摘要:

Autoradiographs of the total alpha activity distribution in slices through manganese nodules can be used to determine growth rates and to investigate the mode of incorporation of alpha emitters into nodules. Total alpha vs. depth profiles, measured with high resolution by counting alpha tracks in cellulose nitrate detectors, are almost always exponential and apparently record nodule growth. Accumulation rates determined by230Thexmeasurements are in approximate agreement with the alpha track measurements. Sediment accumulation rates may also be measured by this technique.

ISSN:0094-8276    

DOI:10.1029/GL004i009p00351

年代:1977

数据来源: WILEY

摘要:

The Geophysical Monitoring for Climatic Change program of NOAA's Environmental Research Laboratories has measured atmospheric carbon dioxide concentrations at Mauna Loa Observatory, Hawaii, continuously since June 1974. The measurements through 1976 have been analyzed for recent secular concentration changes and show a continuing increase of about 0.9 ppm/year.

ISSN:0094-8276    

DOI:10.1029/GL004i009p00354

年代:1977

数据来源: WILEY

摘要:

The210Pb concentration has been measured in 92 adjacent firn samples collected at the South Pole along a 18 m depth profile. The decay analysis shows that significant changes happened around 1920 and 1954 either in the accumulation rate or in the210Pb content of the new fallen snow.

ISSN:0094-8276    

DOI:10.1029/GL004i009p00357

年代:1977

数据来源: WILEY

摘要:

The spectral analysis of microscale horizontal radar reflectivity fluctuations, created near the top of stratiform clouds by turbulent convection, shows that the fluctuations are not totally random; the spectrum exhibits meaningful spectral peaks, reflecting a dynamic organization of the cloud in several frequency domains. This analytic technic may yield the spectral signature of clouds.

ISSN:0094-8276    

DOI:10.1029/GL004i009p00360

年代:1977

数据来源: WILEY

摘要:

7Be produced by the interaction of cosmic rays with oxygen and nitrogen, predominantly in the stratosphere, has been used to identify and measure stratospheric ozone at the ground level. Simultaneous measurements at Whiteface Mountain, New York, in July 1975 show that the maximum7Be concentrations are accompanied by increased ozone concentrations. Peaks in7Be concentrations occurred on July 5‐6, 11‐12, 16‐17, 23, and 27. Ozone peaks were observed on July 7‐9, 11, 18, 24, and 27. Isentropic trajectory calculations also showed that the trajectories reaching Whiteface Mountain on July 11‐12, 15‐16, 23, and 27 had stratospheric origin. One‐day delay in ozone peaks on July 7‐9, 18, and 24 is attributed to increased tropospheric ozone production. The observed relationship between7Be and ozone is used to deduce an upper limit of 37 ppb stratospheric ozone at Whiteface Mountain during July 1975. Thus, even during midsummer months, when stratospheric‐tropospheric mass exchange is not at a maximum, stratospheric ozone may contribute substantially to the national ambient air quality s

ISSN:0094-8276    

DOI:10.1029/GL004i009p00363

年代:1977

数据来源: WILEY

摘要:

Infrared emission spectra of the long‐wavelength wing of the 6.3 µm water band between 6.7 and 7.6 µm have been measured in the mesosphere using a cryogenic rocketborne spectrometer. The resulting zenith radiance profile has been compared with a high altitude radiance model resulting in a volume mixing ratio of 3.5 ± 2.2 ppm between 49 and 7

ISSN:0094-8276    

DOI:10.1029/GL004i009p00366

年代:1977

数据来源: WILEY

摘要:

On January 19, 1972, in situ measurements by instruments on Explorer 45, orbiting in the magnetosphere near the equatorial plane, and ISIS 2, in a circular polar orbit at 1400 km, simultaneously detected patches of enhanced ionization outside the main body of the plasmasphere. The magnetospheric plasma region extended between L values 3.4‐4.8 and the ionospheric electron density enhancement extended between L values 3.6‐4.4. The two plasma features were detected near 22 hours MLT. From the observations, including some made before and after the simultaneous measurements, we infer that the plasma density enhancement persisted for more than 5 hours and extended over at least 2 hours in magnetic local time near L=5. Our results provide experimental evidence that some detached magnetospheric plasma regions are signatures of a flux tube containing enhanced ionization throughout a volume extending from the topside ionosphere out to the equa

ISSN:0094-8276    

DOI:10.1029/GL004i009p00369

年代:1977

数据来源: WILEY

摘要:

Simultaneous high resolution observations of a distinctive feature in the energy spectrum of conjugate photoelectrons and spacecraft potential relative to the local ionosphere have allowed the net potential difference between magnetic conjugate points at latitudes below the region of low energy (E 〈 100 eV) auroral electron precipitation to be determined. Measurements made at 300 km, from Atmosphere Explorer C show that there is normally no net potential difference between hemispheres in this region which extended up to invariant latitudes as high as 74°. Two types of apparently related anomalous behavior were infrequently observed at high latitudes. During these periods the incident flux of conjugate photoelectrons was either decelerated by about 3 eV or was not detect

ISSN:0094-8276    

DOI:10.1029/GL004i009p00373

年代:1977

数据来源: WILEY

摘要:

The amplitude of Pc 3,4 magnetic pulsations at Calgary is shown to increase as the solar wind velocity increases. The pulsation amplitude dependence on solar wind velocity can be understood in terms of the Kelvin‐Helmholtz instability at the magnetopause boundar

ISSN:0094-8276    

DOI:10.1029/GL004i009p00377

年代:1977

数据来源: WILEY

摘要:

The negative Bouguer anomalies (i.e., mass deficiencies) associated with four young lunar craters are analyzed. Model calculations based on generalizations made from studies of terrestrial impact structures suggest that the major contribution to the Bouguer anomaly for these lunar craters is due to a lens of brecciated material confined within the present crater rim crest and extending vertically to at least a depth of one‐third the crater rim diameter. Calculations also reveal a systematic variation in the magnitude of the mass deficiencies with the cube of the crater diamete

ISSN:0094-8276    

DOI:10.1029/GL004i009p00380

年代:1977

数据来源: WILEY