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  • GEOPHYSICS  (1,578)
  • 2010-2014
  • 1985-1989  (1,578)
  • 1989  (755)
  • 1988  (823)
Collection
Keywords
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  • 2010-2014
  • 1985-1989  (1,578)
Year
  • 1
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    Satellite/rocket ozone comparisons at Natal, Brazil (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Comparisons are presented of satellite, rocket, and balloon ozone profiles near Natal, Brazil (5.9 deg S, 35.2 deg W). The low variability of stratospheric ozone at Natal during March and April of 1985 has allowed intercomparisons of reasonably large data sets, rather than a small number of paired satellite/in situ comparisons. There are sharp differences between the profile from the SBUV instrument on Nimbus 7 and the in situ measurements. These results support the conclusions of the NASA Ozone Trends Panel that there is an instrumental cause for the very large changes in upper stratospheric ozone seen by SBUV. Along with other comparisons, these results are being used in a reassessment of the SBUV instrument and its data reduction procedures. The agreement between the ozone profiles from the SAGE II instrument on the ERBS satellite and the rocket values is excellent over the full range of comparisons. Both SAGE II and ROCOZ-A must convert from altitude to pressure for intercomparisons with SME and with SBUV-type instruments. The conversion between pressure and altitude is as important as the ozone measurements, especially in the upper stratosphere where the scale height for ozone is approximately half that for pressure.
    Keywords: GEOPHYSICS
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  • 2
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    1960 Chile - New estimate of polar motion excitation (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A recent reanalysis of the International Latitude Serivce (ILS) polar motion data-day has been processed using Kalman filtering techniques to generate the polar motion excitation function over the time-span from 1960 to 1965. The resulting excitation function has been examined for the effects of 1960 Chile in an attempt to determine experimentally how large earthquake affect polar motion. The resulting upper bound of about 75 x 10 to the 22nd N-m for a 10-deg dip (about 36 x 10 to the 22nd N-m for 20-deg dip) is consistent with results obtained from previous seismic studies, including a recent normal mode excitation result. Following future great earthquakes, monitoring of polar motion by space-based techniques such as VLBI should continue at high temporal resolution for several weeks in order to directly measure the rheological parameters of the upper mantle.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 1193-119
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  • 3
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    Lithology and structure within the basement terrain adjacent to Clark Mountains, California, mapped with calibrated data from the airborne visible/infrared imaging spectrometer (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Clark Mountains in eastern California form a rugged, highly dissected area nearly 5000 ft above sea level, with Clark Mountain rising to 8000 ft. The rocks of the Clark Mountains and the Mescal Range just to the south are Paleozoic carbonate and clastic rocks, and Mesozoic clastic and volcanic rocks standing in pronounced relief above the fractured Precambrian gneisses to the east. The Permian Kaibab Limestone and the Triassic Moenkopi and Chinle Formations are exposed in the Mescal Range, which is the only place in California where these rocks, which are typical of the Colorado Plateau, are found. To the west, the mountains are bordered by the broad alluvial plains of Shadow Valley. Cima Dome, which is an erosional remnant carved on a batholithic intrusion of quartz monzonite, is found at the south end of the valley. To the east of the Clark and Mescal Mountains is found the Ivanpah Valley, in the center of which is located the Ivanpah Play. Studies of the Clark Mountains with the airborne visible/infrared imaging spectrometer are briefly described.
    Keywords: GEOPHYSICS
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  • 4
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    Microwave limb-sounding of earth's upper atmosphere (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Microwave limb-sounding can be used to improve understanding of earth's upper atmosphere. This paper summarizes general features of the technique. An experiment being developed for the Upper Atmosphere Research Satellite is described. Plans for the future Earth Observing System are discussed.
    Keywords: GEOPHYSICS
    Type: Atmospheric Research (ISSN 0169-8095); 23; 391-410
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  • 5
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    A comparison of solar irradiances measured by SBUV, SME, and rockets (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this paper, Solar Backscatter Ultraviolet (SBUV) measurements of solar irradiance and predictions from the Mg 280-nm index are compared with each other and with coincident Solar Mesosphere Explorer (SME) and rocket measurements. The SBUV irradiances show a systematic decrease with time not seen in the rocket measurements; a correction for this decrease is introduced. The scatter and overall structure in the SME spectra is 3-5 percent, of the order of or larger than most of the changes predicted by the Mg index. The corrected SBUV ratio and the Mg index prediction for it agree to within 1 percent. Such agreement supports a common origin for variations between solar maximum and minimum and those for individual rotations: the degree to which active regions cover the visible hemisphere of the sun.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7091-710
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  • 6
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    Effect of solar proton events in 1978 and 1979 on the odd nitrogen abundance in the middle atmosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Daily average solar proton flux data for 1978 and 1979 are used in a proton energy degradation scheme to derive ion pair production rates and atomic nitrogen production rates. The latter are computed in a form suitable for inclusion in an atmopheric, two-dimensional, time-dependent photochemical model. Odd nitrogen distributions are computed from the model, including atomic nitrogen production from solar protons, and are compared with baseline distributions. The comparisons show that the average effect of the solar protons in 1978 and 1979 was to cause changes in odd nitrogen only above 10 mbar and at latitudes only above about 50 deg in both hemispheres. The influence of the solar proton-produced odd nitrogen on the local abundance of odd nitrogen depends primarily on the background odd nitrogen abundance as well as the altitude and season.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7084-709
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  • 7
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    Non-seasonal changes in total column ozone from satellite observations, 1970-86 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Analyses of nonseasonal changes in total column ozone from satellite observations during the period 1970-86 suggest, when combined with analyses of Dobson network data, that the largest reduction in global ozone since 1959 occurred between 1978 and 1986. The existence of an Arctic region of enhanced ozone depletion with similar but less pronounced characteristics of the Antarctic region is described. Before 1983 large rates of decrease were confined to high latitudes, subsequently regions of large rates of ozone depletion have appeared at midlatitudes.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 219-227
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  • 8
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    Mass extinctions, atmospheric sulphur and climatic warming at the K/T boundary (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The possible climatic effects of a drastic decrease in cloud condensation nuclei (CCN) associated with a severe reduction in the global marine phytoplankton abundance are investigated. Calculations suggest that a reduction in CCN of more than 80 percent and the resulting decrease in marine cloud albedo could have produced a rapid global warming of 6 C or more. Oxygen isotope analyses of marine sediments from many parts of the world have been interpreted as indicating a marked warming coincident with the demise of calcareous nannoplankton at the K/T boundary. Decreased marine cloud albedo and resulting high sea surface temperatures could have been a factor in the maintenance of low productivity in the 'Strangelove Ocean' period following the K/T extinctions.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 63-65
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  • 9
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    Extremely low N2O concentrations in the springtime stratosphere at McMurdo Station, Antarctica (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements have been made of stratospheric N2O using the Stony Brook millimeter-wave remote sensing spectrometer at McMurdo Station, and NO2 mixing ratios are found that are less than 1.5 at 20 km and less than 1.10 at 25 km compared to values measured during the Antarctic summer. The observed mixing ratios are also much less than those predicted by global-scale models of stratospheric chemistry and dynamics. As the NO2 signal remained very weak when McMurdo was at the edges of the ozone hole and showed no signs of recovering during October, it is concluded that the geographical and temporal extent of the region of low NO2 is comparable to or greater than that of the ozone hole. These results argue against theories that require springtime upwelling to explain the Antarctic ozone hole. It is suggested that the air in the Antarctic lower stratosphere during late winter and early spring has been subjected to considerable downward transport.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 53-55
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  • 10
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    Effect of computed horizontal diffusion coefficients on two-dimensional N2O model distributions (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effects of horizontal diffusion coefficients K(yy) and K(yz), computed directly from the residual circulation, on the N2O distribution in a photochemical model were investigated, using a modified version of the two-dimensional model of Guthrie et al. (1984). The residual circulation was computed using the NMC's temperature data and the heating rates reported by Rosenfield et al. (1987). As compared with the effect of the residual circulation alone, the use of horizontal diffusion coefficients produced substantial changes in the N2O distribution and increased the N2O's lifetime values by a few percent. It is suggested that trace gases, such as CH4, CFCl3, CF2Cl2, CH3Cl, and CCl4, which impact the NO(x), HO(x), and Cl(x) radical distributions and therefore ozone, will be influenced in a similar manner by the addition of more realistic diffusion fields.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5213-521
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  • 11
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    VLF noises triggered by whistlers as observed in the topside ionosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: ISIS-1, ISIS-2, and DE-1 VLF electric field data from Kashima station, Japan are used to investigate characteristics of whistler triggered emissions in the topside ionosphere. The occurrence rate for nonducted whistler triggered emission is shown to be distributed randomly between L = 2.0 and 4.2, while the occurrence rate of ducted whistler triggered emissions increases with latitudes between L = 1.5 and 2.9, attains a maximum at L = 2.7, and abruptly drops off at L = 3.0. The findings indicate that some whistler triggered emissions may be generated by the interaction of whistlers with magnetospheric electrons.
    Keywords: GEOPHYSICS
    Type: Radio Research Laboratory, Journal (ISSN 0033-8001); 35; 15-26
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  • 12
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    Effect of a uniform sea-level change on the earth's rotation and gravitational field (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Global water redistriburtion between the oceans, atmosphere and continents causes changes in the earth's rotation and gravitational field. To conserve water mass, the effect of the small uniform change in sea-level must be considered. Explicit formulas are provided for these sea-level corrections to the gravitational Stokes coefficients, polar motion and length of day. In two recent publications, this sea-level correction term for polar motion was given incorrectly. These errors which arose from normalization conventions with the ocean function are corrected.
