stronger than the second (June-November) cycle. The balanced winds are calculated from satellite data, showing corresponding seasonality in the semiannual oscillation wind regimes. Strong coupling is observed during the first cycle between equatorial and North Polar temperature. A model of this coupling suggests that planetary Rossby wave momentum deposition in the northern winter is the cause of the seasonal variation in the easterly phase of the semiannual oscillation.

Delisi, Donald P.↗
NASA NTRS1984

Constraints on bulk composition, seasonal variation, and global dynamics of Pluto's atmosphere

The potential seasonal variation of Pluto's atmosphere is investigated by considering the behavior of the candidate atmospheric constituents Ne, N2, CO, O2, and Ar when individually mixed with CH4. The effects of diurnal and latitudinal variation of insolation and eclipses on the atmosphere are also studied. Seasonal effects are shown to dominate. It is shown that the atmospheric bulk may not be a minimum near aphelion but rather at intermediate distances from the sun during summer/winter where inadequate ice deposits may allow the atmosphere to collapse by freezing out over winter latitudes. The likely global circulation regimes for each model atmosphere are investigated as a function of temperature, and it is concluded that if CH4, O2, or CO dominates the atmosphere, Pluto will exhibit cyclic variations between an axially symmetric circulation system at perihelion and a baroclinic wave regime at aphelion. If N2 dominates the wave regime should hold continuously.

Stern, S. A.↗
NASA NTRS1983

Transport and the seasonal variation of ozone

The transport mechanisms responsible for the seasonal behavior of total ozone are deduced from the comparison of model results to stratospheric data. The seasonal transport is dominated by a combination of the diabatic circulation and transient planetary wave activity acting on a diffusively and photochemically determined background state. The seasonal variation is not correctly modeled as a diffusive process. The buildup of total ozone at high latitudes during winter is dependent upon transient planetary wave activity of sufficient strength to cause the breakdown of the polar vortex. While midwinter warmings are responsible for enhanced ozone transport to high latitudes, the final warming marking the transition from zonal mean westerlies to zonal mean easterlies is the most important event leading to the spring maximum. The final warming is not followed by reacceleration of the mean flow; so that the ozone transport associated with this event is more pronounced than that associated with midwinter warmings.

Rood, R. B.↗
NASA NTRS1984

Large seasonal variations in Triton's atmosphere

Consideration is given to the consequences of Triton's surface covering of volatile substances in view of the circularity of Neptune's orbit, which implies that Triton would have virtually no seasonal variations in either surface temperature or atmospheric bulk despite the complex precessional effects of its orbit. It is hypothesized that Triton's most volatile surface substances are probably relegated to latitudes higher than 35 deg, probably forming polar caps whose temperatures would be nearly equal even during the midwinter/midsummer peak insolation of the summer pole. If the summer pole completely sublimates during one of the 'major' summers, Triton's atmosphere may begin to freeze out over the winter caps and yield large and complex seasonal variations.

Trafton, L.↗
NASA NTRS1978

Seasonal variation of the vertical distribution of stratospheric ozone as observed with the Umkehr and BUV methods

Month-to-month variations evidenced by ozone profiles inferred from the classical Umkehr observations and from the back-scattered ultraviolet (BUV) satellite observations made from the Nimbus 4 satellite are examined. Upper stratospheric ozone profiles derived from BUV and Umkehr data display similar seasonal variations of about the same phase and magnitude for the 38 km to 50 km region. Between 28 km and 38 km, the seasonal variations are less marked, but the same rough picture emerges for both data sets. If both data sets indicate an increasing (or decreasing) trend over a period of years, it is not possible to conclude that a trend exists unless separate means exists for monitoring stratospheric dust. Because of the stratosphere well above the Junge layer seems less likely to be affected by volcanic debris, BUV data should be superior to Umkehr data for monitoring trends in the 38 km to 50 km range, provided that the calibration problems of flying such a monitoring instrument in space can be overcome.

Mateer, C. L.↗
NASA NTRS2019

Seasonal Variations of Titan's Brightness

The absolute brightness of astronomical bodies can be represented by the emitted power, which plays important roles in their radiated energy budgets. The Cassini observations include three seasons of Titan, which provides an unprecedented opportunity to examine the seasonal variations of Titan's emitted power. Our analyses show that Titan's emitted power displays different seasonal behaviors between the Northern Hemisphere and the Southern Hemisphere. The global‐average emitted power decreased by 6.8 ± 0.4% during the Cassini period (2004–2017). Such a temporal variation represents the magnitude of the seasonal cycle of Titan's emitted power, which is at least one order of magnitude stronger than the seasonal variation of Earth's emitted power (<0.5%). More importantly, the ~6.8% decrease of the emitted power is much smaller than the ~18.6% decrease of the solar flux from the change of Sun‐Titan distance, implying a significantly dynamical energy budget on Titan.

Ellen C. Creecy↗
NASA NTRS1990

Seasonal variation of the diurnal cycles of earth's radiation budget determined from ERBE

ERBE scanner data from the Earth Radiation Budget Satellite and NOAA-9 satellites obtained from February 1985 through January 1986 are used to investigate the diurnal cycles of both LW radiation and albedo for each month of the year. Seasonal variations of the diurnal cycles are examined for the deserts, vegetated land, and oceans over the globe. Comparisons are made between clear-sky and total-scene conditions. ERBE satellite data showed that many areas of the earth exhibit significant diurnal variations in both LW flux and albedo. The LW diurnal range was found to be greatest for deserts and smallest for oceans, whereas the albedo diurnal amplitude factor is a maximum over the tropical oceans and a minimum over land. Cloud cover and seasonal variations have a major effect on the diurnal cycles. Generally, maximum diurnal ranges were found in the summer hemisphere and minimum values in the winter hemisphere.

