Mesoscale Convective Systems in

Amazonia in the Wet Season

Maria Assunção F. Silva Dias

Departamento de Ciências AtmosféricasInstituto Astronômico e Geofísico

Universidade de São Paulo

Why are clouds important in LBA?

h

FF

t

c h

0

hF

0F

Shallow cumulus layer

Mixed layer

Tracer continuity equation in the mixed layer

Water vapor

morning

Freitas et al, 2000

GOES-8 visible satellite image at 11:45 UTC March 16, 1998, showing the smoke produced by biomass burning over Roraima state.

GOES-8 IR satellite image at 18:00 UTC March 18, 1998 showing the convective system at northern part of Amazon basin.

Freitas et al, 2000

2/

2/

2/

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,,0

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xx

yy

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cw cloud model

t

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)1(

Convective trajectory equations

wvu ,, mesoscale, regional model

Freitas et al, 2000

Freitas et al, 2000

Non-convective trajectories

Convective trajectories

CO2 CO

1. Observations

2. Internal controls on convection

3. External controls on convection

1. Observations

TRMM-LIS

Seasonal (DJF, JJA, SON)

12/97 - 1/00

Petersen et al, 2000

2.54.5

6.58.5

10.512.5

14.516.5

20-2525-30

30-3535-40

40-4545-50

50-55>55

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Relative F

requ

ency (%

)

Height (km)

dBZ bin

CONGO: DJF 98-00 TRMM-PR 2A25 PDF

20-25 25-30 30-35 35-40 40-45 45-50 50-55 >55

2.54.5

6.58.5

10.512.5

14.516.5

20-25

30-35

40-45

50-55

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Re

lativ

e F

req

ue

nc

y (%

)

Height (km)

dBZ bin

N. AUSTRALIA: DJF 98-00 TRMM-PR 2A25 PDF

20-25 25-30 30-35 35-40 40-45 45-50 50-55 >55

2.54.56.58.5

10.512.5

14.516.5

20-25

30-35

40-45

50-55

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Relative F

requ

ency (%

)

Height (km)

dBZ bin

AMAZON: DJF 98-00 TRMM-PR 2A25 PDF

20-25 25-30 30-35 35-40 40-45 45-50 50-55 >55

2.54.5

6.58.5

10.512.5

14.516.5

20-25

30-35

40-45

50-55

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Relative F

requ

ency (%

)

Height (km)

dBZ bin

W. PAC. WARM POOL: DJF 98-00 TRMM-PR 2A25 PDF

20-25 25-30 30-35 35-40 40-45 45-50 50-55 >55

TRMM-PR 2A-25 RELATIVE FREQ. HISTOGRAMSContinental

?? Ocean

Petersen et al, 2000

TRMM PR: WARM/WET SEASON 1998/99/00

Ice Water (g m3)

0

0.05

0.1

0.15

0.2

0.25

0.3

7 8 9 10 11 12 13 14 15

Height (km)

IWC

g m

3

Afr. Congo (D-F) Sub-trop. Africa (D-F)

N. Australia (D-F) Amazon (D-F)

Brazil (M. Grosso) (D-F) Warm-pool (D-F)

KWAJ. (J-A) G. Mexico (J-A)

Florida (J-A) SE. US (J-A)

Atlantic ITCZ (D-F) S India (J-A)

N India (J-A) EPIC3 (6-12 N) (J-A)

S. China Sea (J-A) Indian Ocean (S-N)

Gulf Str. (J-A) Argentina (D-F)

Height (km)

LIS Flash Density vs. 7-9 km IWC

y = 39.976x - 5.0843

R2 = 0.8008

y = 213.84x2 - 30.779x + 0.5822

R2 = 0.8164

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0.00 0.05 0.10 0.15 0.20 0.25 0.30

IWC (g/m3)

Fla

sh D

ensi

ty (

FL

/km

2 /mo

)

Wet Season (1998-2000): LIS Flash Density vs. IWC (7-9 km)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24

IWC (g/m3)

Fla

sh

es

/km

2/m

on

th

=AMZ/Monsoon

=Ocean/Coast

=Ocean

=Land

AMZ

Congo

WP Warm-pool

Florida

Gulf StreamCntrl. Brazil

Sub-Congo Africa

EPIC

N. IndiaS. India

TRMM-PR IWC (Z-M)

vs. LIS Flash Density

LAND

OCEAN

AMZ (SON)