    Keywords: GEOPHYSICS
    Type: Geophysical Journal (ISSN 0952-4592); 93; 191-193
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  • 13
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    Comparison of SAGE II solar extinction data with airborne measurements of atmospheric backscattering in the troposphere and lower stratosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In April 1986, during passage of the SAGE I satellite, the first simultaneous measurements of the atmospheric backscattering coefficient beta (pi, 10.6 microns) were made with an airborne CO2 lidar. Individual ratios of beta and the SAGE II extinction sigma (1.02 micron) are in reasonable accord with previously calculated values. The trend with height shows a distinctly nonlinear relation, which is probably attributable to steadily changing size distributions of aerosols.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 709-711
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  • 14
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    Balloon-borne measurements of middle atmosphere aerosols and trace gases in Antarctica (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper reviews data on in situ balloon-borne measurements on stratospheric ozone concentrations and aerosol contents obtained prior to 1986, along with the measurements obtained in 1986 during the National Ozone Expedition. The data indicate that the phenomenon of ozone depletion appears to be shaped spatially and temporally by dynamical stratospheric phenomena. In terms of Antarctic stratospheric research, it appears that the most important problems at the moment involve delineating the springtime ozone depletion through accurate in situ measurements of temperature, trace gas, and particle size (in addition to remote sensing from space).
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 26; 113-130
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  • 15
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    A ground-based technique for millimeter wave spectroscopic observations of stratospheric trace constituents (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent concern over possible long term stratospheric changes caused by the introduction of man-made compounds has increased the need for instrumentation that can accurately measure stratospheric minor constituents. The technique of radio spectroscopy at millimeter wavelengths was first used to observe rotational transitions of stratospheric ozone nearly two decades ago, but has not been highly developed until recently. A ground-based observing technique is reported which employs a millimeter-wave superheterodyne receiver and multichannel filter spectrometer for measurements of stratospheric constituents that have peak volume mixing ratios that are less than 10 to the -9th, more than 3 orders of magnitude less than that for ozone. The technique is used for an extensive program of observations of stratospheric chlorine monoxide and also for observations of other stratospheric trace gases such as (O-16)3, vibrationally excited (O-16)3, (O-18)2(O-16), N2O, HO2, and HCN. In the present paper, analysis of the observing technique is given, including the method of calibration and analysis of sources of error. The technique is found to be a reliable means of observing and monitoring important stratospheric trace constituents.
    Keywords: GEOPHYSICS
    Type: Radio Science (ISSN 0048-6604); 23; 106-118
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  • 16
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    Comment on 'A new method of forecasting geomagnetic activity and proton showers' by A. Hewish and P.J. Duffet-Smith (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 36; 205
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  • 17
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    Magnetic clouds, geomagnetic disturbances, and cosmic ray decreases (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Nineteen magnetic clouds are identified in the years from 1978 through 1982 and studied using superposed epoch analysis. The magnetic-field intensity, proton density and proton temperature are enhanced ahead of magnetic clouds that are preceded by shock, while strong magnetic-field intensity and low proton temperature are observed within the clouds. A relatively large (about 2.5 percent) decrease in cosmic-ray intensity is associated with magnetic clouds that are preceded by a shock, perhaps caused by the turbulent sheath behind an interplanetary shock ahead of the magnetic cloud, whereas only a small (0.5 percent) decrease in intensity is associated with the magnetic cloud itself. Magnetic clouds can produce geomagnetic activity with a decrease in Dst index of the order 100 gamma. The magnitude of the change in the Dst index for the case when southward fields arrive first is comparable to that for the case when northward fields arrive first, and the phase is such that geomagnetic activity is associated with southward fields.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2511-251
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  • 18
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    Diurnal variation of nitric oxide at 32 km - Measurements and interpretation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Balloon observations of NO and ozone near sunset and sunrise around 32 km were made on September 19 and October 4, 1985 from Aire sur l'Adour, France. The NO concentration built up rapidly after sunrise, remained fairly steady during the day, and decreased slowly near sunset. This variation is interpreted quantitatively in terms of current photochemistry in relation to ozone.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2451-546
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  • 19
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    Effect of line mixing on atmospheric brightness temperatures near 15 microns (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect of line mixing on the effective blackbody brightness temperature of the earth in the region of the 15-micron nu 2 Q branch of CO2 is calculated. The procedures used to compute line mixing follow those used to successfully model mixing observed in laboratory spectra of two near-infrared CO2 Q branches. The atmospheric radiances are calculated between 664 and 670/cm, a spectral region that is of interest for sounding the upper troposphere and the stratosphere. Mixing was found to lower the observed brightness temperatures by as much as 3 K for some temperature profiles. Ignoring this effect would significantly impact the ability of advanced sounders to produce temperature retrievals which meet the projected accuracy requirement of 1 K/km.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 27; 872-878
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  • 20
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    F region electron temperature signatures of the plasmapause based on Dynamics Explorer 1 and 2 measurements (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A large DE 1 and 2 database covering all local times is used to explore the relationship between electron temperature (Te) signatures in the F region and plamaspheric density structures. The quiet time Te signature remains in the vicinity of 60 deg invariant latitude at all local times, while the plasmapause is found to bulge to about 60 deg at 1500 LT. The plasmasphere in the bulge region is shown to exhibit an internal feature in the vicinity of 60 deg which takes the form of a sharp H(+) gradient. It is suggested that the light-ion gradient may represent a recently created sharp boundary between an old plasmasphere and a new plasmasphere. The present Te characteristics are consisent with plasmasphere depletion and refilling time constants.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1896-190
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  • 21
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    Low-energy bouncing ions in the magnetosphere - A three-dimensional numerical study of Dynamics Explorer 1 data (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1859-187
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  • 22
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    First Viking results - Magnetic field measurements (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The magnetic field experiment on the Swedish Viking satellite consists of a triaxial fluxgate magnetometer system with the sensors mounted on a 2-m boom. Transverse magnetic field perturbations are readily observed which identify the large-scale auroral and cusp-region Birkeland current (BC) systems. A sharp gradient was observed in the dayside region near apogee and 08:40 MLT during a pass on March 25, 1986 which has been interpreted as an earthward-flowing BC of 8 micro-A/sq m. When projected to ionospheric altitudes it is estimated that the current density is 200 micro-A/sq m.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0031-8949); 37; 3, Ma; 479-481
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  • 23
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    Trace gas emissions from a mid-latitude prescribed chaparral fire (1988)
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    Publication Date: 2011-08-19
    Description: Smoke-plume gas samples were collected at altitudes from 35-670 m above the ground over the San Dimas Experimental Forest during a 400-acre prescribed chaparral fire. Mean emission ratios relative to CO2 for CO, H2, CH4, and total nonmethane hydrocarbons were lower than previous values obtained for large biomass-burning field experiments. Comparison of samples from vigorously flaming and mixed stages of combustion revealed little differences in CO2 normalized emission ratios for these gases (except for N2O).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1653-165
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  • 24
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    Measurements of odd nitrogen compounds in the stratosphere by the ATMOS experiment on Spacelab 3 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Spacelab 3's Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment has obtained 30 deg N and 48 deg S vertical profiles of reservoir gases, source gases, and other trace molecules that are important in the middle atmosphere's odd nitrogen, odd chlorine, and odd hydrogen chemical families. The abundances of individual gases and total odd nitrogen levels measured by ATMOS have been compared with prior results obtained from balloon and satellite platforms. The lower-limit profile agrees with ATMOS data to within 16 percent up to 42 km altitude.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1718-173
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  • 25
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    Measurements of atmospheric hydrocarbons and biogenic emission fluxes in the Amazon boundary layer (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Tropospheric mixing ratios of methane, C2-C10 hydrocarbons, and carbon monoxide were measured over the Amazon tropical forest near Manaus, Amazonas, Brazil, in July and August 1985. The measurements, consisting mostly of altitude profiles of these gases, were all made within the atmospheric boundary layer up to an altitude of 1000 m above ground level. Data characterize the diurnal hydrocarbon composition of the boundary layer. Biogenic emissions of isoprene control hydroxyl radical concentrations over the forest. Biogenic emission fluxes of isoprene and terpenes are estimated to be 25,000 micrograms/sq m per day and 5600 micrograms/sq m per day, respectively. This isoprene emission is equivalent to 2 percent of the net primary productivity of the tropical forest. Atmospheric oxidation of biogenic isoprene and terpenes emissions from the Amazon forest may account for daily increases of 8-13 ppb for carbon monoxide in the planetary boundary layer.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1407-141
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  • 26
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    Nonlinear evolution of the Kelvin-Helmholtz instability in the high-latitude ionosphere (1988)
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    Publication Date: 2011-08-19
    Description: The first numerical simulations of the nonlinear evolution of the electrostatic Kelvin-Helmholtz (K-H) instability with ionospheric Perderson conductivity coupling are presented. It is found that the K-H instability develops in a distinctly different manner in the nonlinear regime with Pedersen coupling than without it. Pedersen coupling effects, in conjunction with a neutral wind and density gradient, are shown to result in an increased time scale for K-H instability wave growth, to inhibit K-H vortex formation, to lead to nonlinear structures which can be described as 'breaking waves', and to generate, in the nonlinear regime, small-scale turbulence by means of secondary instabilities growing on primary waves. The spatial power spectra of the electrostatic potential and density fluctuations are computed, and differences with and without Pedersen effects are reported.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 137-152
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  • 27
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    The role of molecular hydrogen and methane oxidation in the water vapour budget of the stratosphere (1988)
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    Publication Date: 2011-08-19
    Description: The detailed photochemistry of methane oxidation has been studied in a coupled chemical/dynamical model of the middle atmosphere. The photochemistry of formaldehyde plays an important role in determining the production of water vapor from methane oxidation. At high latitudes, the production and transport of molecular hydrogen is particularly important in determining the water vapor distribution. It is shown that the ratio of the methane vertical gradient to the water vapor vertical gradient at any particular latitude should not be expected to be precisely 2, due both to photochemical and dynamical effects. Modeled H2O profiles are compared with measurements from the Limb Infrared Monitor of the Stratosphere (LIMS) experiment at various latitudes. Molecular hydrogen is shown to be responsible for the formation of a secondary maximum displayed by the model water vapor profiles in high latitude summer, a feature also found in the LIMS data.
