A5075497396- Geology and Paleoclimatology Research
- Tree-ring climate responses
- Isotope Analysis in Ecology
- Marine and coastal ecosystems
- Methane Hydrates and Related Phenomena
- Plant Water Relations and Carbon Dynamics
- Climate variability and models
- Marine and environmental studies
- Marine Biology and Ecology Research
- Arctic and Antarctic ice dynamics
- Oceanographic and Atmospheric Processes
- Archaeology and ancient environmental studies
- Coastal wetland ecosystem dynamics
- Geological Studies and Exploration
- Pacific and Southeast Asian Studies
- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Aquatic and Environmental Studies
- Landslides and related hazards
- Atmospheric Ozone and Climate
- Horticultural and Viticultural Research
- Cryospheric studies and observations
- Food Industry and Aquatic Biology
- Microbial Community Ecology and Physiology
- Cultural Heritage Materials Analysis
Nagoya University
2012-2024
Research Institute for Humanity and Nature
2013-2022
Waseda University
2019
Graduate School USA
2019
Hokkaido University of Science
2011
Hokkaido University
2001-2010
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine
2006
Iron is an essential nutrient and plays important role in the control of phytoplankton growth (Martin et al., 1989). Atmospheric dust has been thought to be most source iron, supporting annual biological production western subarctic Pacific (WSP) (Duce Tindale, 1991; Moore 2002). We argue here for another iron WSP. found extremely high concentrations dissolved particulate Okhotsk Sea Intermediate Water (OSIW) North (NPIW), water ventilation processes this region probably transport through...
Abstract The far-reaching impacts of central Pacific El Niño events on global climate differ appreciably from those associated with eastern events. Central may become more frequent in coming decades as atmospheric greenhouse gas concentrations rise, but the instrumental record sea-surface temperatures is too short to detect potential trends. Here we present an annually resolved reconstruction NIÑO4 temperature, located equatorial Pacific, based oxygen isotopic time series Taiwan tree...
We developed a 50‐year tree ring δ 18 O chronology for each of three species ( Juniperus indica , Larix griffithii and Picea spinulosa ) using total 12 trees (four per species) from the Bhutan Himalaya. Despite originating different sampled at two altitudes, chronologies are highly correlated with one another r = 0.76–0.89). Response analyses reveal that values controlled mainly by summer precipitation, irrespective species. Based on these results, robust 269‐year was established to...
Abstract. We have constructed a regional tree-ring cellulose oxygen isotope (δ18O) record for the northern Indian sub-continent based on two new records from India and central Nepal three published northwestern India, western Bhutan. The spans common interval 1743 to 2008 CE. Correlation analysis reveals that is significantly negatively correlated with climatic indices: all rainfall (AIR; r = −0.5, p < 0.001, n 138), monsoon index (IMI; −0.45, 51) intensity of monsoonal circulation (r...
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 310:95-108 (2006) - doi:10.3354/meps310095 Different ingestion patterns of 13C-labeled bacteria and algae by deep-sea benthic foraminifera Hidetaka Nomaki1,2,*, Petra Heinz3, Takeshi Nakatsuka4, Motohiro Shimanaga2, Naohiko Ohkouchi1, Nanako O. Ogawa1, Kazuhiro Kogure2, Eiko Ikemoto2, Hiroshi Kitazato1...
We measured organic carbon uptake rates by deep-sea benthic foraminifera and studied differences among species, living depth, seasons to investigate how these protists contribute consumption on the floor. In situ feeding experiments using 13C-labeled algae were carried out in central part of Sagami Bay from 24 29 November 2001 1 12 April 2002. Our results indicate that assimilation higher shallow infaunal species (Uvigerina akitaensis, Bulimina aculeata) lower intermediate (Textularia...
[1] A tree ring cellulose δ18O chronology of Fokienia hodginsii from 1951 to 2002 is established by four cores different trees explore its potential for reconstructing climatic variations in northern Laos. This the first Laos as well this species. We compare and width between cores. The results suggest that time series are more strongly correlated than are. In addition, correlation analysis shows a significantly negative May–October Palmer Drought Severity Index (PDSI), while indices have...
