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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 109 records · Page 6
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NASA NTRS1984

The President's Day cyclone of 18-19 February 1979 - Influence of a tropopause fold on rapid cyclogenesis

The surface and satellite imagery data from the cyclone of February 18-19, 1979 are analyzed. Operational radiosonde data are utilized to study the tropopause fold associated with the polar jet streak. Patterns of vertical motion compatible with the tropopause fold are calculated by the diagnostic ageostrophic circulation equation of Sawyer (1956) and Eliassen (1962); the verification of the calculated patterns is described. The relationship between the stratospheric extrusion and the folded tropopause is determined by examining the potential vorticity and ozone concentrations. The influence of the stratospheric extrusion within the folded tropopause on the development of the cyclone is investigated by analyzing the potential vorticity, static stability, and absolute vorticity from the Eulerian and Lagrangian perspective.

Uccellini, L. W.↗
NASA NTRS1986

Rapid acceleration of energetic particles in the 1982 February 8 solar flare

Hard X-ray and gamma-ray measurements of the February 8, 1982 (1250 UT) solar flare made with spectrometers aboard the ISEE 3 and SMM spacecraft show that bursts of photons from 40 keV to 40 MeV are coincident within + or - 1 s. This indicates that the acceleration of particles to relativistic velocities can occur promptly (within 1 s). As far as the energetic particles interacting at the sun are concerned, the 'two-phase' process, which requires several minutes for particle acceleration to relativistic velocities, cannot account for the present gamma-ray observations. Even the 'two-step' acceleration process, which is assumed to occur in a small magnetic loop, is severely constrained by the present observations.

Kane, S. R.↗
NASA NTRS1985

SAGE studies of the waves and eddy fluxes of ozone and temperature near 55 deg during the late February 1979 stratospheric warming

Ozone data from the Stratospheric Aerosol and Gas Experiment have been used in conjunction with meteorological information to study the waves and eddy fluxes of ozone and temperature near 55 deg N during the late February 1979 stratospheric warming. The results indicate an intense poleward eddy ozone transport in the altitude range between approximately 24 and 38 km, and an equatorward transport above an altitude of about 38 km. It is found that this equatorward eddy ozone transport in the upper stratosphere was accompanied by a poleward eddy heat transport, as expected on the basis of the ozone photochemistry. The results also indicate that the phase relationship between ozone and temperature waves agrees qualitatively with existing model analyses.

Wang, P.-H.↗
NASA NTRS1986

The structure of the atmospheric boundary layer in the central equatorial Pacific during January and February of FGGE

The structure of the atmospheric boundary layer for a region between Hawaii and the equator is studied using dropwindsonde data (about 900 soundings) collected in January and February 1979 as part of the First GARP Global Experiment. These data were used to establish the longitudinal and latitudinal variations in the thermodynamic and wind structure of the boundary layer and describe differences in the structure for convectively active and inactive conditions. Low-level inversions (at a pressure of approximately 850 mb) were found to be an important feature of the structure of the boundary layer for undisturbed conditions. Although the frequency of low-level inversions decreased equatorward from Hawaii, the average height of the inversions observed in these regions did not vary significantly in the north-south direction. For convectively undisturbed conditions, low-level inversions are on the average of sufficient strength to suppress deep convection. However, it is shown they could easily be modified by upward vertical motion to give a boundary layer structure similar to that observed in areas where deep convection was observed.

Firestone, James K.↗
NASA NTRS1988

Observations related to the acceleration, injection, and interplanetary propagation of energetic protons during the solar cosmic ray event on February 16, 1984

This paper presents an analysis of data collected by the worldwide network of neutron monitors and from IMP-8 cosmic-ray telescopes, as well as by particle detectors on the GOES 5 and 6 and ICE satellites, on the solar cosmic ray event that took place on February 16, 1984. Using these data, the intensity-time (IT) profiles, the anisotropy-time profiles, the energy spectra, and the pitch angle distributions of the solar protons near earth were deduced. It was found that the solar protons propagated essentially scatter-free from the sun to the earth. The solar protons had easy access to the IMF lines to earth; the time from the onset to maximum intensity and the shape of the IT profiles at earth as a function of energy could be explained by the diffusion of the flare protons near the acceleration region. The energy spectrum of the solar flare protons injected into the undisturbed IMF at the sun was changing with time in both amplitude and shape. The observations suggest a shock acceleration process.

