A5107963335- Oceanographic and Atmospheric Processes
- Climate variability and models
- Meteorological Phenomena and Simulations
- Atmospheric aerosols and clouds
- Aeolian processes and effects
- Marine and coastal ecosystems
- Particle Dynamics in Fluid Flows
- Tropical and Extratropical Cyclones Research
- Fluid Dynamics and Turbulent Flows
- Ocean Waves and Remote Sensing
- Arctic and Antarctic ice dynamics
- Atmospheric and Environmental Gas Dynamics
- Wind and Air Flow Studies
- Neural Networks and Applications
- Atmospheric chemistry and aerosols
- Geophysics and Gravity Measurements
- Methane Hydrates and Related Phenomena
- Coastal and Marine Dynamics
- Geology and Paleoclimatology Research
- Plant Water Relations and Carbon Dynamics
- Geological formations and processes
- Granular flow and fluidized beds
- nanoparticles nucleation surface interactions
- Solar and Space Plasma Dynamics
- Vehicle emissions and performance
Yonsei University
2014-2024
Leibniz University Hannover
2004
NOAA Oceanic and Atmospheric Research
2002
Arizona State University
1990-1993
Johns Hopkins University
1990
Abstract This paper proposes a revised vertical diffusion package with nonlocal turbulent mixing coefficient in the planetary boundary layer (PBL). Based on study of Noh et al. and accumulated results behavior Hong Pan algorithm, algorithm that is suitable for weather forecasting climate prediction models developed. The major ingredient revision inclusion an explicit treatment entrainment processes at top PBL. new called Yonsei University PBL (YSU PBL). In one-dimensional offline test...
An improved model for the oceanic boundary layer is presented in view of recent observation microstructure upper ocean including high dissipation rate near sea surface. In new surface conditions both turbulent kinetic energy flux and roughness length scale are modified. The parameterization stratification effects on turbulence improved, convective process reformulated basis uniform temperature velocity profiles within mixed layer. Evolutions data Patches Experiment as well time series over...
Large eddy simulation (LES) of the ocean mixed layer was performed in which both wave breaking and Langmuir circulation are realized. Wave represented by random forcing consistent with observed near-surface turbulence, realized Craig–Leibovich vortex force. High- resolution simulations were carried out using parallel computing or without each contribution, circulation, an aim to clarify their respective roles layer. The effects found be mainly limited zone upper few meters. circulations...
In this paper, a new Lagrangian cloud model (LCM) is introduced in which the flow field simulated by large-eddy simulation, and droplets are treated as particles responding to field. order handle extremely large number of within cloud, concept super-droplet, represents real same size, introduced, contributing called weighting factor. A novel method developed realize collision/coalescence droplets, consequent variation droplet spectrum represented terms modification radius factor...
Abstract This paper examines characteristic changes in North Pacific sea surface temperature (SST) variability during the boreal winter (December–February) for two subperiods (1956–88 and 1977–2009) which 1976/77 1988/89 climate transitions occurred. It is found that decadal oscillation (PDO)-like SST plays a dominant role transition, while both Gyre Oscillation (NPGO)-like PDO-like contribute to transition. Furthermore, leading mode from period 1956–88 NPGO-like 1977–2009, indicative of an...
Abstract The mechanism of raindrop formation in a shallow cumulus cloud is investigated using Lagrangian model (LCM). analysis focused on how and under which conditions droplet grows to by tracking the history individual droplets. It found that rapid collisional growth, leading formation, triggered when single droplets with radius 20 μm appear region near top, characterized large liquid water content, strong turbulence, mean size, broad drop size distribution (DSD), high supersaturations....
Abstract The effect of Langmuir circulation (LC) on vertical mixing is parameterized in the ocean mixed layer model (OMLM), based analysis large-eddy simulation (LES) results. Parameterization LC effects carried out terms modifications length scale as well inclusion contribution from Stokes force momentum and TKE equations. performance new OMLM examined by comparing with LES results, together sensitivity tests for empirical constants used parameterization. then applied to general (OGCM)...
Abstract Cloud microphysics parameterizations for shallow cumulus clouds are analyzed based on Lagrangian cloud model (LCM) data, focusing autoconversion and accretion. The accretion rates, A C, respectively, calculated directly by capturing the moment of conversion individual droplets from to raindrops, it results in reproduction formulas C first time. Comparison with various reveals closest agreement Tripoli Cotton, such as , where mixing ratio number concentration droplets, is threshold...
Experiments were carried out to study the sedimentation of a two-dimensional particle cloud. When large number particles (glass beads) uniform size are released from opening into column fresh water, mixture initially descends as thermal; however, after some time, start settling individually, thus leaving parent fluid behind. For given type particle, critical depth zc at which this transition occurs, measured virtual origin, was found change zcws/ν∼(Q/νws)α, with α≂0.3, where ws is terminal...
