Thompson R.L.,Norsk Institutt for Luftforskning NILU |
Patra P.K.,Japan Agency for Marine - Earth Science and Technology |
Chevallier F.,French Climate and Environment Sciences Laboratory |
Maksyutov S.,Japan National Institute of Environmental Studies |
And 16 more authors.
Nature Communications | Year: 2016
Increasing atmospheric carbon dioxide (CO2) is the principal driver of anthropogenic climate change. Asia is an important region for the global carbon budget, with 4 of the world's 10 largest national emitters of CO2. Using an ensemble of seven atmospheric inverse systems, we estimated land biosphere fluxes (natural, land-use change and fires) based on atmospheric observations of CO2 concentration. The Asian land biosphere was a net sink of -0.46 (-0.70-0.24) PgC per year (median and range) for 1996-2012 and was mostly located in East Asia, while in South and Southeast Asia the land biosphere was close to carbon neutral. In East Asia, the annual CO2 sink increased between 1996-2001 and 2008-2012 by 0.56 (0.30-0.81) PgC, accounting for ∼35% of the increase in the global land biosphere sink. Uncertainty in the fossil fuel emissions contributes significantly (32%) to the uncertainty in land biosphere sink change.
Zhang F.,Beijing Normal University |
Zhang F.,Joint Center for Global Change Studies |
Fukuyama Y.,Japan Meteorological Agency JMA |
Wang Y.,Chinese Academy of Meteorological Sciences |
And 8 more authors.
Atmospheric Environment | Year: 2015
In this study, observed episodes of CO2 concentrations at eight Northern Hemisphere (NH) sites from 1993 to 2012 were analyzed. Five-day back trajectories were calculated for a potential source contribution function (PSCF) analysis. A normalized weight factor related to the occurrence of the episodes was applied to derive more reasonable CO2 elevations and sequestrations. Weighted elevated (δCO2(W_E)) and sequestered (δCO2(W_S)) CO2 episodes had large spatial discrepancies due to the differentiation of strength and patterns of CO2 emissions/sinks in different regions. The most significant enhancement in CO2 episodes was observed at Asian sites: δCO2(W_E) increased by approximately 56% at an annual rate of ~4% yr-1 from 1995 to 2010 at Waliguan (WLG) and by approximately 39% (~3% yr-1) from 1997 to 2012 at Yonagunijima (YON). According to the PSCF analysis, these increases are largely attributed to the rapid increase in emissions in China. However, δCO2(W_S) was also enhanced by 34.4% with a growth rate of 2.3% yr-1 at WLG from 1995 to 2010 and ~26.2% (1.7% yr-1) at YON from 1997 to 2012. Both δCO2(W_E) and δCO2(W_S) showed decreasing or relatively flat trends at Monte Cimone and Schauinsland, indicating reductions in emissions and sinks in central Europe. The different intensities/trends in emissions and sinks observed at different sites in the NH show that estimating future CO2 levels is a complex problem. Atmospheric inverse and process-based ecosystem models should use more regional input data at high temporal and spatial resolutions for future carbon flux estimations. © 2015 Elsevier Ltd.
Valdivieso M.,University of Reading |
Haines K.,University of Reading |
Balmaseda M.,ECMWF |
Chang Y.-S.,National Oceanic and Atmospheric Administration |
And 18 more authors.
Climate Dynamics | Year: 2015
Sixteen monthly air–sea heat flux products from global ocean/coupled reanalyses are compared over 1993–2009 as part of the Ocean Reanalysis Intercomparison Project (ORA-IP). Objectives include assessing the global heat closure, the consistency of temporal variability, comparison with other flux products, and documenting errors against in situ flux measurements at a number of OceanSITES moorings. The ensemble of 16 ORA-IP flux estimates has a global positive bias over 1993–2009 of 4.2 ± 1.1 W m−2. Residual heat gain (i.e., surface flux + assimilation increments) is reduced to a small positive imbalance (typically, +1–2 W m−2). This compensation between surface fluxes and assimilation increments is concentrated in the upper 100 m. Implied steady meridional heat transports also improve by including assimilation sources, except near the equator. The ensemble spread in surface heat fluxes is dominated by turbulent fluxes (>40 W m−2 over the western boundary currents). The mean seasonal cycle is highly consistent, with variability between products mostly <10 W m−2. The interannual variability has consistent signal-to-noise ratio (~2) throughout the equatorial Pacific, reflecting ENSO variability. Comparisons at tropical buoy sites (10°S–15°N) over 2007–2009 showed too little ocean heat gain (i.e., flux into the ocean) in ORA-IP (up to 1/3 smaller than buoy measurements) primarily due to latent heat flux errors in ORA-IP. Comparisons with the Stratus buoy (20°S, 85°W) over a longer period, 2001–2009, also show the ORA-IP ensemble has 16 W m−2 smaller net heat gain, nearly all of which is due to too much latent cooling caused by differences in surface winds imposed in ORA-IP. © 2015 The Author(s)
Ohsawa S.,Kyoto University |
Sugimori K.,Toho University |
Yamauchi H.,Japan Meteorological Agency JMA |
Yamauchi H.,Oita Local Meteorological Observatory |
And 5 more authors.
