Question

What is Microwave Remote Sensing? Explain any three factors which influence the interaction between microwaves and Earth’s surface.

Hint:

Microwave sensors see through clouds and provide all-weather, day-night data.

Answer 1

Microwave Remote Sensing employs microwave wavelengths (approx. 1 mm to 1 meter) for Earth observation and atmospheric analysis.
Unlike optical sensors, microwave sensors can penetrate clouds, rain, and vegetation, and operate at night.
This sensing can be passive (radiometers) or active (radars, e.g., Synthetic Aperture Radar).
Applications include soil moisture, terrain mapping, flood monitoring, and sea ice detection.
Microwave interaction with Earth's surface depends on:
1. Surface Roughness: Rougher surfaces scatter microwave signals more. The degree of roughness relative to wavelength dictates backscatter.
2. Dielectric Constant: Surface moisture content influences dielectric properties. Wet surfaces have higher dielectric constants, leading to stronger reflection and backscatter.
3. Incidence Angle: The angle of the radar beam impacts backscattered energy. Steeper angles typically yield stronger returns from smooth surfaces, while shallower angles highlight surface roughness.
Understanding these factors enables analysts to interpret radar images for terrain, vegetation, and surface condition data.