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 is a technique that uses microwave wavelengths (approximately 1 mm to 1 meter) to observe and analyze the Earth’s surface and atmosphere.
Unlike optical sensors, microwave sensors can penetrate clouds, rain, and vegetation canopies, and can even collect data at night.
Microwave remote sensing can be passive (radiometers) or active (radars like Synthetic Aperture Radar).
It is widely used for applications such as soil moisture estimation, terrain mapping, flood monitoring, and sea ice detection.
The interaction between microwaves and the Earth’s surface is influenced by several factors:
1. Surface Roughness: Rough surfaces scatter microwave signals more than smooth surfaces. The degree of roughness relative to the wavelength determines how much energy is backscattered to the sensor.
2. Dielectric Constant: The moisture content of the surface affects its dielectric properties. Wet surfaces have higher dielectric constants, resulting in stronger microwave reflection and backscatter.
3. Incidence Angle: The angle at which the radar beam strikes the surface affects the amount of backscattered energy. Steeper angles usually produce stronger returns from smooth surfaces, while shallow angles emphasize surface roughness.
By understanding these factors, analysts can interpret radar images to extract valuable information about terrain, vegetation, and surface conditions.