How satellites track the weather

Subject :Science and Tech

Section: Space tech

Context:

The Indian Meteorological Department (IMD) warned of “very dense fog” in several states, impacting visibility to less than 50 meters in some areas.

Types of Weather Satellites

Geostationary Satellites (GEO): Orbit at an altitude of approximately 35,786 kilometers above the equator, allowing them to remain stationary relative to a specific point on Earth. They provide continuous monitoring of a specific region, such as a continent or an ocean.
Polar Orbiting Satellites (PO): Orbit the Earth from pole to pole, providing global coverage. They operate at lower altitudes (typically 800-1,200 kilometers) and are crucial for collecting detailed information about the atmosphere, including temperature, humidity, and cloud cover.

India’s Weather Satellites

INSAT 3D and 3DR are currently active in geostationary orbits, aiding in weather monitoring.
India has a history of launching progressively advanced weather satellites, with each new version being an improved and better-equipped iteration of its predecessor.

Instruments and Sensors

Visible and Infrared Sensors: Capture images of clouds, land, and ocean surfaces. They help identify cloud cover, storm systems, and surface temperatures.
Microwave Sensors: Penetrate clouds to measure temperature and humidity levels in different layers of the atmosphere.
Radiation and Energy Sensors: Monitor incoming solar radiation and outgoing thermal radiation to study energy balance in the atmosphere.
Scatterometers: Measure wind speed and direction over the ocean by analyzing the backscattered signals from ocean surfaces.

Data Collection

Satellites continuously collect data on various atmospheric parameters, including temperature, humidity, wind speed, cloud cover, and precipitation.
This data is transmitted to ground stations, where it undergoes processing and analysis.

Applications

Weather Forecasting: Satellites provide real-time data that improves the accuracy of short-term and long-term weather forecasts.
Severe Weather Monitoring: Satellites help track hurricanes, typhoons, tornadoes, and other severe weather events, allowing for early warnings and evacuation planning.
Climate Monitoring: Long-term satellite data contribute to the study of climate patterns, climate change, and the Earth’s overall climate system.

Tracking Snow

The colour scheme is designed to identify different cloud types, stages of thunderstorms, snow areas, and fire detection.
Snow strongly absorbs radiation at 1.6 micrometers (shortwave infrared), causing the red component of the colour scheme to become weak when the satellite tracks snow.

Night Microphysics

Night microphysics involves the difference between two signals to determine colors.
Red color is determined by the difference between two thermal infrared signals (12 micrometers and 10 micrometers).
Green color varies based on the difference between a thermal infrared signal and a middle infrared signal (10.8 micrometers and 3.9 micrometers).
Blue color is determined by the strength of a thermal infrared signal at 10.8 micrometers.

Applications of Color Scheme

The color scheme helps analyze cloud types, thunderstorm stages, snow areas, and fire detection.
By combining day and night microphysics data, scientists can track moisture droplets, temperature differences, and cyclone formation, evolution, and depletion.