Objectif To develop and test radar based-algorithms to infer thevertical profiles of cloud properties such as ice and liquidwater content. To study the properties of natural clouds, theirevolution and their characteristics.An existing 94GHz radar will be upgraded to increase itssensitivity to clouds and will then be deployed alongside twoexisting 35 and 3 GHz radars at Chilbolton in the UK so that thethree radars, together with a 95GHz radiometer, can scan a commonvolume of cloud.The radar upgrade should take 10 months and will be followed by atwelve month period of observations with the three radars and theradiometer. Measurements will be made on both a statistical andan event basis, and will encompass low level water clouds such asstratocumulus, higher level cirrus clouds which are composed ofice particles only, together with clouds of mixed phase.Algorithms will be developed to infer cloud properties from theradar measurements at the three wavelengths. The 3GHzreflectivity is unaffected by attenuation or Mie scattering. Theincreased attenuation at the higher frequencies will be used toderive cloud liquid water content. For ice clouds theattenuation at all three radar frequencies is negligible, but thepresence of larger ice particles results in Mie scattering and areduced radar reflectivity at the higher frequency, and thisreduction can be used to derive a mean size for the iceparticles.In parallel with the establishment of algorithms to infer liquidand ice water content, particle size, and the efficiency of clouddetection by radar, studies will be carried out of cloudevolution. Climate models are very sensitive to the assumedterminal velocity of cirrus particles which affect thepersistence of ice clouds; direct radar measurements of thesevelocities will aid parameterisation schemes.Clouds represent one of the chief sources of uncertainty inclimate studies; small alterations to cloud parameterisationschemes in general circulation models leading to very differentglobal distributions of clouds. The ultimate aim is for aspaceborne cloud radar to provide vertically resolved globalcloud data, this first step is to provide ground based radar datato improve and validate parameterisation schemes. Champ scientifique engineering and technologyelectrical engineering, electronic engineering, information engineeringinformation engineeringtelecommunicationsradio technologyradarnatural sciencesearth and related environmental sciencesatmospheric sciencesclimatology Programme(s) FP3-ENV 1C - Specific research and technological development programme (EEC) in the field of the environment, 1990-1994 Thème(s) 0102 - Anthropogenic climate change Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur UNIVERSITY OF READING Contribution de l’UE Aucune donnée Adresse Earley Gate 2, Whiteknights, Palmer Building RG6 2AU READING / SILCHESTER Royaume-Uni Voir sur la carte Coût total Aucune donnée Participants (3) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire COUNCIL FOR THE CENTRAL LABORATORY OF THE RESEARCH COUNCILS Royaume-Uni Contribution de l’UE Aucune donnée Adresse Chilton OX11 0QX DIDCOT,HARWELL,CHILTON Voir sur la carte Coût total Aucune donnée Società GF Galileo SMA Srl Italie Contribution de l’UE Aucune donnée Adresse Via Albert Einstein 35 50013 Firenze Campi Bisenzio Voir sur la carte Coût total Aucune donnée UNIVERSITE PAUL SABATIER DE TOULOUSE III France Contribution de l’UE Aucune donnée Adresse Avenue Edouard Belin 14 31400 TOULOUSE Voir sur la carte Coût total Aucune donnée