Oceanic Whitecaps:

Good or Bad?Magdalena Anguelova

Bridging the GapOctober 21 - 22 , 2000

Good or Bad for Remote Sensing

The role of whitecaps The characteristics of whitecaps Judging the whitecaps

Good or Bad for Remote Sensing

The role of whitecaps

Climate Changes

Consequences

...know past climate changes well.

...predict future climate changes accurately.

...understand present climate better.

Climate Studies

Satellite Remote Sensing

Parameters;Instruments;

EM spectrum:

Vis IR mWUV

Ocean ColorWinter 97/98

Water color Presence of organisms

Vis IR mWUV

SeaWiFS

Aerosol Concentration

Atmospheric reflection Presence of aerosols

Vis IR mWUV

MODIS

Sea Surface Temperature

Thermal emission Temperature changes

Vis IR mWUV

AVHRR

Wind Speed

Thermal Emission Roughness and foam

Vis IR mWUV

SSM/I

Use of Data

11101110

11

110111

11011

Gross Features vs. Details Understanding; Experience.

Top of theatmosphere

Ts

SR

AU AD

Ocean Ts

ST

Instrument

ST SR + Ts+ AU + AD

SU

+ SU

Composite Signal

Good or Bad for Remote Sensing

The role of whitecaps The characteristics of whitecaps Judging the whitecaps

Good or Bad for Remote Sensing

The characteristics of whitecaps

Oceanic Whitecaps

White foamy patches on a windy day

The Foam

Air/water mixture; Dry and wet foam; Specific properties; Changing throughout

Vis IR mWUV

Whitecaps in the Visible

Bright and white! Excellent reflectors!

Vis IR mWUV

Whitecaps in the Infrared

Reflectance decreases; Some thermal emission;

Vis IR mWUV

Whitecaps in Microwave

Poor reflectors Excellent emitters!

Vis IR mWUV

Whitecaps Signature

High Reflectivity

High Emissivity

So-so

Vis IR mWUV

Good or Bad for Remote Sensing

The role of whitecaps The characteristics of whitecaps Judging the whitecaps

Good or Bad for Remote Sensing

Judging the whitecaps

Desired Signal

SR + Ts )+ AU + AD

ST SR + Ts+ AU + AD+ SU

SR + Ts )+ SU + AD

SR + SU )+ AU + AD

ST – (

ST – (

ST – (

ST – (SR + SU )+ AU + AD

SU

AU

Ts

Ts

The Judgment

Wind speed

SST Aerosols

Ocean Color

Conclusion

Whitecaps must be accounted for; Know well their characteristics;

Questions