Variation of the partial pressure of CO2 in surface water from Kuroshio to Oyashio and the relation between environmental factors and the partial pressure at 144°E off Sanriku, northwestern North Pacific in May, 1997     

Katsuyuki Sasaki  Tsuneo Ono  Katsuhisa Tanaka  Kiyoshi Kawasaki  Hiroshi Saito 《Journal of Oceanography》1998,54(5):593-603

Partial pressure of CO₂ in surface sea water (pCO₂) was measured continuously off Sanriku in May, 1997 by a new pCO₂ measurement system. We have examined the relation of pCO₂ to physical factors such as temperature, salinity and density, chemical and biological factors such as nutrients and carbonate system and chlorophylla. In the Kuroshio region pCO₂ was not correlated to physical, chemical and biological factors in the range of 260 to 290 μatom. In transition water (Tr1) between Kuroshio and the Oyashio second branch, pCO₂ was weakly correlated to physical factors and strongly correlated to nutrients. In transition water (Tr2) between the Oyashio first and second branches, pCO₂ was highly correlated to temperature (SD: 10.9 μatom) and salinity (SD: 8.6 μatom) and also to nutrients. In transition water (Tr1+Tr2), pCO₂ was highly multivariately correlated to temperature (T), salinity (S), chlorophylla (CH) (or nitrate+nitrite (N)) as follows, pCO₂(μatom)= 10.8×T(°C)+27.7×S+2.57CH(μg/1) −769, R²= 0.86, SD = 20.9, or pCO₂(μatom)= 3.9×T(°C)+25.5×S+16.0NO₃(μM) −686, R²= 0.99, SD = 6.4. Moreover, pCO₂ was predicted by only two factors, one physical (S) and the other chemical/biological (N) as follows: pCO₂ (μatom)=32.8×S+19.4N−908, R²=0.97, SD=8.4. The pH measured at 25°C was well correlated with normalized pCO₂ at a fixed temperature. In the Oyashio region pCO₂ was decreased to 160 μatom, probably because of spring bloom, but was not correlated linearly to chlorophylla. The results obtained showed the possibility of estimating pCO₂ of the Oyashio and transition regions in May by satellite remote sensing of SST, but the problem of estimation of pCO₂ in Kuroshio water remains to be solved.  相似文献   

Tropical climates at the Last Glacial Maximum: a new synthesis of terrestrial palaeoclimate data. I. Vegetation, lake-levels and geochemistry   总被引：1，自引：1，他引：0  

I. Farrera  S. P. Harrison  I. C. Prentice  G. Ramstein  J. Guiot  P. J. Bartlein  R. Bonnefille  M. Bush  W. Cramer  U. von Grafenstein  K. Holmgren  H. Hooghiemstra  G. Hope  D. Jolly  S.-E. Lauritzen  Y. Ono  S. Pinot  M. Stute  G. Yu 《Climate Dynamics》1999,15(11):823-856

 Palaeodata in synthesis form are needed as benchmarks for the Palaeoclimate Modelling Intercomparison Project (PMIP). Advances since the last synthesis of terrestrial palaeodata from the last glacial maximum (LGM) call for a new evaluation, especially of data from the tropics. Here pollen, plant-macrofossil, lake-level, noble gas (from groundwater) and δ¹⁸O (from speleothems) data are compiled for 18±2 ka (¹⁴C), 32 °N–33 °S. The reliability of the data was evaluated using explicit criteria and some types of data were re-analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month (MTCO), mean annual temperature (MAT), plant available moisture (PAM) and runoff (P-E). Cold-month temperature (MAT) anomalies from plant data range from −1 to −2 K near sea level in Indonesia and the S Pacific, through −6 to −8 K at many high-elevation sites to −8 to −15 K in S China and the SE USA. MAT anomalies from groundwater or speleothems seem more uniform (−4 to −6 K), but the data are as yet sparse; a clear divergence between MAT and cold-month estimates from the same region is seen only in the SE USA, where cold-air advection is expected to have enhanced cooling in winter. Regression of all cold-month anomalies against site elevation yielded an estimated average cooling of −2.5 to −3 K at modern sea level, increasing to ≈−6 K by 3000 m. However, Neotropical sites showed larger than the average sea-level cooling (−5 to −6 K) and a non-significant elevation effect, whereas W and S Pacific sites showed much less sea-level cooling (−1 K) and a stronger elevation effect. These findings support the inference that tropical sea-surface temperatures (SSTs) were lower than the CLIMAP estimates, but they limit the plausible average tropical sea-surface cooling, and they support the existence of CLIMAP-like geographic patterns in SST anomalies. Trends of PAM and lake levels indicate wet LGM conditions in the W USA, and at the highest elevations, with generally dry conditions elsewhere. These results suggest a colder-than-present ocean surface producing a weaker hydrological cycle, more arid continents, and arguably steeper-than-present terrestrial lapse rates. Such linkages are supported by recent observations on freezing-level height and tropical SSTs; moreover, simulations of “greenhouse” and LGM climates point to several possible feedback processes by which low-level temperature anomalies might be amplified aloft. Received: 7 September 1998 / Accepted: 18 March 1999  相似文献   

