“Cold trap” dehydration in the TTL estimated from the water vapor MATCH Yoichi Inai, Fumio Hasebe and SOWER sonde team 18, 7, 2006

Contents Introduction SOWER campaign 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 M3 M4 M5

Sonde data Frost point Temp MR Range of MR Specific Alt.

~4ppmv/h

WVMR pressure coordinate WVMR PT coordinate MATCH altitude p [hPa] PT [K] 100 ppmv 90ppmv

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 problems Analysis of 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

MR029 Runningmean p hPa,-40 ℃ τ=~20s hPa hPa,-60 ℃ τ=~80s hPa,-30 ℃ τ=~10s

Water increase a lot supersaturation Deep convection Take ~4days TR013>BI003