Meteorology seminar2004.9.3

1. Daisuke NAITO

2. Mamami NOMURA

Miyakojima island

梅雨

台風

SCSMEX ’98

GAME HUBEX ’98-’99

Baiu season ( early )

長江下流域 ’01-’02

X-BAIU’99,’01,’02

Baiu season ( later )

TAMEX ’87LAPS/CREST ’03-’04

Observation at Okinawa ( 13 May – 26 June 1987 )

・MRI Doppler radar ( X-band )

・ ODA radar ( C-band )　 *ODA = Okinawa

　 Development 　 Agency

Radar

Other

・ Sounding ( at NAHA )

AMTEX ’74-’75

Air Mass Transformation Experiment14–28 Feb 1974 and 1975

There are no observation around Miyakojima-island at Baiu/Meiyu season.

・ Boundary layer・ Flux over the ocean

・Medium-Scale　　Depression (Saito1977)・ Precipitation (Takeda 1979)

Evolution of the Kinematic Structure within a Meso-β-Scale Convective System

in the Growing and Mature Stages

KENJI AKAEDA, TATSUO YOKOYAMA, AKIRA TABATA, MASAHITO ISHIHARA AND

HITOSHI SAKAKIBARA

Monthly Weather Review 1991 Volume 119 2264 - 2676

Introduction

Cloud Cluster

Squall cloud cluster

Nonsquall cloud cluster

One meso-β-scale 　　　 convective system

One or several 　 meso-β-scale　　 convective system

We are not understand the structure and the time variation of the convective system in a cloud cluster.

Ogura et al.(1985)

Cloud cluster

Propagating mesoscale convective system( in a early stage)

Stationary mesoscale convective system( in a later stage)

Akaeda et al.(1987)The distribution of convective system changed depending on cloud clusters evolutionary stages.

ObjectsThe structure and evolution of a meso-β-scale convective system (Time variation)

are analyzed.

My motivation in this paper

・ Characteristic of the convection around Okinawa

Similar to convection around Miyako or not ?

・ Technique of single Doppler analysis

・MRI Doppler radar ( X-band )・ODA radar

( C-band )・GMS hourly IR images

・ Surface weather map ( 09JST 6 June 1987 )

・ Sounding ( at NAHA ) ( 21JST 5 June 1987and 09JST 6 June 1987 )

PPI reflectivity data ( 5 min interval )

Volume scan and RHI ( 7 min interval? )

Data

09JST 6 June 1987

Synoptic situation

Low θe

TIME

LCL 986hPaLFC 763hPa

CAPE 567m2/s2

before during

before

during

before

during

Lowest levels - southeast

Lower levels - northwest

Mid to upper levels - southwest

Bulk Richardson number = 27

Moderate shear

OKINAWA

The meso-β-scale convective system

Observation area of ＭＲＩ radar

MRI Doppler radarSTA

GE 1

STA

GE 2

7m/s

STAGE 1 STAGE 2

STAGE 1MRI radar

A-typeStationary cells

B-typeMoving cells

LocationSouthwestern part of the line

Northeastern part of the line

MovementNortheastward at the speed 5.5m/s

Almost stationary

EvolutionSouthwest side of the old cell

Not regular

Nonpropagating stage(line shape)

Outermost contour 45dBZInterval 5dBZ

Reflectivity(dBZ) Doppler velocity(m/s)

斜線部：遠ざかる速度白抜き：近づく速度

減衰

:convergence

:divergence

Rear inflow

STAGE 2Propagating stage(convex shape)

C-typeMoving cells

LocationCentral part of the system

MovementEast-northeastward at the speed 4.5m/s

EvolutionSoutheast side of the old cell

Reflectivity(dBZ) Doppler velocity(m/s)

減衰 Rearinflow

Gust font

Outflow

A3

C1

Conclusion

Discussion

Maximum updraft – near 30m/s (CAPE 567m2/s2 )

So large!!Wmax = (2*CAPE)1/2

= 33.6m/s

The sounding did not represent prestorm environment.

Surface condition( 21JST 5 June ) 23.6℃、 90％

Surface condition( 05JST 6 June ) 25.0℃、 90％

CAPE 567m2/s2

CAPE 1463m2/s2

For my study

Characteristic of the convection around Okinawa・ Very strong reflectivity ( over 50dBZ )

・ Low LCL( the lowest layer is moist )

Technique of single Doppler analysis

・ Very useful for my study I will try soon!

対流雲の発達や内部の詳細な構造の時間変化について調べたものはない。

Akaeda et al 1987

Ogura et al 1985

MRI Doppler radar

通過

Temperature drop(３℃ )

Pressure rise

Gust frontfrom the north

MRI Doppler radar

通過

TIME

減衰

Time variation of echo area

stage1stage2

In stage2 , the strong echo maintained their area and the system was long-lived.

The formation of a squall-line-type circulation is important in maintaining a strong system.