Surface Wave Developments under Tropical Cyclone Goni (2020): Multi-Satellite Observations and Parametric Model Comparisons

Abstract

Over the Philippine Sea, the tropical cyclone (TC) Goni reaches category 5 on 29–31 October 2020. Multi-satellite observations, including CFOSAT SWIM/SCAT and Sentinel-1 SAR data, are jointly analyzed to assess the performances of a parametric model. Recently developed to provide a fast estimation of surface wave developments under rapidly evolving TCs, this full 2D parametric model (KYCM) and its simplified self-similar solutions (TC-wave geophysical model function (TCW GMF)) are thoroughly compared with satellite observations. TCW GMF provides immediate first-guess estimates, at any location in space and time, for the significant wave height, wavelength, and wave direction parameters. Moving cyclones trigger strong asymmetrical wave fields, associated to a resonance between wave group velocity and TC heading velocity. For TC Goni, this effect is well evidenced and captured, leading to extreme waves reaching up to 8 m, further outrunning as swell systems with wavelengths about 200–250 m in the TC heading direction, slightly shifted leftwards. Considering wind field constrained with very highly resolved Sentinel-1 SAR measurements and medium resolution CFOSAT SCAT data, quantitative agreements between satellite measurements and KYCM/TCW GMF results are obtained. Far from the TC inner core (∼10 radii of maximum wind speed), the superposition of outrunning swell systems and local wind waves estimates leads to Hs values very close to altimeter measurements. This case study demonstrates the promising capabilities to combine multi-satellite observations, with analytical self-similar solutions to advance improved understandings of surface wave generation under extreme wind conditions.

Wave Field Properties in Tropical Cyclones From the Spectral Observation of the CFOSAT/SWIM Spaceborne Instrument

“…Model results shown by Yurovskaya et al. (2022) ‐their Figure 4‐ are qualitatively consistent with our statistical results for the moderate class: largest significant wave height close to the TC center and in the right front quadrant, longest (resp. shortest) dominant wavelengths in the right front (resp.…”

“…In this study the authors compared SWIM observations to model results obtained from the two approaches developed by Kudryavtsev et al (2021aKudryavtsev et al ( , 2021b, when Goni had a relative displacement velocity corresponding, according to our classification, to the moderate speed class (U max /V t ∼ 9). Model results shown by Yurovskaya et al (2022) -their Figure 4-are qualitatively consistent with our statistical results for the moderate class: largest significant wave height close to the TC center and in the right front quadrant, longest (resp. shortest) dominant wavelengths in the right front (resp.…”

“…It is also interesting to compare our statistical results with the analysis recently proposed by Yurovskaya et al. (2022) of the cyclone Goni (2020). In this study the authors compared SWIM observations to model results obtained from the two approaches developed by Kudryavtsev et al.…”

“…The impact of the TC relative displacement speed on Hs field is in agreement with the model results of Kudryavtsev et al (2015); Kudryavtsev et al (2021aKudryavtsev et al ( , 2021b, both with the physically based model which treats the wave parameters evolution along wave rays in a Lagrangian reference frame, and with the fully parametric model based on the TC parameters. It is also interesting to compare our statistical results with the analysis recently proposed by Yurovskaya et al (2022) of the cyclone Goni (2020). In this study the authors compared SWIM observations to model results obtained from the two approaches developed by Kudryavtsev et al (2021aKudryavtsev et al ( , 2021b, when Goni had a relative displacement velocity corresponding, according to our classification, to the moderate speed class (U max /V t ∼ 9).…”

On Surface Waves Generated By Extra-Tropical Cyclones. Part II: Simulations

“…The main principle is that the sources of energy and momentum must be specified to reproduce the classical 1D similarity fetch laws [33], derived for spatially homogeneous winds. More recently, such a 2D parametric wave model has been developed to rapidly characterize wave developments under spatio-temporal varying hurricane winds [34][35][36][37]. Modification of this 2D model includes the dependence of the drag coefficient on wind speed and atmospheric stratification, and effect of low air temperature on the air density [38].…”