The Mechanical Energy Input to the Ocean Induced by Tropical Cyclones

Abstract

Wind stress and tidal dissipation are the most important sources of mechanical energy for maintaining the oceanic general circulation. The contribution of mechanical energy due to tropical cyclones can be a vitally important factor in regulating the oceanic general circulation and its variability. However, previous estimates of wind stress energy input were based on low-resolution wind stress data in which strong nonlinear events, such as tropical cyclones, were smoothed out.Using a hurricane-ocean coupled model constructed from an axisymmetric hurricane model and a threelayer ocean model, the rate of energy input to the world's oceans induced by tropical cyclones over the period from 1984 to 2003 was estimated. The energy input is estimated as follows: 1.62 TW to the surface waves and 0.10 TW to the surface currents (including 0.03 TW to the near-inertial motions). The rate of gravitational potential energy increase due to tropical cyclones is 0.05 TW. Both the energy input from tropical cyclones and the increase of gravitational potential energy of the ocean show strong interannual and decadal variability with an increasing rate of 16% over the past 20 years. The annual mean diapycnal upwelling induced by tropical cyclones over the past 20 years is estimated as 39 Sv (Sv ϵ 10 6 m 3 s Ϫ1). Owing to tropical cyclones, diapycnal mixing in the upper ocean (below the mixed layer) is greatly enhanced. Within the regimes of strong activity of tropical cyclones, the increase of diapycnal diffusivity is on the order of (1 Ϫ 6) ϫ 10 Ϫ4 m 2 s Ϫ1. The tropical cyclone-related energy input and diapycnal mixing may play an important role in climate variability, ecology, fishery, and environments.

Modeled sensitivity of upper thermocline properties to tropical cyclone winds and possible feedbacks on the Hadley circulation

“…However, a key finding of these studies suggested annual vertical mixing rates are on the order of 1 cm 2 /s in regions with pronounced TC activity, which is the same order of magnitude as background values prescribed in many current ocean models. Independent research [Liu et al, 2008] using a coupled hurricane-ocean model yielded similar results, finding diapycnal diffusivity by TC's may be as high as ∼6 cm 2 /s.…”

Observed near‐surface flows under all tropical cyclone intensity levels using drifters in the northwestern Pacific

“…Many studies have been conducted on the upper ocean cooling, strong ocean currents, and the enhanced ocean primary production triggered by TCs [O'Brien and Reid, 1967;Price et al, 1994;Chu et al, 2000;Lin et al, 2003aLin et al, , 2003bSriver and Huber, 2007]. Under storms, energy transfer from atmosphere to ocean generally generates surface waves, near-inertial waves, and currents [Price, 1983;Price et al, 1994;D'Asaro, 1985;Nilsson, 1995;Wunsch, 1998;Alford, 2001Alford, , 2003Wang and Huang, 2004;Liu et al, 2008;Jaimes and Shay, 2010].…”

Ocean Responses to Typhoon Namtheun Explored with Argo Floats and Multiplatform Satellites

“…The impacts of typhoons on the ocean are investigated using both observations (D'Asaro, 2003;Han et al, 2012;Price, 1981;Stramma, Cornillon, & Price, 1986;Sun et al, 2010;Wang & Zhao, 2008) and model simulations (Chang, 1985;Chen, Liu, Tang, & Wang, 2003;Emanuel, 1999;Liu, Wang, & Huang, 2008;Price, Sanford, & Forristall, 1994;Tsai, Chern, & Wang, 2008). From satellite imagery, it has been determined that the maximum surface cooling occurs before the passage of the eye of the typhoon (D'Asaro, 2003), or a few days after the passage of the eye (Stramma et al, 1986;Subrahmanyam et al, 2002).…”