ESA - Living Planet Programme - MetOp - Measuring humidity with MHS

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Measuring humidity with MHS

13 October 2006

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As MetOp orbits the Earth, the Microwave Humidity Sounder (MHS) instrument continuously scans down through the atmosphere across the track of the flight path. During each scan cycle the instrument provides data (for each of its five channels) for 90 individual Earth scenes, each with a footprint of about 16 kilometres in diameter at nadir. Each cycle takes 2.67 seconds, but the scan cycle is optimised to maximise the time available monitoring the Earth, which equates to more than 60% of the scan duration.

The MHS scanning reflector collects the upwelling radiation and focuses it into the receiver assembly. Here, the four target frequency bands are separated by a series of quasi-optical lenses, frequency-splitting plates and a polariser to provide the input signal to the four receiver assemblies.

Between consecutive scans of the Earth, the MHS also views and samples data from an area of deep space (used as a cold target), and an on board source (hot target), which provides reference for the self-calibration process.

Credits: ESA - AOES Medialab

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MHS instrument scans down through the atmosphere

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HI RES JPG (Size: 203 kb)

As the MetOp satellite orbits the Earth, the MHS instrument continuously scans down through the atmosphere across the track of the flight path. During each scan cycle the instrument provides data (for each of its five channels) for 90 individual Earth scenes, each with a footprint of about 16 kilometres in diameter at nadir. Each cycle takes 2.67 seconds, but the scan cycle is optimised to maximise the time available monitoring the Earth, which equates to more than 60% of the scan duration.

Credits: ESA - AOES Medialab

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Download:

HI RES JPG (Size: 192 kb)

The MHS instrument gathers data, from which the humidity at different altitudes through the atmosphere can be determined. The swath is about 2 000 kilometres wide (+/- 50°) and corresponds to 90 contiguous pixels for each of the five channels during each scan. The normal field of view is circular, with a footprint of about 16 kilometres in diameter on the Earth's surface at the sub satellite point.

Credits: ESA - AOES Medialab

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