Proceedings with Extended Abstracts (single PDF file) - Radio ...

TOWARD A MULTISENSOR GROUND BASED REMOTE SENSINGSTATIONCatherine Gaffard 1 , Tim Hewison, John NashMet OfficeMeteorology Building, PO Box 243, Earley Gate, University of Reading, RG6 6BB, UK1. IntroductionFuture UK operations require several sites using ground based remote sensing techniques toprovide an upper air network with better spatial and temporal resolution than currently exists.There is currently a network of 5 wind profilers that cover the UK and winds areoperationally assimilated in our global and mesoscale model. Our goal is to get a continuousmonitoring of the lowest 3-km of the troposphere to improve the humidity field and theboundary layer description for numerical weather prediction (NWP). We investigate how asynergy between different ground based remote sensing instruments, like wind profiler,radiometer cloud radar and lidar ceilometer could meet our user needs. A 12-channelmicrowave radiometer is being trialed and a low cost cloud radar is under development.A wind profiler and a ceilometer are operationally operated at Camborne in the southwest ofEngland. At present only the wind and the cloud base information obtained from theseinstruments are used operationally. As it will be illustrated in this paper more informationabout the vertical structure of temperature and humidity is available in the return signal of thewind profiler and of the ceilometer. The main cause of wind profiler radar returns is due to aBragg scattering by turbulent inhomogeneities in the refractive index. Therefore there is aclose link between the return signal and the gradient of the temperature and the humidityprofile. Some studies (Stankov, 2003,1998) have shown that a wind profiler can be used inassociation with other instruments as RASS, radiometer, GPS, humidity profiles could beretrieved at the vertical resolution of the radar.Three intensive observation periods have been conducted, when radiosondes were launchedhourly. These cover three different situations: development of the convective boundary layer,cloud evolution and clear air situation.2. Development of the Convective Boundary Layer Case StudyFigure 1 shows the time-height evolution of the wind profiler signal to noise ratio (SNR).Superimposed in white circles are the cloud bases detected by the ceilometer, which show alot of broken cloud. The cloud base is in the middle of a wide layer of high wind profilersignal to noise ratio, except for a couple of clouds which are just at the edge of the windprofiler signal. For these clouds, the cloud base appears to be more steady. The altitude rangecovered by the wind profiler with a high SNR increases from 1000 m at 08:00 to itsmaximum (2150 m) at around 11:30. During this period, the vertical distribution of the strongwind profiler SNR’s and cloud bases become more spread. This is likely to be due to1 Corresponding Author:Catherine Gaffard, catherine.gaffard@metoffice.com, phone: +44 118 937831, fax: +44 118 3788791365