Y. Yamashita
A5056848061- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Atmospheric Ozone and Climate
- Atmospheric chemistry and aerosols
- Neutrino Physics Research
- Atmospheric and Environmental Gas Dynamics
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Computational Physics and Python Applications
- Dark Matter and Cosmic Phenomena
- Climate variability and models
- Medical Imaging Techniques and Applications
- Atomic and Subatomic Physics Research
- Superconducting Materials and Applications
- Black Holes and Theoretical Physics
- Nuclear physics research studies
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Astrophysics and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Ocean Acidification Effects and Responses
- Ionosphere and magnetosphere dynamics
- Radioactive Decay and Measurement Techniques
- Advanced NMR Techniques and Applications
National Institute for Environmental Studies
2016-2025
Japan Agency for Marine-Earth Science and Technology
2016-2021
The University of Tokyo
2004-2019
University of Oxford
2019
Pacific International Center for High Technology Research
2019
University of Hawaiʻi at Mānoa
2019
University of Hawaii System
2019
National Centre for Atmospheric Science
2019
Yokohama National University
2019
Nippon Dental University
2009-2018
Abstract. We present an overview of state-of-the-art chemistry–climate and chemistry transport models that are used within phase 1 the Chemistry–Climate Model Initiative (CCMI-1). The CCMI aims to conduct a detailed evaluation participating using process-oriented diagnostics derived from observations in order gain confidence models' projections stratospheric ozone layer, tropospheric composition, air quality, where applicable global climate change, interactions between them. Interpretation...
The impact of stratospheric ozone on the tropospheric general circulation Southern Hemisphere (SH) is examined with a set chemistry‐climate models participating in Stratospheric Processes and their Role Climate (SPARC)/Chemistry‐Climate Model Validation project phase 2 (CCMVal‐2). integrations both past future climates reveal crucial role driving SH change: stronger depletion late spring generally leads to greater poleward displacement intensification midlatitude jet, expansion Hadley cell...
Abstract. >We analyse simulations performed for the Chemistry-Climate Model Initiative (CCMI) to estimate return dates of stratospheric ozone layer from depletion caused by anthropogenic chlorine and bromine. We consider a total 155 20 models, including range sensitivity studies which examine impact climate change on recovery. For control (unconstrained nudging towards analysed meteorology) there is large spread (±20 DU in global average) predictions absolute column. Therefore, model...
Abstract. Projections of stratospheric ozone from a suite chemistry-climate models (CCMs) have been analyzed. In addition to reference simulation where anthropogenic halogenated depleting substances (ODSs) and greenhouse gases (GHGs) vary with time, sensitivity simulations either ODS or GHG concentrations fixed at 1960 levels were performed disaggregate the drivers projected changes. These also used assess two distinct milestones returning historical values (ozone return dates) no longer...
[1] The stratospheric climate and variability from simulations of sixteen chemistry-climate models is evaluated. On average the polar night jet well reproduced though its less with a large spread between models. Polar temperature biases are than 5 K except in Southern Hemisphere (SH) lower stratosphere spring. accumulated area low temperatures responsible for cloud formation accurately Antarctic but underestimated Arctic. shape position vortex simulated, as tropical upwelling stratosphere....
The goal of the Chemistry‐Climate Model Validation (CCMVal) activity is to improve understanding chemistry‐climate models (CCMs) through process‐oriented evaluation and provide reliable projections stratospheric ozone its impact on climate. An appreciation details model formulations essential for how respond changing external forcings greenhouse gases ozone‐depleting substances, hence climate forecasts produced by participating in this activity. Here we introduce review used second round...
The accuracy of chemical tracer simulations by atmospheric general circulation model (AGCM)-based chemistry-transport models (ACTMs) depends on the quality AGCM transport properties, even when meteorology is nudged towards reanalysis fields. Here we show that significant improvements in distribution are achieved hybrid vertical coordinate implemented MIROC4.0 AGCM, compared to its predecessors AGCM5.7b based sigma coordinate. Only explicitly resolved gravity waves propagated into...
Abstract Simulated stratospheric temperatures over the period 1979–2016 in models from Chemistry‐Climate Model Initiative are compared with recently updated and extended satellite data sets. The multimodel mean global temperature trends 1979–2005 −0.88 ± 0.23, −0.70 0.16, −0.50 0.12 K/decade for Stratospheric Sounding Unit (SSU) channels 3 (~40–50 km), 2 (~35–45 1 (~25–35 respectively (with 95% confidence intervals). These within uncertainty bounds of observed two reprocessed SSU In lower...
Abstract Trends and variability in tropospheric hydroxyl (OH) radicals influence budgets of many greenhouse gases, air pollutant species, ozone depleting substances. Estimations OH trends based on budget analysis methyl chloroform (CH 3 CCl ) process‐based chemistry transport models often produce conflicting results. Here we use a previously tested model to simulate atmospheric CH for the period 1985–2018. Based mismatches between output observations, derive consistent anomalies inverse...
We have measured the K-series x rays from kaonic hydrogen atoms and succeeded for first time in observing a distinct $K\ensuremath{\alpha}$ peak. The L x-ray peak has also been observed. strong-interaction shift width of atom $1s$ state were determined transition energy line rays. sign was confirmed to be repulsive, with results $\ensuremath{\Delta}{E}_{1s}=\ensuremath{-}323\ifmmode\pm\else\textpm\fi{}63 (\mathrm{statistical})\ifmmode\pm\else\textpm\fi{}11 (\mathrm{systematic}) \mathrm{eV}$...
