Shipboard Investigation of Air-sea Interaction and Cloud Processes in the VOCALS Stratocumulus Region
C. W. Fairall(1), D. Wolfe (1), S. Pezoa (1),S. de Szoeke(1), L. Bariteau (1, 2), Efthymios Serpetzoglou
(3), Virendra Ghate (3), and Paquita Zuidema (3)
Results from NOAA Stratus Cruises2001-2006
Observation SystemsAir-sea Fluxes, Clouds, Precipitation
Cloud Radar and Microwave Radiometer
Measurement Systems for PACS/Stratus Cruises
Instrument/Variable Oct 01 Nov 03 Dec 04 Oct 05 Oct 06 Flux X X X X X Sonde X X X X X Aerosol X X X X Microwave X X X X X Ceilometer X ~ X X X Cloud radar X X ~ C-band radar X X X Drizzle radar X X X X
96oW 90oW 84oW 78oW 72oW 66oW
32oS
24oS
16oS
8oS
0o
Cloud-Aerosol-Drizzle Connection
Cloud-aerosol Indirect Effect Example from Stratus2005:
Minimum in PBL aerosol concentration corresponds to broken cloud period and much higher transmission of solar flux to ocean.
Broken cloud period was during a POC with drizzling mesoscale cloud features.
Note cloud LWP about the same for solid vs broken clouds.
0 5 10 15 20 250
50
100IR
Clo
ud
Fo
rcin
g (
W/m
2 )x-01 o-03 dia-04 rt tri-05 *06
0 5 10 15 200.4
0.6
0.8
1
Local Time of Day (hr)
Clo
ud
fra
ctio
n (
m)
0 5 10 15 201000
1200
1400
1600
1800
Clo
ud
top
(m
)
x-01 o-03 dia-04 rt tri-05 *06
0 5 10 15 20800
1000
1200
1400
1600
Clo
ud
ba
se (
m)
0 5 10 15 200
100
200
LW
P (
g/m
2 )
x-01 o-03 dia-04 rt tri-05 *06
0 5 10 15 200
200
400
600
Local Time of Day (hr)
Clo
ud
Th
ick
(m)
0 5 10 15 20
102
Ae
roso
l (#
/cm3 )
Local Time of Day (hr)
x-01 o-03 dia-04 rt tri-05 *06
Deduce Cloud Optical Properties:Observed cloud transmission coefficient
294.5 294.6 294.7 294.8 294.9 2950
500
1000S
ola
r F
lux
(W/m
2 )
294.5 294.6 294.7 294.8 294.9 2950
0.5
1
Julian Day (2001)
So
lar
Tra
nsm
issi
on
Co
eff.
STRATUS Cloud Optical Properties:LWP and Aerosol Relationships
From the Diurnal Averaging
0 50 100 150 2000
1
2
3
4
5
Op
tica
l Th
ick/
(Nae
r1/
3)
LWP (g/m2)
x-01 o-03 dia-04 rt tri-05 *06
0 50 100 150 2000
5
10
15
20
25
Op
tica
l Th
ick)
LWP (g/m2)
x-01 o-03 dia-04 rt tri-05 *06
Calif Coast
145W Equatorial Pac
Observed Optical thickness vs Observed LWP. Calif coast Naer=300/cc; Eq Pac Naer=50/cc
Observed Optical thickness divided by 1-third power of Observed Aerosol Number Concentration versus Observed LWP
Daily-averaged Stratus observations:SST and Sea-air Temperature difference
280 300 320 340 36017.5
18
18.5
19
19.5
20
Ts
(C)
Local Time of Day (hr)
x-01 o-03 dia-04 rt tri-05 *06
280 300 320 340 360-0.5
0
0.5
1
1.5
2
Ts
- T
a (
C)
Local Time of Day (hr)
x-01 o-03 dia-04 rt tri-05 *06
280 300 320 340 3600
50
100IR
Clo
ud
Fo
rcin
g (
W/m
2 )x-01 o-03 dia-04 rt tri-05 *06
280 300 320 340 3600
0.5
1
Local Time of Day (hr)
Clo
ud
fra
ctio
n (
m)
280 300 320 340 36010
1
102
103
Ae
roso
l (#
/cm
3 )
Local Time of Day (hr)
x-01 o-03 dia-04 rt tri-05 *06
280 300 320 340 3600
100
200
300
LW
P (
g/m
2 )
x-01 o-03 dia-04 rt tri-05 *06
280 300 320 340 3600
500
1000
Local Time of Day (hr)
Clo
ud
Th
ick
(m)
280 300 320 340 3601000
1500
2000
2500
Clo
ud
top
(m
)
x-01 o-03 dia-04 rt tri-05 *06
280 300 320 340 360500
1000
1500
2000
Clo
ud
ba
se (
m)
Diurnal and Daily Average File Formats
• yxz(:,1)=jdd;Julian Day• yxz(:,2)=rld;Downward IR flux W/m^2• yxz(:,3)=rlclrd;Clear sky downward IR flux W/m^2• yxz(:,4)=rsd;Downward solar flux W/m^2• yxz(:,5)=rsclrd;Clear sky downward solar flux W/m^2• yxz(:,6)=tsgd;Ship thermosalinograph water temperature (5 m depth)• yxz(:,7)=tsd; ESRL seasnake water temperature (5 cm depth)• yxz(:,8)=tad; Air Temperature (18 m) C• yxz(:,9)=tau opt; Cloud optical thickness• yxz(:,10)=zbmd; Median cloud base height m• yxz(:,11)=topd; Cloud top height• yxz(:,12)=wmd; Cloud liquid water path g/m^2• yxz(:,13)=cldfd; Cloud fraction• yxz(:,14)=aer_mnd1; Aerosol number, size>.1 micron and size<.2 micron• yxz(:,15)=aer_mnd2; Aerosol number, size>.3 micron and size<.5 micron• yxz(:,16)=aer_mnd3; Aerosol number, size>1 micron and size<5 micron• yxz(:,17)=yrr; Year of the cruise• yxz(:,18)=raind; Rain rate mm/hr• yxz(:,19)=uxd; Northerly wind component m/s• yxz(:,20)=uyd; Easterly wind component m/s• yxz(:,21)=ud; Wind speed m/s• yxz(:,22)=hsd; Sensible heat flux W/m^2• yxz(:,23)=hld; Latent heat flux W/m^2• yxz(:,24)=taud; Stress N/m^2• yxz(:,25)=zb1d; 15% cloud base height m• yxz(:,26)=clodthkd; Cloud thickness m• yxz(:,27)=ndd; Number cloud drops deduced from optical thickness• yxz(:,28)=latd; Latitude• yxz(:,29)=lond; Longitude