摘要:

We have used the Kubelka‐Munk theory of diffuse reflectance to learn about the manifestations of light scattering in reflectance spectra in geologically significant situations. For wavelength‐independent scattering (dimensions of the scattering centers greater than the wavelength of the incident radiation), the band depths and shapes are related to the scattering power of the medium. For wavelength‐dependent scattering (dimensions of the scattering centers comparable to or less than the wavelength of the incident radiation), additionally found were longward shifts in band minima and a general declining trend in reflectance with increasing wavelength. This effect may be responsible for the negative slope in the near‐IR reflectance spectra of the dark regions of Mars. For both kinds of scattering, nodes are observed in sets of normalized reflectance spectra when certain conditions are sa

ISSN:0094-8276    

DOI:10.1029/GL009i002p00113

年代:1982

数据来源: WILEY

摘要:

Results from the recent "CO2Dynamics" cruise in the northeast North Pacific Ocean (June‐July, 1981) are presented. The shipboard CO2data indicate that the excess CO2has penetrated to the deepest depth (1000 ± 300 m( near the Subtropical Front but to a shallower depth outside of the Frontal Zone. In general, the depth of penetration is several hundred meters shallower than in the northwest Pacif

ISSN:0094-8276    

DOI:10.1029/GL009i002p00117

年代:1982

数据来源: WILEY

摘要:

The method described permits any set of numbers within an allowable range to be rounded to any number of significant figures. This is accomplished by generation of an array (rounding position) data bank, which is unique for each combination of the following variables: (1) Chosen decimal position; (2) number range of the number to be rounded; and (3) number of significant figures to which this number is to be rounded. It is especially useful as a subroutine in programs that generate large quantities of figures (such as reserve or resource tonnages) that require rounding.

ISSN:0094-8276    

DOI:10.1029/GL009i002p00120

年代:1982

数据来源: WILEY

摘要:

Geochemical considerations on the overall abundances for major chemical elements of the earth and CI chondrites indicate that the lower mantle is probably more enriched in silica than the upper mantle. It is concluded that about 95% of the lower mantle is composed of material having the perovskite modification and that the "650‐km" seismic discontinuity represents a chemical boundary at which the lower mantle is about 30 to 40% richer in silicon than the upper mantle. These results support those reached earlier on the basis of geophysical constraints. Thus, about half of the earth, either by weight or volume, is composed of ferromagnesium silicate with the perovskite structur

ISSN:0094-8276    

DOI:10.1029/GL009i002p00124

年代:1982

数据来源: WILEY

摘要:

New Hugoniot data on polycrystalline (avg.porosity 6.9%) samples of the magnesiowustite Mg0.6Fe0.4O are presented, covering the pressure range up to 200 GPa. When our data are fit by a single 3rd order Eulerian Hugoniot with KOconstrained to its ultrasonic value of 161.5 GPa, the required isentropic pressure derivative KO′ is 4.37 +/− 0.37. This value is significantly lower than the ultrasonic one of 6.18; existing isothermal compression data, however, are in agreement with our value rather than the ultrasonic one. Our data are adequately explained without phase transitions. There is some marginal evidence for a possible phase transition around 120 GPa. If such a transition indeed occurs it is probably of small volume change compared to the transition observed in FeO; we place an extreme upper bound of 3% on the density change such a transformation could involve and still be consistent with the data. Contrary to earlier hypotheses, we believe that a phase transition in magnesiowustite is not a likely explanation of the seismic effects in the D″ region of the lower mantle. The wustite transition may be a more complex phenomenon than initially supposed— perhaps an effect of nonstoichiometry localized to the iron‐rich end of the solid soluti

ISSN:0094-8276    

DOI:10.1029/GL009i002p00127

年代:1982

数据来源: WILEY

摘要:

Measurements of the H2O emission line at 22.2 GHz show that the concentration in the mesosphere of water vapor molecules can be highly variable, ranging from nearly constant mixing ratios of 2‐4 ppmv, up to a layer near 65 km altitude with peak values around 12 ppmv. Results above 70 km altitude have been used to deduce a value for the vertical eddy diffusion coefficient of (4.4 ± 0.7)×105cm²s

ISSN:0094-8276    

DOI:10.1029/GL009i002p00131

年代:1982

数据来源: WILEY

摘要:

Simultaneous spectral observations in the atmosphere have been obtained for HNO3, HCl and HF in April‐May 1980, by the solar occultation technique, from an aircraft, between 64° North and 62° South. For these three species, the vertical column density above 11.5 km increases from low latitude in both hemisphe

ISSN:0094-8276    

DOI:10.1029/GL009i002p00135

年代:1982

数据来源: WILEY

摘要:

We examine the mean meridional flow in the summer upper mesosphere using data from the Poker Flat MST radar and all other available stations. The observed mean flow is equatorward at about 10‐15 ms−1near 60°N, about an order of magnitude larger than expected from numerical model results. The Rayleigh friction coefficient required to balance the coriolis torque associated with this flow is about 4 days−1, about ten times larger than values currently used in numerical

ISSN:0094-8276    

DOI:10.1029/GL009i002p00139

年代:1982

数据来源: WILEY

摘要:

We have used a high‐latitude ionospheric model to predict the diurnal variations of electron density that should be observed by the EISCAT, Chatanika and Millstone Hill incoherent scatter facilities. Our calculations were for a strong convection model without substorms. Our results provide an indication of the quantitative differences in measured electron density that are expected when the three radars probe the high‐latitude ionosphere simultaneously. The differences are significant and vary with altitude, latitude, local time, and season, and are associated with the UT dependence of the high‐latitude ionosphere which results from the displacement between the geomagnetic and geographic

ISSN:0094-8276    

DOI:10.1029/GL009i002p00143

年代:1982

数据来源: WILEY

摘要:

The diurnal and seasonal behavior of the depletions in the ionospheric electron content, associated with amplitude scintillations measured at Arequipa, Peru for about one year around the recent solar maximum period, are presented. The seasonal variation shows asymmetrical equinoctial maxima, the February‐April period having markedly higher occurrences. Amplitude scintillation measurements at 1.54 GHz and 257 MHz at the nearby magnetic equatorial station Huancayo, Peru also show a similar pattern. A comparison of the three sets of data indicates the simultaneous development of irregularities of different scale sizes and earlier erosion of the smaller scale irregularitie

ISSN:0094-8276    

DOI:10.1029/GL009i002p00147

年代:1982

数据来源: WILEY