AMZ (DJF)

Wet Season Mesoscale Atmospheric Campaign

LBA

January and February, 1999

Rondônia

WETAMC Components:• FAPESP’s: Mesoscale Interactions between Biosphere and

Atmosphere in LBA

• FAPESP’s: Atmospheric Chemistry/LBA

• EUSTACH

• NASA - TRMM/LBA

Objectives

• to understand the coupling between biosphere and atmosphere processes in the wet season in the Amazon region including budgets of heat, water vapor, trace gases and VOC;

• to determine the cloud dynamics and microphysics interactions over rain forest and over adjacent deforested areas including the role of aerosol and biogenic compounds as CCN;

• to understand the local response of clouds and rainfall to large scale forcing;

• to improve modeling of biosphere-atmosphere processes in different scales.

Observations

four radiosonde sites performing 6-8 soundings per day,

three tethered balloon sites for boundary layer meteorology;

1 forest 60 m micrometeorological tower instrumented with 3 levels of eddy correlation measurements and vertical profiles of radiation, temperature, humidity and windspeed;

1 forest 54 m tower instrumented for atmospheric chemistry measurements, including CO2 flux.

forest and pasture arrays for temperature and soil moisture and set of rings for soil respiration.

1 tethered ballon for atmospheric chemistry measurements,

2 pasture towers with profiles, and eddy correlation measurements including CO2 flux.

• 1 pasture tower for atmospheric chemistry measurements and spectral radiation measurements

• 2 wind profiler sodars, 1 with RASS

• network of 4 complete AWS;

• 4-station lightning detection network,

• a dense raingauge network and several disdrometers,

• 2 Doppler radars (including the NCAR S-pol and the TOGA C-band radar),

• a dual-wavelength radar profiler

• Citation II Learjet for in-situ sampling of microphysical variables

• ER-2 carrying the EDOP radar (ER-2 Doppler, X band radar) and AMPR (Airborne Microwave Profiling Radiometer), a multi-frequency radiometer similar to the SMI instrument on TRMM.

Rondônia

10º S

12º S

62º 60º

Faz. Nova Vida

Rancho Grande

Faz. Nossa Senhora (ABRACOS)

Alvorada do Oeste

Nova Brasilândia do OesteRolim de Moura

Faz. Jamaica(G)

Rebio Jarú

Faz. Santa Clara

Faz. Condor

Machadinho D’Oeste

Ouro Preto D’Oeste

62º 60º

WETAMC sites

Fisher et al 2000

LBA winter

LBA summerKwajalein

Downscaling with RAMS 20 km grid

Rondônia Low Levels Wind Regimes

13 Jan - 18 Jan ... Westerly

19 Jan - 26 Jan ... Easterly

27 Jan - 2 Feb ... Westerly

2 Feb - 21 Feb ... Easterly

22 Feb - 28 Feb ... Westerly

Rickembach et al, 2000

Easterly

Westerly

Carvalho et al 2000

Rickenbach et al. 2000

Blakeslee, 2000

w W W

Westerly case

Easterly case

S-pol Rondônia

Petersen et al, 2000

Threshold 235K (Systems)

100

120

140

160

180

200

220

0:45

2:45

4:45

6:45

8:45

10:4

5

12:4

5

14:4

5

16:4

5

18:4

5

20:4

5

22:4

5

Time (UTC)

Rad

ius

(km

)

Westerly

Easterly

Threshold 235K (Systems)Convective Tops: 210K

02468

1012141618

0:45

2:45

4:45

6:45

8:45

10:4

5

12:4

5

14:4

5

16:4

5

18:4

5

20:4

5

22:4

5

Time (UTC)

Nu

mb

er o

f C

on

vect

ive

Top

s

Westerly

Easterly

Carvalho et al, 2000

0

100

200

300

400

500

1 11 21 31 41 51

julian day (1999)

accu

mul

ated

rain

fall

(mm

)

Average accumulated rainfall from net 1

Ji-Paraná airport area

W

W W

Tokai, 2000

2. Internal controls

.

