mesoscale convective systems in amazonia in the wet season maria assunção f. silva dias...
Post on 26-Mar-2015
216 Views
Preview:
TRANSCRIPT
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/
2/
0
)1(1
,,0
xx
xx
yy
yy
ec
t
t
waawwdxdyyx
w
dtwvutrtr
cw cloud model
t
t trajconv
ctrajconv
e
dtwvutrtr
awwaw
ww
0.0
.
,,
)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)
......;...;
0
1ln
133
dt
dr
dt
dr
dt
dr
SHMLCLMLFRCL
MLCNCLCLVDPRdt
dr
PRPRPRPRdt
dr
rrrrrrHrrrrrrr
rrrrrr
rrrrrrr
x
u
x
u
TRp
QQQcdt
d
fufgrgx
p
t
u
agi
grarragrrgrg
ircrricrrvrr
agirT
agirSTagirSTc
agircw
agircvT
i
i
i
i
vdm
DisRadLHp
rjkijkiwiim
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.
top related