Microwave Specular Measurements and Ocean Surface Wave Properties.

Area of Science:

• Oceanography
• Electromagnetics
• Remote Sensing

Background:

• Microwave reflectometers measure ocean surface waves using electromagnetic (EM) wavelengths.
• High wind conditions necessitate accounting for air in foam and whitecaps, which modify relative permittivity.

Purpose of the Study:

• To apply considerations of foam and whitecaps to microwave specular returns from the ocean surface.
• To develop and validate a model for ocean surface wave properties using microwave data.

Main Methods:

• Utilized measurements from Ku and Ka band altimeters and L band reflectometers.
• Developed a closed-form expression connecting normalized radar cross section (NRCS) to surface wave properties.
• Modeled specular NRCS for L, C, X, Ku, and Ka bands up to 99 m/s wind speeds.

Main Results:

• A straightforward integration connects observed specular NRCS to statistical and geometric surface wave properties.
• Accurate forward computation can supplement sparse high-wind reference measurements.
• Provided modeled specular NRCS for multiple microwave bands under various wind conditions.

Conclusions:

• The developed model provides a method to estimate ocean surface wave properties from microwave data.
• Accurate modeling is essential for algorithm development and validation, especially in high-wind scenarios.
• Forward computation offers a valuable supplement to experimental data for understanding ocean wave dynamics.