A Dual-Doppler Radar ObservationA Dual-Doppler Radar Observationon Mesoscale Convective Systemson Mesoscale Convective SystemsPreceding the Genesis of a Tropical DepressionPreceding the Genesis of a Tropical Depressionover the Western North Pacificover the Western North Pacific

Hiroyuki YamadaHiroyuki Yamada11, Ken Gohara, Ken Gohara22,,Qoosaku MotekiQoosaku Moteki11, Tomoki Ushiyama, Tomoki Ushiyama11,,Masaki KatsumataMasaki Katsumata11, Geng, Biao, Geng, Biao11,,Ryuichi ShirookaRyuichi Shirooka11, Hiroshi Uyeda, Hiroshi Uyeda1,21,2

1: JAMSTEC, 2: Nagoya University1: JAMSTEC, 2: Nagoya University

Contents:Contents:• Field experiment at Palau (PALAU-2005)Field experiment at Palau (PALAU-2005)• Preliminary results of a rotating cloud systemPreliminary results of a rotating cloud system• Plan of PALAU-2008Plan of PALAU-2008

Environment of Generating Cyclone

How do MCSs play a role in cyclogenesis?How do MCSs play a role in cyclogenesis?

Palau

PALAU-2005 (June-July)

Pacific Area Long-term Atmospheric observation for Understanding climate change

Case Studied

TD H

Tracking Chart of “Emong”

(from http://www.typhoon2000.ph)

Precipitable Water, Vapor Flux

and Geopotential Height at 925 hPa

Heavy Rain inWestern Japan

• A weak tropical depressionA weak tropical depression• Significant vapor transport to western Japan before the Significant vapor transport to western Japan before the

heavy rain episode in 8-10 July 2005heavy rain episode in 8-10 July 2005

Palau

Overall Evolution

• Formation of a rotating cloud mass over PalauFormation of a rotating cloud mass over Palau• Dissipation over the Philippines SeaDissipation over the Philippines Sea• Redevelopment and TD generation near PhilippinesRedevelopment and TD generation near Philippines

Overall Evolution

• Westerly-propagated tropical waveWesterly-propagated tropical wave

Synoptic Environment

• Westerly-propagated tropical waveWesterly-propagated tropical wave

++ Cyclogenesis Cyclogenesis• Monsoon TroughMonsoon Trough

Internal Structure

• northerly (forward) + southerly (rear)northerly (forward) + southerly (rear)• cyclonic flow in the MCScyclonic flow in the MCS

Internal Structure

Sea Level Pressure

No pressure decrease at the beginning of cyclogenesisNo pressure decrease at the beginning of cyclogenesis

(Cyclogenesis stage)(TD stage)

Summary & Discussion

• Preliminary results of a cloud system during PALAU-2005:Preliminary results of a cloud system during PALAU-2005:

Preceding the evolution of a weak tropical depressionPreceding the evolution of a weak tropical depression

Environment withEnvironment with a large-scale cyclonic flow formed bya large-scale cyclonic flow formed by

a westerly-propagating tropical wave anda westerly-propagating tropical wave and

low level shear along a monsoon troughlow level shear along a monsoon trough

Mesoscale cyclonic flow within the cloud systemMesoscale cyclonic flow within the cloud system

No pressure decrease in the cloud centerNo pressure decrease in the cloud center

A rare observational evidence of tropical cyclogenesis over the A rare observational evidence of tropical cyclogenesis over the north western Pacific oceannorth western Pacific ocean

• Problems:Problems:

Why this system could not develop to a tropical storm?Why this system could not develop to a tropical storm?

How large are the condensation heating and the low-level How large are the condensation heating and the low-level vorticity enough to a typhoon genesis?vorticity enough to a typhoon genesis?

PALAU-2008 Plan

THANK YOU

A freight train near NCAR (Nov 2, 2006)

Background: Impacts of TC to East Asia

DIRECT

INDIRECT

TC-induced P-J pattern(Kawamura and Ogasawara 2006, SOLA)