Effects of Parameterized Orographic Drag on Weather Forecasting and Simulated Climatology Over East Asia During Boreal Summer

Choi, Hyunjoo; Choi, Seok Reyol; Koo, Myung-Seo; Kim, Jung-Eun; Kwon, Young‐Hoo; Hong, Song‐You

doi:10.1002/2017jd026696

Cited by 15 publications

(14 citation statements)

References 22 publications

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“…The next‐generation global model KIM under development at the Korea Institute of Atmospheric Systems (KIAPS) is used in this study (Hong et al, ). KIM consists of a spectral element nonhydrostatic dynamic core on a cubed‐sphere and a state‐of‐the‐art physics package (Baek, ; Choi et al, ; Choi & Hong, ; Hong et al, ; Koo et al, ; Kwon & Hong, ; Park et al, ). The physics package of the most up‐to‐date KIM (version 3.1) is summarized in Table .…”

Section: Methodsmentioning

confidence: 99%

“…The physics package of the most up‐to‐date KIM (version 3.1) is summarized in Table . While most physics schemes originate from the Global/Regional Integrated Model System and the Weather Research and Forecast model but have been revised by KIAPS scientists (see the references in Table ), some physics schemes, such as radiation, gravity wave drag, and cloudiness, have been inventively developed at KIAPS (Baek, ; Choi et al, ; Choi & Hong, ; Park et al, ). The main focus of the present study is an understanding of the formation and dissipation of the shallow convective clouds via interaction with PBL mixings and their modification in order to improve the KIM performance.…”

Section: Methodsmentioning

confidence: 99%

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The Implications for Radiative Cloud Forcing via the Link Between Shallow Convection and Planetary Boundary Layer Mixing

Park

Kwon

2018

JGR Atmospheres

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In this study, the role of shallow convection and its links with planetary boundary layer (PBL) mixing is analyzed using a global atmospheric model. All of the simulations are conducted with the Korean Integrated Model (KIM), which is a next-generation operational global model for Korea Meteorological Administration. The simulation results show that the direct effect of shallow convection enhances additional vertical mixing inside the shallow convective layer, whereas its indirect effect reduces vertical mixing inside the PBL by changing the PBL height, thus vertical mixing strength. It is also found that the impact of shallow convection on low-level clouds is tightly related to the overlapping between PBL and shallowing convection. When the PBL height is located in the higher (lower) part of the shallow convective layer, the mixing across the top of the PBL becomes smaller (larger). Therefore, the diffusivity profile of KIM shallow convection scheme is modified according to the overlapping pattern of PBL mixing and shallow convection. The systematic bias of downward solar radiation at the surface of KIM is improved with the revised diffusivity profile of the shallow convection scheme proposed in this study. PARK AND KWON13,203

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Implications for Radiative Cloud Forcing via the Link Between Shallow Convection and Planetary Boundary Layer Mixing

Park

Kwon

2018

JGR Atmospheres

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“…The parameterization can help reduce systematic model biases, such as the cold-pole bias associated with too strong westerlies in the mid and high latitudes, and delayed breakdown of the polar vortex in Antarctica (Palmer et al 1986;Shin et al 2010;McLandress et al 2012;Pithan et al 2016;Garcia et al, 2017;Garfinkel and Oman 2018). Furthermore, medium-and short-range weather predictions can also benefit from OGW parameterization (Hong et al 2008;Zhong and Chen 2015;Choi and Hong 2015;Choi et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Parameterization of Directional Absorption of Orographic Gravity Waves and Its Impact on the Atmospheric General Circulation Simulated by the Weather Research and Forecasting Model

