Driving Forces of Extreme Updrafts Associated With Convective Bursts in the Eyewall of a Simulated Tropical Cyclone

Abstract

Many studies have indicated that convective bursts (CBs) are closely related to tropical cyclone (TC) intensification, but few studies have been conducted on the mechanisms that control the formation and evolution of CBs. In this study, the 1‐min output data of a simulated TC are used to understand the convective extreme updrafts of CBs in the TC eyewall. Three different reference states including the local square‐area mean (LAM), the lower wavenumber‐components mean (WNM), and the arc‐area mean (ArcM) are used to calculate the driving forces of convective extreme updrafts. Contrary to the WNM and ArcM reference states, the LAM reference state struggles to capture realistic basic state structures. The LAM reference state can be modified through the inclusion of the mean hydrometeor mixing ratio in the basic state to produce physically consistent forcing in relation to the simulated convective extreme updrafts. The simulated convective extreme updrafts in the TC eyewall exhibit two peaks at middle and upper levels, respectively, since the effect of hydrometeor loading, decelerates the air parcels between the updraft maxima. While the positive buoyancy makes air parcels in the CBs accelerate at middle levels, in agreement with previous studies, it is found that, at the upper levels, both the positive buoyancy and the upward vertical perturbation pressure gradient force accelerate the air parcels. This study suggests that the vertical perturbation pressure gradient force also plays an important role in the formation of CBs in the TC eyewall.

Modulation of Asymmetric Inner‐Core Convection on Midlevel Ventilation Leading up to the Rapid Intensification of Typhoon Lekima (2019)

“…Meanwhile, the vortex column shows an evident tilt of about 30 km, with the midlevel vortex center in the downshear‐right quadrant. These features are generally consistent with the wavenumber‐1 (WN‐1) asymmetric structure in sheared TCs as revealed by previous studies (Chen et al., 2006; Corbosiero & Molinari, 2003; Qin et al., 2023; Tao & Zhang, 2019). At 1800 UTC 6 August, the asymmetric precipitation band in both simulations spirals cyclonically into the upshear‐left quadrant (Figures 4b and 4f), hinting at a tendency of axisymmetrization.…”

Spatiotemporal fusion convolutional neural network: tropical cyclone intensity estimation from multisource remote sensing images

“…It is a general term for nonfrontal vortices with organized convection and deterministic circulation. 1 The intensity of a TC is typically defined by the maximum sustained wind (MSW) speed at the TC center or the minimum sea-level pressure (MSLP). Depending on the region of origin, TCs are also referred to as hurricanes, typhoons, or cyclones.…”

“…A tropical cyclone (TC) is a deep and rapidly rotating low-pressure system that originates over tropical or subtropical oceanic waters. It is a general term for nonfrontal vortices with organized convection and deterministic circulation 1 . The intensity of a TC is typically defined by the maximum sustained wind (MSW) speed at the TC center or the minimum sea-level pressure (MSLP).…”

Pacific Decadal Oscillation Modulates the Relationship Between Pacific Meridional Mode and Tropical Cyclone Genesis in the Western North Pacific

“…Tropical cyclones (TCs) over the western North Pacific (WNP) bring about enormous disasters to the Pacific islands and coastal regions (Peduzzi et al., 2012; Qin et al., 2023; Q. Zhang et al., 2009). Understanding variations in TC genesis, which largely determine the subsequent track, impact regions and the associated damages, would greatly benefit seasonal forecasting and thus the disaster mitigation for these regions (Camargo, Barnston, et al., 2007; Klotzbach et al., 2019).…”

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Tropical cyclones (TCs) over the western North Pacific (WNP) bring about enormous disasters to the Pacific islands and coastal regions (Peduzzi et al, 2012;Qin et al, 2023;Q. Zhang et al, 2009).

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