A new ocean mixed layer model (OMLM) was embedded into an general circulation (OGCM) with the aim of providing OGCM that is ideal for application to a climate by predicting sea surface temperature (SST) more accurately. The results from OMLM showed significant improvement in prediction SST compared cases constant vertical mixing and scheme Pacanowski Philander. More accurate reduces magnitude restoring term heat flux thus provides simulated can be coupled atmospheric naturally. also shown...
Abstract The formation of a diurnal thermocline in the ocean mixed layer under stabilizing buoyancy flux was simulated successfully by large-eddy simulation, reproducing various features consistent with observation. analysis simulation result revealed that passes through two different phases: (formation stage) and increasing thickness thereafter (growth stage). Turbulent kinetic energy (TKE) dominates TKE production within layer, but turbulence maintained shear at causes stratification below...
Abstract Analysis of large eddy simulation data reveals that Langmuir circulation (LC) induces a significant enhancement the mixed layer deepening, only if depth (MLD) h is shallow and buoyancy jump across it ΔB small, when simulations are initiated by applying wind stress to motionless with stratification. The difference in entrainment rate between cases without LC decreases hΔB/υL2, where υL velocity scale LC. ratio mixing length l close 1 for larger Rt [=(Nl0/q)2; > ∼1], but...
Abstract The representation of transient air‐sea interactions is critical to the prediction sea surface temperature diurnal cycle and daily variability. This study develops a multilevel upper ocean model more realistically resolve these interactions. based on one‐dimensional turbulence kinetic energy closure developed by Noh et al . [2011], incorporates new numerical techniques improved schemes for physics. primary improvements include: (1) momentum flux penetration scheme better depict...
The settling process of suspended particles in the turbulent flow was investigated by analyzing Lagrangian motion a large number ocean mixed layer simulated eddy simulation (LES), focusing on role Langmuir circulation (LC). At beginning, released near surface are swept down rapidly following downward jets presence LC, contrary to case horizontally uniform propagation absence it. strong vertical mixing LC keeps particle concentration almost after initial period while its mean continues...
Abstract Analysis of large-eddy simulation data the ocean mixed layer under convection reveals that contribution from wind stress decreases with time as a result inertial oscillation in extratropical and it leads to rapid increase bulk gradient Richardson number at depth. The criteria for deepening widely used models, such Niiler–Kraus (NK) model, Price–Weller–Pinkel (PWP) K-profile parameterization (KPP) are examined view these results, its implication on model predictability is discussed.
An atmosphere‐ocean mixed layer coupled model is developed to predict the diurnal variability of sea surface temperature (SST). For this purpose, a new developed, which able reproduce realistic profiles under various atmospheric conditions, ranging from formation thermocline strong wind appearance near stratification weak wind. The predicted warming SST (ΔSST) compared with satellite and buoy data in aspects, including scatterplots, time series, probability density functions ΔSST, order...
Abstract. The roughness sublayer (RSL) is one compartment of the surface layer (SL) where turbulence deviates from Monin–Obukhov similarity theory. As computing power increases, model grid sizes approach gray zone in energy-containing range and lowest located within RSL. From this perspective, RSL has an important implication atmospheric modeling research. However, it not been explicitly simulated mesoscale models. This study incorporates proposed by Harman Finnigan (2007, 2008) into Jiménez...
Abstract Large-eddy simulation of the oceanic mixed layer showed that Langmuir circulation (LC) is weakened under surface heating and ultimately broken down if intensity becomes sufficiently strong. The critical condition for breakdown LC was mainly determined by Hoenikker number Ho, transition occurs in range Ho ∼ 1–2. leads to a drastic change characteristics layer, such as variation rms horizontal velocities with time, ratio spectra vertical velocity field, pitch. stability suggested...
Inclusion of the Prandtl number variation with stratification in a vertical mixing scheme helps to improve simulation tropical Pacific using an ocean general circulation model (OGCM) significantly, by mitigating various persistent problems OGCM such as warm and cold biases central eastern equatorial Pacific, too weak deep Equatorial Undercurrent insufficient zonal slope thermocline. It also makes distributions temperature velocity along equator more realistic. A similar test different...
The seasonal variation of eddy kinetic energy (EKE) the North Pacific Subtropical Countercurrent (STCC) was investigated by analyzing data from an eddy‐resolving OGCM with horizontal resolution 1/12° in comparison satellite altimetry data. Although annual cycle simulated EKE whole STCC domain showed agreement data, a maximum spring and minimum fall, it revealed latitudinal dependence; that is, near 19°N level is higher summer than winter, but winter north 20°N. also reproduced two branches...
Abstract Seasonal variations of the upper ocean, such as mixed layer depth (MLD) and sea surface temperature (SST), responding to atmospheric forcing in North Pacific (10°N–50°N), are investigated by analyzing Argo NCEP/NCAR reanalysis 1 data. The OAFlux data also used for comparison. During early heating period high‐latitude ocean north 30°N, where a seasonal thermocline is formed above deep under strong heating, MLD h found be scaled , L Monin‐Obukhov length scale λ Ekman scale. On other...