Diagnosis of Tropical Cyclone Intensity and Structure Using Upper Tropospheric Atmospheric Motion Vectors

Oyama, Ryo; Sawada, Masahiro; Shimoji, Kazuki

doi:10.2151/jmsj.2017-024

Cited by 10 publications

(12 citation statements)

References 41 publications

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“…Retrieval methods for AMVs were developed in the early 1960s (e.g., Menzel 2001), and are being still updated through advanced sensor technologies and/or the adoption of new algorithms (e.g., Velden et al 2005). AMVs provide unique information for TC analysis and monitoring, even though vertical distributions of AMV datasets are biased in the upper level (e.g., Oyama 2017;Oyama et al 2018). The present investigation used AMVs which were retrieved every 10 min from Himawari-8 TC target observations with a time interval of 5 min (Bessho et al 2016;Oyama et al 2018).…”

Section: Data Descriptionmentioning

confidence: 99%

“…AMVs provide unique information for TC analysis and monitoring, even though vertical distributions of AMV datasets are biased in the upper level (e.g., Oyama 2017;Oyama et al 2018). The present investigation used AMVs which were retrieved every 10 min from Himawari-8 TC target observations with a time interval of 5 min (Bessho et al 2016;Oyama et al 2018). The retrieval scheme was developed by the Meteorological Satellite Center of the Japan Meteorological Agency, and…”

Section: Data Descriptionmentioning

confidence: 99%

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The Diurnal Cycle of Clouds in Tropical Cyclones over the Western North Pacific Basin

Fukuda

Yasunaga

Oyama

et al. 2020

SOLA

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This study examined the diurnal cycles of brightness temperature (TB) and upper-level horizontal winds associated with tropical cyclones (TCs) over the western North Pacific basin, making use of data retrieved from geostationary-satellite (Himawari-8) observations that exhibited unprecedented temporal and spatial resolutions. The results of a spectral analysis revealed that diurnal cycles prevail in TB variations over the outer regions of TCs (300− 500 km from the storm center). The dominance of the diurnal cycle was also found in variations in the radial wind (Vr) in intensive TCs, although there was no dominant cycle in tangential wind variation. In addition, coherence spectra demonstrated that the diurnal cycles of TB and Vr are significantly coupled in intensive TCs. The migration speed of TB and Vr anomalies exceeded the time-mean Vr, and it was speculated that diurnal cycle signals propagate (i.e., are not advected) toward the outer regions of TCs.

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Section: Data Descriptionmentioning

confidence: 99%

Section: Data Descriptionmentioning

confidence: 99%

The Diurnal Cycle of Clouds in Tropical Cyclones over the Western North Pacific Basin

Fukuda

Yasunaga

Oyama

et al. 2020

SOLA

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“…AMVs are normally derived using the cross‐correlation method (Leese et al, 1971; Schmetz et al, 1993). Even the state‐of‐the‐art AMV products do not cover TC's inner core region (Oyama et al, 2018), presumably because the operational methods do not treat rotation.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the Tangential Winds and Asymmetric Structures in Typhoon Inner Core Region Using Himawari‐8

Tsukada

Horinouchi

2020

Geophysical Research Letters

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Observations of the winds in tropical cyclones are still limited. We propose a new method for deriving the tangential winds in tropical cyclones, which employs a spectral analysis of high‐frequency cloud imaging by latest‐generation geostationary meteorological satellites such as Himawari‐8. The method was applied to the visible images of boundary layer clouds in the eye of Typhoon Lan (2017) over an 8.5‐hr period. The low‐level tangential winds over the central two thirds of the eye in radius were close to a rigid body rotation and increased with time. On its outside was a region with striating clouds rotating at much higher angular velocities, which may have been supergradient. Asymmetric motions were visualized as the deviation from the inner rotation, and the vorticity of some mesovortices were quantified. These asymmetric motions are suggested to transport angular momentum to accelerate the inner rotation.

