DOI: 10.25326/617
title: PHOTOMETER MAP-IO - AOD LEVEL 1.5

description: The objective of the MAP-IO program is to assess the feasibility of building an atmospheric and marine biology observatory on board the Marion Dufresne. This observatory aims to carry out atmospheric observations at the ocean-atmosphere interface and integrated on the atmospheric column over the entire globe with a focus of particular interest for the study of the Indian and Southern Oceans. The MAP-IO program is positioned in an observatory logic with four main objectives; (i) integration into international atmospheric and oceanic networks by providing high quality data on a region devoid of permanent observation, (ii) validating and calibrating space sensors and numerical weather forecasting models, (iii) monitoring global changes on the Indian and Southern Ocean and (iv) observation of atmospheric and biology phytoplankton variability over the Indian and Southern Oceans.

MAP-IO takes advantage of the scientific campaigns at sea planned by the FOF by exploring different poorly documented ocean areas and by increasing and completing the observation systems of the programs with additional measurements. The differentiation value of MAP-IO versus conventional scientific programs at sea, and that it relies on the regular rotations of the TAAFs by documenting the atmosphere and the ocean surface state over a wide variability of sea ​​and latitude conditions. These multi-year observations of the Indian and Southern Oceans make it possible to uniquely document the trends, the mechanisms of ocean-atmosphere exchanges and the atmospheric composition on a seasonal and interannual basis.
CCN: a cloud condensation nuclei chamber (model DMP CCN-100) counts and sizes aerosols that can be activated into cloud droplets. Aerosols enter  into a thermal-gradient diffusion chamber where a supersaturated water vapor condition is created by the difference in diffusion rates between water vapor and heat. Then the cloud droplets formed are counted and sized using an optical light-scattering counter (range 750 nm to 10 µm). The CCN-100 scans the CCN aerosols properties at various supersaturations ranging from 0.07% to 2 %. 

The shipborne CIMEL CE318-T was developed in the frame of the AGORA-Lab program to enable spectral AOD (340 to 1640 nm), spectral downward atmospheric radiances (440 to 1020 nm) and water vapor measurements on mobile platforms and to expand the AErosol RObotic NETwork (AERONET) coverage over the vast ocean area. The system is composed of an optical head, a rotational base, its control unit, air-pumping unit, weather stop unit, GPS-based compass and positioning system units (date, time, geo-location, heading, pitch and roll). The optical head is the standard CE318-T with the version 1 of the shipborne software. The GPS receivers were fixed on the platform together with the photometer robot. In order to track the sun and the moon continuously, the system first targets the sun/moon with the last received time, geo-location, heading, pitch and roll information. When the sun/moon enters in the tracking system field-of-view, the photometer switches into tracking mode like a regular AERONET photometer, however the tracking feedback loop has been accelerated. 

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