Intensity Change of Typhoon Nancy (1961) during Landfall in a Moist Environment over Japan: A Numerical Simulation with Spectral Nudging

Abstract

Intensity change of tropical cyclones (TCs) as they make landfall is closely linked to sustained periods of high surface winds and heavy precipitation. Few studies have investigated the intensity change of intense TCs that make landfall in middle latitudes such as Japan because few intense typhoons make landfall in middle latitudes. In this study, a numerical simulation of intense Typhoon Nancy (1961) was used to understand the intensity change that occurred when Nancy made landfall in Japan. A spectral nudging technique was introduced to reduce track errors in the simulation. During landfall, the simulated storm exhibited the salient asymmetric structure and rapid eyewall contraction. A tangential wind budget indicated that the maximum wind speed decreased concurrent with an increase in surface friction and advection associated with low-level asymmetric flows. Detailed evolution of the storm’s warm core was analyzed with a potential temperature budget. In the upper part of the warm core centered at a 12-km height, cooling due to ventilation by asymmetric flows and longwave radiation overcame heating due to condensation and shortwave radiation during the contraction of eyewall clouds. In the lower part of the warm core, adiabatic cooling more than offset warm-air intrusions associated with asymmetric flows and condensational heating. The condensation was supplied by an abundance of moisture due to evaporation from the ocean in the well-developed typhoon based on a moisture budget. Sensitivity experiments revealed that environmental baroclinicity in the midlatitudes, orography, and radiative processes made minor contributions to the weakening. The weakening was instead controlled by inner-core dynamics and interactions with land surfaces.

Recurvature and movement processes of tropical cyclones over the Bay of Bengal

“…The Cloud Resolving Storm Simulator (CReSS) is a three‐dimensional terrain‐following cloud‐resolving model developed at Nagoya University, Japan (Tsuboki and Sakakibara, 2002); this model can perform numerical simulations of different weather phenomena (i.e., Wang et al ., 2005; Maesaka et al ., 2006; Ohigashi and Tsuboki, 2007; Yamada, 2008; Rafiuddin et al ., 2013) with resolutions on the order of a few tens of meters to a few kilometers. The CReSS model has also successfully simulated TCs (i.e., Tsujino et al ., 2020; Tsujino and Tsuboki, 2020; Wang et al ., 2020), including TCs and monsoon depressions over the BoB (Akter and Tsuboki, 2010; 2012; Fujinami et al ., 2020). The model architecture supports a horizontal curvilinear Arakawa “C” grid and a Lorenz grid in the vertical direction.…”

Convection-permitting simulations reveal expanded rainfall extremes of tropical cyclones affecting South Korea due to anthropogenic warming

“…For example, Mori et al 48 conducted hindcast simulations using the WRF model and successfully reproduced realistic intensity and track of typhoon Haiyan when applying spectral nudging. Many other studies have applied spectral nudging to reproduce the track of TCs similar to observations 33,35,[49][50][51] . We have conducted additional model simulations to identify how much the track and intensity of TC would be changed when spectral nudging is not applied.…”

Changes of Tropical Cyclones Landfalling in China From 1979 to 2018

“…It is worth noting that some TCs may land in China more than once. Considering the obvious change in TC structure and weakening of TC intensity during landfall (Tsujino & Tsuboki, 2020;Tuleya & Kurihara, 1978;Yang et al, 2008Yang et al, , 2011, only the first landfall is analyzed in this study, similar to the studies of Yao- Dong et al (2013) and Zhang and Guan (2014). If a TC reentered the ocean after the first landfall, only the overland period is later analyzed.…”