    Keywords: GEOPHYSICS
    Type: Royal Meteorological Society, Quarterly Journal (ISSN 0035-9009); 114; 281-295
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  • 28
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    ISEE-3 observations of the earth's radio continuum through the bow shock and magnetosheath and in the magnetosphere (1988)
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    Publication Date: 2011-08-19
    Description: On October 1 1983, ISEE-3 crossed the earth's bow shock several times and entered the magnetosphere while continuously recording the nonthermal continuum (NTC) radio emission which is generated inside the magnetosphere. The effects of the solar wind, the bow shock, the magnetosheath, and the magnetopause on the propagation of the NTC are studied. On that day it is found that: (1) the relative values of the NTC low frequency cut-off in the solar wind and in the magnetosheath is due to an unusually high density overshoot in the bow shock, 7 to 11 times the solar wind density; (2) refraction at the interface between the magnetosheath and the solar wind can explain most of the decrease in the source angular size when the observer travels away from the earth; (3) plasma density irregularities in the magnetosheath cause considerable scattering of the NTC, and this effect gives a large apparent size to the NTC source when observed from inside the magnetosheath; and (4) the apparent source is also relatively large inside the magnetosphere, probably due to an approach to ray isotropy caused by oblique reflections from the magnetopause.
    Keywords: GEOPHYSICS
    Type: Annales Geophysicae (ISSN 0980-8752); 6; 309-318
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  • 29
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    New evidence from the South China Sea for an abrupt termination of the last glacial period (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results demonstrating an abrupt change in the rate and character of sedimentation in the South China Sea at the close of the last glacial period are presented. Radiocarbon dating and its position in the oxygen isotope shift suggest that this change may be coincident with the abrupt change in climatic conditions seen at high latitudes in the North Atlantic and the Antarctic at 13 kyr BP. These results support the contention that a major global climatic change occurred between 14 and 13 kyr BP.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 333; 156-158
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  • 30
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    Comparison of OGO 6 measured thermospheric temperatures with the MSIS-86 empirical model (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The thermospheric temperatures measured by the Fabry-Perod interferometer on the OGO 6 satellite are found to be reasonably represented by the mass spectrometer/incoherent scatter 1986 (MSIS-86) empirical model except for two anomalies, one in the South Atlantic and the other near noon local time. These anomalies are likely due to measurement problems. The OGO 6 temperature data were not used in the generation the MSIS models, so this is an independent comparison of measured and model temperatures. The measurements were made primarily during daytime at mid to low latitudes and throughout the day at high latitudes. On average, the measured temperatures are 16 K below the MSIS-86 model temperatures. Latitude gradients during solstices as well as for the yearly average are well represented by the model, as are high-latitude longitudinal and magnetic activity variations.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5965-597
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  • 31
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    Observation of an ionospheric disturbance caused by a gamma-ray burst (1988)
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    Publication Date: 2011-08-19
    Description: A first observation of an ionospheric disturbance from a gamma-ray burst is reported. The burst, GB30801, occurred at 22:14:18 UT on August 1, 1983, and was one of the strongest ever observed. The total fluence was 0.002 erg/sq cm, most of which occurred in the first 4 s of the burst. Simultaneously, a change was observed in the amplitude of a VLF radio signal from a transmitter in Rugby, England indicative of an ionospheric disturbance. Weaker disturbances were also recorded at the same receiving site on signals from VLF stations in Annapolis, Maryland and Lualualei, Hawaii. The times of the burst and the disturbances are coincident within the 10-s resolution of the VLF recording system. No similar disturbances were observed within 60 hr around the time of the burst. In the future, a network of VLF burst monitors may provide measurements of the total ionizing energy fluence from a burst, as well as some limited directional information.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 418-420
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  • 32
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    Gravity domains and assembly of the North American continent by collisional tectonics (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A gravity trend map of North America, based on a horizontal Bouguer gravity gradient map produced from gravity data for Canada and the conterminous United States, is presented and used to define a continental mosaic of gravity trend domains akin to structural domains. Contrasting trend characteristics at gravity domain boundaries support the concept of outward growth of the continent primarily by accretionary tectonics. Gravity patterns, however, indicate a different style of tectonics dominated in the development of now-buried Proterozoic orogenic belts in the south-central United States, supporting a view that these belts formed along the leading edge of a southward-migrating Proterozoic continental margin.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 333
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  • 33
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    Atmospheric ozone at South Pole, Antarctica, in 1986 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results of NOAA's measurements of the ozone vertical distributions at the South Pole and of the annual course of total ozone, conducted in 1986 with balloon-borne electrochemical concentration cell (ECC) ozonesondes and a Dobson spectrophotometer, are described. The major finding was that the stratospheric ozone decreases abruptly between September 20 and October 15, with the bulk decrease occurring between 12 and 21 km. In this period, the column ozone and ozone volume mixing ratio at 16 km (the altitude of the normal ozone maximum at South Pole) decreased by 78 percent, and column ozone between 12 and 21 km decreased by 50 percent. The results of these measurements are compared with data obtained in 1971, and the changes observed in the ozone vertical distributions and in the temporal variations of atmospheric ozone are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5167-518
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  • 34
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    Simultaneous measurement of minor stratospheric constituents with emission far-infrared spectroscopy (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The vertical mixing ratio profiles of H2O, HDO, O3, heavy ozone, HF, HCl, HCN, and OH in the stratosphere are retrieved from high-resolution far-infrared emission spectra. These spectra were obtained with a balloon-borne Fourier transform spectrometer in the spring of 1979 at 32 deg N. The nonlinear least squares fit method is used in the analysis. The results are obtained relative to the O2 mixing ratio, whose emission features can be found in the same spectra. The retrieval of OH together with other species should be particularly significant for the study of upper stratospheric photochemistry, although the errors are relatively large: 28 percent for OH and 16-19 percent for other species.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3851-386
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  • 35
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    Antarctic springtime ozone depletion computed from temperature observations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An observationally based, mechanistic dynamical model is used to simulate the decline of total ozone during September and October for the years 1979 through 1986. Vertical velocities derived from observed stratospheric temperature changes and computed radiative heating rates are used to advect an ozone mixing ratio profile during the Antarctic spring period. An early August 1982 Syowa balloonsonde ozone profile is used to initialize the computations. The model reasonably simulates the September and October changes in total ozone, considering the uncertainties in the observed data and the radiative heating. The simulated decline is found to be very sensitive to the choice of initial ozone profile and to small changes in the radiative heating. The results of this study suggest that the dynamical hypothesis of the Antarctic ozone depletion is both quantitatively credible and consistent with the observed temperature changes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3833-384
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  • 36
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    Resonant geomagnetic field oscillations and Birkeland currents in the morning sector (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The relationship between large-scale Birkeland currents and resonant oscillations of the geomagnetic field is investigated on the basis of Viking magnetic-field, electric-field, and particle measurements and AMPTE-CEE and IMP-8 magnetic-field measurements obtained during April 23-25, 1986. The data are presented in extensive graphs and characterized in detail. The 3-16-mHz 5-60-nT magnetic-field oscillations detected by Viking are also seen by AMPTE-CEE below L = 8.8 and extend from the lower L shells to the boundary between regions 1 and 2 of the Birkeland-current system, and this boundary is shown to be closely related to the interface between the low-latitude boundary layer and the central plasma sheet. It is suggested that the magnetospheric oscillations may be driven by several different solar-wind features, possibly depending on the direction of the IMF.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2661-267
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  • 37
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    A few parts in 10 to the 8th geodetic baseline repeatablity in the Gulf of California using the Global Positioning System (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: GPS geodetic measurements of 350-650 km baselines across the Pacific-North America plate boundary in the Gulf of California are presented. The analysis employs a four-station U.S. fiducial network and combined carrier phase and pseudorange data. Water vapor radiometer data at the Gulf sites are used to calibrate the GPS signal for wet tropospheric path delays. Residual tropospheric delays are modeled as first-order exponentially correlated stochastic processes. The measurement precision for horizontal components is a few parts in 10 to the 8th or better.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 353-356
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  • 38
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    Iridium abundance maxima in the Upper Cenomanian extinction interval (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two iridium abundance peaks, both 0.11 ppb (whole-rock basis) over a local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado. They occur just below the 92-million-year-old Cenomanian-Turonian (C-T) stage boundary. No other peaks were found in 45 meters of strata (about 2.5 million years of deposition) above and below the boundary interval. The broad lower peak straddles the first in a series of extinctions of benthic and nektonic macrobiota which comprise the C-T extinction event. The sharp upper peak occurs stratigraphically about 1.2 meters above the lower peak. The excess Ir might be from meteoroid impacts.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 346-349
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  • 39
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    Boundary layer ozone - An airborne survey above the Amazon Basin (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ozone data obtained over the forest canopy of the Amazon Basin during July and August 1985 in the course of NASA's Amazon Boundary Layer Experiment 2A are discussed, and ozone profiles obtained during flights from Belem to Tabatinga, Brazil, are analyzed to determine any cross-basin effects. The analyses of ozone data indicate that the mixed layer of the Amazon Basin, for the conditions of undisturbed meteorology and in the absence of biomass burning, is a significant sink for tropospheric ozone. As the coast is approached, marine influences are noted at about 300 km inland, and a transition from a forest-controlled mixed layer to a marine-controlled mixed layer is noted.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1452-146