A tree ring δ 18 O chronology is developed for the past 300 years (1705–2004) using 6 cypress trees from northern Vietnam to reconstruct long‐term hydroclimatic variations in summer monsoon season. To best of our knowledge, this first well‐replicated Southeast Asia, as well longest yet produced. Response analyses reveal that significantly correlated with temperature, precipitation, and Palmer Drought Severity Index (PDSI) during period May–October, highest correlation PDSI. Our accounts 44%...
Abstract A tree ring cellulose oxygen isotope (δ 18 O) chronology for the period 1870–2011 was established using samples from four Fokienia hodginsii trees with aim of exploring potential to use δ O records reconstruct climatic variations in Fujian, a subtropical region southeast China. We believe that this is first area. Response analysis revealed significantly correlated precipitation between April and September, relative humidity August October, Palmer drought severity index October. Our...
Abstract The subarctic Pacific is a high‐nutrient low‐chlorophyll (HNLC) region in which phytoplankton growth broadly limited by iron (Fe) availability. However, even with Fe limitation, the western (WSP) has significant and greater seasonal variability lower trophic levels than eastern Pacific. Therefore, differences supply must explain west‐to‐east decrease growth. flux to euphotic zone WSP occurs at “moderate” value, that it significantly higher its value on side, yet not sufficient...
Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose are a novel proxy for summer hydroclimate in monsoonal Asia. In central Japan, we collected 67 conifer wood samples, mainly Chamaecyparis obtusa, with ages encompassing the past 2600 years. The samples were taken from living trees, archeological wood, architectural and buried logs. We analyzed stable oxygen hydrogen (δ2H) these (more than 15 000 rings total) without using pooling method constructed statistically reliable δ18O time...
Abstract The El Niño-Southern Oscillation (ENSO) used to affect the Asian summer monsoon (ASM) and Australian (AusSM) precipitation in different ways but global warming may have changed it. This study built robust annual ASM reconstructions during 1588–2013 (1588–1999) examine ENSO-monsoon relationship how it has changed. During period of 1588–1850 when natural climate variability was dominant, inter-monsoon weak non-stationary. Since 1850, however, both relationships saw an enhancement this...
Marine‐ and terrestrial‐derived biomarkers (alkenones, brassicasterol, dinosterol, long‐chain n ‐alkanes), as well carbonate, biogenic opal, ice‐rafted debris (IRD), were measured in two sediment cores the Sea of Okhotsk, which is located northwestern Pacific rim characterized by high primary productivity. Down‐core profiles phytoplankton markers suggest that productivity abruptly increased during global Meltwater Pulse events 1A (about 14 ka) 1B 11 stayed Holocene. Spatial temporal...
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 357:153-164 (2008) - DOI: https://doi.org/10.3354/meps07309 Benthic foraminifera as trophic links between phytodetritus and benthic metazoans: carbon nitrogen isotopic evidence Hidetaka Nomaki1,*, Nanako O. Ogawa1, Naohiko Ohkouchi1, Hisami Suga1, Takashi Toyofuku1, Motohiro Shimanaga2, Takeshi Nakatsuka3,...
Abstract In this study, we investigated the interannual and intraannual variabilities in oxygen isotope composition (δ 18 O) preserved tree ring cellulose of Pinus taiwanensis lower reaches Yangtze River, southeast China, to explore its potential utility for precipitation reconstruction over period 1855–2013. Intraannual variations δ O show distinct annual cycles that are characterized by maxima early growth near boundary minima middle late portions ring. Seasonal patterns were influenced...
The oxygen isotope ratio (δ18O) of tree-ring cellulose is known to be a reliable proxy for hydroclimate in monsoon Asia. However, δ18O data are still spatially and temporally limited, so denser network Asia required better understand the dynamics circulation its past variability. Here, we present 242-year chronology calculated from five silver fir trees collected western (Indian) Himalaya, region located on northwestern periphery summer incursions. Response analyses using regionalized...