Harrison, E. F.↗
NASA NTRS1990

Comparison of stratospheric ozone profiles and their seasonal variations as measured by lidar and Stratospheric Aerosol and Gas Experiment during 1988

A ground-based, high power, laser remote sensing system for measurements of stratospheric ozone concentration profiles has been in operation at the Jet Propulsion Laboratory Table Mountain Facility located in southern California, since January 1988. The seasonal variations observed in the ozone profiles, during 1988 and as a function of altitude, are described here. These profiles are compared with those from the Stratospheric Aerosol and Gas Experiment satellite instrument made within a radius of 1000 km from the lidar and also with the zonal mean measurements made in the band 34.4 +/- 5 deg. Comparison with the proposed new CIRA ozone reference model has also been carried out. The seasonal variations, between 25 and 50 km, observed by the two instruments and indicated by the reference model are in good agreement.

Mcdermid, I. Stuart↗
DOE OSTI2026

Seasonal variation of the surface cross-shelf exchange in the northern South China Sea: a Lagrangian perspective

Previous studies on cross-shelf exchange, predominantly adopted an Eulerian perspective, struggled to identify water sources and pathways. Using a high-resolution regional ocean modeling system (ROMS) and Lagrangian particle tracking, this study systematically investigates the seasonal variation and dynamics of surface cross-shelf exchange in the northern South China Sea (NSCS) from a Lagrangian perspective. Based on daily released 30-day drifter trajectories we identify the key pathways, source regions for surface cross-shelf exchange, revealing pronounced seasonal variability. Results show the surface cross-shelf exchange generally following monsoon-driven Ekman transport. However, local dynamics, especially topographic modulation, can outweigh the expected Ekman-driven transport, producing surface exchange patterns opposite to that predicted from the prevailing winds. Topographic effects vary across different scales. In the coastal waters of western Guangdong during winter, despite downwelling-favorable winds, the modulation of alongshore currents by island topography induces an eastward pressure gradient. This gradient, through geostrophic balance, drives offshore flows opposite to wind-driven Ekman onshore transport. Furthermore, the eastern widened shelf exhibits a distinct seasonal variation of cross-shelf exchange, with strong offshore transport (opposite to the direction of Ekman transport) in winter and exceedingly weak exchange in summer. Analysis of the underlying mechanisms reveals that this winter offshore transport is primarily attributed to geostrophic flows driven by surface pressure gradient that is jointly modulated by the Kuroshio intrusion and local widened shelf topography, and enhanced by cumulative submesoscale processes. In summer, a persistent and strong along-isobath jet acts as a dynamic barrier, effectively suppressing the exchange. These findings highlight the important role of topography in regulating surface material transport, and have important implications for predicting the advection and dispersion of plankton or oil spills over the continental shelf influenced by monsoon.

Hao, Dongliang↗
NASA NTRS2009

Distributions and Seasonal Variations of Tropospheric Ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) Solar Occultation Spectra

This work reports the first measurements of ethene (C2H4) distributions in the upper troposphere. These are obtained by retrieving vertical profiles from 5 to 20 km from infrared solar occultation spectra recorded in 2005 and 2006 by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS). Background volume mixin^ ratios (vmrs) ranging from a few to about 50 pptv (10(exp -1) are measured at the different altitudes, while for certain occultations, vmrs as high as 200 pptv are observed. Zonal distributions and vertically resolved latitudinal distributions are derived for the two year period analyzed, highlighting spatial - including a North-South gradient - as well as seasonal variations. We show the latter to be more pronounced at the highest latitudes, presumably as a result of less active photochemistry during winter. The observation of C2H4 enhancements in remote Arctic regions at high latitudes is consistent with the occurrence of fast transport processes of gaseous pollution from the continents leading to Arctic haze. Citation: Herbin, H., D. Hurtmans, L. Clarisse, S. Turquety, C. Clerbaux, C. P. Rinsland, C. Boone, P. F. Bernath, and P.-F. Colieur (2009), Distributions and seasonal variations of tropospheric ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) solar occultation spectra,

Herbin, H.↗
NASA NTRS1991

Seasonal variations in the subauroral electron temperature enhancement

A statistical study of the seasonal variations of the subauroral electron temperature enhancement was undertaken using data from the Langmuir probe experiment on the DE 2 satellite throughout most of the mission (1981-1982). In the winter hemisphere the nighttime background electron temperature is the highest and the magnitude of the peak Te responds most weakly to the geomagnetic activity. This behavior can be explained by seasonal trends in the nighttime downward heat flux due to conjugate photoelectrons. Moreover, model results indicate that a factor of about three increase in heat inflow during equinox relative to solstice is required to raise the electron temperature to a given level. This is a consequence of the higher electron densities at the Te peak near equinox. The Te peak occurs on field lines which thread the outer plasmasphere in the vicinity if the plasmapause and thus can be used as a tracer of the plasmapause position.

Fok, M.-C.↗