SWALIDE

Improving our knowledge of the atmospheric water cycle requires vertical measurements resolved in time space of the two main water vapor stable isotopes relative abundance in the lower and mid-troposphere. We aim at meeting this challenge with a high sensitivity differential absorption LIDAR instrumentation, which will allow to fill the undeniable lack of observable data, in order to increase the accuracy of climate models. For this purpose the SWALIDE project proposes to combine state-of-the-art infrared detection technologies based on HgCdTe avalanche photodiodes with the first differential absorption lidar system WAVIL dedicated to the measurement of water vapor isotopic abundance. The first objective is to bring the lidar to an enhanced level of sensitivity for atmospheric science and future observation networks applications. For this, a specific avalanche photodiode with an original monolithic architecture will be developed to provide a breakthrough in terms of sensitivity and operability. To support this objective, the whole instrumentation will be tested and validated by inter-comparisons with other sensors such as industrial spectrometers designed for in situ measurements. The second objective is in line with future space lidar missions, which will extend the observations of water vapor and isotopic abundance to the global scale in order to build an unprecedented climatology of convergence and divergence zones of humidity in the atmosphere. For this purpose, the avalanche photodiode, its amplification and formatting electronics will be designed and built in collaboration with Airbus DS. This will prepare the spin-out of research to industry for future lidar missions that may be proposed by France to the European Space Agency with the support of CNES.