Modeling three-dimensional forest structures to drive canopy radiative transfer simulations of bidirectional reflectance factor

Three-dimensional (3-D) Monte Carlo-based radiative transfer (MCRT) models are usually used for benchmarking in intercomparisons of the canopy radiative transfer (RT) simulations. However, the 3-D MCRT models are rarely applied to develop remote sensing algorithms to estimate essential climate variables of forests, due mainly to the difficulties in obtaining realistic stand structures for different forest biomes over regional to global scales. Fortunately, some of important tree structure parameters such as canopy height and tree density distribution have been available globally. This enables to run the intermediate complexities of the 3-D MCRT models. We consequently developed a statistical approach to generate forest structures with intermediate complexities depending on the inputs of canopy height and tree density. It aims at facilitating applications of the 3-D MCRT models to develop remote sensing retrieval algorithms. The proposed approach was evaluated using field measurements of two boreal forest stands at Estonia and USA, respectively. Results demonstrated that the simulations of bidirectional reflectance factor (BRF) based on the measured forest structures agreed well with the BRF based on the generated structures from the proposed approach with the root mean square error (RMSE) and relative RMSE (rRMSE) ranging from 0.002 to 0.006 and from 0.7% to 19.8%, respectively. Comparison of the computed BRF with corresponding MODIS reflectance data yielded RMSE and rRMSE lower than 0.03 and 20%, respectively. Although the results from the current study are limited in two boreal forest stands, our approach has the potential to generate stand structures for different forest biomes.     

Vertical and horizontal distribution of fluorescent dissolved organic matter in the Southern Ocean

The vertical and horizontal distribution of fluorescent dissolved organic matter (FDOM), determined by fluorescence intensity at 320 nm excitation and 420 nm emission, were clarified in nine stations on two transects at the Southern Ocean, including a subtropical, subantarctic, polar frontal and Antarctic zone. All vertical profiles of fluorescence intensity showed that levels were lowest in the surface waters, increased with increasing the depth in mid-depth waters ( 2000 m), and then stayed within a relatively narrow range from there to the bottom. Such vertical profiles of FDOM were similar to those of nutrients, but were adverse to dissolved oxygen. In water columns below the temperature-minimum subsurface water (dichothermal waters) in the Antarctic zone and below the winter mixed layer in the other zones, we determined the relationships of fluorescence intensity to concentrations of nutrients and apparent oxygen utilization (AOU) over the entire area of the present study, and found significant linear correlations between the levels of fluorescence intensity and nutrient concentrations (r =  0.70 and 0.71 for phosphate and nitrate + nitrite, respectively) and AOU (r = 0.91). From the strong correlation coefficient between fluorescence intensity and AOU, we concluded that FDOM in the Southern Ocean is formed in situ via the biological oxidation of organic matter. The regeneration of the nutrients/consumption of the oxygen/formation of FDOM was active in mid-depth waters. However, the correlations between fluorescence intensities and nutrients and AOU were different in the mid-depth water masses, Subantarctic Mode Water (SAMW), and Antarctic Intermediate Water (AAIW), indicating that the sources of organic matter responsible for FDOM formation were different. A considerable amount of FDOM in the SAMW is thought to be produced by the remineralization of DOM in addition to sinking particulate organic matter, while DOM is less responsible for FDOM formation in the AAIW.     

Expanding fisheries co-management to ecosystem-based management: A case in the Shiretoko World Natural Heritage area,Japan

Fisheries co-management in the Shiretoko World Natural Heritage area was expanded to ecosystem-based management, in which the fisheries sector plays an essential role in management. A marine management plan was drawn up to define the management objectives, strategies to maintain major species, and methods for ecosystem monitoring. A network of coordinating organizations from a wide range of sectors was established to integrate policy measures. Experience from this case could inform ecosystem-based management in other countries where large numbers of small-scale fishers take a wide range of species under a fisheries co-management regime.     

Prediction of earthquake energy input from smoothed fourier amplitude spectrum

This paper attempts to show analytically that the energy-input spectra of damped SDOF systems and undamped MDOF systems excited by an earthquake motion can be predicted by smoothing the Fourier amplitude spectrum of the base acceleration. The spectral window for smoothing in the frequency domain for a damped SDOF system is identical with the probability density function of the time-variant or instantaneous vibration frequency resulting from non-linear hysteresis. The spectral window for an undamped MDOF system is identical with the set of squared participation factors associated with vibration modes. It was found that the increase in damping factor and the increase in participation of higher modes provide wider spectral windows, resulting in more flattened or unaltered energy-input spectra due to enhanced smoothing effects.     

