<title>Water vapor, temperature and wind velocity measurements from space using 2 micron Tm:Ho:YAG</title>

Abstract

In meteorological and climatological fields, the scientific community will increasingly need global measurements of key atmospheric parameters with high spatial resolution (horizontal as well as vertical): the future spaceborne lidars are most suitable instruments for those missions. The next spaceborne applications of lidars are related to "simple" backscatter lidars (ATLID type, currently studied at ESA); the following generation of potentially spaceborne lidars will be DIAL and Doppler wind lidars, presenting a higher level of complexity than the previous ones, mainly due to the large power and complex signal processing required. The present considered wind lidars are based on CO2 lasers, whose space compliance is still to be demonstrated, while alexandrite lasers are considered for water vapor and temperature measurements, but they need flashlamp pumping which poses a lot of severe thermal constraints and lifetime problems: on the other side, the recent developments achieved in solid-state technology allow to envisage diode pumping as the most promising possibility for both previous applications. All these reasons have induced ESA to ponder a future mission dedicated to water vapor, temperature and 'wind velocity measurements and using an eye-safe wavelength in solid-state technology: involved in this ESA contract are AEROSPATIALE and its Subcontractors, namely QUANTEL (laser, France)-with the support of UNIVERSITY of BERNE (Switzerland)-, ALENIA (receiver, Italy), TELDIX (lag-angle compensator, Germany), and the Iidar teams of LABORATOIRE DE METEOROLOGIE DYNAMIQUE and SERVICE DAERONOMIE (France) and of ENEA and UNIVERSITY of ROME (Italy). We have selected Tm,Ho:YAG technology emitting at 2 1tm; the main first results of our studies will be presented at this conference: investigation of spectral lines, transmitter and receiver requirements, parametric studies leading to the final instrument design. 196 / SPIE Vol. 1688 Atmospheric Propagation and Remote Sensing (1992) 0-81 94-0853-0/92/$4.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/17/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Considering the parametric study results [11], the coherent DWL system is the only lidar system meeting the mission requirements, but critical items still remain at subsystem and system level (as diffraction limited laser beam, 80 MHz photomixer,...). SPIE Vol. 1688 Atmospheric Propagation and Remote Sensing (1992) / 201 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/17/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx