Identification of the interstellar cyanomethyl radical (CH2CN) in the molecular clouds TMC-1 and Sagittarius B2

We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds. The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2. This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1. In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident. Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H.     

In situ strength measurements on natural upper-mantle minerals

Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with the residual pressure of fluid inclusions in mantle xenoliths.     

Vertical residual flow in Kasado Bay

Some observations were carried out to understand the structure of the vertical residual flow in Kasado Bay. The results of current measurements at three points in the lower layer indicated that a horizontal counterclockwise tidal residual circulation converges in the lower layer. The velocity of upward residual flow was estimated to be about 4.5×10^–3 cm s^–1. The distributions of water temperature, salinity and grain size in the sediment support the existence of this upward motion.     

Episodic outflow of suspended sediments from the Kii Channel to the Pacific Ocean in winter

Episodic outflow of suspended sediments from the Kii Channel to the Pacific Ocean in winter was observed by the sediment traps experiment above the shelf slope. When the current speed was weak and its direction was south or southwestward above the shelf slope the sinking sediment flux was nearly zero but the sinking sediment flux increased to 22g m^–2 day^–1 after the current speed was strong, its direction changed to south-west or westward and water temperature fell. Such intermitten sinking sediment flux above the shelf slope is considered to be related to the intermittent intrusion of the turbid and cold shelf water into the sub-surface layer of the transparent and warm slope water. Such episodic events may play a very important role in the material transport from the coastal sea to the open ocean.     

Seasonal variation in the transport of suspended matter in the East China Sea

Seasonal variation in the transport of suspended matter across the East China Sea is investigated with the use of results of field observations and diagnostic numerical experiments. Suspended matter is transported from the shelf edge to the inner shelf in summer and from the inner shelf to the shelf edge in autumn and winter due to the vertical circulation mainly induced by the monsoon wind. The maximum transport of suspended matter from the inner shelf to the shelf edge occurs in autumn.     

Coastal upwelling and downwelling events in the Seto Inland Sea

Prominent coastal upwelling and downwelling events due to Ekman transport were observed during the period from 14 to 18 August 1983 along the Misaki Peninsula in the Seto Inland Sea, Japan. The coastline of the Misaki Peninsula is aligned approximately in an ENE-WSW direction. When an ENE wind continued blowing for about two days, the warm water in the upper layer was pushed offshore and cold water in the lower layer upwelled along the peninsula. The estimated upwelling speed 3 m below the sea surface was 0.032 cm sec^–1. On the other hand, when a WSW wind continued blowing for about two days the warm water in the upper layer sank into the lower layer along the peninsula. The estimated downwelling speed 3 m below the sea surface was 0.080 cm sec^–1. The time lag between the variations of the alongshore wind and offshore current was about 0.5 days.     

Convection induced by cooling at one side wall in two-dimensional non-rotating fluid —applicability to the deep Pacific circulation—

In recognition that similarity in the density balance leads to resemblance in circulation between the two-dimensional non-rotating and three-dimensional rotating systems which have similar density stratification, we investigate convection induced by cooling at one side wall and heating at the sea surface by using a two-dimensional non-rotating model as idealized representation for the deep Pacific circulation. In the model, various vertical profiles are taken for the side wall cooling, which are assumed to correspond to the density structure of the Anatarctic Circumpolar Current. In a small diffusivity range, two important features are found to be robust against change in the vertical profile of the side wall cooling. One is that the density stratification is horizontally almost uniform. The other is that the balance in the density equation between the vertical advection and the vertical diffusion holds in the interior. Consequently, the vertical density balance, together with the equation of continuity, determines the circulation pattern for the prescribed vertical profile of the side wall cooling. The multi-layered meridional flow, which is expected to exist in the deep Pacific, is shown to form for certain vertical profiles of the side wall cooling.     

Convergence,divergence and vertical velocity at a tidal front in Hiuchi-Nada,Japan

The detailed flow structure around a tical front in Hiuchi-Nada, Japan was observed with the use of ADCP (Acoustic Doppler Current Profiler). The surface convergence region is observed at the transition zone between vertically well mixed area and the stratified area. The surface divergence regions exist next to the surface convergence region. The strong downward current is estimated in the middle layer just below the surface convergence region. The maximum surface convergence and the maximum downward velocity in the middle layer are 1.0×10^–4 s^–1 and 0.12 cm s^–1, respectively.     

Seasonal variation of water temperature in the Seto Inland Sea

The seasonal variation of water temperature in the Seto Inland Sea, Japan is examined using data analysis and numerical experiments and is shown to be controlled by heat exchange through the sea surface and horizontal heat dispersion from the Pacific Ocean. The average water temperature goes down from the Pacific Ocean to the center of the Seto Inland Sea indicating that 4.0 to 6.0×10¹⁵ cal day^?1 (1.6 to 2.5×10¹⁶ joule day^?1) of heat is transported from the Pacific Ocean to the Seto Inland Sea and is lost through the sea surface. The amplitude of seasonal variation of water temperature is large at the center of the Seto Inland Sea and the maximum water temperature is reached first at Bisan Straits and last at Iyo-Nada.     

Seasonal variation of circulations in the East China Sea and the Yellow Sea

Seasonal variation of the water circulations in the East China Sea and the Yellow Sea is investigated with use of a robust diagnostic numerical model. Water circulations in four season are calculated diagnostically from the observed water temperature and salinity data from JODC (Japan Oceanographic Data Center) and wind data from COADS (Comprehensive Ocean-Atmosphere Data Set). Counter-clockwise circulations are developed at the upper and middle layers and a clockwise one at the lower layer in the central part of he Yellow Sea in summer. On the other hand, a clockwise circualtion is developed from the surface to the bottom in the Yellow Sea and a counter-clockwise one in, the northern part of the East China Sea in winter.