1. Total surface flux (+up) from models
asymmetry = average N-S W/m^2 [±20N, 90W-coast]
CORE = Common Ocean-ice Reference Experiments, Large and Yeager 2004
CORE, Large and Yeager 2004

3. NOAA ship observations
October 2001, (6 years) 20˚S, 75-85˚W Fall 2001, 2003, 2004, 95˚ and 110˚W, ±10˚N
Assess fluxes from ground
Investigate processes:
Surface meteorology
Turbulent and radiative fluxes
Cloud vertical structure: top, base, and LCL.
Rawinsondes
Column water vapor and liquid water path
Aerosols

4. 20˚S surface heat fluxes 250 200 150 100 flux (W m-2) 50 -50 -100 -150
solar
150
100
net
flux (W m-2) 50
sensible
Latent heat flux increases from 60 (75W) to 100 W/m2 (85W), because of increasing SST.
Sensible is small.
Net warming decreases negligibly to west, primarily by latent cooling increase.
Longwave is constant 30W/m2 cooling. Probably cloud base temperature is nearly constant, but cloud fraction decreases slightly as SST warms.
Insolation increases detectably 25 W/m2 from 75 to 85W, consistent with more broken cloud to west.
-50
longwave
-100
latent
-150
-86
-84
-82
-80
-78
-76
-74
longitude

5. October heat fluxes 95 & 110˚W
GFDL CM2.1
IROAM
October heat fluxes 95 & 110˚W
-40
-40
latent
-80
-80
-120
-120
-160
-160
-12 -8 -4 4 8 12
-12 -8 -4 4 8 12
sensible
-10
-10
-20
-20
-12 -8 -4 4 8 12
-12 -8 -4 4 8 12
-25
-25
longwave
-50
-50
-75
-75
-12 -8 -4 4 8 12
-12 -8 -4 4 8 12
300
300
change WORS to TAO
Model
TAO buoy
WHOI ( ) analysis
[Yu and Weller 2007]
CORE ( )
[Large and Yeager 2004]
NOAA ship observations
250
250
solar
200
200
150
150
100
100
-12 -8 -4 4 8 12
-12 -8 -4 4 8 12
200
200
150
150
100
net
100 50 50
-50
-50
-100
-100
-12 -8 -4 4 8 12
-12 -8 -4 4 8 12
north latitude

6. October heat fluxes 20˚S Model WHOI ORS buoy WHOI (1984-2002) analysis
GFDL CM2.1
IROAM
October heat fluxes 20˚S
-40
-40
latent
-80
-80
-120
-120
100 85 70
100 85 70
-10
-10
sensible
-20
-20
-30
-30
-40
-40
100 85 70
100 85 70
-25
-25
longwave
-50
-50
-75
-75
-100
-100
100 85 70
100 85 70
300
300
analyses (WHOI and CORE) do well, even where models are worst
NOAA ship observations are available 75-85W, where model errors are largest. Compare with models and study processes.
250
250
solar
200
200
150
150
100 85 70
100 85 70
Model
WHOI ORS buoy
WHOI ( ) analysis
CORE ( )
NOAA ship observations
160
160
120
120
net 80 80 40 40
100 85 70
100 85 70
west longitude

7. cloud height height (km) degrees longitude diurnal sampling -85 -82.5
250 6 18 12 25 50
-85
-82.5
-80
-77.5
-75
0.5 1
1.5 2 3 4 5 6 7
degrees longitude
height (km)
surface LCL
cloud base
cloud top
Cloud top and cloud base deepen ~300 m from 75 to 85W; thickness remains the same.
Lifting condensation level of a surface parcel stays the same across longitude, indicating that the PBL is entraining dry air and decoupling the cloud layer from the surface layer.
Numbers indicate individual cruises by last digit of cruise year.