Disclaimer: Copyright infringement is not intended.
The Union Ministry of Earth Sciences approved an X-band radar to be installed in the Wyand district of Kerala.
A radar system typically consists of a transmitter that emits radio signals and a receiver that detects any reflected energy from targets.
The device employs radio waves to calculate the distance, velocity, and physical properties of objects in its vicinity.
A transmitter sends out a signal aimed at an item whose properties must be determined (for example, a cloud in meteorology).
The item echoes a portion of the emitted signal back to the device, which is tracked and analyzed by a receiver.
A radar system's transmitter emits a narrow beam of radio waves in brief bursts.
Objects reflect waves in their path, and some of the energy returns to the radar.
The radar's receiver calculates how long it takes for the pulse to be transmitted, hit a target, then return to the radar.
The radar calculates the distance to the target by measuring the time it takes the pulse to return. The radar can also calculate the target's velocity by measuring the phase and amplitude of the pulse.
The radar may use reflected energy to calculate the target's distance, direction, speed, shape, and range.
Radars for air surveillance and air defence, mostly operate in the VHF band (30 to 300 MHz).
Modern air surveillance radars with a long detection range even operate in the frequency range of up to two gigahertz (GHz).
The C-band (4 to 8 GHz) is used for weather radar and monitoring the sea surface.
Applications
Weather radar, also known as a Doppler radar, is a common application.
The Doppler effect is the change in frequency of sound waves as their source moves towards and away from a listener.
In meteorology, Doppler radars can reveal how fast a cloud is moving and in which direction based on how the cloud’s relative motion changes the frequency of the radiation striking it.
A pulse-Doppler radar can measure the intensity of various things. Ex. Of rainfall by emitting radiation in pulses and tracking how often they’re reflected to the receiver.
In this way, modern Doppler radars can monitor weather conditions and anticipate new wind patterns, the formation of storms, etc.
An X-band radar is radar that emits radiation in the X-band of the electromagnetic spectrum: 8-12 GHz, corresponding to wavelengths of around 2-4 cm, which is in the microwave part of the spectrum.
The radar's narrower wavelengths allow it to provide higher-resolution images.
However, the higher the frequency of certain radiation, the faster it will attenuate. As a result, X-band radars have a reduced effective range.
Doppler radar works on Rayleigh scattering, which occurs when the scatterer is substantially smaller than the wavelength of the radiation.
To see tiny particles such as raindrops or fog, a radar must employ lower wavelength radiation, such as in the X-band.
In Wayanad, the new radar will track the movements of particles like soil to provide landslide warnings.
The device will also do high temporal sampling by rapidly monitoring its surroundings, allowing it to notice particle motions that occur in shorter intervals of time.
Scattering of lightIt can be described as the phenomenon in which light rays deviate from their straight path when it hits an obstacle such as molecules of gas or dust, water vapours, etc. The amount of scattering is inversely proportional to the fourth power of the wavelength. This means that shorter wavelengths scatter more than longer wavelengths. For example, blue light scatters more than red light because it has a shorter wavelength. Most of the scattered light is at the same wavelength (or color) as ---- this is called Rayleigh Scattering. However a small amount of light (typically 0.0000001%) is scattered at different wavelengths (or colors), which depend on the chemical structure of the analyte – this is called Raman Scatter. Read more about it here: |
The India Meteorological Department (IMD) started using radar for weather applications in the early 1950s.
The first indigenously designed and manufactured X-band storm detection radar was installed in 1970 in New Delhi.
In 1996, IMD replaced many outdated X-band radars with digital X-band radars.
In its X-band radar network, India has both wind-finding and storm-detecting radars, and some with dual capabilities.
The country also uses S-band radars (2-4 GHz) for long-range detection. The first S-band cyclone detection radar was installed in Visakhapatnam in 1970 and the first locally made variant was commissioned in Mumbai in 1980.
India is set to have more than 50 additional Doppler radars in a few years.
The Union Cabinet approved the ₹2,000-crore ‘Mission Mausam’ to upgrade meteorological infrastructure in India.
This includes installing up to 60 meteorological radars until 2026 under the Mission’s first phase.
India has started the process to procure and install 10 X-band Doppler radars to improve weather forecasting in the northeast States and in Himachal Pradesh’s Lahaul and Spiti district.
NISAR, short for ‘NASA-ISRO Synthetic Aperture Radar’ is a collaborative project of NASA and the Indian Space Research Organisation (ISRO).
It will use radar imaging to produce a high-resolution map of the earth’s landmasses.
Its payload consists of an L-band radar (1.25 GHz, 24 cm) built by NASA and an S-band radar (3.2 GHz, 9.3 cm) built by ISRO.
Together they will track and record changes in the earth’s various natural processes.
It is expected to be launched onboard an ISRO GSLV Mk II rocket in 2025, at a total cost of $1.5 billion and the most of the cost will be borne by NASA.
Important articles for reference
Sources:
|
PRACTICE QUESTION Q.Consider the following statements about the “X-band radar” recently seen in the news:
How many of the above statements is/are correct? A.Only one B.Only two C. All Three D.None Answer: B Explanation: Statement 1 is correct: An X-band radar is radar that emits radiation in the X-band of the electromagnetic spectrum: 8-12 GHz, corresponding to wavelengths of around 2-4 cm, which is in the microwave part of the spectrum. Statement 2 is correct: The smaller wavelengths allow the radar to produce images of higher resolution. However, the greater the frequency of some radiation, the faster it will be attenuated. So X-band radars have a relatively shorter range. Statement 3 is incorrect: Doppler radar relies on Rayleigh scattering, when the scatterer is much smaller than the wavelength of the radiation. A radar trying to ‘see’ smaller particles like rain droplets or fog will need to use radiation of lower wavelengths, like in the X-band. |
© 2024 iasgyan. All right reserved