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“…In this study it will be demonstrated that shorter sampling times and continuous rapid scanning combined with the advanced sensors on these newgeneration satellites will substantially improve the quality and quantity of the AMVs, and thus their potential impacts on the U.S. Navy regional and global model analyses and predictions. Oyama (2017) has demonstrated that composites of TC outflows at the cloud tops computed from AMVs can be related to the intensification rates. Oyama et al (2018) then compare the maximum tangential winds in the outflow estimated from 30-min-interval Himawari-8 target observations with the maximum surface wind evolutions throughout the lifetime of two typhoons and suggest that Himawari-8 AMVs can be used to monitor TC intensification and related structural changes.…”

Section: Introductionmentioning

confidence: 99%

“…Oyama (2017) has demonstrated that composites of TC outflows at the cloud tops computed from AMVs can be related to the intensification rates. Oyama et al (2018) then compare the maximum tangential winds in the outflow estimated from 30-min-interval Himawari-8 target observations with the maximum surface wind evolutions throughout the lifetime of two typhoons and suggest that Himawari-8 AMVs can be used to monitor TC intensification and related structural changes.…”

Section: Introductionmentioning

confidence: 99%

Demonstration with Special TCI-15 Datasets of Potential Impacts of New-Generation Satellite Atmospheric Motion Vectors on Navy Regional and Global Models

Elsberry

Hendricks

Velden

et al. 2018

Weather and Forecasting

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A dynamic initialization assimilation scheme is demonstrated utilizing rapid-scan atmospheric motion vectors (AMVs) at 15-min intervals to simulate the real-time capability that now exists from the new generation of geostationary meteorological satellites. The impacts of these AMVs are validated with special Tropical Cyclone Intensity Experiment (TCI-15) datasets during 1200–1800 UTC 4 October leading up to a NASA WB-57 eyewall crossing of Hurricane Joaquin. Incorporating the AMV fields in the Spline Analysis at Mesoscale Utilizing Radar and Aircraft Instrumentation (SAMURAI) COAMPS Dynamic Initialization (SCDI) means there are 30 and 90 time steps on the 15- and 5-km grids, respectively, during which the mass fields are adjusted to these AMV-based wind increments during each 15-min assimilation period. The SCDI analysis of the three-dimensional vortex structure of Joaquin at 1800 UTC 4 October closely replicates the vortex tilt analyzed from the High-Definition Sounding System (HDSS) dropwindsondes. Vertical wind shears based on the AMVs at 15-min intervals are well correlated with the extreme rapid decay, an interruption of that rapid decay, and the subsequent period of constant intensity of Joaquin. Utilizing the SCDI analysis as the initial conditions for two versions of the COAMPS-TC model results in an accurate 72-h prediction of the interruption of the rapid decay and the period of constant intensity. Upscaling a similar SCDI analysis based on the 15-min interval AMVs provides a more realistic intensity and structure of Tropical Storm Joaquin for the initial conditions of the Navy Global Environmental Model (NAVGEM) than the synthetic TC vortex used operationally. This demonstration for a single 6-h period of AMVs indicates the potential for substantial impacts when an end-to-end cycling version is developed.

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Diagnosis of Tropical Cyclone Intensity and Structure Using Upper Tropospheric Atmospheric Motion Vectors

Abstract: 21The high temporal and spatial resolutions of geostationary satellite observations achieved by

Cited by 10 publications

References 41 publications

The Diurnal Cycle of Clouds in Tropical Cyclones over the Western North Pacific Basin

The Diurnal Cycle of Clouds in Tropical Cyclones over the Western North Pacific Basin

Estimation of the Tangential Winds and Asymmetric Structures in Typhoon Inner Core Region Using Himawari‐8

Demonstration with Special TCI-15 Datasets of Potential Impacts of New-Generation Satellite Atmospheric Motion Vectors on Navy Regional and Global Models

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