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  • 40
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    Tropospheric nitric oxide measurements over the Amazon Basin (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Horizontal and vertical distributions of nitric oxide (NO) were measured over the Amazon Basin during NASA's Global Tropospheric Experiment (GTE) Amazon Boundary Layer Experiment mission in July-August 1985. During transit flights between the Virginia coast and Manaus, Brazil, NO mixing ratios were 12-15 pptv at 5 km altitude. Values up to 200 pptv were observed in electrically active clouds. During longitudinal surveys over the Amazon region, NO mixing ratios in the lower planetary boundary layer decreased from 25-60 pptv over the central basin to 10-12 pptv in coastal regions. In the convective cloud layer or free troposphere, NO mixing ratios averaged 13 pptv in regions not influenced by biomass burning. No longitudinal trend above the mixed layer could be detected. A steep negative gradient with increasing altitude was noted within the mixed layer before midday. Mixing ratios decreased from 60 pptv at 0.2 km to about 15 pptv at the top of the mixed layer (1 km). By midday, growth of the mixed layer height and enhanced mixing reduced the gradient, and evidence for mixing of NO into the convective cloud layer was noted.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1396-140
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  • 41
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    Tropospheric ozone and aerosol distributions across the Amazon Basin (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: As a part of the NASA Global Tropospheric Experiment to study the Amazon boundary layer, ozone and aerosol distributions were made measured in July-August 1985 by a NASA Electra aircraft on several long-range flights spanning different areas between Tabatinga and Belem, Brazil. Both positive and negative correlations were found in PBL between aerosol concentrations and O3 mixing ratios. The negative correlations result from the downward transport of relatively clean O3-rich air from the upper troposphere into PBL (which normally has higher aerosol loading and lower O3 concentrations than troposphere); positive correlations are found in biomass-burning plumes, where the aerosols are emitted into the air and O3 is photochemically produced. It was found that, in the dry season, a significant portion of the ozone over the rain forest is a result of biomass burning and that the distribution of photochemically produced O3 is strongly affected by synoptic-scale transport from large fires to the south/southeast.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1431-145
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  • 42
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    Structure and growth of the mixing layer over the Amazonian rain forest (1988)
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    Publication Date: 2011-08-19
    Description: The structure and growth of the atmospheric mixed layer over the Amazonian rain forest were examined using measurements obtained during the NASA Amazon Boundary Layer Experiment. Measurements of temperature, moisture, and horizontal wind were carried out in and above the mixed layer by means of a tethered balloon, rawinsonde, and aircraft; fluxes of sensible and latent heat were measured at the top of the canopy. It was found that the mixing layer grows rapidly, at 5-8 cm/sec, soon after sunrise to a mean maximum height of 1200 m by 1300 LT; during undisturbed conditions, mixed layer heights of 1000 are common between 1000 and 1600 LT. No horizontal inhomogeneities in the mixed layer structure or depth were found over large distances. A simple mixed layer model was applied to show how fluxes of species might be estimated using only quantities measured at the surface and prescribing an initial condition and boundary condition for the mixed layer.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1361-137
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  • 43
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    Antarctic ozone - Meteoric control of HNO3 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Atmospheric circulation leads to an accumulation of debris from meteors in the Antarctic stratosphere at the beginning of austral spring. The major component of meteoric material is alkaline, comprised predominantly of the oxides of magnesium and iron. These metals may neutralize the natural acidity of stratospheric aerosols, remove nitric acid from the gas phase, and bond it as metal nitrates in the aerosol phase. Removal of nitric acid vapor has been previously shown to be a critical link in the photochemical depletion of ozone in the Antarctic spring, by allowing for increased catalytic loss from chlorine and bromine.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 1-4
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  • 44
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    Measurements of air-broadened and nitrogen-broadened Lorentz width coefficients and pressure shift coefficients in the nu4 and nu2 bands of C-12H4 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Air-broadened and N2-broadened halfwidth and pressure shift coefficients of 294 transitions in the nu4 and nu2 bands of C-12H4 have been measured from laboratory absorption spectra recorded at room temperature with the Fourier transform spectrometer in the McMath solar telescope facility of the National Solar Observatory. Total pressures of up to 551 Torr were employed with absorption paths of 5-150 cm, CH4 volume mixing ratios of 2.6 percent or less, and resolutions of 0.005 and 0.01/cm. A nonlinear least-squares spectral fitting technique has been utilized in the analysis of the twenty-five measured spectra. Lines up to J double-prime = 18 in the nu4 band and J double-prime = 15 in the nu2 band have been analyzed.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 27; 631-651
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  • 45
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    On the possible role of the reaction O + HO2 - OH + O2 in OH airglow (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Experimental data on the so-called 'perhydroxyl' reaction O + HO2 - OH + O2 by which vibrationally excited OH is produced in the upper atmosphere are briefly reviewed. Both isotopic labeling studies and studies on the temperature dependence of the rate constant and the possible importance of its inverse are considered. The implication of the results for analysis of OH airglow data are emphasized. Some additional results on the dynamics of reactions related to OH airglow which may affect interpretation of OH emission measurements are summarized.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 285-288
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  • 46
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    Ground-level detection of low- and medium-frequency auroral radio emissions (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Natural radio emissions in the frequency range of several hundred kHz were detected at ground level in the auroral region during a ground-level observing program conducted near Fairbanks, Alaska in the spring of 1986 in an attempt to detect auroral cyclotron-maser-generated whistler modes. Most of the strongest emissions were observed in a small time interval around midnight magnetic local time, suggesting a close tie-in with auroral processes. The results support earlier reports of radio noise from the aurora at frequencies of about 100 kHz and indicate the importance of extending the upper frequency of ground-based high-latitude VLF stations to the vicinity of 1 MHz.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 277-283
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  • 47
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    Uncertainty estimates in geomagnetic field modeling (1989)
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    Publication Date: 2011-08-19
    Description: This paper presents an extension of the conventional uncertainty analysis which characterizes the sources of uncertainty in the coefficients of the geomagnetic field models. The new formalism accounts for the systematic errors introduced by the omission of such sources as the presence of crustal fields, the external fields, and the field from the truncated terms. The usefulness of this formalism depends on two critical conditions. The first of these is the knowledge of the statistical properties of the fields whose parameters are not solved in the analysis, i.e., the crustal field and the external field. The second critical point in the practical use of the method is the approximation used for the weight matrix.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 12281-12
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  • 48
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    Indicators of transport and vertical motion from correlations between in situ measurements in the Airborne Antarctic Ozone Experiment (1989)
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    Publication Date: 2011-08-19
    Description: Analysis of small-scale structure in the in situ measurements made from the ER-2 during the Airborne Antarctic Ozone Experiment shows the existence of a region at the boundary of the chemiclly perturbed region where the mixing ratios and small-scale structure of trace gases are influenced by transport across the boundary. This transition region is characterized by horizontal interchange and vertical layering of air parcels from within and outside of the chemically perturbed region and negative small-scale correlations between ClO and ozone. The horizontal transport in this region creates large surface areas between dissimilar air masses, providing the potential for substantial mixing. Correlations between ClO and O3 show that the transition region extends to 2-4 deg of latitude to either side of the boundary of the chemically perturbed region. A + or - 4-deg-wide transition region would contain nearly as much air as the chemically perturbed region proper. Analysis of water vapor and nitrous oxide data suggests that diabatic descent is associated with dehydration. This could be caused by strong radiative cooling of those polar stratospheric clouds in which enough water condenses for the particles to fall and dehydrate the air.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11669-11
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  • 49
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    Potential vorticity and mixing in the south polar vortex during spring (1989)
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    Publication Date: 2011-08-19
    Description: Fluid dynamic aspects of the Antarctic ozone hole phenomena are studied. Data collected by the ER-2 aircraft as part of the Airborne Antarctic Ozone Experiment (AAOE) are used to calculate the potential vorticity distribution on potential temperature surfaces. Most of the ER-2 flights show a monotonic decrease in potential vorticity and nitrous oxide toward the pole on isentropic surfaces.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11625-11
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  • 50
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    Diagnostic studies of the Antarctic vortex during the 1987 Airborne Antarctic Ozone Experiment - Ozone miniholes (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Localized rapid reductions in total ozone (miniholes), which were observed during the Airborne Antarctic Ozone Experiment, are studied with particular attention given to meteorological aspects. It is suggested that miniholes are forced by tropospheric weather features and that they are largely reversible distortions to the airflow around the vortex. The relationship between the miniholes and upper tropospheric and lower stratospheric synoptic-scale disturbances is studied. Trajectory calculations are presented which demonstrate the exchange of air from low latitudes with air from within the vortex, with the vortex air subsequently moving to lower latitudes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11641-11
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    Trace gases in the Antarctic Atmosphere (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Whole-air samples collected aboard the NASA ER-2 and DC-8 aircraft as part of the Airborne Antarctic Ozone Experiment were analyzed in a field laboratory set up at Punta Arenas, Chile. Mixing ratios obtained from gas chromatographic analyses of these samples are presented for CH4, CO, N2O, CFCl3, CF2Cl2, C2F3Cl3, CH3CCl3, and CCl4. A comparison of CFCl3/N2O mixing ratios from the flights of September 16-29, 1987 provides evidence of sustained subsidence.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11599-11
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  • 52
