june 2015 -80.62 -67.45 -75.01 -38.75 -67.89 -26.40 -60.31 -19.72 0 5 10 15 20 25 30 ieee Geoscience and remote sensing magazine Altitude. km 4) Merlin: carbon and iTs iMpacT on The cliMaTe The remote sensing of the two main greenhouse gases of anthropogenic origin, carbon dioxide -79.02 -139.62 3) Megha-Tropiques and The waTer cycle The French-Indian Megha-Tropiques mission [12] was designed to investigate atmospheric circulation, the water cycle and climate change in the tropical belt. The main scientific objectives are to improve our knowledge of the transport and distribution of the water vapor in the atmosphere and the consequences on the energy budget in the intertropical regions, as well as to study the formation and the evolution of tropical convective systems (Figure 10). These data provide valuable information for understanding climate changes and a better forecast of extreme events in tropics. Circling Earth on a slightly inclined orbit, the satellite covers the tropical belt from 23°N to 23°S with at least 3 measurements per day with three instruments: ◗ Madras: a 9 channels self-calibrating microwave imager in the range 18,7 GHz-157 GHz aimed mainly at studying precipitation and clouds. ◗ Saphir: a 6-channel microwave radiometer in the 183,31 GHz +/- 12 GHz bandwidth used to retrieve water vapor vertical profiles and horizontal distribution, ◗ Scarab: a cross track scanning radiometer that measures outgoing radiative fluxes at the top of the atmosphere The satellite was launched in 2011 and is still operational although the Madras instrument failed in 2013. Figure 9. Calipso: 532 nm Total Attenuated Backscatter From dark blue 10-4 to white 10-1 Polar Stratospheric Clouds 24 July 2006 (Crédit NASA CNES). -69.18 -166.12 1.0 # 10-1 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 # 10-2 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 # 10-3 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 # 10-4 The CALIPSO satellite is still operational. It uses the French standard PROTEUS platform and its payload is composed of one backscattering lidar, provided by NASA, and an infrared imager provided by CNES. 47