A5023155771- Meteorological Phenomena and Simulations
- Ionosphere and magnetosphere dynamics
- Climate variability and models
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Tropical and Extratropical Cyclones Research
- Ocean Waves and Remote Sensing
- Wind and Air Flow Studies
- Solar and Space Plasma Dynamics
- Atmospheric aerosols and clouds
- Atmospheric and Environmental Gas Dynamics
- Oceanographic and Atmospheric Processes
- Geomagnetism and Paleomagnetism Studies
- Fluid Dynamics and Turbulent Flows
- Seismic Waves and Analysis
- Astro and Planetary Science
- Reservoir Engineering and Simulation Methods
- Atmospheric chemistry and aerosols
- Precipitation Measurement and Analysis
- Air Traffic Management and Optimization
- Planetary Science and Exploration
- Coastal and Marine Dynamics
- Fluid Dynamics and Vibration Analysis
- Urban Heat Island Mitigation
- Geological and Geophysical Studies
Yonsei University
2015-2024
NSF National Center for Atmospheric Research
2019
Seoul National University
1994-1995
Goddard Space Flight Center
1993
North Carolina State University
1991-1993
This study numerically investigates dry and moist convection forced by an urban heat island using a two-dimensional, nonhydrostatic, compressible model with explicit cloud microphysical processes (Advanced Regional Prediction System). The is represented specified heating. Extensive numerical experiments various heating amplitudes, representing the intensity of island, uniform basic-state wind speeds, relative humidities, are performed to examine their roles in characterizing urban-induced...
Gravity wave momentum flux induced by thermal forcing representing latent heating due to cumulus convection is investigated analytically from a viewpoint of subgrid-scale drag for the large-scale flow, and possible way parameterize in models proposed. For formulations its vertical derivative, two-dimensional, steady-state, linear perturbations uniform basic-state wind are considered. The calculated zero below bottom, varies with height region, remains constant above top value. sign at...
Abstract The characteristics of aviation turbulence over South Korea during the recent five years (2003–08, excluding 2005) are investigated using pilot reports (PIREPs) accumulated by Aviation Meteorological Agency (KAMA). Among total 8449 PIREPs, 4607 (54.53%), 1646 (19.48%), 248 (2.94%), 7 (0.08%), and 1941 (22.97%) correspond to categories null, light, moderate, severe, missing, respectively. In terms temporal variations, annual number events increased from 2003 2008, seasonal frequency...
A circulating water channel is constructed to examine urban street-canyon flow. In the cases of an even-notch street canyon in which model buildings on both sides have equal heights, one vortex observed canyons with aspect ratios 1 and 1.5, two counterrotating vortices are 2, 2.4, 3. all cases, center (or upper vortex) located slightly downstream center, downward motion stronger than upward upstream. The magnitudes maximum updraft downdraft almost independent ratio. case a stepup notch,...
Characteristics of gravity waves induced by mesoscale convective storms and the wave sources are investigated using a two-dimensional cloud-resolving numerical model. In nonlinear moist (control) simulation, system reaches quasi-steady state after 4 h in which cells periodically regenerated from gust front updraft. storms, there two types forcing: forcing form divergences momentum heat flux, diabatic forcing. The magnitude source is 2 to 3 times larger than source, especially upper...
Abstract The phase-speed spectrum of momentum flux by convectively forced internal gravity waves is analytically formulated in two- and three-dimensional frameworks. For this, a three-layer atmosphere that has constant vertical wind shear the lowest layer, uniform above, piecewise buoyancy frequency forcing region above considered. wave at cloud top determined spectral combination wave-filtering resonance factor diabatic forcing. basic-state stability configuration restricts effectiveness...
Characteristics of stratospheric gravity waves generated by Typhoon Ewiniar (2006) are investigated using the Weather Research and Forecasting (WRF) model, high‐resolution European Center for Medium‐Range Forecasts (ECMWF) analysis data, Atmospheric Infrared Sounder (AIRS) observations. In numerical simulations, convective forcing in troposphere shows nearly isotropic features, which propagate various directions with a maximum typhoon‐moving direction. However, anisotropic since only wave...
