Comments on ‘Sensitivity of tropical-cyclone models to the surface drag coefficient’

2012 ◽  
Vol 139 (676) ◽  
pp. 1957-1960 ◽  
Author(s):  
George H. Bryan
Keyword(s):  
Tropical Cyclone ◽  
Drag Coefficient ◽  
Surface Drag

scholarly journals Sensitivity of tropical-cyclone models to the surface drag coefficient

2010 ◽  
Vol 136 (653) ◽  
pp. 1945-1953 ◽  
Author(s):  
Michael T. Montgomery ◽  
Roger K. Smith ◽  
Sang V. Nguyen
Keyword(s):  
Tropical Cyclone ◽  
Drag Coefficient ◽  
Surface Drag

scholarly journals Sensitivity of tropical-cyclone intensification to perturbations in the surface drag coefficient

2012 ◽  
Vol 140 (679) ◽  
pp. 407-415 ◽  
Author(s):  
Gerald L. Thomsen ◽  
Michael T. Montgomery ◽  
Roger K. Smith
Keyword(s):  
Tropical Cyclone ◽  
Drag Coefficient ◽  
Surface Drag

scholarly journals Relationship between Sea Surface Drag Coefficient and Wave State

2021 ◽  
Vol 9 (11) ◽  
pp. 1248
Author(s):  
Jian Shi ◽  
Zhihao Feng ◽  
Yuan Sun ◽  
Xueyan Zhang ◽  
Wenjing Zhang ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
Momentum Flux ◽  
Sea Surface ◽  
Sea Spray ◽  
Wave Age ◽  
High Wind ◽  
Surface Drag ◽  
Wave State ◽  
Wind Speeds ◽  
Strong Winds

The sea surface drag coefficient plays an important role in momentum transmission between the atmosphere and the ocean, which is affected by ocean waves. The total air–sea momentum flux consists of effective momentum flux and sea spray momentum flux. Sea spray momentum flux involves sea surface drag, which is largely affected by the ocean wave state. Under strong winds, the sea surface drag coefficient (CD) does not increase linearly with the increasing wind speed, namely, the increase of CD is inhibited by strong winds. In this study, a sea surface drag coefficient is constructed that can be applied to the calculation of the air–sea momentum flux under high wind speed. The sea surface drag coefficient also considers the influence of wave state and sea spray droplets generated by wave breaking. Specially, the wave-dependent sea spray generation function is employed to calculate sea spray momentum flux. This facilitates the analysis not only on the sensitivity of the sea spray momentum flux to wave age, but also on the effect of wave state on the effective CD (CD, eff) under strong winds. Our results indicate that wave age plays an important role in determining CD. When the wave age is >0.4, CD decreases with the wave age. However, when the wave age is ≤0.4, CD increases with the wave age at low and moderate wind speeds but tends to decrease with the wave age at high wind speeds.

scholarly journals Experimental Study of High Wind Sea Surface Drag Coefficient

2015 ◽  
Author(s):  
I.A. Repina ◽  
A.Yu. Artamonov ◽  
M.I. Varentsov ◽  
A.V. Kozyrev ◽  
◽  
...  
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Sea Surface ◽  
High Wind ◽  
Surface Drag ◽  
Wind Sea

scholarly journals Dynamics of Lower-Tropospheric Vorticity in Idealized Simulations of Tropical Cyclone Formation

2019 ◽  
Vol 76 (3) ◽  
pp. 707-727 ◽  
Author(s):  
Yaping Wang ◽  
Christopher A. Davis ◽  
Yongjie Huang
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Mass Flux ◽  
Cloud Model ◽  
Vertical Wind Shear ◽  
Lower Troposphere ◽  
Cold Pool ◽  
Surface Drag ◽  
Near Surface ◽  
Cold Pools

Abstract Idealized simulations are conducted using the Cloud Model version 1 (CM1) to explore the mechanism of tropical cyclone (TC) genesis from a preexisting midtropospheric vortex that forms in radiative–convective equilibrium. With lower-tropospheric air approaching near saturation during TC genesis, convective cells become stronger, along with the intensifying updrafts and downdrafts and the larger area coverage of updrafts relative to downdrafts. Consequently, the low-level vertical mass flux increases, inducing vorticity amplification above the boundary layer. Of interest is that while surface cold pools help organize lower-tropospheric updrafts, genesis still proceeds, only slightly delayed, if subcloud evaporation cooling and cold pool intensity are drastically reduced. More detrimental is the disruption of near saturation through the introduction of weak vertical wind shear. The lower-tropospheric dry air suppresses the strengthening of convection, leading to weaker upward mass flux and much slower near-surface vortex spinup. We also find that surface spinup is similarly inhibited by decreasing surface drag despite the existence of a nearly saturated column, whereas larger drag accelerates spinup. Increased vorticity above the boundary layer is followed by the emergence of a horizontal pressure gradient through the depth of the boundary layer. Then the corresponding convergence resulting from the gradient imbalance in the frictional boundary layer causes vorticity amplification near the surface. It is suggested that near saturation in the lower troposphere is critical for increasing the mass flux and vorticity just above the boundary layer, but it is necessary yet insufficient because the spinup is strongly governed by boundary layer dynamics.

scholarly journals MEP and planetary climates: insights from a two-box climate model containing atmospheric dynamics

2010 ◽  
Vol 365 (1545) ◽  
pp. 1355-1365 ◽  
Author(s):  
Tim E. Jupp ◽  
Peter M. Cox
Keyword(s):  
Drag Coefficient ◽  
Entropy Production ◽  
Rotation Rate ◽  
Free Parameter ◽  
Extrasolar Planets ◽  
Climate Model ◽  
Analogous Result ◽  
Atmospheric Dynamics ◽  
Surface Drag ◽  
Box Models

A two-box model for equator-to-pole planetary heat transport is extended to include simple atmospheric dynamics. The surface drag coefficient C D is treated as a free parameter and solutions are calculated analytically in terms of the dimensionless planetary parameters η (atmospheric thickness), ω (rotation rate) and ξ (advective capability). Solutions corresponding to maximum entropy production (MEP) are compared with solutions previously obtained from dynamically unconstrained two-box models. As long as the advective capability ξ is sufficiently large, dynamically constrained MEP solutions are identical to dynamically unconstrained MEP solutions. Consequently, the addition of a dynamical constraint does not alter the previously obtained MEP results for Earth, Mars and Titan, and an analogous result is presented here for Venus. The rate of entropy production in an MEP state is shown to be independent of rotation rate if the advective capability ξ is sufficiently large (as for the four examples in the solar system), or if the rotation rate ω is sufficiently small. The model indicates, however, that the dynamical constraint does influence the MEP state when ξ is small, which might be the case for some extrasolar planets. Finally, results from the model developed here are compared with previous numerical simulations in which the effect of varying surface drag coefficient on entropy production was calculated.

Sign in / Sign up

Export Citation Format

Share Document