The aim of the Atmospheric Monitoring (AM) subsystem is to observe the condition of the  atmosphere in the field of view of the JEM-EUSO main telescope, to obtain information on the scattering and extinction properties of the atmosphere at the location of EAS and in the atmosphere column along the line of sign toward EAS.

The AM of JEM-EUSO will involve:

• an Infra-Red Camera (IR Camera);
• a LIght Detection And Ranging (LIDAR) device;
• the real time global atmospheric model parameters from global atmospheric models.

The principle of AM of JEM-EUSO is sketched in Figure.

The IR Camera is composed by an optic system, a μbolometer array detector, an instrument control unit and an instrument calibration unit. The IR Camera will provide imaging of the temperature of the top of the clouds from which information on location and altitude of the clouds in JEM-EUSO Field of View (FoV) will be derived.

 The LIDAR is composed of a transmission and receiving systems. The transmission system comprises a laser and a pointing mechanism to steer the laser beam in the direction of triggered EAS events.  The receiver will be the main JEM-EUSO telescope, to achieve the coverage of the entire 60º FoV with the LIDAR observation. The LIDAR will determine the detailed scattering and extinction properties of the atmosphere at the location of each triggered EAS event.

Real-time models of the atmosphere are used to deduce the parameters relevant for the modeling of the transmission and extinction properties of the air, needed for the analysis of the LIDAR data, for the calibration of the infrared camera data, and for the modeling of development of EAS in the atmosphere.