Using urban effect corrected temperature data and a tree phenology model to project geographical shift of cherry flowering date in South Korea

Temperate zone deciduous tree phenology may be vulnerable to projected temperature change, and associated geographical impact is of concern to ecologists. Although many phenology models have been introduced to evaluate climate change impact, there has been little attempt to show the spatial variation across a geographical region due to contamination by the urban heat island (UHI) effect as well as the insufficient spatial resolution of temperature data. We present a practical method for assessing climate change impact on tree phenology at spatial scales sufficient to accommodate the UHI effect. A thermal time-based two-step phenological model was adapted to simulate and project flowering dates of Japanese cherry (Prunus serrulata var. spontanea) in South Korea under the changing climates. The model consists of two sequential periods: the rest period described by chilling requirements and the forcing period described by heating requirements. Daily maximum and minimum temperature are used to calculate daily chill units until a pre-determined chilling requirement for rest release is met. After the projected rest release date, daily heat units (growing degree days) are accumulated until a pre-determined heating requirement for flowering is achieved. Model parameters were derived from the observed bud-burst and flowering dates of cherry tree at the Seoul station of the Korea Meteorological Administration (KMA), along with daily temperature data for 1923–1948. The model was validated using the observed data at 18 locations across South Korea during 1955–2004 with a root mean square error of 5.1 days. This model was used to project flowering dates of Japanese cherry in South Korea from 1941 to 2100. Gridded data sets of daily maximum and minimum temperature with a 270 m grid spacing were prepared for the climatological normal years 1941–1970 and 1971–2000 based on observations at 56 KMA stations and a geospatial interpolation scheme for correcting urban heat island effect as well as elevation effect. We obtained a 25 km-resolution, 2011–2100 temperature projection data set covering peninsular Korea under the auspices of the Inter-governmental Panel on Climate Change—Special Report on Emission Scenarios A2 from the Meteorological Research Institute of KMA. The data set was converted to 270 m gridded data for the climatological years 2011–2040, 2041–2070 and 2071–2100. The phenology model was run by the gridded daily maximum and minimum temperature data sets, each representing climatological normal years for 1941–1970, 1971–2000, 2011–2040, 2041–2070, and 2071–2100. According to the model calculation, the spatially averaged flowering date for the 1971–2000 normal is earlier than that for 1941–1970 by 5.2 days. Compared with the current normal (1971–2000), flowering of Japanese cherry is expected to be earlier by 9, 21, and 29 days in the future normal years 2011–2040, 2041–2070, and 2071–2100, respectively. Southern coastal areas might experience springs with incomplete or even no flowering caused by insufficient chilling required for breaking bud dormancy.     

Seismic resistance capacity of beam–column connections in high‐rise buildings: E‐Defense shaking table test

A series of E‐Defense shaking table tests are conducted on a large‐scale test specimen that represents a high‐rise steel building. Two types of connections featuring the connection details commonly used in 1970s, in the early days of high‐rise construction in Japan, are adopted: the field‐welded connection consisting of welded unreinforced flanges and a bolted web type, and the shop‐welded connection in which the flanges and web are all‐welded to the column flange in the shop. To examine the seismic capacity of a total of 24 beam‐to‐column connections of the specimen, particularly when it is subjected to long‐period ground motion characterized not so much by large amplitude as by very many cycles of repeated loading, the test specimen is shaken repeatedly until the connections fractured. The test results indicate that a few of the field‐welded connections fractured from the bottom flange weld boundary in a relatively small cumulative rotation primarily due to the difficulties in ensuring the welding and inspection performance in the actual field welding. The shop‐welded connections are able to sustain many cycles of plastic rotation, with an averaged cumulative plastic rotation of 0.86 rad. Two shop‐welded connections exhibit ductile fractures but only after experiencing many cycles. The presence of RC floor slabs promotes the strain concentration at the toe of the weld access hole in the bottom flange by at least twice compared with the case without the slab, which had resulted in a decrease in the cumulative plastic rotation by about 50%. Copyright © 2010 John Wiley & Sons, Ltd.     

Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural,chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)

In the southern Chinese Tianshan, the southernmost part of the Central Asian Orogenic Belt (CAOB), widespread ophiolitic mélanges form distinct tectonic units that are crucial for understanding the formation of the CAOB. However, the timing of tectonic events and the subduction polarity are still in controversy. In order to better understand these geological problems, a comprehensive study was conducted on the Heiyingshan ophiolitic mélange in the SW Chinese Tianshan. Detailed structural analysis reveals that the ophiolitic mélange is tectonically underlain by sheared and weakly metamorphosed pre-Middle Devonian rocks, and unconformably overlain by non-metamorphic and undeformed lower Carboniferous (Serpukhovian) to Permian strata. The igneous assemblage of the mélange comprises OIB-like alkali basalt and andesite, N-MORB-like tholeiitic basalt, sheeted diabase dikes, cumulate gabbro and peridotite. Mafic rocks display supra-subduction signatures, and some bear evidence of contamination with the continental crust, suggesting a continental marginal (back-arc) basin setting. Zircons of a gabbro were dated at 392 ± 5 Ma by the U–Pb LA-ICP-MS method. Famennian–Visean radiolarian microfossils were found in the siliceous matrix of the ophiolitic mélange. Mylonitic phyllite which displays northward-directed kinematic evidence yielded muscovite ⁴⁰Ar/³⁹Ar plateau ages of 359 ± 2 Ma and 356 ± 2 Ma.These new data, combined with previously published results, suggest that the mafic protoliths originally formed in a back-arc basin in the Chinese southern Tianshan during the late Silurian to Middle Devonian and were subsequently incorporated into the ophiolitic mélange and thrust northward during the Late Devonian to early Carboniferous. Opening of the back-arc basin was probably induced by south-dipping subduction of the Paleo-Tianshan Ocean in the early Paleozoic, and the Central Tianshan block was rifted away from the Tarim block. Closure of the back-arc basin in the early Carboniferous formed the South Tianshan Suture Zone and re-amalgamated the two blocks.     

A study of phase transformation in hedenbergite to 40 GPa at ∼1200° C

Phase transformations in a natural sample of hedenbergite ((Ca_0.93Fe_0.61Mn_0.34Mg_0.08Na_0.01Zn_0.02Al_0.003)Si₂O₆) have been studied by X-ray diffraction up to 40 GPa at ∼ 1200°C in a diamond anvil cell interfaced with a laser heating system. The starting hedenbergite phase decomposed into a garnet plus γ-spinel and stishovite at ∼ 14 GPa; then into garnet plus stishovite and wüstite at ∼ 18 GPa; and finally into perovskite plus stishovite and wüstite at pressures higher than ∼ 24 GPa. On decompression to 0.1 MPa, all the high pressure phases are retained except for the cubic perovskite, which reverts back into the ɛ-CaSiO₃ phase, in accordance with previous reports. Energy-dispersive SEM analyses show that the garnet is present as a calcium-rich ABO ₃-type phase. As no garnet phase has been previously observed either in pure CaSiO₃ or in pure CaMgSi₂O₆, it appears that the observed calcium-rich garnet phase has been stabilized by the presence of other cations such as the Na⁺, Zn²⁺, Mn²⁺, Fe²⁺, Mn³⁺, Fe³⁺ and Al³⁺.     

Environmental control of carbon isotope variations in Pennsylvania black-shale sequences, Midcontinent, U.S.A.

A reversal of the conventional carbon isotope relationship, “terrestrial-lighter-than-marine” organic matter, has been documented for two Pennsylvanian (Desmoinesian) cyclothemic sequence cores from the Midcontinent craton of the central United States. “Deep” water organic-rich phosphatic black shales contain a significant proportion of algal-derived marine organic matter (as indicated by organic petrography, Rock-Eval hydrogen index and ratios) and display the lightest δ¹³C-values (max −27.80‰ for kerogen) while shallower water, more oxic facies (e.g. fossiliferous shales and limestones) contain dominantly terrestrial organic matter and have heavier δ¹³C_kerogen-values (to −22.87‰ for a stratigraphically adjacent coal). δ¹³C-values for extract fractions were relatively homogeneous for the organic-rich black shales with the lightest fraction (often the aromatics) being only 1‰, or less, more negative than the kerogen. Differences between extract fractions and kerogens were much greater for oxic facies and coals (e.g. saturates nearly 5‰ lighter than the kerogen).A proposed depositional model for the black shales calls upon a large influx of nutrients and humic detritus to the marine environment from the laterally adjacent, extremely widespread Pennsylvanian (peat) swamps which were rapidly submerged by transgression of the epicontinental seas. In this setting marine organisms drew upon a CO₂-reservoir which was in a state of disequilibrium with the atmosphere, being affected by isotopically light “recycled-CO₂” derived from the decomposition of peaty material in the water column and possibly from the anoxic diagenesis of organic matter in the sediments.     