Bulletin of Volcanology | Year: 2014
A drastic change in lake water color from blue-green to brown was observed in the summit crater lake of Mt. Shinmoe-dake, Kirishima Volcano about 8 months after its 2008 eruption. The color change lasted for about 2 months (April-June 2009). The discoloration was attributed to a brownish color suspension that had formed in the lake water. X-ray fluorescence and Fourier transform infrared analyses of a sample of the suspension identified schwertmannite (Fe8O8(OH)6(SO4)). A cultivation test of iron-oxidizing bacteria for the sampled lake water with lakebed sediment revealed that the crater lake hosts iron-oxidizing bacteria, which likely participated in schwertmannite formation. We suggest that pyrite (FeS2) provided an energy source for the iron-oxidizing bacteria since the mineral was identified in hydrothermally altered tephra ejected by the August 2008 eruption. From consideration of these and other factors, the brownish discoloration of the summit crater lake of Mt. Shinmoe-dake was inferred to have resulted from a combined volcanic-microbial process. © 2014 Springer-Verlag Berlin Heidelberg.
Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model
Katata G.,Japan Atomic Energy Agency |
Katata G.,Karlsruhe Institute of Technology |
Chino M.,Japan Atomic Energy Agency |
Kobayashi T.,Japan Atomic Energy Agency |
And 9 more authors.
Atmospheric Chemistry and Physics | Year: 2015
Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of cumulative surface deposition of total 131I and 137Cs and air dose rate obtained by airborne surveys. The new source term was also tested using three atmospheric dispersion models (Modèle Lagrangien de Dispersion de Particules d'ordre zéro: MLDP0, Hybrid Single Particle Lagrangian Integrated Trajectory Model: HYSPLIT, and Met Office's Numerical Atmospheric-dispersion Modelling Environment: NAME) for regional and global calculations, and the calculated results showed good agreement with observed air concentration and surface deposition of 137Cs in eastern Japan. © 2015 Author(s).
PubMed | Norsk Institutt for Luftforskning NILU, Meteorological Research Institute MRI, Central Aerological Observatory CAO, French Climate and Environment Sciences Laboratory and 6 more.
Type: | Journal: Nature communications | Year: 2016
Increasing atmospheric carbon dioxide (CO2) is the principal driver of anthropogenic climate change. Asia is an important region for the global carbon budget, with 4 of the worlds 10 largest national emitters of CO2. Using an ensemble of seven atmospheric inverse systems, we estimated land biosphere fluxes (natural, land-use change and fires) based on atmospheric observations of CO2 concentration. The Asian land biosphere was a net sink of -0.46 (-0.70-0.24) PgC per year (median and range) for 1996-2012 and was mostly located in East Asia, while in South and Southeast Asia the land biosphere was close to carbon neutral. In East Asia, the annual CO2 sink increased between 1996-2001 and 2008-2012 by 0.56 (0.30-0.81) PgC, accounting for 35% of the increase in the global land biosphere sink. Uncertainty in the fossil fuel emissions contributes significantly (32%) to the uncertainty in land biosphere sink change.
Realini E.,Kyoto University |
Realini E.,Geomatics Research & Development GReD srl |
Sato K.,Kyoto University |
Sato K.,Japan Aerospace Exploration Agency |
And 5 more authors.
International Association of Geodesy Symposia | Year: 2016
Local-scale monitoring of the temporal and spatial variability of precipitable water vapour (PWV) is crucial to improve the nowcasting and forecasting of localized meteorological hazards. While GPS is now routinely employed to retrieve PWV from estimated tropospheric delays (GPS meteorology), even the densest GPS networks available have a spatial resolution of the order of tens of kilometers, which is too coarse for detecting local fluctuations of water vapor. A densification of existing networks, at least in urban areas, is necessary to provide reliable and continuous water vapor monitoring with sufficiently high horizontal resolution. Densifying existing networks down to few kilometers of inter-station distances, however, introduces at least two issues: first, a horizontal smoothing effect occurs, induced by the significant overlapping of the inverse cones above low elevation angles typically used for GPS observation processing; second, an issue of economic nature might arise if geodetic receivers are used for large-scale densifications (e.g. for early warning systems serving large cities). We tackle the first issue by using only high-elevation slant delays for PWVretrieval, and in particular by exploiting the Japanese Quasi-Zenith Satellite System (QZSS), and the second issue by investigating the use of low-cost single-frequency receivers with local ionosphere delay models. In this work we describe the results obtained in PWV retrieval from high-elevation GPS and QZSS slant delays, estimated using a dense network of receivers installed near Kyoto, Japan. © Springer International Publishing Switzerland 2015.