Heat-Mitigation Effects of Irrigated Rice-Paddy Fields Under Changing Atmospheric Carbon Dioxide Based on a Coupled Atmosphere and Crop Energy-Balance Model     

Ikawa  Hiroki  Kuwagata  Tsuneo  Haginoya  Shigenori  Ishigooka  Yasushi  Ono  Keisuke  Maruyama  Atsushi  Sakai  Hidemitsu  Fukuoka  Minehiko  Yoshimoto  Mayumi  Ishida  Sachinobu  Chen  Charles P.  Hasegawa  Toshihiro  Watanabe  Tsutomu 《Boundary-Layer Meteorology》2021,179(3):447-476

Boundary-Layer Meteorology - Known as the heat-mitigation effect, irrigated rice-paddy fields distribute a large fraction of their received energy to the latent heat during the growing season. The...  相似文献   

Influence of evaporation from the forest floor on evapotranspiration from the dry canopy     

Kenichi Daikoku  Shigeaki Hattori  Aiko Deguchi  Yu Aoki  Mari Miyashita  Kazuho Matsumoto  Junichi Akiyama  Shinichi Iida  Tae Toba  Yuji Fujita  Takeshi Ohta 《水文研究》2008,22(20):4083-4096

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The nature of megafaunal extinctions during the MIS 3–2 transition in Japan     

Christopher J. Norton  Youichi Kondo  Akira Ono  Yingqi Zhang  Mark C. Diab 《Quaternary International》2010,211(1-2):113-122

The nature of late Quaternary megafaunal extinctions has been the subject of intense debate since the 1960s. Traditionally, scientists cite either climatic changes or human predation as the primary reason for worldwide megafaunal extinctions. In many island cases (e.g., Madagascar, New Zealand), scientists have had a tendency to lean toward humans as being the direct or indirect dominant cause for the relatively quick extirpation of indigenous megafaunas. This study evaluates the record for megafaunal (e.g., Palaeoloxodon, Mammuthus, Sinomegaceros) extinctions in the Japanese islands and draw the tentative conclusion that: (1) humans directly and/or indirectly influenced the extinction of some large herbivores; and (2) the megafaunal extinctions likely began earlier than originally proposed; during the marine isotope stage (“MIS”) 3–2 transition (～30–20 ka) rather than during the MIS 2–1 (～15–10 ka) shift that roughly coincides with the advent of the Jomon period in Japan. However, we temper our findings due to the current paucity of sites in Japan that have associated archaeology and vertebrate paleontological materials that date to the MIS 3–2 transition.  相似文献   

Bathymetric patterns of meiofaunal abundance and biomass associated with the Kuril and Ryukyu trenches, western North Pacific Ocean   总被引：2，自引：0，他引：2  

Makoto Itoh  Kiichiro KawamuraTomo Kitahashi  Shigeaki KojimaHideki Katagiri  Motohiro Shimanaga 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(1):86-97

The abundance and biomass of metazoan meiofauna and their relationships with environmental factors [chloroplastic pigment equivalents (CPE) and sediment characteristics] were studied quantitatively around and within the Kuril Trench (560-7090 m) and the Ryukyu Trench (1290-7150 m), which are located in eutrophic and oligotrophic regions, respectively, of the western North Pacific. Faunal abundance and biomass, as well as the CPE content of sediments, were considerably higher in the Kuril region than in the Ryukyu region. In both cases, CPE tended to decrease with water depth, but relatively high values were found in the deepest areas, suggesting that organic matter has accumulated in both trenches. Meiofaunal abundance and biomass were lower than expected from sediment CPE values at hadal stations below 6000 m. Differences in the density and biomass of meiofauna between these two trenches appeared to reflect differences in overall ocean productivity above them. When the analysis was restricted to each region, however, no association was found between the abundance and biomass of meiofauna and food availability. Furthermore, the factors regulating the bathymetric patterns in these meiofaunal parameters appeared to differ between the two trenches.  相似文献   

Discriminating residual and colluvial soils using topographic analysis in a small,forested catchment in Japan     

Kenji Maeda  Takafumi Tanaka  Ohta Takeshi  Shigeaki Hattori 《水文研究》2007,21(16):2144-2156

