Cloud Top Heights of Cloud Top Heights of Cumulonimbi, Cumulonimbi, Thermodynamically Estimated Thermodynamically Estimated from Objective Analysis Data from Objective Analysis Data during the Baiu Season during the Baiu Season Teruyuki KATO Teruyuki KATO ( ( Meteorological Research Meteorological Research Institute / JMA Institute / JMA ) ) 006: 006: 5th International Conference on Mesoscale Meteorology and Typhoon 5th International Conference on Mesoscale Meteorology and Typhoon
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Teruyuki KATO ( Meteorological Research Institute / JMA )
3/11/2006: 5th International Conference on Mesoscale Meteorology and Typhoon. Cloud Top Heights of Cumulonimbi, Thermodynamically Estimated from Objective Analysis Data during the Baiu Season. Teruyuki KATO ( Meteorological Research Institute / JMA ). Purposes of today’s presented study. - PowerPoint PPT Presentation
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Cloud Top Heights of Cumulonimbi, Cloud Top Heights of Cumulonimbi, Thermodynamically Estimated from Thermodynamically Estimated from
Objective Analysis Data Objective Analysis Data during the Baiu Seasonduring the Baiu Season
Teruyuki KATOTeruyuki KATO(( Meteorological Research Institute / Meteorological Research Institute /
JMAJMA))
3/11/2006: 3/11/2006: 5th International Conference on Mesoscale Meteorology and Typhoon5th International Conference on Mesoscale Meteorology and Typhoon
Purposes of today’s presented studyPurposes of today’s presented study
• to clarify the to clarify the thermodynamically atmospheric conditionsthermodynamically atmospheric conditions around the Baiu Frontal Zonearound the Baiu Frontal Zone
in relation to the development of cumulonimbi.in relation to the development of cumulonimbi.
• to examine the condition under which to examine the condition under which convection with cloud tops less than the melting levelconvection with cloud tops less than the melting level ca ca
n form, and its cause.n form, and its cause.
Such convection was often observed around the Baiu frSuch convection was often observed around the Baiu frontal Zone (e.g., Zhang et al. 2006).ontal Zone (e.g., Zhang et al. 2006).
By using objective analysis data,By using objective analysis data,
Objective analysis data and statistical areaObjective analysis data and statistical area
Data used in this studyData used in this study
Regional Analysis data Regional Analysis data of the JMAof the JMA
Resolution:Resolution: 20 km 20 km
Vertical grids:Vertical grids: -p plane-p plane p planep plane
Available:Available: 6 hourly 6 hourly
Period:Period: June & July June & July in 2001-2005in 2001-2005
Statistical areaStatistical area
JULYJULY
JUNEJUNE
Cloud top heights of cumulonimbi, Cloud top heights of cumulonimbi, thermodynamically estimated in this studythermodynamically estimated in this study
~ Level of Neutral Buoyancy (LNB) of an air with the m~ Level of Neutral Buoyancy (LNB) of an air with the maximum aximum ee at the low level, except the surface at the low level, except the surface
temperaturetemperatureat the low-levelat the low-level
DomainDomain ::Around Japan Islands:Around Japan Islands:
JUNEJUNE JULYJULY
JUNEJUNE JULYJULY
Over the SeaOver the Sea
On the landOn the land
Appearance Appearance rate of LNBrate of LNB
toto
Lapse rateLapse rateBetweenBetween
500500mm-altitude-altitudeandand
700700hPa-levelhPa-level
5K/km5K/km
5K/km5K/km
5K/km5K/km
5K/km5K/km
ConclusionsConclusionsIn the appearance rate of LNB during the Baiu season,In the appearance rate of LNB during the Baiu season, >> Upper and middle peaks are found on the land. Upper and middle peaks are found on the land. (~ 150hPa) (~ 700hPa) (~ 150hPa) (~ 700hPa) >> Another peak (~ 900hPa) is also found over the sea. Another peak (~ 900hPa) is also found over the sea.
CauseCause:: Stabilization of atmospheric conditions around the Japan Stabilization of atmospheric conditions around the Japan Islands, brought from the inflow of middle-level airs warmed by Islands, brought from the inflow of middle-level airs warmed by convective activities convective activities overover upstream areas, upstream areas, especiallyespecially China Continent China Continent
Factor to divide LNB into upper and middle peaks isFactor to divide LNB into upper and middle peaks is (( ~ ~ 150150hPahPa )()( ~ ~ 700700hPahPa ))
For For > about 5K/km and large > about 5K/km and large ee of lifted air, LNB appears at the of lifted air, LNB appears at the upper level. For the other, LNB appears at the middle level.upper level. For the other, LNB appears at the middle level.
dependent mainly on mean lapse late dependent mainly on mean lapse late below the middle level. below the middle level.
Pre
ssur
e (h
Pa)
e (K)
Profile of e
*
600
200hPa
700
500
200
U ~ 6 K km-1
L > 5 K km-1
Tropopause
Middle-level Peak
Profile of e
*
Upper-level Peak
Formation mechanism of Formation mechanism of Upper- and Middle-level Peaks of LNBUpper- and Middle-level Peaks of LNB