A5042467795- Atmospheric Ozone and Climate
- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Meteorological Phenomena and Simulations
- Ionosphere and magnetosphere dynamics
- Heat Transfer and Boiling Studies
- Solar and Space Plasma Dynamics
- Atmospheric chemistry and aerosols
- Oceanographic and Atmospheric Processes
- Geophysics and Gravity Measurements
- Heat Transfer and Optimization
- Spacecraft and Cryogenic Technologies
- Complex Systems and Time Series Analysis
- Geological and Tectonic Studies in Latin America
- Urban Heat Island Mitigation
- Phase Equilibria and Thermodynamics
- Recommender Systems and Techniques
- Statistical and numerical algorithms
- Astro and Planetary Science
- Advanced Bandit Algorithms Research
- Environmental Impact and Sustainability
- Thermodynamic properties of mixtures
- Food Chemistry and Fat Analysis
- Customer churn and segmentation
- Forecasting Techniques and Applications
Aichi University of Education
2015-2025
Osaka University
2019
University of Washington
2003-2006
University of Washington Applied Physics Laboratory
2005
Kyoto University
1999-2005
Kitasato University
2004
Abstract The stratosphere can have a significant impact on winter surface weather subseasonal to seasonal (S2S) timescales. This study evaluates the ability of current operational S2S prediction systems capture two important links between and troposphere: (1) changes in probabilistic skill extratropical by precursors tropics troposphere (2) predictability extratropics after stratospheric weak strong vortex events. Probabilistic exists for events when including tropospheric over North Pacific...
Abstract The stratosphere has been identified as an important source of predictability for a range processes on subseasonal to seasonal (S2S) time scales. Knowledge about S2S within the is however still limited. This study evaluates what extent in extratropical exists hindcasts operational prediction systems database. found exhibit extended compared troposphere. Prediction with higher stratospheric skill tend also analysis includes assessment events, including early and midwinter sudden...
Abstract Experiments with Whole Atmosphere Community Climate Model (WACCM) under perpetual January conditions indicate that stratospheric sudden warmings (SSWs) are twice as likely to occur in El Niño winters than La Niña winters, basic agreement the limited observational dataset. Tropical SST anomalies mimic and lead changes shape of probability distribution functions (PDFs) day-to-day variability, resulting a warmer pole weaker vortex on average for conditions. The tropical forcing induces...
Abstract Major sudden stratospheric warmings (SSWs), vortex formation, and final breakdown dates are key highlight points of the polar vortex. These phenomena relevant for stratosphere‐troposphere coupling, which explains interest in understanding their future changes. However, up to now, there is not a clear consensus on projected changes robust, particularly Northern Hemisphere, possibly due short data record or relatively moderate CO 2 forcing. The new simulations performed under Coupled...
Using a stratospheric zonal wind data archive of radiosonde observations at equatorial stations for 1953–2008, this study investigates whether or not signals the quasi‐biennial oscillation (QBO) vary with El Niño–Southern Oscillation (ENSO) cycle. The QBO are represented by trajectories in phase space spanned time series two leading modes variability. Two properties trajectories, distance from origin and rate change argument, which proxies amplitude progression QBO, respectively, first...
Abstract The Quasi‐biennial Oscillation (QBO) dominates the interannual variability of tropical stratosphere and influences other regions atmosphere. high predictability QBO implies that its teleconnections could lead to increased skill seasonal decadal forecasts provided relevant mechanisms are accurately represented in models. Here modelling sampling uncertainties examined using a multi‐model ensemble QBO‐resolving atmospheric general circulation models have carried out set coordinated...
Abstract This study explores forecasts for five distinctive major stratospheric sudden warmings (MSSWs) using subseasonal‐to‐seasonal prediction data with lead times up to about 2 weeks. Results reveal model‐to‐model variability of the forecasts, as some models, such European Centre Medium‐Range Weather Forecasts and National Centers Environmental Prediction forecast MSSWs better. also demonstrate greater difficulty forecasting vortex split (three five) than displacement (the other two). It...
Abstract. The stratosphere can be a source of predictability for surface weather on timescales several weeks to months. However, the potential predictive skill gained from stratospheric variability limited by biases in representation processes and coupling with climate forecast systems. This study provides first systematic identification model across wide range subseasonal It is found that many systems considered exhibit warm global-mean temperature lower middle stratosphere, too strong/cold...
Abstract This study investigates the predictability of three major stratospheric sudden warmings (MSSWs) vortex split type: Southern Hemisphere case in September 2002 and two Northern cases January 2009 February 1989. The author examines changes MSSWs with lead time, as well connection to lower-atmospheric features for pre- post-MSSW periods. Japan Meteorological Agency (JMA)’s 1-month ensemble hindcast (HC) experiment data are compared Japanese 25-year Reanalysis Project (JRA-25)/JMA...
Abstract. This study uses an ensemble of climate model experiments coordinated by the Quasi-Biennial Oscillation initiative (QBOi) to analyze Madden-Julian (MJO) in presence either perpetual El Niño or La Niña sea surface temperatures during boreal winter. In addition prescribed Southern (ENSO) conditions, nine models internally generate QBOs, meaning each may influence MJO. The diagnostics used include wavenumber-frequency spectra tropical convective and dynamical fields, measures MJO...