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    Ground-based infrared measurements of tropospheric source gases over Antarctica during the 1986 austral spring (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Simultaneous measurements of the atmospheric burdens of CH4, N2O, CO2, CF2Cl2, and CO above McMurdo Station, Antarctica, have been derived from solar absorption spectra obtained by the Jet Propulsion Laboratory high-resolution Fourier transform spectrometer. In all cases the burdens are smaller than midlatitude values. Furthermore, retrievals of N2O and CH4 indicate that the tropospheric mixing ratios were normal and that the depletion of the burdens can best be accounted for by a downward shift of the volume mixing ratio profiles by some 6-8 km. This rules out the possibility of large-scale upwelling of ozone-poor tropospheric air into the stratosphere being the cause of the Antarctic springtime ozone depletion.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11613-11
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  • 53
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    Nitrous oxide as a dynamical tracer in the 1987 Airborne Antarctic Ozone Experiment (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In situ N2O measurements were made using an airborne tunable laser absorption spectrometer (ATLAS) on 12 flights into the Antarctic vortex, as well as on five transit flights outside the vortex region in August and September 1987, as part of the Airborne Antartic Ozone Experiment. Vertical profiles of N2O were obtained within the vortex on most of these flights and were obtained outside the vortex on several occasions. Flights into the vortex region show N2O decreasing southward between 53 and 72 S latitude on constant potential temperature surfaces in the lower stratosphere. The data lead to two important conclusions about the vortex region: (1) the lower stratosphere in August/September 1987 was occupied by 'old' air, which had subsided several kilometers during polar winter; (2) the N2O profile in the vortex was in an approximately steady state in August/September 1987, which indicates that the spring upwelling, suggested by several theories, did not occur.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11589-11
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  • 54
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    Quasi-biennial modulation of the Antarctic ozone depletion (1989)
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    Publication Date: 2011-08-19
    Description: The quasi-biennial oscillation (QBO) in total ozone and temperature has been extracted from 9 years of Total Ozone Mapping Spectrometer (TOMS) observations and National Meteorological Center (NMC) analyses. Years in which QBO-related variations in the total ozone and temperature are positive are found to correspond to years with smaller September Antarctic total ozone hole decline rates and vice versa. The QBO appears to be responsible for September decline rate deviations up to 0.4 Dobson units (DU) per day. Also, the QBO at mid-latitudes appears to be better correlated with the 30-mbar tropical QBO winds than with those at 50 mbar. Possible mechanisms that would explain these phenomena are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11559-11
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  • 55
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    Lagrangian photochemical modeling studies of the 1987 Antarctic spring vortex. I - Comparison with AAOE observations (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results from the Lagrangian photochemical model integrated along computed air parcel trajectories intersected by the ER-2 aircraft are presented and compared with AAOE observations. According to the model, the BrO observations made from the ER-2 within the dehydrated denitrified region are consistent with there being approximately 5 parts per trillion by volume of BrO(y) at 428 K in spring. Within the high ClO region, ozone destruction rates are expected to exceed 2 percent/d with approximately 80 percent due to the ClO dimer mechanism.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11529-11
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    A chemical definition of the boundary of the Antarctic ozone hole (1989)
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    Publication Date: 2011-08-19
    Description: A program designed to study the Antarctic ozone hole using ER-2 high-altitude and DC-8 aircraft was conducted out of Punta Arenas, Chile during August 17-September 22, 1987. Graphs are presented of ozone and chlorine monoxide when crossing the boundary of the chemically perturbed region on August 23 and on September 21. Interpretations of ClO, H2O, and N2O measurements are presented, indicating ongoing diabetic cooling and advective poleward transport across the boundary.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11437-11
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    Measurements of ozone in the Antarctic atmosphere during August and September 1987 (1989)
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    Publication Date: 2011-08-19
    Description: Mixing ratios changed dramatically for ozone in the austral polar stratosphere during August and September 1987. Data were obtained with an ultraviolet photometer mounted in the equipment bay of an ER-2 aircraft. Measurements were made between the latitudes of 53 and 72 deg S at pressure altitudes (U.S. Standard Atmosphere, 1976) up to 21 km in a series of flights from Punta Arenas, Chile, over the Palmer Peninsula. Additional data were obtained between 37 N and 53 deg S on the ferry flights leaving from and returning to Moffett Field, California. The sampling-collecting system and the analytical techniques are described. In September the mixing ratios for ozone at pressure altitudes above 15 km in the southernmost part of the flights over the Palmer Peninsula were significantly lower than values for midlatitudes. The various latitudes of the ER-2 aircraft's encounters with the boundary of the region of depleted ozone lie between 59 and 71 deg S. Near the 425 K potential temperature surface and well within the vortex, the measured mixing ratio of ozone declined from about 2 parts per million by volume (ppmv) to about 0.6 ppmv during the period of the ER-2 flights. The distributions of ozone as a function of altitude indicate the presence of layering of ozone.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11449-11
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    Airborne measurements of stratospheric constituents over Antarctica in the austral spring 1987. I - Method and ozone observations (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A Fourier transform spectrometer was flown aboard a DC-8 on 10 flights over Antarctica during August and September, 1987, as part of the Airborne Antarctic Ozone Experiment (AAOE). Observing the sun at infrared wavelengths, it was possible to determine the integrated column amount above the flight altitude for ozone and a number of other chemical species that are believed to be important in the perturbed chemistry of the 'ozone hole'. The paper describes the method, the observations, the data analysis procedure, and the ozone results. During the observation period, ozone developed a steep gradient near the edge of the polar vortex; deep within the vortex, the average ozone column decreased by about 1.6 percent per day during September.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11413-11
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    Filter measurement results from the Airborne Antarctic Ozone Experiment (1989)
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    Publication Date: 2011-08-19
    Description: Filter samples obtained as part of the AAOE to determine the total nitrate, sulfate, acidic chloride, and acidic fluoride content along the flight path of the NASA ER-2 are studied. These compounds were obtained in the aerosol and vapor phase. The ratio of particulate sulfate observed outside the chemically perturbed region (CPR) of the vortex to that inside the CPR was 2.6. The ratio of total acidic chloride to total acidic flouride within the CPR is near 1, indicating the removal of chloride from the air mass or the partitioning of chloride into an unmeasured species.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11285-11
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  • 60
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    Condensed nitrate, sulfate, and chloride in Antarctic stratospheric aerosols (1989)
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    Publication Date: 2011-08-19
    Description: The 1987 Airborne Antarctic Ozone Experiment, in which the NO3, Cl, and SO4 contents of stratospheric aerosols were estimated, is discussed. The aerosol size and chemical composition measurements were carried out on samples collected during August 17 to September 4, 1987. The data indicate that condensed nitrate is found below a threshold temperature of 193.6 + or - 3.0 K, which is generally found at latitudes exceeding 64 deg S. A negative correlation exists between condensed nitrate and ozone correlation.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11271-11
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    Balloon-borne measurements of aerosol, condensation nuclei, and cloud particles in the stratosphere at McMurdo Station, Antarctica, during the spring of 1987 (1989)
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    Publication Date: 2011-08-19
    Description: Measurements of the vertical profile of particles with condensation nuclei counters and eight channel aerosol detectors at McMurdo Station, Antarctica, in 1987 verified observations made in 1986 concerning the absence of upwelling in the polar vortex and the presence of a condensation nuclei layer in conjunction with the ozone hole region. New observations of a bimodal aerosol size distribution, consisting of a large-particle mode mixed in with the small-particle sulfate mode, at temperatures below -79 C are consistent with the presence of nitric acid-water particles at low concentrations. Higher concentrations of large particles were observed in association with nacreous clouds. An unusual particle layer which contained enhanced concentrations of both the small-particle (sulfate) mode and the large-particle (nitric acid) mode was detected at temperatures below -85 C, suggesting simultaneous nucleation and growth phenomena. The vortex condensation nuclei layer was observed to form at the same time as the ozone hole, indicating that formation of the layer is triggered by photochemical processes and may be important in controlling ozone depletion above 22 km.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11253-11
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  • 62
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    Observational results using the microwave temperature profiler during the Airborne Antarctic Ozone Experiment (1989)
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    Publication Date: 2011-08-19
    Description: The Microwave Temperature Profiler (MTP) measures profiles of air temperature versus altitude. The altitude coverage is about 5 km at a flight altitude of 20 km (66,000 feet), and the profiles are obtained every 14 s. The MTP instrument is installed on NASA's ER-2 aircraft, which flew 13 missions over Antarctica during the Airborne Antarctic Ozone Experiment. Altitude temperature profiles were used to derive potential temperature cross sections. These cross sections have been useful in detecting atmospheric waves. Many wave encounters have been identified as 'mountain waves'. The mountain waves are found to extend from the lowest altitudes measured to the highest (about 24 km). The southern part of the Palmer Peninsula was found to be associated with mountain waves more than half the time. Altitude temperature profiles were also used to measure the lapse rate along the flight track. Lapse rate versus latitude plots do not show significant changes at the ozone hole boundary.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11223-11
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  • 63
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    Morphology of calcite crystals in clast coatings from four soils in the Mojave desert region (1989)
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    Publication Date: 2011-08-19
    Description: Pedogenic calcite-crystal coatings on clasts were examined in four soils along an altitudinal gradient on Kyle Canyon alluvium in southern Nevada. Clast coatings were studied rather than matrix carbonate to avoid the effects of soil matrix on crystallization. Six crystal sizes and shapes were recognized and distinguished. Equant micrite was the dominant crystal form with similar abundance at all elevations. The distributions of five categories of spar and microspar appear to be influenced by altitudinally induced changes in effective moisture. In the drier, lower elevation soils, crystals were equant or parallel prismatic with irregular, interlocking boundaries while in the more moist, higher elevation soils they were randomly oriented, euhedral, prismatic, and fibrous. There was little support for the supposition that Mg(+2) substitution or increased (Mg + Ca)/HCO3 ratios in the precipitating solution produced crystal elongation.
