> For the complete documentation index, see [llms.txt](https://satdocs.hydrosat.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://satdocs.hydrosat.com/explore-thermal/understanding-our-products.md).

# Understanding Our Products

Now that you've got the basics down, let's look at how Hydrosat's data products fit in.

Hydrosat's data processing pipeline translates measurements from our satellites into progressively higher-level data products, ranging from raw sensor observations to analysis-ready surface temperature. 

The bottom line is that every pixel in a thermal image tells a story, but the context for that story depends on exactly which data product you're looking at. 

<div data-with-frame="true"><figure><img src="https://3702723385-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FBgOfOR7RYuK5Fm69JAWF%2Fuploads%2FtoWHsxZWC0WBd1kbqhtO%2FPicture1.png?alt=media&amp;token=551030b8-bbd9-4f6b-8868-64649475b242" alt=""><figcaption><p>Each data product represents a different physical quantity and therefore can be used for different analyses.</p></figcaption></figure></div>

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## Level-1A Radiance

If you're using the Level-1A data product, you're looking at the closest representation of what the satellite saw.&#x20;

Level-1A pixels are at-sensor radiance values in units of watts per square meter per steradian per micrometer (W/m²/sr/µm). You can think of this as the uncorrected thermal radiation that reached the detector after traveling through the atmosphere.

Radiance data is a good choice if you're interested in applying your own higher-level processing or developing advanced workflows. It's not the best choice if you want to dive right into analyzing conditions at the land surface.
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## Level-1B Brightness Temperature

The Level-1B brightness temperature product is still a direct representation of what the satellite observed, but it's a little more intuitive to work with than Level-1A radiance.

Pixel values represent the apparent temperature in units Kelvin based solely on the radiation measured by the satellite. In other words, this is the temperature a blackbody would need to have in order to emit that amount of radiation.

You might use brightness temperature if you want an intuitive thermal measurement that avoids additional assumptions and uncertainties introduced during Level-2 processing.
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## Level-2 Surface Temperature

The Level-2 data product is our best estimate of what's happening at the Earth's surface, after accounting for emissivity and the atmosphere.

Each pixel value is a temperature in units Kelvin that describes how hot the Earth's surface was—including vegetation, soil, water, pavement, and other surfaces—at the moment the satellite passed overhead.

If you're interested in monitoring something like urban heat, vegetation dynamics, or drought, surface temperature will give you the most direct window into that process.

<div data-with-frame="true"><figure><img src="https://3702723385-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FBgOfOR7RYuK5Fm69JAWF%2Fuploads%2F1ZBfSG72K1ag71CLubRa%2FPicture1.png?alt=media&amp;token=84e9a41b-d330-4f79-8505-433a97e067a4" alt=""><figcaption><p>Unlike Level-1 products, which describe what the satellite directly measured, Level-2 products estimate the physical state of the Earth's surface by correcting for atmospheric effects and emissivity. <em>Imagery © 2025 Hydrosat.</em></p></figcaption></figure></div>
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