“Cold trap” dehydration in the TTLestimated from the water vapor MATCH

Yoichi Inai, Fumio Hasebe

and SOWER sonde team

18, 7, 2006

Contents • Introduction

• SOWER campaign 2004-2005

• MATCH definition

• Analysis of sonde data

• Analysis of MATCH pair

• Summary

• Future problems

Dehydration hypotheses• Vertical ascent in the tropics Brewer(1949),Newell&Gould-Stewart(1981)

• Overshooting convective cloud Danielsen(1982),Sherwood(2000)

• Dehydration pump Fujiwara et al.(2001)

• Cold trap Holton&Gettelman(2001)

GCM study Hatsushika&Yamazaki(2003)

Trajectory model study Fueglistaler et al.(2005),Jensen & Pfister(2004),Fueglistaler&Haynes(2005)

Hatsushika&Yamazaki(2003)

Randel et al.(2001)

Cold region

• Meteorological field ECMWF operational analysis 　　 2.5°×2.5°

• Equiva ｌ ent black body temperature GOES09 IR1 　　 0.05°×0.05°

• Water 　 Vapor data SOWER04-05 Campaign ( frostpoint hygrometer; Snow white, CFH )

← 　 MATCH pair○ 　 observation point

Wave number = 2　 ~2°/day

M1

M2

M3M4

M5

pT p

H

T

H

pTH

, pF p

G

F

G

pFG

,

FTpSD

FTpmean

,,:

,,:

Sonde data

p TF

p

F

T

Frost point

Temp

pT

p

MR

Range of MR

Specific Alt.

WVMR pressure coordinate

WVMR PT coordinate

MATCH altitude

p [hPa] PT [K]

100 ppmv90ppmv

Deep convection

MATCH

p [hPa] PT [K]

Summary• Dec 2004 – Jan 2005 SOWER Campaign data in tropical

western Pacific are analyzed.

• An objective definition of water vapor MATCH is introduced.

• The range of water vapor mixing ratio on a specific potential temperature is estimated considering the time interval required for mirror to reach vapor-ice equilibrium.

• 5 sonde pairs are found to MATCH. 2 of them have been closely discussed. There found some inconsistency in that the air parcel was

not exposed to low temperature enough to be expected from the water vapor mixing ratio of the downstream observation.

Future problemsAnalysis of 2005-2006 campaign data• CFH at Tarawa and Biak

Analysis of individual sounding data • Dehydration of air from convective out flow.

Use of higher resolution ECMWF data

Temperature biases between ECMWF and sonde temperature

• Reevaluation of dehydration by taking the biases