A multimodel assessment of the performance chemistry‐climate models (CCMs) in extratropical upper troposphere/lower stratosphere (UTLS) is conducted for first time. Process‐oriented diagnostics are used to validate dynamical and transport characteristics 18 CCMs using meteorological analyses aircraft satellite observations. The main chemical climatological UTLS generally well represented by models, despite limited horizontal vertical resolution. seasonal cycle lowermost stratospheric mass...
The interference fragmentation function translates the of a quark with transverse projection spin into an azimuthal asymmetry two final-state hadrons. In e+e- annihilation product functions is measured. We report nonzero asymmetries for pairs charge-ordered pi+pi- pairs, which indicate significant in this channel. results are obtained from 672 fb-1 data sample that contains 711 \times 106 and was collected at near ?(4S) resonance, Belle detector KEKB asymmetric-energy collider.
Simulations of 15 coupled chemistry climate models, for the period 1960–2100, are presented. The models include a detailed stratosphere, as well including realistic representation tropospheric climate. simulations assume consistent set changing greenhouse gas concentrations, temporally varying chlorofluorocarbon concentrations in accordance with observations past and expectations future. ozone results analyzed using nonparametric additive statistical model. Comparisons made recent past,...
[1] We use observations of N2O and mean age to identify realistic transport in models order explain their ozone predictions. The results are applied 15 chemistry climate (CCMs) participating the 2010 World Meteorological Organization assessment. Comparison observed simulated N2O, compact correlation identifies with fast or slow circulations reveals details model ascent tropical isolation. This process-oriented diagnostic is more useful than alone because it compensating deficiencies that...
Abstract. Monthly averaged surface erythemal solar irradiance (UV-Ery) for local noon from 1960 to 2100 has been derived using radiative transfer calculations and projections of ozone, temperature cloud change 14 chemistry climate models (CCM), as part the CCMVal-2 activity SPARC. Our show influence ozone depletion recovery on irradiance. In addition, we investigate UV-Ery changes caused by due increasing greenhouse gas concentrations. The latter include effects both stratospheric changes....
Abstract. Ozone fields simulated for the first phase of Chemistry-Climate Model Initiative (CCMI-1) will be used as forcing data in 6th Coupled Intercomparison Project. Here we assess, using reference and sensitivity simulations produced CCMI-1, suitability CCMI-1 model results this process, investigating degree consistency amongst models regarding their responses to variations individual forcings. We consider influences methane, nitrous oxide, a combination chlorinated or brominated...
The evolution of stratospheric ozone from 1960 to 2100 is examined in simulations 14 chemistry‐climate models, driven by prescribed levels halogens and greenhouse gases. There general agreement among the models that total column reached a minimum around year 2000 at all latitudes, projected be followed an increase over first half 21st century. In second century, continue increasing, level off, or even decrease depending on latitude. Separation into partial columns above below 20 hPa reveals...
The changes in breakup time of the Antarctic polar vortex years 1980–2004 are examined using output chemistry climate model (CCM) calculations, data from National Centers for Environmental Prediction/the Center Atmospheric Research (NCEP/NCAR) Reanalysis, and European Medium‐Range Weather Forecasts Reanalysis (ERA40). CCM used this study is Climate System Research/National Institute Studies (CCSR/NIES). calculations performed with two ensemble members REF1 scenario validation (CCMVal) one...
To understand how greenhouse gas (GHG) emissions may affect future stratospheric ozone, 21st century projections from four chemistry‐climate models are examined for their dependence on six different GHG scenarios. Compared to higher emissions, lower result in smaller increases tropical upwelling with resultant reductions ozone the stratosphere and less severe cooling upper globally. Increases reactive nitrogen hydrogen that lead additional chemical destruction mainly play a role scenarios...
Coupled chemistry‐climate model simulations covering the recent past and continuing throughout 21st century have been completed with a range of different models. Common forcings are used for halogen amounts greenhouse gas concentrations, as expected under Montreal Protocol (with amendments) Intergovernmental Panel on Climate Change A1b Scenario. The Antarctic ozone hole compared using commonly diagnostics: minimum ozone, maximum area below 220 DU, mass deficit DU. Despite fact that processes...
Abstract. Major mid-winter stratospheric sudden warmings (SSWs) are the largest instance of wintertime variability in Arctic stratosphere. Because SSWs able to cause significant surface weather anomalies on intra-seasonal timescales, several previous studies have focused their potential future change, as might be induced by anthropogenic forcings. However, a wide range results been reported, from increase frequency an actual decrease. Several factors explain these contradictory results,...
Abstract We quantify the stratospheric injection of brominated very short‐lived substances (VSLS) based on aircraft observations acquired in winter 2014 above Tropical Western Pacific during CONvective TRansport Active Species Tropics (CONTRAST) and Airborne TRopopause EXperiment (ATTREX) campaigns. The overall contribution VSLS to bromine was determined be 5.0 ± 2.1 ppt, agreement with 5 3 ppt estimate provided World Meteorological Organization (WMO) Ozone Assessment report (WMO 2014), but...
The Southern Hemisphere (SH) zonal-mean circulation change in response to Antarctic ozone depletion is re-visited by examining a set of the latest model simulations archived for Chemistry-Climate Model Initiative (CCMI) project. All models reasonably well reproduce late 20th century. related SH-summer changes, such as poleward intensification westerly jet and expansion Hadley cell, are also captured. experiments exhibit quantitatively same multi-model mean trend, irrespective whether ocean...
Abstract. Understanding and modeling the large-scale transport of trace gases aerosols is important for interpreting past (and projecting future) changes in atmospheric composition. Here we show that there are large differences global-scale properties among models participating IGAC SPARC Chemistry–Climate Model Initiative (CCMI). Specifically, find up to 40 % timescales connecting Northern Hemisphere (NH) midlatitude surface Arctic Southern high latitudes, where mean age ranges between 1.7...