Results from several persistent train spectra intercompared

Some results following from two contemporary photographical programs (Slovakia and Japan) for persistent meteor train spectra are compared. It shows that even though both programs are not too different according to their lenses and films used, the spectral interval detected is very different. In this respect prism as a dispersion element is more favourable than the grating with blaze wavelength near 610 nm. However, some results previously assumed as typicai for presented persistent trains-e.g. the forbidden Herzberg O₂ emission, the NO₂ continuum and OH red emissions-seem to be substanciated especially due to higher and linear dispersion of those grating spectra.     

Preservation of the shell matrix protein dermatopontin in 1500 year old land snail fossils from the Bonin islands

Organic molecules such as proteins can be preserved in certain fossils. The bulk properties of fossil proteins of both vertebrates and invertebrates have been studied for over half a century. Named proteins have so far been identified, however, only in vertebrate fossils, such as collagen from mammoth bones. Using immunological assays, we examined 1500 year old fossils of the extinct land snail Mandarina luhuana from the Bonin islands for the presence of dermatopontin, a molluscan shell matrix protein. First, we examined the shell microstructure and mineralogy of the fossil shells using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) in order to estimate the extent of diagenetic alteration. The results suggest that the original microstructure and mineralogy of the shells are preserved. Antiserum raised against the Type-1 dermatopontin fragment of the living land snail Euhadra brandtii showed significant immunological reactivity with the extracts from the fossil shells of M. luhuana. Immunological binding curves drawn for the shell extracts of extant M. aureola and the extinct M. luhuana confirmed the presence of dermatopontin in the fossil shells and provided an estimate that about 75–98% of the original dermatopontin was lost from the M. luhuana fossils. This is the first report of a named protein being identified in invertebrate fossils.     

Identification of shear strength and seismic coefficient by back analyzing surficial slides in the 2004 Mid-Niigata prefecture earthquake

Sliding of natural and artificial slopes generally occurs during or following strong earthquakes. Such sliding is greatly affected by a combination of geological conditions and earthquake loading. Earthquake-induced landslides often cause more damage to infrastructure and human lives than the earthquake itself. Pseudo-static analysis is widely implemented as one of several design methods used in engineering practice to assess the seismic stability of natural and artificial slopes. However, the most important issue of pseudo-static analysis is to select the most appropriate method for measuring seismic coefficient. In order to investigate this, back analysis was conducted for surficial slides subjected to strong ground motion during the 2004 Mid-Niigata prefecture earthquake in Japan. This paper surveyed the stochastic properties of earthquake-induced surficial slides and clearly showed that the obtained results were applicable to back analysis of shear strength and seismic coefficient. In back analysis, soil properties such as soil strength and density and sliding depth were assumed as random variables owing to their uncertainties. Seismic coefficient is also assumed to be a random variable and varies with distance from the epicenter fault line. The analysis of 4504 recorded surficial slides clearly shows a unique relationship of landslide occurrence ratio with slope angle and distance from the epicenter fault line. This study’s results enhance the calculation of the shear strength of weathered soil covering slopes and the horizontal seismic coefficient through back analysis procedure. By considering possible stochastic properties of variables, some case studies were implemented in the back analysis.     

Records of environmental and ecological changes related to excavation in varve sediment from Lake Hiruga in central Japan

Journal of Paleolimnology - Sub-annual-scale environmental and ecosystem changes since the mid-18th century were reconstructed in a semi-closed lagoon, Lake Hiruga, located along the Sea of Japan...     

VIDEO AND PHOTOGRAPHIC SPECTROSCOPY OF 1998 AND 2001 LEONID PERSISTENT TRAINS FROM 300 TO 930 nm

Spectra of persistent meteor trains were observed at wavelength between 300 and 930 nm. Two obtained train spectra during the 1998 and 2001 Leonid meteor showers are reported here. During the 1998 Leonids, one train was detected by a photographic camera with a spectrograph covering 370–640 nm region. On the other hand, during the 2001 Leonids, video observations were carried out using image intensified cameras in ultraviolet (UV), visible and near infrared (near-IR) wavelengths. Temperatures in persistent trains have been measured by atmospheric O₂ A(0,1) band at the wavelength near 864.5 nm. From a video spectrum obtained just 7 s after parent fireball’s flare, a rotational temperature of 250 K at altitude of 88.0±0.5 km was estimated. We can say that the cooling time scale of train strongly depends on the initial mass of its fireball at least for Leonids. Based on cooling constant calculated from our results, we estimated a temperature of ∼ ∼130 K as a final exothermic temperature at early stage of persistent trains.     

