Further observations of 8-μm polar brightenings of Jupiter

North to south scans of Jupiter at 7.8-μm wavelength in early 1981 confirm polar brightening events that correlate with LCM_III, such that a polar limb is bright when the corresponding magnetic pole is tilted eartward. The correlation with magnetic features of the planet suggests that the energy source for the brightenings is magnetospheric particles incident upon the polar regions of the atmosphere. The northern polar events are more prominent and more regular than the southern ones. The polar emission may be indirectly related to the ultraviolet absorber observed near the poles by Voyager 2.     

Poroelastic Modeling of a Heterogeneous Geologic Medium: A Case Study from Kanto Basin in Japan

Vertical geological heterogeneity, such as clay content and grain size variation, may affect land subsidence caused by groundwater extraction. In order to test this hypothesis, one-dimensional pore-water mass balance and force balance equations of a water-saturated poroelastic medium were solved under different heterogeneous geological conditions. Results showed that clay content and grain size variation in sandstone could affect subsidence rates by up to an order of magnitude due to the changes in stiffness and permeability of the medium, indicating the importance of small-scale heterogeneity in subsidence simulation studies. Predicted values of subsidence were in good agreement with field measurements for two sites in the Kanto groundwater basin in Japan, showing the applicability of the model to other groundwater basins with clay-rich aquifers.     

The rotation period of Neptune's upper atmosphere

Significant variations in the near-infrared brightness of Neptune during July and August 1980 were observed. These observations show a well-defined, large-amplitude variation in Neptune's J-K color, with a period of 17.73 ± 0.1 hr and are interpreted as diurnal variations resulting from the 17.73-hr rotation period of the upper atmosphere of Neptune in the presence of inhomogeneous weather. These results qualitatively corroborate those of D. P. Cruikshank (1978, Astrophys. J.220, L57-L59) in an earlier study using similar techniques. In addition, variations were observed in the 5-μm spectral region which are in phase with the variations seen at shorter wavelengths. A new 5-μm measurement of Uranus is also reported.     

The phosphine abundance on Saturn derived from new 10-micrometer spectra

Spectra of Saturn in the spectral region 10.0–10.7 μm are presented which confirm the presence of PH₃. Comparison to synthetic spectra indicates a PH₃ mixing ratio of at least 2 × 10^?6. No spectral features due to NH₃ or C₂H₄ were observed.     

The dust coma of Comet P/Giacobini-Zinner in the infrared

We present 1-20 micrometers photometry of P/Giacobini-Zinner obtained at the NASA Infrared Telescope Facility, during 1985 June-September (r = 1.57-1.03 AU). A broad, weak 10 micrometers silicate emission feature was detected on August 26.6; a similar weak emission feature could have been hidden in the broadband photometry on other dates. The total scattering and emitting cross section of dust in the inner coma was similar to that in other short-period comets, but a factor of 10 (r = 1.56 AU) to 100 (r = 1.03 AU) lower than the amount of dust in Comet Halley. The thermal emission continuum can be fit with models weighted toward either small or large absorbing grains. The dust production rate near perihelion was approximately 10(5) g/s (small-grain model) to approximately 10(6) g/s (large-grain model). The corresponding dust/gas mass ratio on August 26 was approximately 0.1-1. A silicate-rich heterogeneous grain model with an excess of large particles is compatible with the observed spectrum of Giacobini-Zinner on August 26. Thus, weak or absent silicate emission does not necessarily imply an absence of silicates in the dust, although the abundance of silicate particles < or = 1 micrometer radius must have been lower than in Comet Halley.     

Characterization of bottom sediments from Osaka Bay,Japan

The physical, chemical, and dewatering characteristics of 19 bottom sediments from Osaka Bay, Japan, have been analyzed to aid in the development of sediments in the coastal bay area. The sediments in the east near Osaka Port were highly polluted from the influence of human activities and were difficult to dewater. These sediments were composed of fine particles, low in pH, zetapotential, and initial settling rate, and were high in ignition loss, metal concentrations, compression volume, specific resistance, cake water content, and drying index. However, the sediments near Akashi Channel showed the reverse where they are affected by strong tidal current. A correlation analysis has been made of all the parameters. There are significant relationships between all the dewatering parameters. Therefore, sediments difficult to dewater by gravity settling are also difficult to dewater by vacuum filtration and solar evaporation. Sediments containing fine particles and pollutants are difficult to dewater. Several forms of pollutants can occur in the sediments.     

Spatially resolved infrared observations of Saturn: I. Equatorial limb scans at 20 μm

Drift scans of the equator of Saturn have been obtained through narrow band filters at 17.8, 19.7, and 22.7 μm. Spatial resolution was ?17% of the equatorial diameter. These observations clearly differentiate otherwise tenable atmospheric models. A published model by A. Tokunaga and R.D. Cess [Icarus32, 321–327 (1977)] is shown to represent these new observations significantly better than other models from the literature.     

Spatially resolved infrared observations of Saturn II. The temperature enhancement at the South pole of Saturn

North-South scans of Saturn at 17.8, 19.7, and 22.7 μm show enhanced emission from the South polar region. This effect is consistent with the polar brightening observed in the 12 μm ethane band (Gillett and Orton, 1975; Rieke, 1975), and it indicates that the temperature inversion is hotter at the South pole than at the equator. A model for the temperature inversion of the South pole is constructed and compared to the observations.     

Comparison of stable isotopes,ratios of Cl/Cl and I/I in brine and deep groundwater from the Pacific coastal region and the eastern margin of the Japan Sea

Fifty-three samples, including brines associated with oil and natural gas reservoirs and groundwater samples from deep boreholes, were collected from the Pacific and Japan Sea coastal regions in Japan. The ¹²⁹I/¹²⁷I and ³⁶Cl/Cl ratios, and stable isotopes (δD and δ¹⁸O) are compared to investigate differences related to the geotectonic settings of the two regions. The δD and δ¹⁸O data indicate that brine and groundwater from the Pacific coastal region reflect mixing of meteoric water with connate seawater in the pores of sedimentary rocks. On the other hand, brine and groundwater from the Japan Sea coastal region have been hydrothermally altered. In particular, brines associated with petroleum accumulations at Niigata and Akita showed the same isotopic characteristics as fluids found in the Kuroko deposits of the Green Tuff region in northeastern Japan. There is little difference in the ³⁶Cl/Cl ratios in brine and groundwater from the Pacific and Japan Sea coasts. Most brine and some deep groundwater, except those from the Pleistocene Kazusa Group, have already reached the average secular equilibrium ratio of 9.9 ± 2.7 × 10⁻¹⁵ for their mudstone and sandstone reservoirs. There was no correlation between the ³⁶Cl/Cl ratios and differences in geotectonic setting between the Pacific and the Japan Sea coast. The molar I/Br ratio suggests that the I in all of water samples was of biogenic origin. The average ¹²⁹I/¹²⁷I ratio was 290 ± 130 × 10⁻¹⁵ to 294 ± 105 × 10⁻¹⁵ in both regions, showing no relationship to the different geotectonic settings. The uncontaminated brine and groundwater samples are likely to have retained the original ¹²⁹I/¹²⁷I ratios of marine I released from the old organic matter stored in sedimentary rock.