The turbulent structure of the internal boundary layer near the shore

The mean structure within the internal boundary layer (IBL) near the shore, which develop from the coast in the presence of a sea breeze, has been described in Part I of this study (Ogawa and Ohara, 1984). This paper presents the results of the similarity and energy budget analysis for the purpose of parameterization of the turbulent structure within the IBL. The analysis of the turbulent kinetic energy balance, turbulent intensities and spectra show that the wind is strongly affected by mechanical turbulence in comparison with the past results in a fully developed convective layer where thermal convection dominated. The standard deviations of the wind velocities normalized by the friction velocity u _* (surface-layer scaling parameter) are functions only of the normalized height z/Z _i within 160 m of the shoreline, where Z _i is the IBL. On the other hand, the standard deviations of temperature normalized by _* (mixing-layer scaling parameter) have less scatter with distance than those normalized by T _* (surface-layer scaling parameter). The data showed that both u _* (not a mixed-layer parameter), and Z _i (not a surface-layer parameter) are necessary to describe the turbulent characteristics of the IBL near the shore.Deceased March, 1984.     

The turbulent structure of the internal boundary layer near the shore

A field experiment to measure the turbulent structure of the internal boundary layer near the shore was conducted using three instrumented meteorological poles, a kytoon, and a crane-mounted ultrasonic anemometer-thermometer, as well as three reference ultrasonic anemometer-thermometers positioned near the poles. Part 1 of this study gives the explicit details and general characteristics for one run of the experiment. Part 2 (Ohara and Ogawa, 1984) will present a similarity and energy budget analysis. The mean velocity profiles showed that there was wind speed acceleration due to the sea-land temperature difference. In addition, the velocity profiles consisted of three distinct regions; the region near the ground had the largest gradient followed by a transition zone which had a small velocity gradient, while above, the profile resembled the oncoming sea breeze. In general, the turbulence was greatest near the shore, gradually decreasing inland. The lowest region had large turbulence intensities and the transition region had some intermittent turbulence characteristics between the lower strong unstable layer and the relatively turbulent-free region above.Deceased March 1984.Present address: The Institute of Behavioral Sciences, Yoyagi, Tokyo 151, Japan.     

Excitation processes of infrared atmospheric emissions

Excitation rates of the infrared emissions which are likely to occur in the mesosphere and thermosphere are quantitatively evaluated. They include the 9.6 μm band of O₃, the 15 and 4.3 μm bands of CO₂ and the 5.3 and 2.8 μm bands of NO. These emissions may be excited through nonthermal processes such as chemiluminescent reactions and resonant fluorescence in the thermosphere, whereas they are of thermal origin in the stratosphere and mesosphere. Increase of the non-thermal excitation rate caused by precipitating electrons could be responsible for the enhancement of the 4.3 μm band of CO₂, and the 5.3 and 2.8 μm bands of NO observed in the auroral thermosphere.     

Frequency dependent power fluctuations: a feature of the ESR system or physical?

The k-dependence of the Reviced power in high signal-to-noise ratio (SNR) conditions, occurring for naturally enhanced ion-acoustic lines (NEIALs) and for real satellites, is investigated by using the EISCAT Svalbard Radar (ESR), where the data are recorded in eight separate channels using different frequencies. For the real satellites we find large variations of the relative powers from event to event, which is probably due to a different number of pulses catching the satellite over the integration period. However, the large power difference remains unexpected in one case. Over short time scale (10 s) the relative power difference seems to be highly stable. For most NEIAL events the differences between channels are within noise level. In a few cases variations of the relative power well above both the estimated and expected 1-sigma level occur over a signal preintegrated profile. We thus suggest that the frequency dependence of the power in NEIAL events has its origin in the scattering medium itself as the most plausible explanation.     

Factors Controlling the Fractionation and Seasonal Mobility Variations of Ga and In in Systems Impacted by Acidic Thermal Waters: Effects of Thermodynamics and Bacterial Activity

