Classification of Precipitation Systems in Mature and Early Weakening Stages of Typhoons around Japan

Shimazu, Yoshio

doi:10.2151/jmsj1965.76.3_437

Cited by 25 publications

(22 citation statements)

References 6 publications

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“…9a) has become very asymmetric with a maximum in a triangular region northwest of the storm track, minimum precipitation in a curved slot that extends from northwest of the center cyclonically into the southern tropical cyclone core, and a weak trailing rainband feature to the southeast. The triangular region of maximum precipitation is similar to the ''delta'' rain region identified by Shimazu (1998) in radar imagery as being common in typhoons that are approaching midlatitude frontal zones near Japan, and is generally located in the leftfront quadrant with respect to the typhoon track. Stratiform precipitation [Ͻ25 mm (3h) Ϫ1 ] is developing to the northeast of the tropical cyclone center during step 2 (Fig.…”

Section: Simulations a Validation Of Simulated Cloud Features Duringmentioning

confidence: 71%

Simulations of the Transformation Stage of the Extratropical Transition of Tropical Cyclones

Ritchie¹,

Elsberry²

2001

Mon. Wea. Rev.

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The physical mechanisms associated with the transformation stage of the extratropical transition of a tropical cyclone are simulated with a mesoscale model using initial environmental conditions that approximate the mean circulations defined by Klein et al. The tropical cyclone structural changes simulated by the U.S. Navy Coupled Ocean-Atmosphere Model Prediction System mesoscale model during the three steps of transformation compare well with available observations. During step 1 of transformation when the tropical cyclone is just beginning to interact with the midlatitude baroclinic zone, the main environmental factor that affects the tropical cyclone structure appears to be the decreased sea surface temperature. The movement of the tropical cyclone over the lower sea surface temperatures results in reduced surface heat and moisture fluxes, which weakens the core convection and the intensity decreases. During step 2 of transformation, the low-level temperature gradient and vertical wind shear associated with the baroclinic zone begin to affect the tropical cyclone. Main structural changes include the development of cloud-free regions on the west side of the tropical cyclone, and an enhanced ''delta'' rain region to the northwest of the tropical cyclone center. Gradual erosion of the clouds and deep convection in the west through south sectors of the tropical cyclone appear to be from mechanically forced subsidence due to the convergence between the midlatitude flow and the tropical cyclone circulation. Whereas the warm core aloft is advected downstream, the mid-to low-level warm core is enhanced by subsidence into the tropical cyclone center, which implies that the low-level cyclonic circulation may continue to be maintained.Step 3 of transformation is the logical conclusion of structural changes that were occurring during steps 1 and 2. Even though the tropical cyclone circulation aloft has dissipated, a broad cyclonic circulation is maintained below 500 mb. Although the low-level warm core is reduced from step 2, it is still significantly stronger than at step 1, and a second warm anomaly is simulated in a region of strong subsidence upshear of the tropical cyclone remnants. Whereas some precipitation is associated with the remnants of the northern eyewall and some cloudiness to the north-northeast, the southern semicircle is almost completely clear of clouds and precipitation.

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Section: Simulations a Validation Of Simulated Cloud Features Duringmentioning

confidence: 71%

Simulations of the Transformation Stage of the Extratropical Transition of Tropical Cyclones

Ritchie¹,

Elsberry²

2001

Mon. Wea. Rev.

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“…In the northern semicircle of the cyclone, anticyclonic outflow intensified in the upper troposphere, associated with horizontal divergence to the north of the cyclone. It was induced by the circulation at the entrance of the jet streak and its associated midtropospheric warm frontogenesis, generating the ''delta rain shield'' of Shimazu (1998). Although the cyclone center located in a weakly baroclinic environment in the lower troposphere, frontogenesis was relatively inactive with potentially unstable stratification.…”

Section: Discussionmentioning

confidence: 99%

“…4) shows a relatively narrow precipitation region in the southern semicircle of the cyclone and a wide region in the northern semicircle, the latter of which corresponds to the ''delta rain shield'' described by Shimazu (1998). Strong convective echoes are found just west of the eye.…”

Section: Best Track Analysis and Imagerymentioning

confidence: 93%

“…He described the following characteristic features of the extratropical transformation: dissipation of a central dense overcast (CDO) in satellite imagery, intrusion of dry air into the cyclone center at 700 hPa, dissipation of cloud and radar echo in the southern semicircle of the cyclone, and ''intrusion of lower front into the center of the cyclone''. Shimazu (1998) defined the ''delta rain shield'' which is generated in the northern semicircle of the cyclones when a tropical cyclone approaches the mid-latitude frontal zone.…”

Section: Introductionmentioning

confidence: 99%

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Extratropical Transformation of Typhoon Vicki (9807): Structural Change and the Role of Upper-tropospheric Disturbances.

