Oceanic Whitecaps: Good or Bad? Magdalena Anguelova Bridging the Gap October , 2000
Good or Bad for Remote Sensing n The role of whitecaps n The characteristics of whitecaps n Judging the whitecaps
Good or Bad for Remote Sensing n The role of whitecaps
Climate Changes
Consequences
n n...know past climate changes well. n n...predict future climate changes accurately. n n...understand present climate better. Climate Studies
Satellite Remote Sensing Parameters; Instruments; EM spectrum: VisIRmWUV
Ocean Color Winter 97/98 n Water color n Presence of organisms VisIRmWUV SeaWiFS
Aerosol Concentration n Atmospheric reflection n Presence of aerosols VisIRmWUV MODIS
Sea Surface Temperature n Thermal emission n Temperature changes VisIRmWUV AVHRR
Wind Speed n Thermal Emission n Roughness and foam VisIRmWUV SSM/I
Use of Data
Gross Features vs. Details n Understanding; n Experience.
Top of the atmosphere TsTs SRSR AUAU ADAD Ocean TsTs STST Instrument ST ST SRSR + T s + AU+ AU + AD+ AD SUSU + SU+ SU Composite Signal
Good or Bad for Remote Sensing n The role of whitecaps n The characteristics of whitecaps n Judging the whitecaps
Good or Bad for Remote Sensing n The characteristics of whitecaps
Oceanic Whitecaps n White foamy patches on a windy day
The Foam n Air/water mixture; n n Dry and wet foam; n n Specific properties; n n Changing throughout VisIRmWUV
Whitecaps in the Visible n Bright and white! n Excellent reflectors! VisIRmWUV
Whitecaps in the Infrared n Reflectance decreases; n Some thermal emission; VisIRmWUV
Whitecaps in Microwave n Poor reflectors n Excellent emitters! VisIRmWUV
Whitecaps Signature High Reflectivity High Emissivity So-so VisIRmWUV
Good or Bad for Remote Sensing n The role of whitecaps n The characteristics of whitecaps n Judging the whitecaps
Good or Bad for Remote Sensing n Judging the whitecaps
Desired Signal SRSR + T s )+ AU+ AU + AD+ AD ST ST SRSR + T s + AU+ AU + AD+ AD + SU+ SU SRSR + T s ) + SU+ SU + AD+ AD SRSR + SU )+ SU )+ AU+ AU + AD+ AD S T – ( SRSR + SU )+ SU )+ AU+ AU + AD+ AD S U AU AU Ts Ts Ts Ts
The Judgment Wind speed SST Aerosols Ocean Color
Conclusion n Whitecaps must be accounted for; n Know well their characteristics; Questions