Abstract. Two-way coupling between the stratosphere and troposphere is recognized as an important source of subseasonal-to-seasonal (S2S) predictability can open windows opportunity for improved forecasts. Model biases can, however, lead to a poor representation such processes; drifts in model's circulation related model biases, resolution, parameterizations have potential feed back on affect stratosphere–troposphere coupling. We introduce set diagnostics using readily available data that be...
Abstract. This study examines Quasi-Biennial Oscillation (QBO) teleconnections and their modulation by the El Niño-Southern (ENSO), using a multi-model ensemble of Atmospheric Processes And Role in Climate (APARC) QBO initiative (QBOi) models. Some difficulties arise examining observed QBO-ENSO from distinguishing ENSO influences outside region, due to aliasing between over historical record. To separate signals, simulations are conducted with annually-repeating prescribed sea-surface...
Abstract The effect of stratospheric radiative damping time scales on variability and stratosphere–troposphere coupling is investigated in a simplified global circulation model by modifying the vertical profile stratosphere while holding it fixed troposphere. Perpetual-January conditions are imposed, with sinusoidal topography zonal wavenumber 1 or 2. depth duration simulated sudden warmings closely track lower-stratospheric scales. Simulations most realistic profiles exhibit extended...
Abstract This study investigates the predictability of major stratospheric sudden warmings (MSSWs) with a chief question: how far in advance can MSSWs be forecasted? An average picture and case-to-case variations MSSW are revealed by analyzing operational 1-month ensemble prediction data Japan Meteorological Agency from 2001/02 to 2012/13 comparison Japanese 55-year Reanalysis Project (JRA-55) data. The further related planetary wave forcing (PWF) troposphere stratosphere. A contingency...
Abstract This paper presents statistical analyses of possible associations between major stratospheric sudden warming (SSW) and tropospheric blocking events in the Northern Hemisphere (NH) with 49 yr NCEP–NCAR reanalysis data from 1957/58 to 2005/06. Using a random shuffling or “bootstrap” method, these explore two hypotheses claiming that occur preferentially last longer association SSWs (pre- post-SSW periods are considered separately). In defined randomly redistributed evaluate...
Abstract This study explores a possible connection between predictability variations of major stratospheric sudden warmings ( MSSWs ) during Northern winter and the geometry polar vortex. We compare 1‐month hindcasts from 1979 to 2012 Japan Meteorological Agency Japanese 55‐year Reanalysis data. Results show that error medium range (≈14 day) forecasts 21 actual do depend on observed vortex: errors are larger for vortex split when is highly stretched as characterized by high aspect ratio an...
Abstract Reanalysis data provide a good estimate of global atmospheric temperature and wind fields. However, the available reanalysis datasets reveal nonnegligible discrepancies in their mean state temporal variability. In this study, quality eight is evaluated by examining dynamical consistency extratropical stratosphere. The quantified computing residual zonal-mean momentum equation. generally small lower stratosphere, especially at below 30 hPa, but increases significantly aloft both...
<p>Major sudden stratospheric warmings (SSWs), vortex formation and final breakdown dates are key highlight points of the polar vortex. These phenomena relevant for stratosphere-troposphere coupling, which explains interest in understanding their future changes. However, up to now, there is not a clear consensus on projected changes robust, particularly Northern Hemisphere, possibly due short data record or relatively moderate CO<sub>2</sub> forcing....
Internal variability of a troposphere–stratosphere coupled system is investigated in series numerical experiments with simple global circulation model under perpetual winter condition. In order to examine the relative importance forced planetary waves interaction zonal mean flow and baroclinic disturbances, amplitude sinusoidal surface topography wavenumber 1 or 2 swept as an experimental parameter; 1000-day integrations are performed for 110 combinations external parameters. Intraseasonal...
Internal variations of the troposphere–stratosphere coupled system with intraseasonal and interannual timescales are investigated in a parameter sweep experiment simple global circulation model under periodic annual forcing. In order to examine role forced planetary waves variations, amplitude sinusoidal surface topography is chosen as an experimental parameter; 100-yr integrations performed for each 10 topographic amplitudes from 0 3000 m. The extratropical stratospheric depends on its mean...
The effects of the equatorial quasi-biennial oscillation (QBO) on stratospheric sudden warming (SSW) events are investigated by performing long time integrations with a simple global circulation model under perpetual winter condition. Zonal momentum forcing is imposed to produce westerly or easterly phase QBO in stratosphere, and parameter that determines strength direction swept for nine values as an experimental parameter. polar night jet weaker stratosphere warmer runs "QBO wind" forcing,...
Interannual variation is a year-to-year which defined as deviation from the climatological annual cycle of meteorological quantity. It can be caused by an external forcing atmospheric circulation system, or generated internally within system. On other hand, intraseasonal low-frequency season, and it basically considered to result internal processes may exist even under constant conditions. In this article, some observational facts on interannual variations polar stratosphere are presented,...
Abstract. The agreement between reanalysis datasets, in terms of the zonal-mean momentum budget, is evaluated during sudden stratospheric warming (SSW) events. It revealed that there a good among datasets lower stratosphere and troposphere concerning zonal wind, but less so upper stratosphere. Forcing equation are also relatively similar atmosphere, their uncertainties typically larger than zonal-wind tendency. Similar to tendency, forcing degraded Discrepancies reanalyses increase onset SSW...