Variations in snowmelt energy and energy balance characteristics with larch forest density on Mt Iwate,Japan: observations and energy balance analyses

The variation in snowmelt energy and energy components were evaluated with respect to forest density. Surface snowmelt rates, surface evaporation from snow cover and meteorological elements were measured in the open and under sparse (411 trees/ha) and dense (1433 trees/ha) larch canopies. The surface snowmelt rate decreased as the forest density increased. Based on the observations and energy balance analyses, we concluded the following. (1) Albedo decreased while the bulk coefficient for latent heat increased with forest density. (2) The duration of snowmelt increased with forest density because the energy for nocturnal cooling of the snow cover decreased. (3) When comparing the open and forested sites, the changes in snowmelt energy with forest density were caused by sensible heat flux. However, the contribution of net radiation was highest in the forested sites. Therefore, the effects of forest cover on the snowmelt energy were different when comparing both the open and forested sites and the sparse and densely forested sites. (4) The ratio of net radiation to snowmelt energy increased with forest density; although both snowmelt energy and net radiation decreased with increased forest density, the snowmelt energy decreased more rapidly. Sensible heat also decreased as forest density increased. Both albedo and downward long‐wave radiation influenced net radiation. Copyright © 1999 John Wiley & Sons, Ltd.     

Concentrations of 137Cs, 90Sr, 108m Ag, 239+240 Pu and atom ratio of 240Pu/239Pu in tanner crabs, Chionoecetes japonicus and Chionoecetes opilio collected around Japan

The anthropogenic radionuclides, ¹³⁷Cs, ⁹⁰Sr, ^108mAg, ^239+240Pu, were measured in two Chionoecetes species, red queen crab (Chionoecetes japonicus) and snow crab (Chionoecetes opilio) collected around Japan during 1996–2007. There was no increase in the concentrations of these radionuclides and no large variation of the atom ratio of ²⁴⁰Pu/²³⁹Pu during this research period. These results indicated that the source of the radionuclides was not the radioactive wastes dumped by the former USSR and Russia and originated from past nuclear weapon tests. The higher atom ratio in the crab species than that from global fallout would be contributed by the Pacific Proving Grounds close-in fallout. The variability of the concentration of radionuclides in the crab species would result from the variability of the composition and quantity in the diet. However, the decrease in the concentration of radionuclides with sampling depth would depend on the concentration in the seawater and diet.     

Diagnostic metrics for evaluation of annual and diurnal cycles

Two sets of diagnostic metrics are proposed for evaluation of global models?? simulation of annual and diurnal cycles of precipitation. The metrics for the annual variation include the annual mean, the solstice and equinoctial asymmetric modes of the annual cycle (AC), and the global monsoon precipitation domain and intensity. The metrics for the diurnal variation include the diurnal range, the land?Csea contrast and transition modes of the diurnal cycle (DC), and the diurnal peak propagation in coastal regions. The proposed modes for the AC and DC represent faithfully the first two leading empirical orthogonal functions and explain, respectively, 82% of the total annual variance and 87% of the total diurnal variance over the globe between 45°S and 45°N. The simulated AC and DC by the 20-km-mesh MRI/JMA atmospheric general circulation model (AGCM) are in a wide-ranging agreement with observations; the model considerably outperforms any individual AMIP II GCMs and has comparable performance to 12-AMIP II model ensemble simulation measured by Pearson??s pattern correlation coefficient. Comparison of four versions of the MRI/JMA AGCM with increasing resolution (180, 120, 60, and 20?km) reveals that the 20-km version reproduces the most realistic annual and diurnal cycles. However, the improved performance is not a linear function of the resolution. Marked improvement of the simulated DC (AC) occurs at the resolution of 60?km (20?km). The results suggest that better represented parameterizations that are adequately tuned to increased resolutions may improve models?? simulation on the forced responses. The common deficiency in representing the monsoon domains suggests the models having difficulty in replicating annual march of the Subtropical Highs that is largely driven by prominent east-west land?Cocean thermal contrast. Note that the 20-km model reproduces realistic diurnal cycle, but fails to capture realistic Madden-Julian Oscillation.     

Accelerated continental-scale snowmelt and ecohydrological impacts in the four largest Siberian river basins in response to spring warming

River runoff from the four largest Siberian river basins (the Ob, Yenisei, Lena, and Kolyma) considerably contributes to freshwater flux into the Arctic Ocean from the Eurasian continent. However, the effects of variation in snow cover fraction on the ecohydrological variations in these basins are not well understood. In this study, we analysed the spatiotemporal variability of the maximum snow cover fraction (SCF_max) in the four Siberian river basins. We compared the SCF_max from 2000 to 2016 with data in terms of monthly temperature and precipitation, night-time surface temperatures, the terrestrial water storage anomaly (TWSA), the normalised difference vegetation index (NDVI), and river runoff. Our results exhibit a decreasing trend in the April SCF_max values since 2000, largely in response to warming air temperatures in April. We identified snowmelt water as the dominant control on the observed increase in the runoff contribution in May across all four Siberian river basins. In addition, we detected that the interannual river runoff was predominantly controlled by interannual variations in the TWSA. The NDVI in June was strongly controlled by the timing of the snowmelt along with the surface air temperature and TWSA in June. The rate of increase in the freshwater flux from the four Siberian rivers decreased from 2000 to 2016, exhibiting large interannual variations corresponding to interannual variations in the TWSA. However, we identified a clear increase trend in the freshwater flux of ~4 km³/year when analysing the long-term 39-year historical record (1978–2016). Our results suggest that continued global warming will accelerate the transition towards the earlier timing of snowmelt and spring freshwater flux into the Arctic Ocean. Our findings also highlight the effects of earlier snowmelt on ecohydrological changes in the Northern Hemisphere.