摘要:

Densities of a fertile peridotite (PHN 1611) and a depleted sterile peridotite (PHN 1569) have been calculated to be 3.39 and 3.30, respectively. These densities were calculated from the cell dimensions of the component minerals, the mineral analyses, and the bulk rock analyses. Studies of kimberlite nodules suggest that lighter, sterile peridotites overlie heavier, more fertile peridotites uniformly in the upper mantle beneath southern Africa. A temperature difference of 500°C reduces the density of fertile peridotite PHN 1569 to approximately 3.33, which is insufficient to cause it to float in sterile peridotite. However, if fertile peridotite PHN 1569 undergoes 25% partial melting and the garnet is dissolved, its zero pressure density would be reduced to approximately 3.2, which is less than that of depleted, sterile mantle

ISSN:0094-8276    

DOI:10.1029/GL003i009p00509

年代:1976

数据来源: WILEY

摘要:

The cross‐sectional form and stability of large hydraulic fractures are found to be very sensitive to symmetric gradients in fluid pressure and regional stress. Horizontal sections through vertical fractures may be subjected to symmetric pressure gradients by locating inflow and outflow wells near the fracture center and tips. A dumbbell form, resulting from flow from the tips toward the center, has a limital length beyond which the fracture closes at the center and propagates unstably at the tips. A diamond form, resulting from the opposite sense of flow, has no limital length and a stable propagation. These features of fracture form and stability may play an important role in the design of hydraulic fractures for geothermal energy productio

ISSN:0094-8276    

DOI:10.1029/GL003i009p00513

年代:1976

数据来源: WILEY

摘要:

The development of a new analytical technique to detect SO2in the ppb‐range permits the measurement of SO2in the upper troposphere and the lower stratosphere. First results of aircraft‐ascents are presented showing SO2‐concentrations of 145 ng SO2/m³ STP for 13 km al

ISSN:0094-8276    

DOI:10.1029/GL003i009p00517

年代:1976

数据来源: WILEY

摘要:

An instantaneous rate model of Oxand HOxchemistry has been used to determine the role of vibrationally excited hydroxyl radicals, HO (v ≤ 9), in the stratosphere. Due to very rapid quenching the steady state populations of vibrationally excited hydroxyl radicals are very low, (O ≤ [HO(v)] ≤ 104molecules/cm³), and the extent of reaction due to vibrational excitation is l

ISSN:0094-8276    

DOI:10.1029/GL003i009p00521

年代:1976

数据来源: WILEY

摘要:

Neutral wind velocities in the lower atmosphere can be measured with powerful radars operating at a wide range of frequencies. We report the first such Doppler measurement in the auroral zone, using the Chatanika Radar Facility near Fairbanks, Alaska. A sample result from near the tropopause is in good agreement with nearly concurrent Fairbanks radiosonde data.

ISSN:0094-8276    

DOI:10.1029/GL003i009p00525

年代:1976

数据来源: WILEY

摘要:

Radiometrically inferred areal observations of the atmospheric water vapor burden have been made in the 270 to 520 cm−1spectral band over western U. S. and the extreme eastern Pacific from the NASA C‐141 Kuiper Airborne Observatory. Before this very few observations from the upper troposphere and lower stratosphere over such a broad area have been made. 30600 individual observations from eight separate synoptic situations involving eight jet maxima were computer‐averaged over 2° latitude × 2° longitude boxes and related to the polar continental jet. Mean water vapor burdens ranged from 4.6×10−4g cm−2to 14.3×10−4g cm−2at 13.4 km with a striking peak just north of the jet wind maximum over a region of strong upwa

ISSN:0094-8276    

DOI:10.1029/GL003i009p00529

年代:1976

数据来源: WILEY

摘要:

A time series of aerosol concentration profiles for the lower stratosphere was obtained at 34° S. (Mildura, Australia) during the 12 months after the eruption of Fuego volcano in Guatemala in October 1974. A persistent thin aerosol‐rich layer was found at or near 17 km; it existed from late 1974 and was replenished in the southern winter of 1975. The available evidence indicates that the initial layer was probably not due to the Fuego erupti

ISSN:0094-8276    

DOI:10.1029/GL003i009p00533

年代:1976

数据来源: WILEY

摘要:

Simultaneous measurements of the O+(²D ‐ ²P) emission at 7319‐30Å and the atomic oxygen density in the optically thin region of the atmosphere offer a straightforward means of determining the photoionization frequency, I∞, for the production of O+(²P) ions. The ionization frequency is found to be 4.7 × 10−8sec−1±30% on June 8, 1974 and 3.4 × 10−8sec−1±30% on December 17, 1975. The wavelength dependent solar flux intensity in the relevant spectral region was also measured June 8, 1974 on the same spacecraft (Atmosphere Explorer‐C). A calculation of I∞using this solar flux and currently accepted values of the photoionization excitation cross sections gives a value of 4.9 × 10−8sec−1, thus confirmi

ISSN:0094-8276    

DOI:10.1029/GL003i009p00537

年代:1976

数据来源: WILEY

摘要:

One of the dominant electron cooling processes in the ionosphere is caused by electron impact induced fine structure transitions among the ground state levels of atomic oxygen. This fine structure cooling rate is based on theoretical cross sections. Recent advances in the numerical cross section determinations to include polarization effects and more accurate representations of the atomic target result in new lower values. These cross sections are employed in this paper to derive a new fine structure cooling rate which is between 40% and 60% of the currently used rate. A new generalized formula is presented for the cooling rate (from which the fine structure cooling rate is derived), valid for arbitrary mass and temperature difference of the colliding particles and arbitrary inelastic energy difference.

ISSN:0094-8276    

DOI:10.1029/GL003i009p00541

年代:1976

数据来源: WILEY

摘要:

The equations governing the equatorial electrojet are solved with the inclusion of winds due to gravity waves and observed winds in the day‐time. It is shown that the gravity wave winds modulate the electrojet significantly in the region 110‐150 km even at the dip‐equator. The results show that the stronger the wind shear, the more will be its effect on the electrojet. The local contribution of observed winds to the electrojet as reported byRees et al(1975) seems to be an over‐e

ISSN:0094-8276    

DOI:10.1029/GL003i009p00545

年代:1976

数据来源: WILEY