The geometry of the chromosphere-corona transition region inferred from the center-to-limb variation of the radio emission

Based on the observations of the EUV spectroheliograms, the effective chromosphere-corona transition region is assumed to be restricted in a small volume element in the boundaries of the supergranular network. The center-to-limb variation of the quiet Sun at cm and dm wavelengths is analyzed to determine where the transition region is located in the network boundaries. Expressions are derived for the theoretical center-to-limb variation of the hypothetical brightness temperature only from the transition region, taking into account the orientation of the spicules. Comparison with the observations shows that the spicule-sheath model (Brueckner and Nicolas, 1973) and the hot plagette model (Foukal, 1974) are not compatible with the observations, because the limb brightening predicted by these models is too great. A new picture is therefore proposed that thin platelet transition regions are placed on top of the chromosphere and scattered between the network boundaries (the platelet transition-region model). This model is in accord with the observed center-to-limb variation of the radio emission.     

Effect of Rock Hardness and Moisture Content on Tafoni Weathering in the Granite of Mount Doeg-sung, Korea

Many tafoni occur on the granite tors of Mount Doeg-sung, Korea. Relationships are investigated between growth processes of granite tafoni and rock properties such as rock hardness and moisture content. Field evidence shows that the rock surface of the inner backwalls and ceiling of tafoni have reduced hardness and higher moisture content compared to the outer visor of tafoni and to vertical cliff walls with no tafoni. This suggests that tafoni arise in weathered rock where conditions of low strength and high moisture content are both satisfied.     

Recent increase of DIC in the western North Pacific

The temporal variation of the total dissolved inorganic carbon (DIC) content in the western North Pacific is investigated by comparing the DIC distribution obtained from the data sets of three different periods, the GEOSECS data observed in 1973, the CO₂ dynamics Cruise data observed in 1982, and recent Japanese data sets observed during the early 1990s. The overall feature of the signal of temporal DIC change during 1973 and early 1990s agreed with that of former studies, and did not significantly change with the calculation scheme (the grid-selection method vs. the multiple regression method). The observed increase in DIC among the different time scales showed a good inner consistency, which also indicates the stability of the method used in the DIC change calculation. The apparent rate of increase of the DIC inventory in the upper 1000 m water column, however, differed significantly by the data set used for the calculation: It was 5.6±2.4 g C/m²/year, based on the data comparison between 1982 and the early 1990s, while it became 7.6±2.4 g C/m²/year when based on the data between 1973 and the early 1990s. This result provides us an information about the data-dependency on the former estimation of temporal DIC change.     

Rapid development of arctic cyclone in June 2008 simulated by the cloud resolving global model NICAM

In this study, we conducted a numerical simulation of a rapid development of an arctic cyclone (AC) that appeared in June 2008 using a cloud resolving global model, Nonhydrostatic ICosahedral Atmospheric Model (NICAM). We investigated the three dimensional structure and intensification mechanism of the simulated AC that developed to the minimum sea level pressure of 971 hPa in the model. According to the result, the AC indicates a barotropic structure with a warm core in the lower stratosphere and a cold core in the troposphere. The development of the AC is accompanied by an intense mesoscale cyclone (MC) showing baroclinic structure with a marked local arctic front. The upper level warm core of the AC is formed by an adiabatic heating associated with the downdraft in the lower stratosphere. The rapid development of the AC is caused by the combination of the intensification of the upper level warm core and the merging with the baroclinically growing MC in the lower level. The merging of the AC and MC and the vertical vortex coupling with the upper air polar vortex are the most important mechanisms for the rapid development of the arctic cyclone.     

Biotic response of benthic foraminifera in Aso-kai lagoon,central Japan,to changes in terrestrial climate and ocean conditions (~AD 700–1600)

We investigated responses of shallow-water benthic foraminifera to changes in climate and ocean conditions, using sediment core ASC2 from Aso-kai lagoon, central Japan. Six AMS ¹⁴C dates reveal that the studied interval corresponds to sediments deposited from ~AD 700 to 1600. Sulfur content of the bulk sediment and multi-dimensional scaling (MDS) axis 1 of fossil benthic foraminifera indicate that the composition of the benthic foraminifera community was closely related to dissolved oxygen (DO) concentration in the hypolimnion. The sulfur content and MDS axis 1 also revealed two shifts over the 900-year interval. In the first phase (~AD 700–1250), the Shannon–Wiener Index (H′), E (S₂₀₀), evenness and rank abundance curve (RAC) kurtosis indicate a gradual deterioration in structure of the benthic foraminifera community. In that period, there are statistically significant correlations between the faunal composition (MDS axis 1) and faunal structure [Shannon–Wiener (H′), E (S₂₀₀), evenness and RAC kurtosis]. In the second phase (~AD 1250–1600), however, faunal composition and structure show no marked correspondence. Instead, abundance of benthic foraminifera fluctuated on a scale of ~200 years. Thus, a shift in the biotic response of benthic foraminifera in Aso-kai lagoon occurred in ca. AD 1250. Gradual deterioration of benthic foraminifera, with taxonomic losses, is consistent with declining DO in the first phase, possibly associated with the increasing influence of the Tsushima Warm Current. The possibility that closure of Aso-kai lagoon and development of the sand bar affected benthic foraminifera cannot, however, be ruled out. No corresponding response was observed in the second phase, during which there was no distinct taxonomic loss. Large variations in abundance, however, were a consequence of strength of the East Asian summer and winter monsoons. The shift in the biotic response of benthic foraminifera in Aso-kai lagoon during the period AD 700–1600 was apparently a result of changes in climate and ocean conditions on the East Asian continental margin.     