Distributional changes in rainfall and river flow in Sarawak,Malaysia

Climate change may not change the rainfall mean, but the variability and extremes. Therefore, it is required to explore the possible distributional changes of rainfall characteristics over time. The objective of present study is to assess the distributional changes in annual and northeast monsoon rainfall (November-January) and river flow in Sarawak where small changes in rainfall or river flow variability/distribution may have severe implications on ecology and agriculture. A quantile regression-based approach was used to assess the changes of scale and location of empirical probability density function over the period 1980-2014 at 31 observational stations. The results indicate that diverse variation patterns exist at all stations for annual rainfall but mainly increasing quantile trend at the lowers, and higher quantiles for the month of January and December. The significant increase in annual rainfall is found mostly in the north and central-coastal region and monsoon month rainfalls in the interior and north of Sarawak. Trends in river flow data show that changes in rainfall distribution have affected higher quantiles of river flow in monsoon months at some of the basins and therefore more flooding. The study reveals that quantile trend can provide more information of rainfall change which may be useful for climate change mitigation and adaptation planning.     

Seasonal and spatial variations in water chemistry and nitrate sources in six major Korean rivers

Seasonal and spatial variations in water chemistry and contaminant sources were investigated in six major rivers in South Korea that vary widely in drainage area and length. The dissolved-load content of the rivers varied seasonally, and some dissolved ions such as Cl^? and NO₃ ^? showed large spatial differences in all of the rivers. The water type changed from Ca–HCO₃ in the upper reaches to Na–Cl–NO₃ in the lower reaches, indicating anthropogenic contamination in the lower reaches. Compared with two relatively pristine rivers (the Sumjin and Mankyung rivers), the other four rivers, which flow through agricultural and urban areas, registered much higher Cl^? and NO₃ ^? concentrations. Statistical analysis showed that seasonal and spatial variations in water chemistry occurred in all the rivers. The nitrogen and oxygen isotopes of dissolved nitrate indicated that the rivers flowing through urban and agricultural areas were significantly affected by manure, sewage, or both.     

Daily streamflow modelling and assessment based on the curve‐number technique

A cell‐based long‐term hydrological model (CELTHYM) that can be integrated with a geographical information system (GIS) was developed to predict continuous stream flow from small agricultural watersheds. The CELTHYM uses a cell‐by‐cell soil moisture balance approach. For surface runoff estimation, the curve number technique considering soil moisture on a daily basis was used, and release rate was used to estimate baseflow. Evapotranspiration was computed using the FAO modified Penman equation that considered land‐use‐based crop coefficients, soil moisture and the influence of topography on radiation. A rice paddy field water budget model was also adapted for the specific application of the model to East Asia. Model sensitivity analysis was conducted to obtain operational information about the model calibration parameters. The CELTHYM was calibrated and verified with measured runoff data from the WS#1 and WS#3 watersheds of the Seoul National University, Department of Agricultural Engineering, in Hwaseong County, Kyounggi Province, South Korea. The WS#1 watershed is comprised of about 35·4% rice paddy fields and 42·3% forest, whereas the WS#3 watershed is about 85·0% forest and 11·5% rice paddy fields. The CELTHYM was calibrated for the parameter release rate, K, and soil moisture storage coefficient, STC, and results were compared with the measured runoff data for 1986. The validation results for WS#1 considering all daily stream flow were poor with R², E² and RMSE having values of 0·40, ?6·63 and 9·69 (mm), respectively, but validation results for days without rainfall were statistically significant (R² = 0·66). Results for WS#3 showed good agreement with observed data for all days, and R², E² and RMSE were 0·92, 0·91 and 2·23 (mm), respectively, suggesting potential for CELTHYM application to other watersheds. The direct runoff and water balance components for watershed WS#1 with significant areas of paddy fields did not perform well, suggesting that additional study of these components is needed. Copyright © 2002 John Wiley & Sons, Ltd.