Deep Dive Into GOES and Sentinel Satellite Band Channels: Features and Applications

Satellites play a crucial role in remote sensing, enabling us to gather valuable information about the Earth's surface. And when we talk about satellites–spectral sensitivity, sensor characteristics, and radiometric calibration are some of the most important features that define any. So let’s look at them in greater detail.

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Understanding spectral sensitivity and radiometric calibration

To start, spectral sensitivity describes how well a sensor can detect and measure the intensity of radiation at specific wavelengths. By capturing radiation in specific spectral bands, sensors can gather information about the physical properties, composition, and conditions of objects on the Earth's surface. This spectral information is then utilized for various applications, including land cover classification, vegetation health assessment, and burned area detection, among others.

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On the other hand, radiometric calibration refers to the process of calibrating satellite sensors to accurately measure the amount of reflected radiation from different land cover types, including burned areas. By calibrating the satellite sensors, we can obtain reliable and consistent data for monitoring the extent of damage caused by fires on climate, ecology, properties, and human health.

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These become important rubrics in determining which satellite is more efficient for your remote sensing requirements. In this blog, we will specifically dig deeper into Sentinel and GOES satellites and talk about why Sentinel satellites are better for mapping burned areas.

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Mapping burned areas of historical fires—Sentinel vs. GOES satellites

In remote sensing, the dNBR ratio is one of the most popular ways of mapping burned areas using band channels. The calculation of dNBR involves comparing pre and post-fire spectral reflectance values of vegetation and charred surfaces. The Normalized Burn Ratio (NBR) is computed for both pre and post-fire images using near-infrared (NIR) and shortwave-infrared (SWIR) bands. The NBR values are then differenced to obtain dNBR, representing the change in vegetation cover and burn severity.

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Higher dNBR values indicate more severe burn areas with greater vegetation loss, while lower values correspond to less severe burns or unburned areas. 

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Starting with the basic facts we know about satellites:

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GOES:

1. Geostationary Orbit: GOES are placed in a geostationary orbit, which means they remain fixed over a specific location on the Earth's surface. 
2. Spectral Bands: GOES satellites typically have a range of spectral bands covering various wavelengths. For example, GOES-16 (GOES-East) and GOES-17 (GOES-West) have 16 spectral bands in the visible, near-infrared, and infrared regions. 
3. Spatial Resolution: The spatial resolution of GOES satellite images varies depending on the spectral band ranging from 0.5 to 2 kilometers.‍
4. Temporal Resolution: GOES satellites provide images at high temporal resolution, typically every 5 to 15 minutes, enabling real-time monitoring of weather conditions.

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Sentinel Satellites (Sentinel-2):

1. Low Earth Orbit: Sentinel satellites like Sentinel-2 are placed in a low Earth orbit. They orbit the Earth at a much lower altitude and have a wider coverage range than GOES satellites. Sentinel-2 operates in a sun-synchronous orbit, providing global coverage.
2. Multispectral Imaging: Sentinel-2 carries a multispectral imaging instrument that captures data in several spectral bands. Sentinel-2A and Sentinel-2B have 13 spectral bands, including visible, near-infrared, and shortwave infrared bands. 
3. Spatial Resolution: Sentinel-2 has a higher spatial resolution compared to GOES, with the highest resolution bands providing 10-meter spatial resolution. The spatial resolution varies across the different spectral bands.‍
4. Temporal Resolution: The revisit time of Sentinel-2 is typically around five days, depending on the latitude. This means that a specific location on Earth will be revisited approximately every five days, allowing for regular monitoring and change detection.

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So which is better?

Based on the information above, we can conclude that Sentinel-2’s dedicated bands (B8 and B12) in the NIR and SWIR regions and robust atmospheric correction mechanisms make it the best choice for precise burned area mapping and analysis.

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At Ambee, we provide hyperlocal and actionable forest fire data for locations across the globe. To provide our customers with the most accurate results, we combine and calibrate data from multiple sources, one of which is satellite data. While enhancing our historical forest fire data, we found GOES data for burned area mapping to be often inaccurate, leaving us to use either Sentinel or VIIRS MODIS.

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Learn more about Ambee's newly enhanced and upgraded forest fire API. We also have a product dedicated to forest fires. Get a complete picture of the wildfire risk analytics tool and the intent behind its development.

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Let us know what you think about GOES and Sentinel Satellite. Get in touch now!