Presentation is loading. Please wait.

Presentation is loading. Please wait.

Complex dielectric constant of sea foam for microwave remote sensing Magdalena D. Anguelova Peter W. Gaiser Naval Research Laboratory, Washington, DC 15th.

Similar presentations


Presentation on theme: "Complex dielectric constant of sea foam for microwave remote sensing Magdalena D. Anguelova Peter W. Gaiser Naval Research Laboratory, Washington, DC 15th."— Presentation transcript:

1 Complex dielectric constant of sea foam for microwave remote sensing Magdalena D. Anguelova Peter W. Gaiser Naval Research Laboratory, Washington, DC 15th Conference on Air-Sea Interaction 20-24 August 2007, Portland, OR

2 2 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. GaiserObjective Model the high variability of whitecap coverage or u – wind speed (u 10 or u * ?)  T – atmospheric stability (= T air – T sea ) X – wind fetch d – wind duration U cur – water currents T s – sea surface temperature S – salinity C k – concentration, type (k) of surface active materials

3 3 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. GaiserApproach Improve existing or develop new models; Investigate correlations; Extensive database: W + various factors; Measurements: W + various factors; Existing W measurements: Photographs/video images; Insufficient for extensive database; Alternative approach: From satellites to get global coverage; wide range of meteo & environ conditions; Whitecap variability: The first step

4 4 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Whitecaps from satellite data WindSat, 10.7 GHz, H pol.,1 March, 2006

5 5 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Variability: Modeling vs. Oceanographic Whitecaps from satellite data

6 6 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Estimate whitecap coverage Model Initial version Anguelova & Webster, JGR, 2006 WindSat version Anguelova et al., IGARSS’06 Minimize TOA TOA T B Srfc Srfc T B Measure Atm corr

7 7 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Estimate whitecap coverage Modeling vs. oceanographic variability Atmospheric correction to obtain e meas Model rough surface emissivity e r Foam permittivity Foam thickness Void fraction Constant VS Profile in depth Model foam emissivity e f

8 8 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Whitecaps (sea foam) Whitecaps on the surface Bubble plumes below the surface Sea-salt production Mixing, gas exchange

9 9 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Foam void fraction Soap foam Breaking wave foam

10 10 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser seawater air Foam as matching impedance Air:  = 1 Seawater:  = O(30-70)

11 11 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser seawater air Foam as matching impedance seawater air foam (10%) foam (98%) Air:  = 1 Seawater:  = O(30-70)

12 12 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Void fraction profile Seamless match of dielectric properties

13 13 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Void fraction profile

14 14 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Effect on the foam retrievals Constant versus gradual profile: important choice; Profile functional form: not a significant choice.

15 15 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Foam dielectric constant ε'ε"ε'ε" 6.8 GHz 37.0 GHz 18.7 GHz

16 16 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Mixing rules

17 17 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Mixing rule suitability Three criteria to compare: Applicability for wide void fraction range; Behavior at the air-foam and foam-water boundaries; Effect on foam emissivity calculations: Comparison with measurements and models; Emissivity and T B error due to mixing rule choice; Mixing rule choice: Looyenga.

18 18 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Effect of mixing rule choice Important with constant void fraction

19 19 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Effect of mixing rule choice Comparable with void fraction profile

20 20 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. GaiserSummary Long-term goal: modeling the high variability of whitecap coverage; Physically-based retrievals of whitecap coverage from satellite data; Need to minimize the variability in the retrievals due to modeling of e meas, e r, and e f ; Foam emissivity model: Foam as impedance match; Void fraction profile: Constant value vs a profile in depth; Functional form; Foam permittivity with various mixing rules; Foam layer thickness – fixed vs distribution.

21 21 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Additional slides

22 22 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Foam retrievals choice Looyenga mixing rule + exponential void

23 23 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Foam retrievals choice Looyenga mixing rule + exponential void

24 24 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Distribution of thicknesses Log-normal Distribution peak @ d = 3.53 cm Reising et al., 2002

25 25 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Effect on foam retrievals Changes due to the inclusion of thinner layers

26 26 of 20 15 Air-Sea Interaction Conference, 21 August, 2007, M. Anguelova & P. Gaiser Effect on foam retrievals Changes due to choice of distribution parameters


Download ppt "Complex dielectric constant of sea foam for microwave remote sensing Magdalena D. Anguelova Peter W. Gaiser Naval Research Laboratory, Washington, DC 15th."

Similar presentations


Ads by Google