Abstract On 2 April 2007, nine cases of moderate-or-greater-level clear-air turbulence (CAT) were observed from pilot reports over South Korea during the 6.5 h 0200 to 0830 UTC. Those CAT events occurred in three different regions Korea: west coast, Jeju Island, and eastern mountain areas. The characteristics possible mechanisms are investigated using Weather Research Forecasting model. simulation consists six nested domains focused on Korean Peninsula, with finest horizontal grid spacing...
A convective gravity‐wave parameterization (GWP) is introduced in the Met Office Unified Model (MetUM) addition to existing GWPs, and tropical quasi‐biennial oscillation (QBO) simulated. We replace a significant amount of momentum flux, which originally launched by background GWP, with (CGW) flux broad wave spectrum that explicitly determined sources. Compared experiment without CGW parameterization, including results greater variability duration each phase QBO, closer observed. Including...
Abstract The Quasi‐Biennial Oscillation initiative (QBOi) is a model intercomparison programme that specifically targets simulation of the QBO in current global climate models. Eleven models or versions participated QBOi study have upper boundaries above mesosphere and therefore simulate region where stratopause semiannual oscillation (SAO) dominant mode variability zonal winds tropical stratosphere. Comparisons SAO simulations these are presented here. These show amplitudes phases...
Abstract In this study, we estimate atmospheric turbulence in the free atmosphere terms of Thorpe scale ( L T ) and eddy dissipation rate ε using U.S. high vertical‐resolution radiosonde data over 4 years (September 2012 to August 2016) at 68 operational stations. addition, same calculations are conducted for 12 (October 2005 September 2017) four stations among These have a vertical resolution approximately 5 m extend an altitude 33 km, thus, can be retrieved entire troposphere lower...
Abstract A Lagrangian spectral parameterization of gravity wave drag (GWD) induced by cumulus convection (GWDC) is developed based on ray theory and several assumptions implemented into the NCAR Whole Atmosphere Community Climate Model. The calculates explicitly (GW) propagation that has been treated too simply in existing column-based parameterizations. For comparison with parameterization, a hydrostatic Boussinesq version used present study. One-day convective GW-packet trajectories...
Abstract The convective source and momentum flux spectra of a parameterization gravity wave drag (GWDC) are validated in three-dimensional spectral space using mesoscale numerical simulations for various ideal real storms. From this, two important free parameters included the GWDC parameterization—the moving speed propagation direction—are determined. In simulations, spectrum shows nearly isotropic features terms magnitude, its primary peak any azimuthal direction occurs at phase that equals...
Abstract. Convective gravity wave (GW) sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any analysis therefore compromises between spectral spatial resolution. Future satellite borne limb imagers will for first provide real 3-D volumes observations. These be however limited which impose further constraints on technique. In this study three dimensional few-wave approach fitting sinusoidal to is introduced. The method applied simulated GWs...
Abstract The contributions of the equatorial waves to quasi‐biennial oscillation (QBO) are investigated using Hadley Centre Global Environment Model version 2 (HadGEM2). A gravity wave parameterization that couples its source spectrum convection is used. modes identified in spectral domain, based on their distinct characteristics associated with momentum and heat fluxes. Kelvin parameterized (PGWs) transport westerly into stratosphere by ∼0.35 0.8 mPa, respectively, while easterly carried...
Abstract. The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on estimation conventional pressure-level data sets, Kelvin (3–9 m s−1 month−1) dominates net all wave modes (3–11 in easterly-to-westerly transition phase at 30 hPa. In opposite phase, small (1–5 month−1). By comparing results with those from native model-level set ERA-Interim reanalysis, it suggested that use conventional-level causes to be underestimated...