Debrunner, H.↗
NASA NTRS1988

Infrared measurements of atmospheric gases above Mauna Loa, Hawaii, in February 1987

The IR absorptions spectra of 13 minor and trace atmospheric gases, recorded by the NOAA's Geophysical Monitoring for Climate Change (GMCC) program station at Mauna Loa, Hawaii, for four days in February 1987, were analyzed to determine simultaneous total vertical column amounts for these gases. Comparisons with other data indicate that the NOAA GMCC surface volume mixing ratios are good measures of the mean volume mixing ratios of these gases in the troposphere and that Mauna Loa is a favorable site for IR monitoring of atmospheric gases. The ozone total columns deduced from the IR spectra agreed with the correlative Umkehr observations.

Rinsland, C. P.↗
NASA NTRS1989

The spatial, spectral, and temporal character of the hard X-ray flare of 1982 February 3

This paper presents spatially resolved, hard and soft X-ray, 17 GHz microwave and H-alpha observations of an X1.1 flare which occurred on February 3, 1982. The bulk of the 25-50 keV hard X-ray emission during impulsive peaks is produced by two sources of differing brightness which are separated by about 50 arcsec. Soft X-ray images reveal a single component that resides between the two hard sources. On the decay of the event, X-ray spectra provide direct evidence for a hot component that dominates the less than 50 keV flux. Hard X-ray images obtained at these times show a single source that is nearly coincident with the soft X-ray source. Interferometric microwave observations obtained during impulsive peaks support the idea that microwave emission is produced in the vicinity of high magnetic fields near the sunspot. The influence of an asymmetric loop or system of asymmetric loops is essential to interpreting the observations.

Nitta, Nariaki↗
NASA NTRS1989

Meteorological atlas of the Northern Hemisphere lower stratosphere for January and February 1989 during the Airborne Arctic Stratospheric Expedition

Northern Hemisphere meteorological data for the months of January and February 1989 in the lower stratosphere are shown. National Meteorological Center (NMC) data, and Total Ozone Mapping Spectrometer (TOMS) data are used to display polar stereographic projections of 100-mb temperatures, 50-mb temperatures, 50-mb geopotential heights, total ozone, and Ertel's potential vorticity (Epv) on both 400 K and 460 K isentropic surfaces. In addition, latitude/height cross sections at 10 E of balanced wind isotachs, wind vectors, potential temperature, and temperature are also shown. Horizontal traces of NASA ER-2 and DC-8 flight tracks are also included. Vertical profiles of NMC temperatures following flight paths of both aircraft are shown. In addition, vertical profiles of wind speed are contoured following the ER-2 for estimating the lateral penetration into the polar vortex, while vertical profiles of Ertel's potential vorticity are included for estimating the vertical penetration of the DC-8 into the stratosphere.

Newman, Paul A.↗
NASA NTRS1990

Turbulent statistics in the vicinity of an SST front: A north wind case, FASINEX February 16, 1986

The technique of boxcar variances and covariances is used to examine NCAR Electra data from FASINEX (Frontal Air-Sea Interaction EXperiment). This technique was developed to examine changes in turbulent fluxes near a sea surface temperature (SST) front. The results demonstrate the influence of the SST front on the MABL (Marine Atmospheric Boundary Layer). Data shown are for February 16, 1986, when the winds blew from over cold water to warm. The front directly produced horizontal variability in the turbulence. The front also induced a secondary circulation which further modified the turbulence.

Stage, Steven A.↗
NASA NTRS1989

The ion energy spectra in the ring current during the geomagnetic storm of February 1986

The largest geomagnetic storm in several decades occurred in February 1986, with a minimum Dst of -312 nT. In this experiment, the CHEM instrument on the AMPTE/CCE spacecraft has been used to study the development of this storm in more detail. By comparing measurements of phase space density (f) vs magnetic moment (mu) for four ion species H(+), O(+), He (+), and He(++) during consecutive passes through the ring current region, a distinction can be made between flux increases that require the injection of a new population and those that are consistent with the adiabatic acceleration of a pre-existing population. It is shown that the smaller flux observed during the outbound pass compared to the preceding inbound pass at the time of minimum Dst is due to the difference in local times of the two measurements. This local time difference is consistent with a greatly enhanced convection electric field, which brings a new population from the magnetotail to the post-noon, but not to pre-noon local time sector.

Kistler, L. M.↗
NASA NTRS1989

Relationships between SC- and SI-associated ULF waves and ionospheric HF Doppler oscillations during the great geomagnetic storm of February 1986

The SC- and SI-associated ionospheric Doppler velocity oscillations and geomagnetic pulsations during the great geomagnetic storm of February 1986 are interpreted. This is done by considering the 'dynamo-motor' mechanism of ionospheric E-field and the global compressional oscillations of the magnetosphere and the ionosphere, respectively.

