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3rd HyMeX workshop 1-4 June 2009 Heraklion (Gournes), Crete-Greece

RaNHyM: A water vapour lidar based network of experimental sites for the Mediterranean hydrological cycle

Gian Luigi Liberti (ISAC-CNR); A. Behrendt, M. Cacciani, F. Congeduti, D. Dionisi, A. Di Sarra, P. Di Girolamo, D.Fua, P.Keckhut, F. Madonna, F. Marzano, G. Mastrantonio, P. Minnett, G. Pace, G. Pappalardo, M.R. Perrone, V. Rizi, S. Federico, N.Spinelli, D.Summa, Xuan Wuang and V. Wulfmeyer

This proposal includes a set of observations of the water vapour and other related quantities over the central Mediterranean to be carried out within HyMeX. The observations rely on the coordinated activity of:
. an existing network of 11 (3 of which moveable) experimental sites in Italy, France and Germany equipped with water vapour lidars (Raman and DIAL), some of which including temperature or ozone measurement capability, standard meteorological surface measurements and additional instruments (primarily for characterization of aerosols, clouds, and radiation), a well equipped remote marine station on the island of Lampedusa as long term 'open ocean' observatory,
. a moving experimental site including a set of high quality instruments (DIAL (Differential Absorption Lidar), Rotational Raman lidar, X-band radar and Joss-Valdvogel Disdrometer),
. the R/V URANIA equipped, in addition to the standard instrument set, with the RSMAS sea-going equipment for high quality atmospheric observations during dedicated campaigns.

Each site in the proposed network is characterized by the capability to perform high quality measurements of the water vapour (WV) vertical structure up to the upper troposphere by means of high performance WV lidars (Raman and DIAL); furthermore, each site is equipped with a radiosounding systems and/or is in the vicinity operational WMO sounding sites. In addition, all stations are located within experimental sites hosting different instruments producing complementary data helping in the interpretation of the measurements (e.g. lidar for aerosol with analysis of depolarization, photometers and further instrumentation to obtain an accurate description of the atmospheric state in terms of WV (e.g. MW radiometers), meteorological parameters, cirrus and cloud location, radiative fluxes). Three of the experimental observatories can be also moved to other sites of interest. The observatories are located at sites covering a wide range of conditions (i.e. altitude, distance from the sea, land use) representative of a large part of the Coastal areas in the Mediterranean. Several sites have been carrying out regular lidar observations during last years.
The main scientific objectives of the network coordinated operation are:
a. studies on the water budget of the Mediterranean Sea, through the characterization of the atmospheric water transport, and the identification of constraints for a better determination of the evaporative fluxes; the measurement network will also allow the investigation of sub-regional scale water vapour transport phenomena, and quantify the water vapour evolution in urban and coastal areas;
b. investigation of the moisture distribution and evolution, also in relation to heavy precipitation events;
c. investigation of the water vapour/aerosol/radiation relationships and water vapour/aerosol/clouds interactions;
d. investigation of the feedbacks between aerosol, radiative fluxes, evaporation, and clouds, and of the role of marine particles in the marine environment.

The network will provide high quality observations of the water vapour distribution, atmospheric structure and composition, and radiative fluxes during the different phases of Hymex. Continuous measurements from the island of Lampedusa will provide background long-term information.
A description of the network and several cases of coordinated observations will be discussed.