The effect of sulfur content on density of the liquid Fe–S at high pressure

The density of liquid Fe–S was measured at 4 GPa and 1,923 K using a sink/float method with a composite density marker. The density marker consisted of a Pt rod core and an Al₂O₃ tube surrounding. The uncertainty in the density of the composite marker is much smaller than that of the composite sphere, which had been used in previous density measurements. The density of liquid Fe–S decreases nonlinearly with increasing sulfur content at 4 GPa and 1,923 K. This tendency is consistent with the results measured at ambient pressure. The molar volume of FeS calculated from the measured density gradually increases with sulfur content. The excess molar volume from ideal mixing of Fe and S at 4 GPa was negative value. The new method proposed here is applicable to the density measurement of other Fe alloys at high pressure. The tendency of the molar volume and the excess molar volume with sulfur content at ambient pressure is consistent with these at high pressure at least up to 4 GPa. The excess molar volume at high pressure is essential for estimating the amount of light elements in the outer core.     

Correlation between dissolved He concentration and Cl in groundwater at Äspö, Sweden

Tunnel excavation at Äspö Island, Sweden, has caused severe groundwater disturbance, gradually extending deeper into the tunnel as present-day Baltic seawater intrudes through fractures connecting to the surface. However, the paleo-hydrogeochemical conditions have remained in the deep highly saline waters that have avoided mixing. A correlation has been observed between dissolved ⁴He concentration and Cl⁻ ion concentration, measured every two years from 1995 to 2001 at Äspö. Groundwater mixing conditions can be examined by the correlations between 1/Cl, ³⁶Cl/Cl, and ³H concentrations. Subsurface production is responsible for the majority of the ³⁶Cl and excess dissolved ⁴He of interstitial groundwater in fractures. The secular equilibrium ratio of ³⁶Cl/Cl in rock was theoretically estimated to be (5.05 ± 0.82) × 10⁻¹⁴ based on the neutron flux intensity, a value comparable to the measured ³⁶Cl/Cl ratio in rock and groundwater. The degassing crustal ⁴He flux was estimated to be 2.9 × 10⁻⁸  1.3 × 10⁻⁶ (ccSTP/cm²a) using the HTO diffusion coefficient for the Äspö diorite. The ⁴He accumulation rate ranges from 6.8 × 10⁻¹⁰ (for the in situ accumulation rate) to 7.0 × 10⁻⁹ (ccSTP/(g_water · a) considering both ⁴He in situ production and the degassing flux, assuming ⁴He is accumulated constantly in groundwater. By comparing the subsurface ³⁶Cl increase with ⁴He concentrations in groundwater, the ⁴He accumulation rate was determined from data for groundwater arriving at the secular equilibrium of ³⁶Cl/Cl. The ⁴He accumulation rate was found to be (1.83 ± 0.72) × 10⁻⁸ ccSTP/(g_water · a) without determining the magnitude of degassing ⁴He flux.     

A report on failures of current meter moorings set east of Tsushima Island from 1983 to 1987

On the basis of field records, we describe failures of current meter moorings deployed in the Tsushima Strait from 1983 to 1987. In order to avoid future failures of current meter moorings, we should communicate frequently with the fishermen's union and deploy the moorings with reserve flotation and acoustic release.     

Seasonal variation of <Superscript>228</Superscript>Ra/<Superscript>226</Superscript>Ra ratio in surface water from the East China Sea and the Tsushima Strait

A total of 21 surface water samples were collected on the east side of the East China Sea (ECS) (3 sites) and at the Tsushima Strait (1 site), and ²²⁶Ra and ²²⁸Ra activities were measured using low-background γ-spectrometry. The ²²⁸Ra/²²⁶Ra ratios among the samples exhibited notable seasonal variation (²²⁸Ra/²²⁶Ra = 0.2–2.6) accompanying changes of salinity (31.7–34.7). Seasonal water circulation within the ECS is hypothesized to cause the change by altering the mixing ratio of ²²⁸Ra-rich continental shelf water and ²²⁸Ra-poor Kuroshio water.     

Dp 2 and polar substorm

The morphological distinction between DP 2 fluctuations and polar substorms (DP 1) is explained, and the relation between these two modes of the disturbance is examined. It is found that although DP 1 and 2 tend to occur together, they are not coherent, indicating that they are driven by different electric field systems. The distinction between DP 2 fluctuations and sudden impulses is also discussed.     

Spatial structure of transverse oscillations in the interplanetary magnetic field

The spatial structure of the transverse oscillations in the interplanetary magnetic field at 1 AU is studied by comparing the simultaneous observations by Explorer 33 and 35 satellites at the maximum separation of about 200R _E. The anisotropy characteristics of these oscillations suggest that the oscillations sampled are Alfvén waves. It is found that the size of the region of the wave coherence is related to the solar wind velocity; the size is 80R _E when the wind velocity is lower than 500 km s^–1 but becomes less than this when the wind velocity is higher. An inference is made that the solar atmospheric turbulence contributing to the faster solar wind is finer in scale than that associated with the slower wind.A postgraduate student at the Tokai University