What is a Weather RADAR?
Weather radar (also known as Doppler weather radar) is equipment that transmits pulses of electromagnetic radiation into the atmosphere to discover precipitation, measure its velocity and intensity, and identify the precipitation type such as rain, snow, or hail.
When the electromagnetic pulse impacts an item such as a raindrop or a snowflake, the wave bounces back to the radar with data that meteorologists may examine. Meteorologists may utilize this information to establish places where risky weather conditions occur. Consequently, radar may be a fantastic weapon in a meteorologist's inventory for helping to safeguard life and property.
How does a Weather RADAR work?
Weather radar employs either a solid-state or tube transmitter to deliver energy pulses (also known as radar beams) into the air to detect precipitation. This focussed beam radiates outward from an antenna (also known as a radar dish). If the radar beam bounces off precipitation such as rain or hail, the beam will return to the weather disk, where the data is processed into numerous parameters. This allows a meteorologist to evaluate and comprehend the weather happening hundreds of miles distant from the radar.
Weather forecasters assess the distance to an impending storm and the quantity of precipitation by the intensity and speed of the pulse returning to the weather radar location. Precipitation kind, speed, turbulence, and many other relevant decisions may also be made, such as identifying the debris that a tornado would toss into the air (known as a debris ball). You can read this amazing article on IBM for more information.
Types of Weather RADAR Bands:
This radar's larger wavelength enables the beam to penetrate many precipitation bands, widening the range for analysis more than the C-Band radar.
C-Band radars are generally designed for short-range weather observation but may be utilized in medium- to long-range precipitation analysis
X-Band radars have a narrower wavelength that makes them more sensitive to lighter particles
Components of a Weather RADAR
- Transmitter: It generates the electromagnetic energy pulse.
- Antenna: Modern radar tools are constructed of a huge radar dish and a protective coating to prevent damage. The dish may spin to acquire data and information from various places. Meanwhile, an antenna shoots pulses and receives the reflected pulses into the environment. As the energy signal interacts with things, energy waves disperse, reflecting back to the weather radar.
- Radar Processor: A radar processor assembles and evaluates the radar data that returns to the dish/antenna. It utilizes information such as the distance of the transmission to estimate the weather prediction
- Receiver: It is used for receiving and decoding the signal
- Display system: This is used to display the weather information to the end-user.
Using RADAR Designer App in MATLAB:
Under the "Apps" section, we will be using the Radar Designer App Tool under the Signal Processing and Communications Toolbox. On opening it, we will get to see as below:
To design a weather radar, we will be clicking on New Session->Weather RADAR. After that, the weather RADAR will be loaded with default parameters. Let us create a C- band weather radar. A C-band RADAR has a 4-8cm wavelength and a frequency of 4-8GHz. We will change the default range of the RADAR to 120 km. The antenna height is about 10m. We will be simulating a cloudy day, so we will change the "Precipitation" to "Cloudy", under the "Environment" tab, and cloud type as "Cumulus" clouds, as they are the common clouds. The final parameters of the weather RADAR are shown below:
What is SNR?
A signal-to-noise ratio, sometimes abbreviated S/N or SNR, measures the intensity of the intended signal compared to background noise (undesired signal). S/N may be calculated by applying a fixed formula that compares the two levels and returns the ratio, revealing if the noise level affects the intended signal.
The ratio is commonly given as a single numeric number in decibels (dB). The ratio might be zero, a positive number, or a negative number. A signal-to-noise ratio > 0 dB implies that the signal level is larger than the noise level. The greater the ratio, the better the signal quality. The lowest number is an SNR of 0, which means noise and signal levels are the same.
Below is the graph showing the SNR v/s Range of the Weather RADAR:
As we can see that the SNR ratio decreases sharply between 2500-3000km, but it will not be a problem, as our weather RADAR is needed for the operation of up to 120 km range( marked in red). Hence, C-band weather RADAR is suitable for a good SNR in a decent range.
What is blind speed?
The radar blind speed is when the target will not be seen on the radar. This speed may be computed based on the frequency/wavelength of the wave and the Pulse Repetition Time. The radar blind speed is calculated as:
Where v=blind speed, PRT=Pulse Repetition Time. The graph depicting the Bling Speed v/s Range is shown below:
The losses associated with Weather RADAR:
Many factors can cause signal losses in weather radar. They can be environmental losses, precipitation loss, atmospheric gas losses, and lens effect loss (due to atmospheric refraction). Shown below are the losses for our weather RADAR. Since we have taken a clean environment with no precipitation and other hindrance factors, we do not experience any loss.
Similarly, we can explore other interesting results of our weather RADAR! After we have designed the weather RADAR and given all parameters, we can export it as a MATLAB script file by clicking on Export-> Export SNR v/s Range MATLAB Script File.
The benefits and advantages of a weather RADAR are:
- Predict incoming storms: With a high-quality weather radar system, your team can identify dangerous events like tornadoes, hail, or floods and locate and compute the pace of precipitation to support exact arrival timings.
- Reliable and high-quality data: High-quality data can assist meteorologists, broadcasters, and other businesses in translating ideas into action in a speedy, efficient way by offering reliable predictions and accurate outcomes.
- Credibility: Inaccuracies in predictions may easily disappoint viewers. Delivering more accurate data helps establish confidence and credibility with viewers to help keep them coming back.
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