teruyuki kato ( meteorological research institute / jma )
DESCRIPTION
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 PresentationTRANSCRIPT
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
Heig
ht
Dry Adiabat Originating LevelLifting Condensation Level
Profile of TemperatureProfile of Temperaturein the environmental fieldin the environmental field
Neutral Buoyancy Neutral Buoyancy LevelLevel (LNB) (LNB)
Moist Adiabat
Level of FreeConvection (LFC)
Temperature
e e is conseis conse
rved.rved.
Equivalent potential temperature e
Profile Profile of of ee**
~ 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
NOTE: NOTE: Originating level - LFC Originating level - LFC < 200 hPa< 200 hPa
Appearance frequency of LNB around the Japan IslandsAppearance frequency of LNB around the Japan Islands
First half (June)First half (June) Second half (July)Second half (July)Upper-air sounding dataUpper-air sounding data
Appearance frequency of LNB Appearance frequency of LNB overover Northwestern Pacific Northwestern Pacific
Upper-air sounding dataUpper-air sounding data
Appearance Appearance frequency of LNB frequency of LNB
over the over the other areasother areasaround the around the
Baiu frontal zoneBaiu frontal zone
②②
③③
④④
⑤⑤
Dependency of LNB on Atmospheric StabilityDependency of LNB on Atmospheric Stability
LLee**minmin
LNBLNBmaxmax
Lapse rateLapse rateLarge ← stability → Small
Saturated equivalent Saturated equivalent potential temperaturepotential temperature
Equivalent Equivalent potential potential temperaturetemperature
1000hPa-level temperature of Celsius 25 degrees
相当温位相当温位
1000hPa-level Temperature
LLee**minmin
LNBLNBmaxmax
Dependency of LNB on low-level temperatureDependency of LNB on low-level temperature
JUNE JULY
Over the SeaOver the Sea
On the landOn the land
JUNEJUNE JULYJULY
JUNEJUNE JULYJULY
DomainDomain ::Around Japan Islands:Around Japan Islands:
Appearance Appearance rate of LNBrate of LNB
toto
MaxiumMaxiumequivalentequivalentpotential potential
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
Adiabatic Adiabatic heatingheating
Upper-level Peak
L < 5 K km-1
Originating Level