    Keywords: GEOPHYSICS
    Type: Soil Science Society of America, Journal (ISSN 0038-0776); 53; 211-219
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    Silicification of holocene soils in northern Monitor Valley, Nevada (1989)
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    Publication Date: 2011-08-19
    Description: Chemical, physical, and microscopic data for three soils in the northern Monitor Valley are analyzed. The soils ranked in order of increasing age are: Mule, Rotinom, and Nayped. The procedures and techniques used to obtain and study that data are described. It is observed that: (1) redistribution of carbonate is detectable in all soils; (2) clay illuviation is insignificant in the Mule soil, weak but identifiable in the Rotinom soil, and significant in the Nayped soil; and (3) the maximum sodium adsorption ratio (SAR) and electrical conductivity (EC) for the Mule soil is between 64-89 cm, for the Rotinom soil the values are below 100 cm, and for Nayped the maximum SAR values range from 51-117 cm and maximum EC values are between 117-152 cm. The relationship between volcanic glass weathering and the amount of silica cementation in the soils is studied. It is noted that silicification of Monitor Valley holocene soils is due to there being enough moisture to release silica from volcanic glass, but not enough to leach the weathering products from the profile.
    Keywords: GEOPHYSICS
    Type: Soil Science Society of America, Journal (ISSN 0038-0776); 53; 158-164
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    The Antarctic ozone hole (1988)
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    Publication Date: 2011-08-19
    Description: Observations of Antarctic ozone levels and the discovery of a hole in the Antarctic region are examined. The effects of chlorofluorocarbons (CFCs) on the level of stratospheric ozone are analyzed. Three cycles explaining the cause of ozone depletion in the poles are proposed. A comparison of field data and proposed depletion cycles reveals that the chemical origin of the ozone hole is due to CFCs. The potential global effects of the Antarctic ozone hole are discussed.
    Keywords: GEOPHYSICS
    Type: Oceanus (ISSN 0029-8182); 31; 47-52
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    Self-limiting physical and chemical effects in volcanic eruption clouds (1989)
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    Publication Date: 2011-08-19
    Description: One-dimensional aerosol microphysical and photochemical models are used to study the chemistry of stratospheric volcanic clouds. The results indicate that the aerosol microphysical processes of condensation and coagulation produce larger particles as the SO2 injection rate is increased. Larger particles have a smaller optical depth per unit mass and settle out of the stratosphere at a faster rate than smaller ones, restricting the total number of particles in the stratosphere. The microphysical processes moderate the impact of volcanic clouds on the earth's radiation budget and climate, suggesting that volcanic effects may be self limiting. It is noted that the injection of HCl into the stratosphere, which could lead to large ozone changes, is limited by a cold trap effect in which HCl and water vapor condense on ash particles in the rising volcanic plume and fall out as ice.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11165-11
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    Stratospheric ozone measurements from the 1985 MAP/GLOBUS NO(x) campaign (1989)
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    Publication Date: 2011-08-19
    Description: Nine experiments obtained stratospheric ozone measurements during the fall 1985 Middle Atmosphere Program (MAP) Global Budget of Stratospheric Trace Constituents (GLOBUS) NO(x) campaign. Measurements are grouped into four sets from four air masses and compared. Agreement between individual experiments and weighted mean profiles is generally within 10 percent and within absolute accuracies. Dobson Umkehr values in layer 5 differ by more than absolute accuracies from weighted mean profiles. Brewer sonde values for one data set are outside absolute accuracies near the ozone peak. Solar UV occultation measurements are 30-35 percent less than the weighted mean profile and outside absolute accuracies. Measurements from the Exospheric Satellite backscattered ultraviolet experiment, not previously compared with other techniques, agree within 10-15 percent of weighted mean profiles. Results of the campaign are generally consistent with those of four previous intercomparison campaigns.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11074-11
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  • 68
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    Secular increase of the total vertical column abundance of carbon monoxide above central Europe since 1950 (1989)
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    Publication Date: 2011-08-19
    Description: The secular increase of the total vertical column abundance of carbon monoxide has been derived from sets of infrared solar spectra recorded from an altitude of 3.58 km at the Jungfraujoch Station, Switzerland, in 1950-1951 and in 1985-1987. The results are based on equivalent width measurements of the R3 line of the 1-0 vibration-rotation band of (C-12)(0-16) at 2159.30/cm. The set of 1985-1987 observations indicates a strong seasonal cycle in the total column abundance of CO, with a + or - 25 percent modulation between minimum values in late summer and the maximum values in late winter. Variability on shorter time scales is also present in both the old and recent data sets. The mean cumulative rate of increase of the total column abundance of CO above the Jungfraujoch is found to be (0.85 + or - 0.20) percent/yr between 1950-1951 and 1985-1987. The present findings are compared with trends reported in earlier studies.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11021-11
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    The morphology of strike-slip faults - Examples from the San Andreas Fault, California (1989)
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    Publication Date: 2011-08-19
    Description: The dilatational strains associated with vertical faults embedded in a horizontal plate are examined in the framework of fault kinematics and simple displacement boundary conditions. Using boundary element methods, a sequence of examples of dilatational strain fields associated with commonly occurring strike-slip fault zone features (bends, offsets, finite rupture lengths, and nonuniform slip distributions) is derived. The combinations of these strain fields are then used to examine the Parkfield region of the San Andreas fault system in central California.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 10204-10
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    Carrier phase ambiguity resolution for the Global Positioning System applied to geodetic baselines up to 2000 km (1989)
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    Publication Date: 2011-08-19
    Description: A technique for resolving the ambiguities in the GPS carrier phase data (which are biased by an integer number of cycles) is described which can be applied to geodetic baselines up to 2000 km in length and can be used with dual-frequency P code receivers. The results of such application demonstrated that a factor of 3 improvement in baseline accuracy could be obtained, giving centimeter-level agreement with coordinates inferred by very-long-baseline interferometry in the western United States. It was found that a method using pseudorange data is more reliable than one using ionospheric constraints for baselines longer than 200 km. It is recommended that future GPS networks have a wide spectrum of baseline lengths (ranging from baselines shorter than 100 km to those longer than 1000 km) and that GPS receivers be used which can acquire dual-frequency P code data.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 10187-10
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    A search for five month solar induced periodicity in the stratosphere (1989)
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    Publication Date: 2011-08-19
    Description: Recent studies of solar UV spectra and various indices of solar activity indicate a strong period at about 5 months. In the 10.7 cm solar radio flux (F10.7), a conventional index for the solar EUV and UV variabilities, the spectral power of the 5 month period is comparable to the well known 27 day solar period. However, in the solar UV flux at 205 nm, directly measured from the Nimbus-7 SBUV spectrometer, the (spectral) power of the 5 month period is about half that of the 27 day period. This paper examines the possible impact of the 5 month solar period on ozone and temperature at various pressure levels in the stratosphere and discusses the implications of differences in solar forcing at the 27 day and 5 month periods. It is shown that ozone, both in the lower and the upper stratosphere, has a measurable response to solar UV forcing at 27 days. Such a solar response is not observed at 5 month period because of a relatively weaker 5 month solar UV component in the solar signal and a strong interference from dynamical signals associated with planetary wave activity.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 711-714
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    SAGE II inversion algorithm (1989)
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    Publication Date: 2011-08-19
    Description: The operational Stratospheric Aerosol and Gas Experiment II multichannel data inversion algorithm is described. Aerosol and ozone retrievals obtained with the algorithm are discussed. The algorithm is compared to an independently developed algorithm (Lenoble, 1989), showing that the inverted aerosol and ozone profiles from the two algorithms are similar within their respective uncertainties.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 8339-835
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    SAGE II aerosol validation - Selected altitude measurements, including particle micromeasurements (1989)
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    Publication Date: 2011-08-19
    Description: The validity of particulate extinction coefficients derived from limb path solar radiance measurements obtained during the Stratospheric Aerosol and Gas Experiment (SAGE) II is tested. The SAGE II measurements are compared with correlative aerosol measurements taken during January 1985, August 1985, and July 1986 with impactors, laser spectrometers, and filter samplers on a U-2 aircraft, an upward pointing lidar on a P-3 aircraft, and balloon-borne optical particle counters. The data for July 29, 1986 are discussed in detail. The aerosol measurements taken on this day at an altitude of 20.5 km produce particulate extinction values which validate the SAGE II values for similar wavelengths.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 8367-838
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    SAGE II aerosol data validation and initial data use - An introduction and overview (1989)
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    Publication Date: 2011-08-19
    Description: The process of validating data from the Stratospheric Aerosol and Gas Experiment (SAGE) II and the initial use of the validated data are reviewed. The instruments developed for the SAGE II, the influence of the eruption of El Chichon on the global stratospheric aerosol, and various data validation experiments are discussed. Consideration is given to methods for deriving aerosol physical and optical properties from SAGE II extinction data and for inferring particle size distribution moments from SAGE II spectral extinction values.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 8335-833
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    Application of internal gravitational field equations to geophysical measurement of G (1989)
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    Publication Date: 2011-08-19
    Description: The spherical harmonic equation for the gravitational potential inside the earth is presented. The equation satisfies Poisson's equation and converges uniformly. It obviates the need for downward continuation of the exterior potential with its attendant convergence difficulties but of course requires some knowledge of the earth's density distribution. The equation is used to derive the general expression for the geophysical measurement of the gravitational constant G made inside the earth, such as in boreholes and mine shafts. Numerical evidence is also presented to show that the long- to intermediate-wavelength gravity anomalies can masquerade as the 'fifth force' if not properly corrected for.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 7563-756
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    Denitrification in the Antarctic stratosphere (1989)
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    Publication Date: 2011-08-19
    Description: Rapid loss of ozone over Antarctica in spring requires that the abundance of gaseous nitric acid be very low. Precipitation of particulate nitric acid has been assumed to occur in association with large ice crystals, requiring significant removal of H2O and temperatures well below the frost point. However, stratospheric clouds exhibit a bimodal size distribution in the Antarctic atmosphere, with most of the nitrate concentrated in particles with radii of 1 micron or greater. It is argued here that the bimodal size distribution sets the stage for efficient denitrification, with nitrate particles either falling on their own or serving as nuclei for the condensation of ice. Denitrification can therefore occur without significant dehydration, and it is unnecessary for temperatures to drop significantly below the frost point.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 339; 525-527
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    Operational aspects of CASA UNO '88-The first large scale international GPS geodetic network (1989)
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    Publication Date: 2011-08-19
    Description: For three weeks, from January 18 to February 5, 1988, scientists and engineers from 13 countries and 30 international agencies and institutions cooperated in the most extensive GPS (Global Positioning System) field campaign, and the largest geodynamics experiment, in the world to date. This collaborative eperiment concentrated GPS receivers in Central and South America. The predicted rates of motions are on the order of 5-10 cm/yr. Global coverage of GPS observations spanned 220 deg of longitude and 125 deg of latitude using a total of 43 GPS receivers. The experiment was the first civilian effort at implementing an extended international GPS satellite tracking network. Covariance analyses incorporating the extended tracking network predicted significant improvement in precise orbit determination, allowing accurate long-baseline geodesy in the science areas.
