Studies for future satellite missions

EarthCARE - Earth Clouds, Aerosols and Radiation Explorer

Earth Clouds, Aerosols and Radiation Explorer - Imager Retrieval Methods and ATLID Synergy (IRMA)

The EarthCARE satellite is a joint mission by the European and Japanese Space Agencies scheduled for launch in 2016. The spacecraft will have four instruments: the Cloud Profiling Radar (CPR) with Doppler capability, the high spectral resolution Lidar (ATLID) and Multi-Spectral Imager (MSI) and the Broad-Band Radiometer (BBR). The satellite measurements will be used to retrieve global profiles of cloud, aerosol, and precipitation properties and along with Top-Of-Atmosphere (TOA) Long- and Short-wave fluxes.

The main objects of the ESA-project IRMA is the development of EarthCARE L2 data products and algorithms for Multi Spectral Imager (MSI) stand alone and ATLID synergistic products.

The MSI will measure the thermal radiance emitted by the Earth and the backscattered solar radiation in seven specified spectral channels (see Fig1).

Model des MSI-Instruments

Model des MSI-Instruments


MSI is nadir-viewing pushbroom. The spatial resolution of 500x500m² is particularly impressive in view of the required signal-noise ratio. The MSI will have a swath width of 150 km, asymmetrically tilted from the sun, -35 km to 115 km relative to nadir.

The cloud microphysical retrieval based on the combination of the non-absorbing visible (0.6 µm, 0.8 µm) channels and the absorbing near infrared (1.6µm, 2.2µm) channels. MSI has no dedicated channel for cloud top detection therefor the cloud top height retrieval is limited to the infrared window-channels. A synergetic cloud top height is developed by using the information of the ATLID to improve the retrieval. Additionally synergetic analysis using the ATLID and MSI are developed using data from CALIOP and MODIS (Fig2).

EarthCARE scene

Fig. 02: Illustration of a 3d EarthCARE scene based on CALIOP and MODIS data 2 January 2007. Source: Anja Hünerbein/TROPOS

Information about the MSI-channels (Albiñana, et al., 2010)

[Translate to English:] Channel Center Wavelength (mu) Bandwith (50%)
VIS 0.67 20 nm
NIR 0.865 20 nm
SWIR-1 1.65 50 nm
SWIR-2 2.21 0.1 mu
TIR 1 8.80 0.9 mu
TIR 2 10.80 0.9 mu
TIR 3 12.00 0.9 mu

MSI cloud products

The following MSI cloud products have been developed:

  • cloud optical and microphysical properties (cloud optical thickness, effective cloud droplet radius/ effective ice crystal diameter)– based on a bi-spectral approach (VIS or NIR and SWIR1 or SWIR2 bands)
  • liquid water path – based on cloud optical thickness and cloud microphysical properties
  • cloud geometrical top height – based on a single IR approach and using the MSI/ATLID synergy


Pérez Albiñana, Abelardo, Robert Gelsthorpe, Alain Lefebvre, Maximillian Sauer, Erich Weih, Klaus-Werner Kruse, Ralf Münzenmayer, Guy Baister, Mark Chang, 2010: The multi-spectral imager on board the EarthCARE spacecraft, in Infrared Remote Sensing and Instrumentation XVIII, Marija Strojnik; Gonzalo Paez, Editors, Proceedings of SPIE Vol. 7808, 780815.