Structures of multiple fronts observed in the Baiu frontal zone over the East China Sea: Aircraft...

Structures of multiple fronts observed in the Baiu frontal zone over the East China Sea:

Aircraft observation on 27 June 2004

Institute of Observational Research for Global Change (IORGC),Japan Agency for Marine-Earth Science and Technology

Qoosaku MOTEKICoauthors are T. Shinoda, S. Shimizu, S. Maeda, H. Minda, K. Tsuboki, H. Uyeda: HyARC, Nagoya Univ.T. Kato: 　　　　　　　　　　　　　　　　　　　　　　　 Meteorological Research Institute

CHINA

KOREA

KYUSHU

Multiple fronts in the Baiu frontal zoneover the East China Sea

(Moteki et al., 2004, JMSJ)

Aircraft observation on 27 June 2004

CHINA

KOREA

KYUSHU

In situ measurement: p, T, Td, u, v, w at 500 m MSL,0852-0950 JST

Drop sondes: dropped from 12 km MSL at 6 points,1023-1209 JST

NAHA

CHEJU

Objectives of this study

To show observational evidence for the fact that multiple fronts exist inside the Baiu frontal zone.

To quantitatively show their features (horizontal gradients of PT, Qv, etc.)

Case overview (09 JST 26 - 03 JST 27 JUNE 2004)

Aircraft observation on 27 June 2004In situ measurement: p, T, Td, u, v, w 　 at 500 m MSL,

0852-0950 JSTDrop sondes: dropped from 12 km MSL at 6 points,

1023-1209 JST

Definitions on the basis of cloud image at 10 JST

CHINA

KOREA

KYUSHU

Baiu frontal zone: the zone with a north-south width of about 500 km including 3 cloud zones.

NAHA

CHEJU

Definitions on the basis of cloud image at 10 JST

CHINA

KOREA

KYUSHU

Frontal zone 1 (FZ1): the zone on the southern side of BFZ.

NAHA

CHEJU

Frontal zone 2 (FZ2): the zone in the middle of BFZ.

Frontal zone 3 (FZ3): the zone on the northern side of BFZ.

Flight level data at 500 m from 0852-0950 JST

S N

FZ1 FZ2 FZ3

ΔPT

(K/100km) 6.4 3.0

ΔQv

(g/kg/100km) 1.7 3.0 3.2

Vertical cross section based on dropsonde data

S

PT

Qv

S N

Vertical cross section based on dropsonde data

S N

( )v

F confluencey y

0, 0v

y y

Vertical cross section based on dropsonde data

S N

RH

Melting level

Schematic illustration of the multiple frontal structures

S N

ConclusionsThe multiple frontal structures that formed in different time and had different features were observed on 27 June 2004 over the East China Sea.

FZ1: small ΔPT, ΔQv=1.7(g/kg/100km), no rainfall.

FZ2: ΔPT=6.4(K/100km), ΔQv=3.0(g/kg/100km), strong rainfall.

FZ3: ΔPT=3.0(K/100km), ΔQv=3.2(g/kg/100km), moderate rainfall.

Hypothesis

Although the Baiu front analyzed on the surface weather map seems to have stagnated, it is replaced with the new front from the old front in a few hours.

The old frontThe old front

The new frontThe new front

FZ0

FZ1

FZ2

FZ3

FZ4

L

Synoptic low(passed at 18Z

on 24)

The position of stationary front

Time-Lat. Sec. of TBB(09JST23-09JST28)

Case overview (04 JST 27 - 10 JST 27 JUNE 2004)

Vertical cross section based on dropsonde data

S N

PT

Qv

Vertical cross section based on dropsonde data

S N

PT

V

Confluence term of FGF with RANAL

FZ1

FZ2

FZ3

Confluence term of FGF with RANAL

FZ1

FZ2

FZ3

Shear term of FGF with RANAL

FZ1

FZ2

FZ3

Heating term of FGF with RANAL

FZ1

FZ2

FZ3

FGF with RANAL

FZ1

FZ2

FZ3

Convergence with RANAL (09JST27)

FZ1

FZ2

FZ3

Convergence with RANAL (21JST26)

FZ1

FZ2

Convergence with RANAL (03JST26)

FZ1