Kitabatake

2002

Journal of the Meteorological Society of Japan

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Extratropical transformation of Typhoon Vicki (9807) is diagnosed in relation to its environment, particularly with respect to interactions with upper tropospheric disturbances, using the gridded dataset of global analysis (GANAL) produced by the Japan Meteorological Agency. TY Vicki made landfall on Japan with its maximum intensity on 22 September 1998, causing damage with strong winds. Vicki lost the diabatically generated potential vorticity (PV) anomaly at 00UTC 23 September 1998, when it was supposed to complete the extratropical transformation. It still had a considerable diabatic PV anomaly during passage over Japan, which is consistent with the cyclone intensity. At 06UTC 22 September, Vicki was located in the lower-baroclinic zone, and strong horizontal divergence directly above the cyclone center was dissipated in the upper troposphere, which suggest that was already beginning extratropical transformation. Regarding the upper tropospheric environment, Vicki was moving northward to the right entrance of the jet streak, and a trough, i.e., mesoscale PV anomaly, approached to the west of Vicki.To the north of the cyclone, mid-tropospheric warm frontogenesis and the associated northward outflow were induced. To the west of the cyclone, the upper-tropospheric frontogenesis associated with the jet entrance and the trough contributed to upper-tropospheric outflow from the cyclone and midtropospheric dry-air inflow. These contributed to organizing a wide rainfall region in the northern semicircle of the cyclone and to limiting the rainfall region in the southwest of the cyclone center. It is also suggested that interactions between upper-and mid-tropospheric outflow, and the midlatitude jet streak to the north of the cyclone contributed to a deepened layer of horizontal divergence that delayed the weakening of the cyclone during the start of the extratropical transformation.

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“…The connecting band, which joins the principal band and the eyewall, crosses the streamlines and contains either stratiform clouds or weak convective clouds. Shimazu (1998) classified precipitation systems accompanying tropical cyclones approaching Japan on the basis of data from a conventional radar network. Rain shields whose distance from the storm center was within 150-250 km were called inner rain shield.…”

Section: Introductionmentioning

confidence: 99%

A Mechanism for Heavy Precipitation over the Kii Peninsula Accompanying Typhoon Meari (2004)

Murata

2009

Journal of the Meteorological Society of Japan

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An extremely heavy precipitation event occurred in the mountainous Kii Peninsula in Japan, associated with Typhoon Meari in 2004. A marked characteristic of this heavy precipitation was its extreme rainfall rate, more than 100 mm h À1 . Another feature was that the area of precipitation was far from the storm center, more than 500 km. From radar and surface observations, it was found that the heavy rains were composed of a stationary precipitation system and two moving precipitation systems.In order to evince a physical mechanism for the precipitation systems, the event was analyzed in detail using data from cloud-resolving simulations and observations. The results demonstrated that the heavy precipitation was produced in a synergistic manner from the three precipitation systems. The following are identified as the key factors for the formation and maintenance of each precipitation system: a) elimination of vertical convective instability in a low-level warm and moist easterly on the eastern slope of the mountainous region, b) moisture supply due to a low-level confluent flow along the boundary between the low-level easterly and south-easterly flow, and lifting of a slightly warmer south-easterly flow, and c) low-level convergence due to cold pool, running nearly parallel to the rainband axis and located slightly to the southwest of the band, acting as an obstacle to the low-level inflow into the system. Precipitation e‰ciency revealed that precipitation was enhanced when moving precipitation systems merged with the stationary precipitation system. The enhancement was attributed to the greater rate of conversion of cloud water to rainwater via accretion of cloud water by rain, under the condition of intense water vapor flux convergence. The moving precipitation systems provided raindrops for the accretion of cloud droplets in the stationary precipitation system. Based on our findings, extremely heavy precipitation in the present case is caused by the enhancement of the accretion process due to the merger of precipitation systems in addition to precipitation in each system.

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Classification of Precipitation Systems in Mature and Early Weakening Stages of Typhoons around Japan

Cited by 25 publications

References 6 publications

Simulations of the Transformation Stage of the Extratropical Transition of Tropical Cyclones

Simulations of the Transformation Stage of the Extratropical Transition of Tropical Cyclones

Extratropical Transformation of Typhoon Vicki (9807): Structural Change and the Role of Upper-tropospheric Disturbances.

A Mechanism for Heavy Precipitation over the Kii Peninsula Accompanying Typhoon Meari (2004)

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