Formosat-2 de-commissionned


It is with a deep nostalgia that I learned that Formosat-2 has just been decommissionned, after some of its components broke down after 12 years of acquisitions (nominal life extended by 8 years !).


When the satellite was launched, we were searching for data sets that would allow us simulate the features of VENµS satellite (which was then announced for 2008-2009, but still not launched yet :( ) and of the "GMES continental" satellite which finally became Sentinel-2. We needed high resolution images with a frequent repetitivity under constant view angles.


We were starting to use SPOT time series, limiting their view angles to +/- <10 degrees off-nadir, and we kept asking for the Indian OceanSat which was on the orbit targetted by Venµs (we never got any answer), when we first heard of Formosat-2. Formosat-2 had exactly the features we needed : 8m resolution, 24 km field of view, a one day repeat cycle (constant view angles !) and 4 spectral bands including the blue one which was lacking on SPOT.

The first dates of our first Formosat-2 time series in Morocco


With the help of Gilbert Pauc (a few months before he retired), CNES set up an agreement with SPOT Image and the Taiwan Space Agency, to trade Formosat-2 time series against radiometric calibration work from CNES. As a result, CNES took charge of Formosat-2 calibration for all its life (I started it, being still in CNES Image quality team), and we benefited from a few free time series and from a reduced price for the next ones (reduced but still expensive : 1000€/image).


The first 3 time series we obtained were acquired in Morocco, and in Toulouse and La Crau, in France, in 2005-2006. And before summer 2006, with the help of Hendrik Trom and then Vincent Debaecker, we had produced our first cloud masks and aerosol optical depths with a new processor which later became MACCS, and we started showing some first application examples. (this website was redesigned in 2014, but its content was written in 2006).


Later on, more Formosat-2 time series were bought on several sites (in Mali, in the Landes Forest, in the Atlas mountains, near Ottawa, or in Barrax, which helped us enhancing the robustness of our approaches. The Kalideos project also bought some data on its sites and distributed them to the users .


Without Formosat-2, we wouldn't have developed our multi-temporal methods for cloud detection and atmospheric correction which are now included within MACCS, we would not have made so much progress in our ortho-rectification of the images (registering Formosat-2 images was not a piece of cake !), Kalideos users would have had less interesting data sets, we would have lacked material to justify the interest of SPOT (Take5) experiments and of THEIA's processing of LANDSAT and Sentinel-2 data. And finally, the users of Sentinel-2 would have been less prepared to using the new data sets.


So, thanks a lot to Formosat-2 and to all those who contributed !

References  :

Hagolle, O., Huc, M., Pascual, D. V., & Dedieu, G. (2010). A multi-temporal method for cloud detection, applied to FORMOSAT-2, VENµS, LANDSAT and SENTINEL-2 images. Remote Sensing of Environment114(8), 1747-1755.

Hagolle, O., Dedieu, G., Mougenot, B., Debaecker, V., Duchemin, B., & Meygret, A. (2008). Correction of aerosol effects on multi-temporal images acquired with constant viewing angles: Application to Formosat-2 images.Remote Sensing of Environment112(4), 1689-1701.

Bsaibes, A., Courault, D., Baret, F., Weiss, M., Olioso, A., Jacob, F., ... & Kzemipour, F. (2009). Albedo and LAI estimates from FORMOSAT-2 data for crop monitoring. Remote sensing of environment113(4), 716-729.

Merlin, O., Duchemin, B., Hagolle, O., Jacob, F., Coudert, B., Chehbouni, G., ... & Kerr, Y. (2010). Disaggregation of MODIS surface temperature over an agricultural area using a time series of Formosat-2 images. Remote Sensing of Environment114(11), 2500-2512.

Courault, D., Bsaibes, A., Kpemlie, E., Hadria, R., Hagolle, O., Marloie, O., ... & Desfonds, V. (2008). Assessing the potentialities of FORMOSAT-2 data for water and crop monitoring at small regional scale in South-Eastern France.Sensors8(5), 3460-3481.

Hadria, R., Duchemin, B., Jarlan, L., Dedieu, G., Baup, F., Khabba, S., ... & Le Toan, T. (2010). Potentiality of optical and radar satellite data at high spatio-temporal resolutions for the monitoring of irrigated wheat crops in Morocco.International Journal of Applied Earth Observation and Geoinformation12, S32-S37.

Duchemin, B., Simonneaux, V., Mougenot, B., Khabba, S., Hadria, R., Benhadj, I., ... & Er-Raki, S. (2008). Agrometerological study of semi-arid areas: an experiment for analysing the potential of FORMOSAT-2 time series of images in the Marrakech plain. International Journal of Remote Sensing29(17-18), 5291-5300.

Courault, D., Hadria, R., Ruget, F., Olioso, A., Duchemin, B., Hagolle, O., & Dedieu, G. (2010). Combined use of FORMOSAT-2 images with a crop model for biomass and water monitoring of permanent grassland in Mediterranean region. Hydrology and Earth System Sciences Discussions14, 1731-1744.

Hagolle, O., Huc, M., Villa Pascual, D., & Dedieu, G. (2015). A multi-temporal and multi-spectral method to estimate aerosol optical thickness over land, for the atmospheric correction of formosat-2, Landsat, venμs and Sentinel-2 images. Remote Sensing7(3), 2668-2691.

Duchemin, B., Hagolle, O., Mougenot, B., Benhadj, I., Hadria, R., Simonneaux, V., ... & Boulet, G. (2008). Agrometerological study of semi‐arid areas: an experiment for analysing the potential of time series of FORMOSAT‐2 images (Tensift‐Marrakech plain). International Journal of Remote Sensing29(17-18), 5291-5299.

Dejoux, J. F., Dedieu, G., Hagolle, O., Ducrot, D., Menaut, J. C., Ceschia, E., ... & Gascoin, S. (2012). Kalideos OSR MiPy: un observatoire pour la recherche et la démonstration des applications de la télédétection à la gestion des territoires.Revue Française de Photogrammétrie et de Télédétection, (197), 17-30.

Duchemin, B., Fieuzal, R., Rivera, M. A., Ezzahar, J., Jarlan, L., Rodriguez, J. C., ... & Watts, C. (2015). Impact of sowing date on yield and water use efficiency of wheat analyzed through spatial modeling and FORMOSAT-2 images. Remote Sensing7(5), 5951-5979.



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  • Andrew French on 08/09/2016 at 20:04 said:

    How about news on Venus site selections? It has been a while since we submitted proposals and some site priorities are contingent upon selection success or not.

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