Rainfall Type Estimation from the Information on Life Stage of Deep Convection

(Feasibility of assigning the life stage of deep convection)

 

Toshiro Inoue, Daniel Vila* and Tomoo Ushio**Meteorological Research Institute, Tsukuba, Ibaraki, Japan

*INA, Buenos Aires, Argentina

** Osaka Prefecture Univ., Osaka, Japan

Motivation

IR rainfall estimation is less physical than PMW and PR rainfall estimation. Because IR observes just cloud instead of rain.

Advantage of the IR is high temporal observation from geostationary orbit.

If we can define the life stage by tracking the deep convection using high temporal observations from geostationary satellite.

Then, we might use the information on the life cycle of deep convection for rainfall estimation.

Developing Mature Decaying

convective rain stratiform rain

TYPE:1 Con. ; TYPE:2 Strat.

Rainfall Rate at 2Km observed by PR/TRMM

~1 mm/h ~8 mm/h

TBB-BTD Characteristics for Ice(Function of effective radius and optical thickness)

TBB

BT

D

EffectiveRadius

Ci-Dense

Cu/Sc

Ci-ThinCi-Thick

Cb

MSG-IR MSG-VIS

MSG-BTDSplit WindowLarger BTD-whiteSmaller BTD-black

Data

GOES-W,E 0.1*0.1 Lat/Lon Grid Hourly Split Window Over Eastern Pacific, South America

MSG(Meteosat-8) 0.05*0.05 Lat/Lon Grid 15 minutes Split Window Over Africa

253K

CiBTD>1Cb

BTD<1

Cloud type (Cb, Ci) classified by the BTD within 253K cloud area.

Definition of Deep Convection

T1

T2

T3

T4

T5

T6

T7

T8

T9

T10

T11

T12

Cloud Type Map Classified by the Split Window

15 minutes interval taken by Meteosat-8

The deep convection starts from 17:45 UTC on 24 May, 2003 to 20:35 UTC on May 24, 2003.

Cloud Type Map Classified by the Split Window

GOES-W 2 hourly from 12UTC May 09, 2001

1°

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12HOUR

# O

F P

IXELS

CB CI

Time Evolution of Deep Convection

Cloud number of Cb (blue) and Ci (green) within 253K cloud area.

% of Cb and Ci within Convection

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6 7Time (every 15 minutes)

CbCi (Anvil)

% of Cb and Ci within Convection

0%20%40%60%80%

100%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Time (hour)

CbCi (Anvil)

Evolution of Percentage of Cb and Ci within DC

The life time is short in left case, while the life timeis longer in right case.

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8

Time (hour)

# o

f 0.1

grid 3 hour

4 hour5 hour6 hour7 hour8 hour

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7 8

Time (hour)

# o

f C

i w

ithin

253K C

loud

3 hour4 hour5 hour6 hour7 hour8 hour

Time evolution of size (top) and % of Ci (bottom)

Cloud Type Map

Percentage of convectiveRain by PR

2°

Evolution of Cb and CiConvective-rain>50%

Convective-rain<50%

1°

Summary

The percentage of Ci classified by the split window within 253K cloud is a good indicator to tell the life stage for simple deep convection case from single snap shot image.

We could assign different rainfall rate for the same TBB depending on the life stage.

Mean Size of Deep Convection

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7

Time (hour)

Size

(# o

f 0.1

lat/

lon

grid

)

3 hour4 hour5 hour6 hour7 hour

% of Cirrus Cloud within 253K Cloud

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7

Time (hour)

% of

Cirr

us C

loud 3 hour

4 hour5 hour6 hour7 hour

VIS and BTD

VISBTD87-11

BTD11-12IR

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10 11 12 13

系列1 系列2 系列3 系列4 系列5 系列6

系列7 系列8 系列9 系列10 系列11 系列12

0

50

100

150

200

250

1 2 3 4 5 6 7 8 9 10 11 12 13

系列1 系列2 系列3 系列4 系列5 系列6

系列7 系列8 系列9 系列10 系列11 系列12

Time evolution of size (top) and # of Ci (bottom)