AVHRR A Spot

New 41-year long climate data record of polar Atmospheric Motion Vectors

 

AVHRR A Spot
AVHRR A Spot

A new 41-year long climate data record of polar Atmospheric Motion Vectors has now been developed.

Last Updated

04 February 2022

Published on

04 February 2022

EUMETSAT has developed an algorithm to retrieve Atmospheric Motion Vectors (AMVs) from the AVHRR instruments (on Metop and NOAA  satellites) since 1979. This algorithm, in the single satellite mode, has been used to provide the global reanalysis operated by the Copernicus Climate Change Service (C3S) with a 41-year long consistent homogenous polar AMV data record utilising all available AVHRR instruments since 1979. The data record will be used as an input to the next major global reanalysis of C3S called ERA6.

Time series of AVHRR AMV
Figure 1: Time series of the 30-day running mean of the Arctic area averaged atmospheric motion vector wind speed and altitude (presented in pressure units) over the Arctic derived from three generations of AVHRR instruments flown on 16 satellites from 1979-2020 shown at the top. The left bar shows the typical coverage of the Arctic area with AMVs from a single satellite on one day.

The AVHRR infrared radiances used to derive the AMVs have been previously re-calibrated and reprocessed to serve as homogeneous input to this climate data record. These radiances are also in use by the Climate Monitoring SAF to generate climate records for cloud properties and surface radiation parameters such as albedo.

By tracking clouds in the infrared window channel of AVHRR from one orbit to the next, the wind speed, direction and altitude can be derived. Due to the nature of low earth orbiting satellites, overlapping areas from a single satellite of two consecutive orbits are only available in the polar regions down to about 45° latitude.

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