Correlation between climate sensitivity and aerosol forcing and its implication for the “climate trap”

Climate sensitivity and aerosol forcing are dominant uncertain properties of the global climate system. Their estimates based on the inverse approach are interdependent as historical temperature records constrain possible combinations. Nevertheless, many literature projections of future climate are based on the probability density of climate sensitivity and an independent aerosol forcing without considering the interdependency of such estimates. Here we investigate how large such parameter interdependency affects the range of future warming in two distinct settings: one following the A1B emission scenario till the year 2100 and the other assuming a shutdown of all greenhouse gas and aerosol emissions in the year 2020. We demonstrate that the range of projected warming decreases in the former case, but considerably broadens in the latter case, if the correlation between climate sensitivity and aerosol forcing is taken into account. Our conceptual study suggests that, unless the interdependency between the climate sensitivity and aerosol forcing estimates is properly considered, one could underestimate a risk involving the “climate trap”, an unpalatable situation with a high climate sensitivity in which a very drastic mitigation may counter-intuitively accelerate the warming by unmasking the hidden warming due to aerosols.     

Flux of low salinity water from Aniva Bay (Sakhalin Island) to the southern Okhotsk Sea

In this study, we examined the relationship between the low salinity water in the shelf region of the southern Okhotsk Sea which was seasonally sampled (0–200 m), and fluxes of low salinity water from Aniva Bay. To express the source of freshwater mixing in the surface layer, we applied normalized total alkalinity (NTA) and stable isotopes of seawater as chemical tracers. NTA-S diagrams indicate that NTA of low salinity water in the upper 30 m layer just off the Soya Warm Current is clearly higher than in the far offshore region in summer and autumn. Using NTA-S regression lines, we could deduce that the low salinity and high NTA water in the upper layer originates from Aniva Bay. For convenience, we defined this water as the Aniva Surface Water (ASW) with values S < 32, NTA > 2450 μmol kg⁻¹. Formation and transport processes of ASW are discussed using historical data. The interaction between the maximum core of high NTA water on the bottom slope of eastern Aniva Bay and an anticyclonic eddy at the mouth of Aniva Bay are concluded to control ASW formation. Upwelling of the Cold Water Belt water at the tip of Cape Krillion is considered to cause ASW outflow from Aniva Bay.     

Emission metrics under the 2 °C climate stabilization target

In multi-gas climate policies such as the Kyoto Protocol one has to decide how to compare the emissions of different greenhouse gases. The choice of metric could have significant implications for mitigation priorities considered under the prospective negotiations for climate mitigation agreements. Several metrics have been proposed for this task with the Global Warming Potential (GWP) being the most common. However, these metrics have not been systematically compared to each other in the context of the 2 °C climate stabilization target. Based on a single unified modeling framework, we demonstrate that metric values span a wide range, depending on the metric structure and the treatment of the time dimension. Our finding confirms the basic salient point that metrics designed to represent different aspects of the climate and socio-economic system behave differently. Our result also reflects a complex interface between science and policy surrounding metrics. Thus, it is important to select or design a metric suitable for climate stabilization based on an interaction among practitioners, policymakers, and scientists.     

Crystallization temperature determination of Itokawa particles by plagioclase thermometry with X‐ray diffraction data obtained by a high‐resolution synchrotron Gandolfi camera

The crystallization temperatures of Itokawa surface particles recovered by the space probe Hayabusa were estimated by a plagioclase geothermometer using sodic plagioclase triclinicity. The Δ131‐index required for the thermometer, which is the difference in X‐ray diffraction peak positions between the 131 and 11 reflections of plagioclase, was obtained by a high‐resolution synchrotron Gandolfi camera developed for the third generation synchrotron radiation beamline, BL15XU at SPring‐8. Crystallization temperatures were successfully determined from the Δ131‐indices for four particles. The observed plagioclase crystallization temperatures were in a range from 655 to 660 °C. The temperatures indicate crystallization temperatures of plagioclases in the process of prograde metamorphism before the peak metamorphic stage.     

On-line sensing system of dynamic ship's attitude by use ofservo-type accelerometers

For an accurate automatic measurement of ship's attitude the paper proposes an intelligent online sensing system which uses four servo-type accelerometers and one servo-type inclinometer appropriately located on the ship. Through an adequate location of the accelerometers, the heaving, rolling, and pitching signals of the ship are separated from each other with adequate linear combinations of the four sensors' outputs. Furthermore, the inclinometer is utilized to extract a bias signal of the pitching. By introducing linear dynamic models and linear observation equations on the three signals, their online measurement is reduced to the state estimation of the linear dynamic systems. A bank of Kalman filters are used to execute the online state estimation and to overcome changes in parameters in the dynamic models with time