Soil moisture plays an important role in hydrology. Understanding factors (such as topography, vegetation, and meteorological conditions) that influence spatio‐temporal variability in soil moisture, and how this influence is manifested, is important for understanding hydrological processes. A number of distributed (quasi‐)physical hydrological models have been developed to investigate this subject. Previous studies have shown that the spatial differences in the distribution of soil types (residual and colluvial soils) dominantly reflect spatio‐temporal fluctuations in soil moisture and runoff. We present a methodology for assessing the spatial distribution of residual and colluvial soils, which differ with respect to their physical characteristics, in a 0·88 km² forested catchment with complex topography and a complex land‐use history. Our method is based on penetration resistance profile data; in this data set, each data point represents soil physical characteristics within an area of about 25 m². If the spatial distribution of soils under similar meteorological, geological, historical land use, and other conditions could be characterized on the basis of similarity in topographic features, then the spatial distribution of soil could be predicted based on relationships between various topographic indices (e.g. topographic index and local slope). We tested whether our model correctly assessed the reference data. The model's results were 90·5% correct for residual soils and 87·3% correct for colluvial soils. Further studies will quantify the relationships between topographic features of land covered by residual and colluvial soils and changes in spatio‐temporal variations in the catchment (e.g. vegetation and land use) as a function of geology or meteorology. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Equation of state of hexagonal aluminous phase in basaltic composition to 63 GPa at 300 K     

S. Ono  K. Hirose  M. Isshiki  K. Mibe  Y. Saito 《Physics and Chemistry of Minerals》2002,29(8):527-531

A laser-heated diamond-anvil cell that is capable of operating up to a pressure of 63 GPa, with X-ray diffraction facilities using a synchrotron radiation source at the SPring-8, has been developed to observe the compressibility of a hexagonal aluminous phase, [K_0.15Na_1.66Ca_0.11Mg_1.29Fe²⁺ _0.86Al_3.13Ti_0.09Si_1.98] _Σ9.27O₁₂. The hexagonal aluminous phase is a potassium host mineral from the subducted oceanic crust in the Earth's lower mantle. A sample was heated using a YAG laser at each pressure increment to relax the deviatoric stress in the sample. X-ray diffraction measurements were carried out at 300 K using an angle-dispersive technique. Pressure was measured using an internal platinum pressure calibrant. The observed unit-cell volumes were used to obtain a third-order Birch–Murnaghan equation of state: unit-cell volume V _o=185.94(±16) ų, density ρ _o=4.145 g/cm³, and bulk modulus K _o=198(±3) GPa when the first pressure is derivative of the bulk modulus K ^′ _o is fixed to 4. The density of hexagonal aluminous phase is lower than that of coexisting Mg-perovskite in the subducted oceanic crust.  相似文献   

Compressibility of the calcium aluminosilicate, CAS, phase to 44 GPa     

Shigeaki Ono  Tsuyoshi Iizuka  Takumi Kikegawa 《Physics of the Earth and Planetary Interiors》2005,150(4):331-338

In situ X-ray diffraction measurements on a calcium aluminosilicate (CAS) phase have been carried out using a laser-heated diamond anvil cell up to a pressure of 44 GPa, employing a synchrotron radiation source. CAS is the major mineral formed from sediments subducted into the Earth's mantle. The sample was heated using a YAG laser after each pressure increment to relax the deviatoric stress in the sample. X-ray diffraction measurements were carried out at T = 300 K using an angle-dispersive technique. The pressure was calculated using an internal platinum metal pressure calibrant. The Birch–Murnaghan equation of state for the CAS phase obtained from the experimental unit cell parameters showed a density of ρ₀ = 3.888 g/cm³ and a bulk modulus of K₀ = 229 ± 9 GPa for K^′₀ = 4.7 ± 0.7. When the first pressure derivative of the bulk modulus was fixed at K^′₀ = 4, then the value of K₀ = 239 ± 2 GPa. From the experimental compressibility, the density of the CAS phase was observed to be lower than the density of co-existing Al-bearing stishovite, calcium perovskite, calcium ferrite-type phases, and (Fe,Al)-bearing Mg-perovskite in subducted sediments in the lower mantle. Therefore, the density of subducted sediments in the lower mantle decreases with increasing mineral proportion of the CAS phase.  相似文献   

Magnetic grain‐size distribution of the enhanced component in the loess–palaeosol sequences in the western Loess Plateau of China     

Toshiaki Mishima  Masayuki Torii  Hitoshi Fukusawa  Yugo Ono  Xiao-Min Fang  Bao-Tian Pan  Ji-Jun Li 《Geophysical Journal International》2001,145(2):499-504

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