Sato K.,Kyoto University |
Realini E.,Kyoto University |
Tsuda T.,Kyoto University |
Oigawa M.,Kyoto University |
And 3 more authors.
Journal of Disaster Research | Year: 2013
This work describes a system aimed at the near realtimemonitoring of precipitable water vapor (PWV) by means of a dense network of Global Navigation Satellite System (GNSS) receivers. These receivers are deployed with a horizontal spacing of 1-2 km around the Uji campus of Kyoto University, Japan. The PWV observed using a standard GPS meteorology technique, i.e., by using all satellites above a low elevation cutoff, is validated against radiosonde and radiometer measurements. The result is a RMS difference of about 2 mm. A more rigorous validation is done by selecting single GPS slant delays as they pass close to the radiosonde or the radiometer measuring directions, and higher accuracy is obtained. This method also makes it possible to preserve short-term fluctuations that are lost in the standard technique due to the averaging of several slant delays. Geostatistical analysis of the PWV observations shows that they are spatially correlated within the area of interest; this confirms that such a dense network can detect inhomogeneous distributions in water vapor. The PWV horizontal resolution is improved by using high-elevation satellites only, with the aim of exploiting at best the future Quasi- Zenith Satellite System (QZSS), which will continuously provide at least one satellite close to the zenith over Japan.
Takagi A.,Japan Meteorological Agency JMA |
Fujiwara K.,Japan Meteorological Agency JMA |
Ohkura T.,Kyoto University |
Luis A.C.,Institute of Volcanology and Seismology |
And 4 more authors.
Journal of Disaster Research | Year: 2015
Determining the location and the amount of volume change of the pressure source beneath a volcano during the eruption preparation stage is an important issue in monitoring the magma accumulation. To do so, we have implemented a GPS campaign survey network around the Mayon volcano and monitored ground deformation since 2005. Rapid grounddeflating deformation was detected accompanied by the 2009 eruption. The Mogi model pressure source was estimated to be 8.5 km deep beneath the summit and the amount of volume change −13 × 106 m3. In magma accumulation preceding the 2009 eruption, round deformation showed a weak inflationary trend, ut it was difficult to evaluate the source parameters definitively. After the 2009 eruption, no deformation has been detected by the Continuous GPS observation network since 2012. Trend of many baselines of continuous and campaign network turned to extension since 2014. Magma may have started accumulating beneath the Mayon volcano. © 2014 Fuji Technology Press. All rights reserved.
Kimura T.,Japan Agency for Marine - Earth Science and Technology |
Araki E.,Japan Agency for Marine - Earth Science and Technology |
Takayama H.,Japan Meteorological Agency JMA |
Kitada K.,Japan Agency for Marine - Earth Science and Technology |
And 3 more authors.
IEEE Journal of Oceanic Engineering | Year: 2013
In the Integrated Ocean Drilling Program (IODP), the long-term borehole monitoring system (LTBMS) has been planned for installation into boreholes in seafloor settings in the Nankai Trough, Japan. The LTBMS sensors are extremely sensitive instruments for collecting broadband dynamics to elucidate the mechanisms of megathrust earthquakes, which occur repeatedly in plate subduction zones. However, during IODP Expedition 319, it became apparent that the strong ocean current 'Kuroshio' causes vortex-induced vibration (VIV) that damages sensors during installation. Consequently, the LTBMS sensors must be not only highly sensitive but also robust to prevail against VIV. Therefore, sensors with antivibration mechanisms were developed by a Japan Agency for Marine-Earth Science and Technology (JAMSTEC, Kanagawa, Japan) project team. After development was completed, noise evaluation tests and vibration and shock tests simulating vibration and shock in the installation scheme were conducted to confirm that the antivibration mechanism was functional. Power spectral density analysis was conducted using background noise recorded in a low-noise location before and after the vibration and shock tests. Results show that the sensor response was not changed by the vibration or shock tests. Finally, all sensors were loaded onto D/V Chikyu for installation at the C0002 site during IODP Expedition 332. © 1976-2012 IEEE.