This work assessed both the fractionation and the seasonal mobility variations of Ga and In in systems impacted by acidic thermal waters. This was accomplished by performing thermodynamic calculations using the PHREEQC algorithm and by assessing the activity of acidophilic iron-oxidizing bacteria. The pH of the Kusatsu thermal waters in Gunma Prefecture, central Japan, is rapidly increased following the addition of a lime suspension. After an abrupt pH increase, under which conditions free ions of Ga and In and their complexes with Cl^? and SO₄^2? exist only in negligible quantities, the majority of dissolved Ga and In is removed by sorption onto suspended hydrous ferric oxides (HFOs). These HFOs are then transported to an artificial lake without significant sedimentation along the river. Subsequently, the suspended HFOs settle out and are added to sediments without significant fractionation between Ga and In. The Tamagawa thermal waters in Akita Prefecture, northeast Japan, are also treated with lime. However, complete neutralization requires mixing with some tributary streams, leading to a gradual downstream increase in pH. Dissolved Ga is, in general, sorbed by HFOs in upstream areas, leading to wide dispersal of Ga across the entire watershed. In comparison, In is transported to the lake inlet predominantly as a Cl^? complex species without significant removal along the river, with the majority being precipitated in an artificial lake, where Cl^? concentrations are too low to form stable complex species with In, and thus, dissolved In is sorbed by HFOs. As a result, In is effectively concentrated within downstream lakebed sediments, whereas Ga is dispersed along the river. Seasonal variations in Ga mobility within the Tamagawa field between snowmelt and low-flow seasons are primarily controlled by pH, because hydrolysis reactions of these metals, which are related to sorption reactions, tend to occur in the upstream regions in the snowmelt season. However, under warmer conditions, HFO formation preferably occurs due to the activity of acidophilic iron-oxidizing bacteria. Thus, under similar pH variations, dissolved Ga is more effectively removed by HFOs during warmer seasons. On the contrary, because HFOs are abundantly formed in low-flow season, even under colder conditions, before In hydrolysis reaction starts to occur, In mobility is less affected by water temperature and then bacterial activity.     

Characteristics of earthquake-induced landslides in a heavy snowfall region—landslides triggered by the northern Nagano prefecture earthquake, March 12, 2011, Japan

The northern Nagano Prefecture earthquake, M_JMA?6.7 (Mw?6.2), which is inferred to have been triggered by the huge (Mw?9.0) March 11, 2011 Tohoku earthquake, occurred on March 12, 2011, in northern Nagano Prefecture, an area in Japan famous for heavy snowfall. A large number of landslides were triggered by the 12 March earthquake, and it caused building damage in the area of the epicenter. To clarify characteristics of the distribution and dynamic behavior of these landslides, we analyzed aerial photographs and conducted field surveys in and around the epicentral area. Large-scale landslides with long distance run-outs are a remarkable characteristic of the landslides induced by this earthquake. The long travel distance is considered to be related to the thick snowpack at the time the earthquake occurred. Moderate scale deep-seated landslides and shallow landslides were also observed in the study area. Based on an analysis of landslides with the active fault on which the earthquake is believed to have occurred, most of these landslides were distributed on the hanging wall of the active fault, within a distance of 12?km from the fault.     

Does freshening of surface water enhance heterotrophic prokaryote production in the western Arctic? Empirical evidence from the Canada Basin during September 2009

This study examined possible environmental factors that affect prokaryote variables in surface waters (upper 100 m of water column) in the Canada Basin, western Arctic Ocean. We collected data on prokaryote abundance and heterotrophic production ([³H]leucine incorporation) at eight stations deployed along a slope-to-offshore transect during September 2009. Prokaryote production and growth tended to increase with increasing chlorophyll a (Chl. a) and temperature and with decreasing salinity. The combination of Chl. a, temperature, and salinity accounted for a large fraction (74%) of the variability in prokaryote production, with the highest contribution made by Chl. a (r ² = 0.56), followed by salinity (r ² = 0.14) and temperature (r ² = 0.03). Similarly, the variability in prokaryote growth rate was largely accounted for by the combination of the three environmental variables (overall r ² of 0.64), with Chl. a making the largest contribution to variability (r ² = 0.33), followed by salinity (r ² = 0.27) and temperature (r ² = 0.05). These data are consistent with the notion that organic matter supply associated with freshwater inputs to surface layers can result in enhanced prokaryote production and growth in the Canada Basin. Our results provide insights into the regulation of the microbial loop in the Canada Basin where freshening has been proceeding rapidly due to increasing river discharge and sea-ice melting.     

Effects of the Chemical Compositions of Salars de Uyuni and Atacama Brines on Lithium Concentration during Evaporation

During Li recovery from salar brines, Li concentration is typically increased to about 60,000 mg L^?1 by evaporation. We investigated the concentration changes of Li, Na, K, Mg, Cl, SO₄, and B during evaporation of both natural Uyuni and artificial Atacama brines. The Uyuni brine exhibited a maximum Li concentration of 6810 mg L^?1 at 31 days of evaporation, at which point the majority of the Na and K in the brine was removed. The Li concentration decreased with further evaporation due to precipitation as Li₂SO₄, such that the level at the 56 day mark was approximately 4130 mg L^?1. In contrast, the artificial Atacama brine showed no pronounced Li precipitation, even after 54 days, at which point the Li concentration was 21,800 mg L^?1. The initial concentrations of Na and K in the Atacama brine were higher than those in the Uyuni brine, and the Atacama solution still retained K after 54 days of evaporation. The order of precipitation of cation species during the evaporation of both brines was: Na, followed by K, Mg, and Li. Thus, Li precipitation in the Atacama brine might be prevented due to the more favored precipitations of Na and K, such that significant Li removal did not occur in this brine.