Impact of Cyclonic Ocean Eddies on Upper Ocean Thermodynamic Response to Typhoon Soudelor

Abstract

By using multiplatform satellite datasets, Argo observations and numerical model data, the upper ocean thermodynamic responses to Super Typhoon Soudelor are investigated with a focus on the impact of an ocean cyclonic eddy (CE). In addition to the significant surface cooling inside the CE region, an abnormally large rising in subsurface temperature is observed. The maximum warming and heat content change (HCC) reach up to 4.37 °C and 1.73 GJ/m2, respectively. Moreover, the HCC is an order of magnitude larger than that calculated from statistical analysis of Argo profile data in the previous study which only considered the effects caused by typhoons. Meanwhile, the subsurface warming outside the CE is merely 1.74 °C with HCC of 0.39 GJ/m2. Previous studies suggested that typhoon-induced vertical mixing is the primary factor causing subsurface warming but these studies ignored an important mechanism related to the horizontal advection caused by the rotation and movement of mesoscale eddies. This study documents that the eddy-induced horizontal advection has a great impact on the upper ocean responses to typhoons. Therefore, the influence of eddies should be considered when studying the responses of upper ocean to typhoons with pre-existing mesoscale eddies.

Ocean Response to Successive Typhoons Sarika and Haima (2016) Based on Data Acquired via Multiple Satellites and Moored Array

“…In the regions around the Northwest Pacific, TCs with maximum wind speeds greater than 32.7 m/s are usually referred to as typhoons. The response of ocean to a tropical cyclone is dramatic and not only impacts the local ocean environment [1][2][3][4], global ocean heat transport [5][6][7], and kinetic energy budget [8][9][10], but also changes the development of the tropical cyclone itself through TC-ocean feedbacks [11][12][13][14]. The response is indeed a hot topic in the study of the atmosphere and oceans.…”

“…The TC-induced near-inertial current enhances the velocity shear in the mixed layer [31], deepens the mixed layer, cools sea surface, and warms subsurface [6,7]. The sea surface temperature (SST) cooling was usually by 1-6 • C [2,4,[31][32][33][34][35], and by more than 10 • C in some extreme cases [36,37]. Owing to the rightward (or leftward) bias of the current response, the temperature response is also usually biased to the right side (or left side) of the TC track in the Northern (or Southern) Hemisphere [15,22].…”

Upper Ocean Response to Two Sequential Tropical Cyclones over the Northwestern Pacific Ocean

“…During the passage of a TC, the strong wind stress could typically produce intense oceanic entrainment and upwelling [2][3][4], which leads to physical and biological responses of the upper ocean. Sea surface temperature (SST) decrease, the most striking phenomenon, is usually observed in the range of 1-9 • C with stronger cooling to the right side of a TC's track [5][6][7][8][9]. The sea surface cooling has a negative feedback to a TC by suppressing the TC development in turn [10].…”

“…Owing to the complex pre-TC conditions of different regions, the responses of the upper ocean in these regions are well worth studying in detail. Although the upper ocean response to a single TC has been commonly focused on [6][7][8][9][17][18][19][20], inadequate attention is paid to how sequential TCs affect the upper ocean from both physical and biological aspects.…”

Response of Coastal Water in the Taiwan Strait to Typhoon Nesat of 2017

“…Furthermore, our previous works (e.g., [2,50,[88][89][90][91][92][93]) indicate thatoceanic thermohaline and dynamic features play an important role in upper ocean response to a single or sequential typhoons based on multiple observation data and model simulations. However, these works were mainly in the marginal sea (the South China Sea) and we may further follow the study of this paper, and study how some special topographic features such as with many islands or straits influences the structure of the oceanic response to typhoons in the future.…”