scholarly journals Supplementary material to "The impact threshold of the aerosol radiation forcing on the boundary layer structure in the pollution region"

2020 ◽  
Author(s):  
Dandan Zhao ◽  
Jinyuan Xin ◽  
Chongshui Gong ◽  
Jiannong Quan ◽  
Yuesi Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Layer Structure ◽  
Boundary Layer Structure ◽  
Supplementary Material ◽  
The Impact

Impact of Parameterized Boundary Layer Structure on Tropical Cyclone Rapid Intensification Forecasts in HWRF

2017 ◽  
Vol 145 (4) ◽  
pp. 1413-1426 ◽  
Author(s):  
Jun A. Zhang ◽  
Robert F. Rogers ◽  
Vijay Tallapragada
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Inner Core ◽  
Layer Structure ◽  
Intensity Change ◽  
Rapid Intensification ◽  
Near Surface ◽  
Boundary Layer Structure ◽  
Tangential Wind ◽  
The Impact

Abstract This study evaluates the impact of the modification of the vertical eddy diffusivity (Km) in the boundary layer parameterization of the Hurricane Weather Research and Forecasting (HWRF) Model on forecasts of tropical cyclone (TC) rapid intensification (RI). Composites of HWRF forecasts of Hurricanes Earl (2010) and Karl (2010) were compared for two versions of the planetary boundary layer (PBL) scheme in HWRF. The results show that using a smaller value of Km, in better agreement with observations, improves RI forecasts. The composite-mean, inner-core structures for the two sets of runs at the time of RI onset are compared with observational, theoretical, and modeling studies of RI to determine why the runs with reduced Km are more likely to undergo RI. It is found that the forecasts with reduced Km at the RI onset have a shallower boundary layer with stronger inflow, more unstable near-surface air outside the eyewall, stronger and deeper updrafts in regions farther inward from the radius of maximum wind (RMW), and stronger boundary layer convergence closer to the storm center, although the mean storm intensity (as measured by the 10-m winds) is similar for the two groups. Finally, it is found that the departure of the maximum tangential wind from the gradient wind at the eyewall, and the inward advection of angular momentum outside the eyewall, is much larger in the forecasts with reduced Km. This study emphasizes the important role of the boundary layer structure and dynamics in TC intensity change, supporting recent studies emphasizing boundary layer spinup mechanism, and recommends further improvement to the HWRF PBL physics.

scholarly journals The impact threshold of the aerosol radiation forcing on the boundary layer structure in the pollution region

2020 ◽  
Author(s):  
Dandan Zhao ◽  
Jinyuan Xin ◽  
Chongshui Gong ◽  
Jiannong Quan ◽  
Yuesi Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Layer Structure ◽  
Atmospheric Environment ◽  
Absolute Difference ◽  
Air Pollution Control ◽  
Aerosol Radiative Forcing ◽  
Boundary Layer Structure ◽  
Improvement Measures ◽  
The Impact

Abstract. Recently, there has been increasing interest in the relation between particulate matter (PM) pollution and atmospheric boundary layer (ABL) structure. However, this has yet to be fully understood because most studies have been superficial. This study aimed to qualitatively assess the interaction between PM and ABL structure in essence, and to further quantitatively estimate the effects of aerosol radiative forcing (ARF) on the ABL structure. Multi-episode contrastive analysis stated the key to determining whether haze outbreak or dissipation was the ABL structure (i.e., stability and turbulence kinetic energy (TKE)) satisfied relevant conditions. However, it seemed that the ABL structure change was in turn highly related to the PM level and ARF. |SFC-ATM| (SFC and ATM is respectively the ARF at the surface and interior of the atmospheric column) is the absolute difference between ground and atmosphere layer ARFs, and the change in |SFC-ATM| is linearly related to the PM mass concentration. However, the influence of ARF on the boundary layer structure is nonlinear. With increasing |SFC-ATM|, the TKE level exponentially decreased, which was notable in the lower layers/ABL but disappeared above the ABL. Moreover, the threshold of the ARF effects on the ABL structure was determined for the first time, namely, once |SFC-ATM| exceeded ~ 55 W m−2, the ABL structure would quickly stabilize and would thereafter change little with increasing ARF. The threshold of the ARF effects on the boundary layer structure could provide useful information for relevant atmospheric environment improvement measures and policies, such as formulating the objectives of phased air pollution control.