Abstract In a companion paper, the Multiscale Gravity Wave Model (MS-GWaM) has been introduced and its application to global model as transient subgrid-scale parameterization described. This paper focuses on examination of intermittency gravity waves (GWs) modeled by MS-GWaM. To introduce variability in wave sources, convective GW sources are formulated, using diabatic heating diagnosed convection parameterization, they coupled MS-GWaM addition flow-independent source extratropics accounting...
Abstract The role of gravity waves (GWs) in a sudden stratospheric warming (SSW) event that occurred January 2009 (SSW09) is investigated using the MERRA-2 dataset. Nearly 2 weeks prior to central date (lag = 0), at which zonal-mean zonal wind 10 hPa and 60°N first becomes negative, westward GW drag (GWD) significantly enhanced lower mesosphere stratosphere. At 5 days before lag 0, planetary (PWs) wavenumber (ZWN-2) stratosphere are enhanced, while PWs ZWN-1 weakened, evident from amplitudes...
Abstract. In January 2020, unexpected easterly winds developed in the downward-propagating westerly quasi-biennial oscillation (QBO) phase. This event corresponds to second QBO disruption history, and it occurred 4 years after first of 2015/16. According several previous studies, strong midlatitude Rossby waves propagating from Southern Hemisphere (SH) during SH winter likely initiated disruption; nevertheless, wave forcing that finally led has not been investigated. this study, we examine...
Abstract Atmospheric predictability from subseasonal to seasonal time scales and climate variability are both influenced critically by gravity waves (GW). The quality of regional global numerical models relies on thorough understanding GW dynamics its interplay with chemistry, precipitation, clouds, across many scales. For the foreseeable future, GWs other relevant processes will remain partly unresolved, continue rely parameterizations. Recent model intercomparisons studies show that...
Typhoon Rusa (2002) is simulated using a three‐dimensional mesoscale model (MM5), and the characteristics of gravity waves generated by convection associated with typhoon are investigated. The in stratosphere propagate two directions, northwestward southeastward according to convective bands propagating same although itself moves north‐northeastward. Spectral analyses show that inertio‐gravity (IGWs) have dominant horizontal wavelength 300–600 km, vertical 3–11 period 6–11 hrs. A large...
Abstract At 1034 UTC 2 September 2007, a commercial aircraft flying from Jeju, South Korea, to Osaka, Japan, at an altitude of approximately 11.2 km encountered severe turbulence above deep convection. To investigate the characteristics and generation mechanism this event, real atmosphere is simulated using Weather Research Forecasting model with six nested domains, finest which horizontal grid spacing 120 m. The reproduces well observed large-scale flows location timing along evolving Three...
Abstract The forecast skill of upper-level turbulence diagnostics is evaluated using available observations [viz., pilot reports (PIREPs)] over East Asia. six years (2003–08) PIREPs used in this study include null, light, and moderate-or-greater intensity categories. are a subset indices the Graphical Turbulence Guidance (GTG) system. To investigate optimal performance component GTG combinations Asia, various statistical evaluations sensitivity tests performed. examine dependency system on...
Abstract. This paper describes a comprehensive observational filter for satellite infrared limb sounding of gravity waves. The considers instrument visibility and observation geometry with high level accuracy. It contains four main processes: filter, projection the wavelength on tangent-point track, aliasing effect, calculation observed vertical wavelength. geometries SABER (Sounding Atmosphere using Broadband Emission Radiometry) HIRDLS (High Resolution Dynamics Limb Sounder) are mimicked....
The realism of ray‐based spectral parameterization convective gravity wave drag, which considers the updated moving speed source and multiple propagation directions, is tested against Atmospheric Infrared Sounder (AIRS) onboard Aqua satellite. Offline calculations are performed using global reanalysis data for January July 2005, temperature variances (GWTVs) calculated at z = 2.5 hPa (unfiltered GWTV). AIRS‐filtered GWTV, directly compared with AIRS, by applying AIRS visibility function to...