Convective dynamics (Cotton & Anthes, 1989)

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0

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133

dt

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i

Cotton & Anthes, 1989

Wallace & Hobbs, 1972

(a) condensation(b) collection

Warm rain processes

Wallace & Hobbs, 1972

Seinfeld & Pandis,1998

Cloud condensation nuclei in Amazonia in the wet season

- primary organic aerosol

- secondary organic aerosol: add soluble material (sulfates) to particles that come from elsewhere or ar nucleated at clod tops.

G.Roberts, 2000

M. Andrea, 2000

TRMM observed first direct evidence of smoke from forest fires TRMM observed first direct evidence of smoke from forest fires inhibiting rainfallinhibiting rainfall

Rosenfeld DGEOPHYSICAL RESEARCH LETTERS 26: (20) 3105-3108 OCT 15 1999

Although it has been known that smoke from biomass burning suppresses warm rain processes, it was not known to what extent this occurs. The satellite observations of the Tropical-Rainfall-Measuring-Mission (TRMM), presented here, show that warm rain processes in convective tropical clouds infected by heavy smoke from forest fires are practically shut off. The tops of the smoke-infected clouds must exceed the freezing level, i.e., grow to altitudes colder than about -10 degrees C, for the clouds to start precipitating. In contrast, adjacent tropical clouds in the cleaner air precipitate most of their water before ever freezing. There are indications that rain suppression due to air pollution prevails also in the extra-tropics.

Cold rain processes

Cotton & Anthes, 1989

Williams et al, 1999

(Westerly)(Easterly)

(End of dry season)

(Easterly)

(Westerly)

3. External controls

Cutrim et al, 1995, BAMS

0

1

2

3

4

56

7

8

9

10

11:2212:25

12:2613:30

13:3114:35

14:3615:39

15:4016:44

UTC

Pasture

Pasture(interface)

Forest

Forest(interface)

20

22

24

26

28

30

0 2 4 6 8 10 12 14 16 18 20 22

time (UTC)

Te

mp

era

ture

(C

)

pasture (Ouro Preto)

forest (Rebio Jaru)

05

101520

0 2 4 6 8 10 12 14 16 18 20 22

time (UTC)

rain

fall

(mm

)

pasture

forest

7 Feb 1999

0

20

40

60

80

100

0 3 6 9 12 15 18 21 24

(UTC)

p(s

urf

ace)

-p(L

CL

) (

hP

a)

rebio

abracos

7 February 1999

R NET

rain

LE

H

ABRACOS-BR/EC

7 Feb 1999

Development of the CBL

PASTURE FORESTLocalTime DRY WET DRY WET

8 62 31 (10) 94 29 (25) 75 28 (12) 124 50 (16)

11 517 241 (13) 475 99 (26) 267 114 (13) 491 133 (26)14 1471 479 (13) 775 127 (28) 902 307 (13) 813 128 (19)17 1641 595 (13) 927 166 (12) 1094 385 (13) 1002 195 (16)

Fisch et al, 2000

Easterly

Westerly

Carvalho et al 2000

CPTEC/INPE ANALYSIS

24Feb99

Net 1 - 26 Jan 1999

0

10

20

30

0 5 10 15 20 25

local time

rain

fall

(mm

)

Pereira et al, 2000

12Z 26 Jan e 0Z 27Jan

0

10

20

30

40

50

60

J F M A M J J A S O N D

month

nu

mb

er

of

ca

se

s

LONG LIVED SQUALL LINES

SHORT LIVED SQUALL LINES

COASTAL CONVECTIVE LINES

Cohen et al, 1989

Amazonian Squall Lines - 1979-1986

Silva Dias e Ferreira, 1992

E WN S N

Average soundings in Belém at 12 UTC during GTE/ABLE 2B

II - Coastal Convective lines

IV - 5 consecutive days with squall lines

I - All squall line days

III - No convective lines

Cohen et al, 1995

May 4

May 5

May 6

Wind

700 hPa

(Atlantic

Easterly

Wave)

Vórtice Ciclônico de Altitude

0

100

200

300

400

500

1 11 21 31 41 51

julian day (1999)

accu

mul

ated

rain

fall

(mm

)

Average accumulated rainfall from net 1

Ji-Paraná airport area

W

W W

Summary

- shallow cumulus respond to in different ways in the wet and dry seasons. Does that impact rainfall?

- large scale forcing (dynamics, thermodynamics) imposes a mode of convection which has a symbiotic relationship with cloud microphysics and CCN.