Search Results

You are looking at 1 - 10 of 11 items for :

  • Planetary atmospheres x
  • Tropical Cyclone Intensity Experiment (TCI) x
  • All content x
Clear All
Yi Dai, Sharanya J. Majumdar, and David S. Nolan

( Zhang and Kieu 2005 ; Davis et al. 2008 ). The question of whether a TC will intensify or weaken under strong shear (>10 m s −1 ) likely depends on the relative strength of the environmental shear and the TC intensity. This relative strength is difficult to establish, however, since the two factors are physically interconnected. Additionally, in the real atmosphere, it is difficult to isolate the precise role of shear due to competing factors, such as environmental humidity or ocean temperature (e

Restricted access
Jie Feng and Xuguang Wang

-hurricane case (not shown). Fig . 2. (a) Distribution and (b) resolution of 61 (black) and 74 (red) vertical model levels. All the experiments used the same HWRF model physics, which is mostly in accordance with those in the 2015 operational HWRF ( Tallapragada et al. 2016 ; see “Basic model physics” column of Table 1 ). The difference is that, as suggested by Lu and Wang (2019) , the modified turbulent mixing parameterization ( Zhu et al. 2019 ) is used in the planetary boundary layer scheme to strengthen

Restricted access
Benjamin C. Trabing, Michael M. Bell, and Bonnie R. Brown

complexities of the real atmosphere make diagnosing the impact of individual PI parameters very difficult. In this study, we employ a high-resolution, three-dimensional, full-physics model on a “weather” time scale of 8 days to diagnose the physical mechanisms behind why changing upper-tropospheric temperatures modify TC intensification, and to investigate the use of PI theory in understanding TC maximum intensity on weather time scales. One potential mechanism by which a colder upper

Full access
Jonathan Martinez, Michael M. Bell, Robert F. Rogers, and James D. Doyle

1. Introduction Accurate forecasts of tropical cyclone (TC) intensity changes remain one of the most difficult weather predictions, even for short lead times. This is in part due to multiscale interactions, which require operational forecast models to precisely capture the evolution of the atmosphere over a vast range of scales in the vicinity of a TC. DeMaria et al. (2014) demonstrated that although intensity forecast errors have not improved as much as track forecast errors over the past

Full access
Nannan Qin and Da-Lin Zhang

evident in the planetary boundary layer (PBL), where radial inflows are peaked. In addition, Xu and Wang (2015) found that TC intensification rate is negatively and positively correlated with the RMW and storm intensity (i.e., V MAX ), respectively. The highest RI tends to occur when the RMW is less than 40 km with V MAX of about 40 m s −1 . Although little progress has been made in operationally predicting the RI of TCs, cloud-permitting simulations of some rapidly intensifying TCs, such as

Full access
Russell L. Elsberry, Eric A. Hendricks, Christopher S. Velden, Michael M. Bell, Melinda Peng, Eleanor Casas, and Qingyun Zhao

) field. Model dynamics will then adjust the mean and asymmetric wind fields, which in the lower model levels will take into account the planetary boundary layer frictional effects and enthalpy fluxes. Whereas these internal adjustments will determine the intensity change, the TC vortex dynamics and physics prediction are expected to also improve the interaction between the vortex and its environment in conjunction with the better depiction of the outflow jets from the high temporal and spatial

Full access
William A. Komaromi and James D. Doyle

to systematically explore the effect of modifying the environmental inertial stability and the resulting effect on the strength, structure, and direction of the storm outflow. Last, predictability issues associated with TC intensity change and the relative positions of the TC and the trough will be investigated. 2. Methodology a. Numerical model configuration The numerical simulations in this study are performed using the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) for Tropical

Full access
Xu Lu and Xuguang Wang

simulated maximum intensity in both the idealized and the operational HWRF. On the other hand, Bryan and Rotunno (2009b) found in the axisymmetric model that the maximum intensity of storms is insensitive to vertical diffusivity. Zhu et al. (2018) found that there was an unrealistic discontinuity of vertical diffusion near the boundary layer top in the HWRF planetary boundary layer (PBL) scheme applied in the HWRF Model (e.g., Fig. 1 ). This parameterization of vertical diffusivity K m was

Full access
Patrick Duran and John Molinari

of the background environment. More recent literature (e.g., Wirth 2003 ) has noted that strong, shallow temperature inversions immediately above the cold-point tropopause are a common feature in the tropics, now known as the tropopause inversion layer (TIL). On the planetary scale, TIL formation and maintenance has been tied to planetary wave dynamics ( Grise et al. 2010 ) and vertical gradients of radiative heating across the tropopause ( Randel et al. 2007 ), but the relative contributions of

Full access
Jie Feng and Xuguang Wang

and Pan 2006 ), and the Ferrier–Aligo microphysics scheme ( Ferrier 1994 , 2005 ), 2) the modified surface layer ( Kwon et al. 2010 ) and nonlocal planetary boundary layer ( Hong and Pan 1996 ) parameterization schemes, and 3) the Eta Geophysical Fluid Dynamics Laboratory (GFDL) longwave and shortwave radiation schemes ( Schwarzkopf and Fels 1991 ; Lacis and Hansen 1974 ). Note that the SAS cumulus scheme is only implemented for the outer two domains (i.e., 18- and 6-km grids), but not for the

Full access