Yumoto, K.↗
NASA NTRS1990

January-february Tropospheric Climate for the Northern Hemisphere and the 11-year Solar Cycle, the QBO and the Southern Oscillation

Examined here is a recently discovered association between the 11-year solar cycle and the atmosphere that is most easily detectable when the two phases of the Quasi-biennial Oscillation (QBO) are considered individually rather than pooled. The influence of the Southern Oscillation (SO) for either of the two QBO phases is then combined with that of the solar cycle in the form of two-predictor multiple regression. The strong and well-defined relationship between the 11-year 10.7 cm solar flux cycle and the lower troposphere Northern Hemisphere January-February climate for QBO phase-stratified samples (van Loon and Labitzke 1988, Barnston and Livezey 1989) failed for the west QBO phase in 1989. Here, the opposing 1989 event is explained, at least in part, on the basis of the phase of the SO (the cold tropical Pacific SST event of 1988 to 1989). It is demonstrated that both the SO and the solar flux have moderate and quasi-independent correlations with the climate over certain regions, and where there is strong overlap they can work either in harmony or in opposition. In 1989 in North America the influences of the SO and the flux conflicted to an unprecedented extent, and the SO was the controlling influence in most regions of the continent (western Canada being one exception). The 1989 event draws attention to the smallness of the QBO phase-stratified samples and the still more serious holes in the two-dimensional sample space of flux and SO when both factors are viewed as predictors within one QBO phase.

Barnston, Anthony G.↗
NASA NTRS1990

A numerical investigation of East Coast cyclogenesis during the cold-air damming event of 27-28 February 1982. I - Dynamic and thermodynamic structure

A cyclogenesis event combined with strong cold-air damming, coastal frontogenesis, and extensive mixed precipitation, which occurred on February 27-28, 1982 at the South Carolina coast is investigated numerically. The prestorm environment and subsequent cyclogenesis was simulated using a nested version of the Penn State/NCAR mesoscale model with 35-km fine-mesh resolution. The model was found to successfully reproduce most principal synoptic and mesoscale features associated with this cyclogenesis case, including the storm path and intensification, the coastal front structure, cold-air damming, circulations induced by a polar jet streak, low-level jets, and precipitation. The results of this study reveal the existence of two moist airstreams fed by an onshore flow from the marine boundary layer east of the coastal front.

Lapenta, William M.↗
NASA NTRS1991

Analysis of a general circulation model simulation of the atmospheric response to the observed sea surface temperature anomalies of January and February 1983

A new version of the Goddard Laboratory for Atmospheres GCM is utilized to simulate the influence of an observed sea surface temperature anomaly on rainfall and atmospheric circulation. The model can reproduce many essential features of the observed tropical rainfall and circulation anomalies during January-February 1983. Particularly, the model simulates realistic patterns of tropical anomalies of sea level pressure, 200 mb geopotential heights, and horizontal winds at the 200 and 850 mb levels. The model-simulated tropical precipitation anomaly patterns appear realistic, although the precipitation is rather excessive and the atmosphere is too energetic.

Sud, Y. C.↗
NASA NTRS1991

Measurements of ClO and O3 from 21 deg N to 61 deg N in the lower stratosphere during February 1988 - Implications for heterogeneous chemistry

The decline in stratospheric ozone at northern midlatitudes in wintertime may be caused by chlorine photochemistry that has been enhanced by heterogeneous reactions. The possibility that the heterogeneous reaction of N2O5 on sulfate aerosols is the cause of this decadal ozone decline is examined by comparing ClO and O3 measurements made in the lower stratosphere during February, 1988, with results from a 2D model. At midlatitudes, the abundances, latitudinal, and seasonal gradients of the observed ClO are similar to the results of a model with heterogeneous chemistry, but are in strong disagreement with the results from the model with only gas-phase chemistry. At low latitudes, agreement is best with the results of the model with only gas-phase chemistry. Limited observations indicate that the amount of reactive chlorine is being enhanced, and that heterogeneous chemistry is a likely cause.

King, J. C.↗
NASA NTRS1992

A numerical investigation of East Coast cyclogenesis during the cold-air damming event of 27-28 February 1982. II - Importance of physical mechanisms

This study presents a series of numerical experiments designed to examine the role of several physical processes on the evolution of and interaction between atmospheric phenomena having different scales, each of which contributed to the development of the storm of February 27-28, 1982 along a Carolina coastal front. The physical processes include: the role of diabatic heating associated with convective and grid-scale precipitation, the role of a thermally direct transverse circulation about the entrance region of a strong polar jet streak, and modification of the marine planetary boundary layer by fluxes of heat and moisture over the Gulf Stream. The diabatic heating associated with precipitation is found to have the most significant impact on storm development. Without latent heating, cyclogenesis does not occur along the Carolina coastal front despite the presence of strong low-level baroclinicity and cyclonic vorticity. A less dramatic but still important relationship is found between storm formation and the other two physical mechanisms.

Lapenta, William M.↗