    Keywords: GEOPHYSICS
    Type: IEEE Transactions on Instrumentation and Measurement (ISSN 0018-9456); 38; 648-651
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    Relation between increasing methane and the presence of ice clouds at the mesopause (1989)
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    Publication Date: 2011-08-19
    Description: The possiblity is investigated that a substantial change has occurred in middle-atmospheric water vapor as a result of the increase in atmospheric methane over the past century and a half. It is shown from modeling of mesospheric ice-particle formation that noctilucent cloud brightness should be a sensitive indicator of the water content at the high-latitude summertime mesopause. From an examination of the historical record of noctilucent cloud occurrence, it is found that such clouds are absent from the record before 1885, a finding which is consistent with the hypothesis proposed in this paper.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 338; 490-492
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    Impact of heterogeneous reactions on stratospheric chemistry of the Arctic (1989)
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    Publication Date: 2011-08-19
    Description: The possible depletion of ozone due to heterogeneous reactions occurring in Arctic polar stratospheric clouds (PSCs) is fundamentally different from the Antarctic situation. PSCs in the Arctic are relatively short-lived and occur over limited regions of the Arctic stratosphere. The Arctic situation is examined using a model which calculates photochemical processes as a function of longitude in air circulating with fixed velocity around the pole at fixed pressure level and latitude. The model allows sunlight to vary diurnally and PSCs to occur in specified subregions of the domain. Measurements of chemical species including HCl, ClO, NO2 and HNO3 downwind from a PSC should show obvious changes compared to measurements in air unaffected by clouds. These species concentrations are found to be sensitive to sticking coefficients, cloud characteristics including particle number density and surface area, and to the PSC exposure time.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 131-134
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    Tersail - A numerical model for combined analysis of vegetation canopy bidirectional reflectance and thermal emissions (1988)
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    Publication Date: 2011-08-19
    Description: A modification of the Tergra model (Soer, 1977) is presented, which incorporates the scattering from arbitrarily inclined leaves canopy reflectance model (Verhoef and Bunnik, 1981) for the calculation of albedo and canopy resistance. The combined model, known as Tersail, is capable of simulating the relationship between the bidirectional reflectance and the thermal response of a canopy. The accuracy of the model is tested using data over wheat canopies in Phoenix, Arizona, showing that the model is a good simulator of canopy temperatures under a variety of conditions.
    Keywords: GEOPHYSICS
    Type: Remote Sensing of Environment (ISSN 0034-4257); 26; 287-300
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    Chemistry and transport in a three-dimensional stratospheric model - Chlorine species during a simulated stratospheric warming (1989)
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    Publication Date: 2011-08-19
    Description: The distributions in the stratosphere of a variety of chemical species were calculated for a 6-day period during the February 1979 stratospheric major warming, using winds derived from a spectral forecast model which included O(x), NO(x), HO(x), and ClO(x) chemistries as well as longitudinally varying reaction rate coefficients and photolysis rates for these molecules. The results obtained indicate a particular importance of chemistry and transport for the Cl-containing species ClO, ClONO2, HCl, and HOCl. Dynamical effects dominate the variability of HCl, while diurnal effects dominate that of ClONO2 and ClO. The effects of strong planetary wave activity may be seen in terms of large longitudinal variability of the total HCl and ClONO columns in the stratosphere; in the middle and high northern latitudes, it is sufficiently large to exceed the diurnal variability of the column.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 1057-108
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    A tenfold increase in the abundance of large solid particles in the stratosphere, as measured over the period 1976-1984 (1989)
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    Publication Date: 2011-08-19
    Description: Representative chemical, structural, and morphological analyses of the large (greater than 1 micron diameter) solid particles from three impaction collection surfaces have been performed. These collections sampled the stratosphere at approximately 17-19 km in altitude during 1976, 1981, and 1984. For these sampling periods, the stratospheric solid-particle number densities have been determined to be 0.089, 0.16, and 1.7 particles/cu m of air, respectively, for particles of greater than 1 micron diameter. This rise in solid-particle number density for the stratosphere over the collection period is likely due to the influx of solid rocket exhaust and rocket and satellite debris into the atmosphere in increasingly larger amounts with time. Some of this material is shed from spacecraft during ascent through the atmosphere, but the majority is probably provided during the descent of material from earth's growing belt of debris in low-earth orbit.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 1047-105
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    Inspecting our upper atmosphere (1989)
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    Publication Date: 2011-08-19
    Description: The Upper Atmosphere Research Satellite (UARS) has been proposed for intensive studies of the 15-100 km-altitude region of the earth's atmosphere, begining in 1991. This 14,000-lb satellite will carry a suite of 10 instruments able to study the energy input and loss, photochemistry, and circulation of the upper atmosphere, as well as the extensive web of interactions among these three processes. UARS's remote sensors will give attention to the atmospheric molecular species of the nitrogen, hydrogen, and chlorine families.
    Keywords: GEOPHYSICS
    Type: Aerospace America (ISSN 0740-722X); 27; 24-26
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  • 84
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    An intercomparison of results from ferrous sulphate and photolytic converter techniques for measurements of NO(x) made during the NASA GTE/CITE 1 aircraft program (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two techniques designed for measurements of NO(x (NO + NO2) were intercompared during aircraft flights made in the spring of 1984 in the middle free troposphere over the eastern Pacific Ocean and southwestern U.S. One NO chemiluminescence instrument was equipped with a ferrous sulphate converter, another with a photolytic converter. The ferrous sulphate-equipped instrument was apparently much less specific for NO2. It registered levels about three times larger than the photolytic converter and gave NO2/NO ratios that were much larger than photochemical calculations would indicate as reasonable. Additionally, the results imply that active NO(x) was only 10-20 percent of the total odd nitrogen in the middle free troposphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 15803-15
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  • 85
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    Formation of the Antarctic ozone hole by the ClO dimer mechanism (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New measurements of the low-altitude ClO profile, made during September 1987, are presented along with detailed observations of ozone depletion over McMurdo Station, Antarctica during the same period. The results show that both the rate and altitude range of ozone depletion can be quantitatively accounted for by a mechanism in which the ClO dimer is the important intermediary in the catalytic destruction of ozone. An alternative bromine mechanism appears capable of contributing only 5-15 percent to the ozone loss rate.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 336; 455-458
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  • 86
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    NO and NO2 in the troposphere - Technique and measurements in regions of a folded tropopause (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of NO, NO2, O3, and CO were obtained for tropopause fold events encountered during two flights of the NASA global tropospheric experiment aircraft in 1984. The results suggest that NO(x) may not always be a good tracer of air of recent stratospheric origin. It is suggested that the stratospheric source of NO(x) acts to introduce NO(x) over a short period and through a large vertical region of the troposphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 15813-15
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  • 87
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    Chlorine-hydrocarbon photochemistry in the marine troposphere and lower stratosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The role of chlorine atoms in the oxidation of methane and nonmethane hydrocarbons (NMHCs) in the marine troposphere and lower stratosphere was investigated using a one-dimensional photochemical model that incorporated the chemistry of CH4, NMHCs, NO(x), O(x), and HO(x), as well as organic and inorganic halogens in the troposphere and lower stratosphere. The model predicted that chlorine atoms are present in the marine troposphere at the concentrations of about 1000/cu cm, mostly as a product of the reaction between OH and HCl released from sea spray. The results indicate that Cl atoms cause 20 to 40 percent of NMHC oxidation in the troposphere and 40 to 90 percent in the lower stratosphere. At 15 km, the NMHC-Cl reactions account for nearly 80 percent of the PAN produced. Where available, experimental data confirmed the model predictions.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric Chemistry (ISSN 0167-7764); 7; 261-285
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  • 88
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    The effect of random precipitation times on the scavenging rate for tropospheric nitric acid (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A model for the effective scavenging rate of a soluble species has been developed. The model takes into account the possibility of positive as well as negative correlations between departures from the mean of the scavenging rate and species concentration. The model is demonstrated for the case of late afternoon rainout of nitric acid occurring just prior to the nighttime cessation of its chemical production. The calculations give effective scavenging rates which are about a factor of 2 to 3 greater than those calculated using the models of Rodhe and Grandell (1972) and Giorgi and Chameides (1985).