Xue

Teixeira

et al. 2019

Journal of the Atmospheric Sciences

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In this work, a new parameterization scheme is developed to account for the directional absorption of orographic gravity waves (OGWs) using elliptical mountain-wave theory. The vertical momentum transport of OGWs is addressed separately for waves with different orientations through decomposition of the total wave momentum flux (WMF) into individual wave components. With the new scheme implemented in the Weather Research and Forecasting (WRF) Model, the impact of directional absorption of OGWs on the general circulation in boreal winter is studied for the first time. The results show that directional absorption can change the vertical distribution of OGW forcing, while maintaining the total column-integrated forcing. In general, directional absorption inhibits wave breaking in the lower troposphere, producing weaker orographic gravity wave drag (OGWD) there and transporting more WMF upward. This is because directional absorption can stabilize OGWs by reducing the local wave amplitude. Owing to the increased WMF from below, the OGWD in the upper troposphere at midlatitudes is enhanced. However, in the stratosphere of mid- to high latitudes, the OGWD is still weakened due to greater directional absorption occurring there. Changes in the distribution of midlatitude OGW forcing are found to weaken the tropospheric jet locally and enhance the stratospheric polar night jet remotely. The latter occurs as the adiabatic warming (associated with the OGW-induced residual circulation) is increased at midlatitudes and suppressed at high latitudes, giving rise to stronger thermal contrast. Resolved waves are likely to contribute to the enhancement of polar stratospheric winds as well, because their upward propagation into the high-latitude stratosphere is suppressed.

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“…Since then, the parameterization of the effect of low‐level wave breaking, accompanied by nonlinear resonant amplification of both the hydrostatic and nonhydrostatic waves and lee‐wave trapping in the downstream regions, has resulted in a distinct improvement in both the medium‐range forecast and the seasonal ensemble prediction (Hong et al, ; Kim & Arakawa, ). Furthermore, the introduction of parameterization of the flow‐blocking drag increased the drag in the low troposphere, which led to directly improving the simulations of the low‐level wind and indirectly enhancing those of other synoptic features (Choi et al, ; Choi & Hong, ; Kim & Doyle, ; Lott & Miller, ; Zadra, ).…”

Section: Introductionmentioning

confidence: 99%

“…Choi and Hong (; hereafter C2015) recently updated a mesoscale orographic drag scheme by including the effects of flow‐blocking drag in a global forecast model. Although this approach improved both the weather forecasting and seasonal climatology in the model, the comparison with the results from the Working Group for Numerical Experimentation drag project shows that the SSO scheme of C2015 exerts a relatively large orographic drag in the lower‐to‐middle troposphere, due to the exaggeration in flow‐blocking drag (Choi et al, ; hereafter C2017). Note that the turbulent orographic form drag scheme was not considered in C2015 and C2017.…”

Section: Introductionmentioning

confidence: 99%

A Parameterization of Turbulent‐Scale and Mesoscale Orographic Drag in a Global Atmospheric Model

2018

Self Cite

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The effect of drag due to subgrid orography with turbulent scales, the so‐called turbulent orographic form drag, is introduced by revising the surface exchange coefficient for momentum, to alleviate the overall positive bias in wind speed in the near‐surface and low‐level troposphere over land. Also, the excessive flow‐blocking drag, responsible for negative biases in low‐level wind speed over highly complex terrains, is abated by modifying the height of the blocked layer, which is achieved without a significant deficiency of total surface drag because of additional turbulent orographic form drag. The impact of the revised subgrid‐scale orography parameterization is investigated on the medium‐range forecast (January and July 2016) and seasonal ensemble prediction (June–August 2013 and December 2013 to February 2014) regarding stress partitioning and skill scores. With the revised subgrid‐scale orography schemes, total surface stress and its partitioning resemble those of the ERA‐Interim. Meanwhile, the turbulent (mesoscale orographic) stress is enhanced (reduced) due to the additional turbulent orographic form drag (weakened flow‐blocking drag). For the medium‐range forecast, systematic biases in near‐surface and low‐level wind speed are satisfactorily rectified by adding turbulent orographic form drag (reducing flow‐blocking drag) in the regions with positive biases across the land (negative biases over highly complex terrains) against reanalysis, as well as observation data. Seasonal simulation is also improved because the weak polar night jet and the corresponding warm pole biases are alleviated by the reductions of the orographic gravity wave and resolved wave drag, which are driven by the revised low‐level drag.

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Effects of Parameterized Orographic Drag on Weather Forecasting and Simulated Climatology Over East Asia During Boreal Summer

Cited by 15 publications

References 22 publications

The Implications for Radiative Cloud Forcing via the Link Between Shallow Convection and Planetary Boundary Layer Mixing

The Implications for Radiative Cloud Forcing via the Link Between Shallow Convection and Planetary Boundary Layer Mixing

Parameterization of Directional Absorption of Orographic Gravity Waves and Its Impact on the Atmospheric General Circulation Simulated by the Weather Research and Forecasting Model

A Parameterization of Turbulent‐Scale and Mesoscale Orographic Drag in a Global Atmospheric Model

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