scholarly journals The impact threshold of the aerosol radiative forcing on the boundary layer structure in the pollution region

2021 ◽  
Vol 21 (7) ◽  
pp. 5739-5753
Author(s):  
Dandan Zhao ◽  
Jinyuan Xin ◽  
Chongshui Gong ◽  
Jiannong Quan ◽  
Yuesi Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Layer Structure ◽  
Atmospheric Environment ◽  
Absolute Difference ◽  
Air Pollution Control ◽  
Aerosol Radiative Forcing ◽  
Boundary Layer Structure ◽  
The Impact ◽  
Aerosol Radiative

Abstract. Recently, there has been increasing interest in the relation between particulate matter (PM) pollution and atmospheric-boundary-layer (ABL) structure. This study aimed to qualitatively assess the interaction between PM and ABL structure in essence and further quantitatively estimate aerosol radiative forcing (ARF) effects on the ABL structure. Multi-period comparative analysis indicated that the key to determining whether haze outbreak or dissipation occurs is whether the ABL structure satisfies the relevant conditions. However, the ABL structure change was in turn highly related to the PM level and ARF. |SFC−ATM| (SFC and ATM are the ARFs at the surface and interior of the atmospheric column, respectively) is the absolute difference between ground and atmosphere layer ARFs, and the |SFC−ATM| change is linearly related to the PM concentrations. However, the influence of ARF on the boundary layer structure is nonlinear. With increasing |SFC−ATM|, the turbulence kinetic energy (TKE) level exponentially decreased, which was notable in the lower layers or ABL, but disappeared at high altitudes or above the ABL. Moreover, the ARF effects threshold on the ABL structure was determined for the first time, namely once |SFC−ATM| exceeded ∼55 W m−2, the ABL structure tends to quickly stabilize and thereafter change little with increasing ARF. The threshold of the ARF effects on the boundary layer structure could provide useful information for relevant atmospheric-environment improvement measures and policies, such as formulating phased air pollution control objectives.

The Impact of Horizontal Model Grid Resolution on the Boundary Layer Structure over an Idealized Valley

2014 ◽  
Vol 142 (9) ◽  
pp. 3446-3465 ◽  
Author(s):  
Johannes S. Wagner ◽  
Alexander Gohm ◽  
Mathias W. Rotach
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Layer Structure ◽  
Thermal Structure ◽  
Inversion Layer ◽  
Lower Boundary ◽  
Grid Resolution ◽  
Convective Boundary ◽  
Boundary Layer Structure ◽  
The Impact

The role of horizontal model grid resolution on the development of the daytime boundary layer over mountainous terrain is studied. A simple idealized valley topography with a cross-valley width of 20 km, a valley depth of 1.5 km, and a constant surface heat flux forcing is used to generate upslope flows in a warming valley boundary layer. The goal of this study is to investigate differences in the boundary layer structure of the valley when its topography is either fully resolved, smoothed, or not resolved by the numerical model. This is done by performing both large-eddy (LES) and kilometer-scale simulations with horizontal mesh sizes of 50, 1000, 2000, 4000, 5000, and 10 000 m. In LES mode a valley inversion layer develops, which separates two vertically stacked circulation cells in an upper and lower boundary layer. These structures weaken with decreasing horizontal model grid resolution and change to a convective boundary layer over an elevated plain when the valley is no longer resolved. Mean profiles of the LES run, which are obtained by horizontal averaging over the valley show a three-layer thermal structure and a secondary heat flux maximum at ridge height. Strong smoothing of the valley topography prevents the development of a valley inversion layer with stacked circulation cells and leads to higher valley temperatures due to smaller valley volumes. Additional LES and “1 km” runs over corresponding smoothed valleys reveal that differences occur mainly because of unresolved topography and not because of unresolved turbulence processes. Furthermore, the deactivation of horizontal diffusion improved simulations with 1- and 2-km horizontal resolution.

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