    Keywords: GEOPHYSICS
    Type: Tellus, Series B - Chemical and Physical Meteorology (ISSN 0280-6509); 40B; 285-296
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  • 89
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    Changes in the earth's rate of rotation between A.D. 1672 and 1806 as deduced from solar eclipse timings (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Solar eclipse timings measured between A.D. 1672 and 1806 are analyzed to study the variation of Delta T (= ET - UT) over this interval. These solar eclipse observations confirm the results of Brouwer (1952), Martin (1969), and Stephenson and Morrison (1969) which were obtained from the analysis of occultations in this period. It is believed that Goldstein's (1985) analysis inadequately represents the changes in Delta T.
    Keywords: GEOPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 200; 1-2,
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  • 90
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    Effect of the orbital debris environment on the high-energy Van Allen proton belt (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The lifetimes of high-energy (greater than 55 MeV) protons in the Van Allen radiation belt are calculated, assuming that in time the protons will collide with and be absorbed by particulate orbiting material. The calculations are based on the NASA/DoD Civil Needs Database for orbital debris (Gaines, 1966) and moderate assumptions of future space traffic. It is found that the lifetimes of high-energy protons below 1500 km will decrease, leading to a noticeable redution in their fluxes.
    Keywords: GEOPHYSICS
    Type: Science (ISSN 0036-8075); 242; 1283-128
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  • 91
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    Mantle-derived fluids in diamond micro-inclusions (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Microinclusions in diamonds from Zaire and Botswana differ in composition from the more common large inclusions of the peridotitic or eclogitic assemblages. These sub-micrometer inclusions resemble potassic magmas in their composition, but are enriched in H2O, CO2(3-), and K2O and depleted in MgO. This composition represents a volatile-rich fluid or melt from the upper mantle, which was trapped in the diamonds as they grew.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 335; 784-789
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  • 92
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    Stratospheric NO2 over Antarctica as measured by the Solar Mesosphere Explorer during austral spring, 1986 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents the results of polar NO2 measurements carried out by the SME satellite during the fall and spring of 1985 and 1986 and compares the results with observations at the north pole and the results of model calculations. During the austral spring, a polar low was observed in stratospheric NO2 densities measured between 24 and 40 km, consistent with the predictions of standard photochemical theory. The geographic extent of the area of low NO2 densities was found to decrease as the hours of sunlight increased, in marked contrast to the behavior of the Antarctic ozone hole during the same period. A comparison of measurements with model calculations for NO2 imply that much of the odd nitrogen is converted to HNO3 during the polar night. Data also suggest no evidence that changes in high-altitude odd nitrogen are influencing the ozone below, or that the 'ozone hole' penetrates above 24 km to affect odd nitrogen there.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 12561-12
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  • 93
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    Measurement of nighttime stratospheric N2O5 from infrared emission spectra (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The mixing ratio profile of N2O5 has been inferred from high-resolution emission spectra obtained with a balloon-borne Fourier spectrometer. The observations were taken for the period from midnight to predawn on September 16, 1986 at 32 deg N latitude. The inferred volume mixing ratio from nighttime average spectra has a peak of about 1.8 x 10 to the -9th in the 32-35 altitude range. The inferred mixing ratio is generally less than the theoretical predictions from a one-dimensional model.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 1177-118
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  • 94
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    The interannual variability of polar stratospheric clouds and related parameters in Antarctica during September and October (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Antarctic polar stratospheric cloud (PSC) sightings by the orbiting SAM II sensor during September and October show a pronounced quasi-biennial oscillation (QBO) signal, and October sightings have increased markedly over the past 10 years in years of westerly QBO phase. The QBO in PSC frequency is likely to affect the rate of Antarctic heterogeneous chemical processes and, hence, ozone depletion. Studies of the observed long-term temperature trend suggest that the decadal PSC trend probably results from the ozone decline, through its effect on stratospheric heating rates. A more detailed analysis of data from 1986 to 1987 shows that there were more PSCs in 1987, and that they persisted much later into the spring season as compared to 1986. Qualitatively similar behavior was found for the OClO column abundances and 18-km ozone depletion observed at McMurdo Station during these 2 years. These observations suggest that both the intensity and duration of heterogeneous chemical processes are likely greater during colder OBQ-westerly phase years.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 1157-116
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  • 95
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    Electron density profile description in the international reference ionosphere (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Problems encountered during efforts to reformulate the IRI description of the electron density profile are examined. Consideration is given to Booker's (1979) proposal that the unique, analytic profile functions should cover the entire ionospheric height range. The IRI topside model is reviewed and the electron density profile of the middle and lower ionosphere are discussed. Rawer's (1983) procedure for combining the topside, middle, and lower ionospheric profiles into one analytic profile is reviewed.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics (ISSN 0021-9169); 51; 781-790
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  • 96
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    Growth of Greenland ice sheet - Interpretation (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An observed 0.23 m/year thickening of the Greenland ice sheet indicates a 25 percent to 45 percent excess ice accumulation over the amount required to balance the outward ice flow. The implied global sea-level depletion is 0.2 to 0.4 mm/year, depending on whether the thickening is only recent (5 to 10 years) or longer term (less than 100 years). If there is a similar imbalance in the northern 60 percent of the ice-sheet area, the depletion is 0.35 to 0.7 mm/year. Increasing ice thickness suggests that the precipitation is higher than the long-term average; higher precipitation may be a characteristic of warmer climates in polar regions.
    Keywords: GEOPHYSICS
    Type: Science (ISSN 0036-8075); 246; 1589-159
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  • 97
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    Concentrations and size distributions of Antarctic stratospheric aerosols (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Particle Measuring Systems laser particle spectrometer (ASAS-X and FSSP) probes were used to measure aerosol particle concentrations and size distributions during 11 ER-2 flights between Punta Arenas (53 deg S) and Antarctica (up to 72 deg S) from August 17 to September 22, 1987. The time resolution was 10 s, corresponding to a spatial resolution of 2 km. The data were divided into two size classes (0.05-0.25 and 0.53-5.5 micron radius) to separate the small particle from the coarse particle populations. Results show that the small-particle concentrations are typical for a background aerosol during volcanic quiescence. This concentration is generally constant along a flight track; in only one instance a depletion of small particles during a polar stratospheric cloud (PSC) encounter was measured, suggesting a nucleation of type I PSC particles on background aerosols. Temporary increases of the coarse particle concentrations indicated the presence of tenuous polar stratospheric clouds that were encountered most frequently at the southernmost portion of a flight track and when the aircraft descended to lower altitudes. During 'particle events', particle modes were found at 0.6-micron radius, corresponding to type I PSCs, and occasionally, at 2.0-micron radius corresponding to type II PSCs.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 16459-16
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  • 98
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    A video atlas of TOMS ozone data, 1978-88 (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Total Ozone Mapping Spectrometer (TOMS), on-board NASA's Nimbus-7 weather satellite, has been observing ozone over the earth once daily for the last 10 yr. A time-lapse atlas of 3440 color-coded images drawn from the TOMS archive from 1978 to 1988 has been visualized on a standard VHS videotape that is now available from NASA. The rapid and complex ozone variations presented demonstrate the difficulty of separating man-induced climate changes from natural variability. This article presents a few images from the atlas and describes interesting features in the animation, such as the correlation between ozone and 'the weather', and the recent deepening of the annual ozone hole over the South Pole. Originally intended as a browsing tool for the TOMS digital database, the videotape is a vivid presentation of the earth's atmospheric dynamics and chemistry that is recommended for scientists, educators, policy makers, and citizens concerned about the global environment.
    Keywords: GEOPHYSICS
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 70; 1564-156
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  • 99
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    The diamagnetic effect during AMPTE's tail releases - Initial results (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A series of four plasma injection experiments were performed by the AMPTE-IRM spacecraft in the nighttime magnetosphere between 12 and 18 earth radii geocentric distance during spring 1985. The most prominent effect of these tail releases is the creation of magnetic cavities. The lifetime of the cavities ranged from a few seconds to some minutes, depending mainly on the ion species and secondly on the ambient field strength. Due to the subsonic and sub-Alfvenic environment, the interaction between the plasma cloud and the ambient plasma flow played only a minor role in these cases (in contrast to the releases in the solar wind), and thus the diamagnetic effect could be studied extensively. The perturbation of the exterior field and fine structures in the current-carrying shell were observed. The thickness of the shell and the current distribution in this layer were deduced from the magnetic recordings each time IRM entered the cavity.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 8; 1, 19
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  • 100
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    Magnetic ULF fluctuations in the compressional zone of AMPTE's artificial comets (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The two Ba releases in the solar wind, termed artificial comets (the first in interplanetary space, the second in the terrestrial magnetosheath), showed a number of common magnetic features. Both times a magnetic cavity was detected and a field pile-up observed with magnitudes several times the ambient field strength upstream of the cavity. The magnetic fluctuations in the compressed region are generally enhanced by a factor comparable to the amount of field pile-up. There is a peak in the spectra of both events around 0.1 Hz in the component which is perpendicular to the solar-wind velocity vector and almost field-aligned. This magnetosonic wave has been interpreted as the fundamental mode of resonance oscillations of the compression zone. For frequencies beyond 2 Hz the spectra decrease more steeply in the case of the second 'comet' than in the first. This is due to the interaction of the supersonic solar wind with the first comet. The spectra obtained during the first comet at the solar-wind/ion-cloud interface are identical to those observed during bow-shock crossings.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 8; 1, 19; 23-26
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