The Experimental Cloud Lidar Pilot Study (ECLIPS) was initiated to obtain statistics on cloud-base height, extinction, optical depth, cloud brokenness, and surface fluxes. Two observational phases have taken place, in October-December 1989 and April-July 1991, with intensive 30-day periods being selected within the two time intervals. Data are being archived at NASA Langley Research Center and, once there, are readily available to the international scientific community. This article describes the scale of the study in terms of its international involvement and in the range of data being recorded. Lidar observations of cloud height and backscatter coefficient have been taken from a number of ground-based stations spread around the globe. Solar shortwave and infrared longwave fluxes and infra-red beam radiance have been measured at the surface wherever possible. The observations have been tailored to occur around the overpass times of the NOAA weather satellites. This article describes in some detail the various retrieval methods used to obtain results on cloud-base height, extinction coefficient, and infrared emittance, paying particular attention to the uncertainties involved. The above methods are then illustrated by both model simulations and by selected results from various laboratories. The ECLIPS data are shown to represent a valuable resource for cloud parameter-izations in models and for model validations.

Abstract. We present the new airborne Doppler radar KuROS (Ku-band Radar for Observation of Surfaces), which provides measurements of the normalized radar cross section σ° and of the Doppler velocity over the sea. The system includes two antennae rotating around a vertical axis, although only the results from the lower incidence (14°) antenna are presented here. We also give first results from observations performed during two field campaigns held in 2013 (HyMeX and PROTEVS campaigns). Sea wave directional spectra computed by the radar from tilt modulation of σ° are consistent with those given by the directional wave rider moored in the Mediterranean basin, both in terms of significant wave height H s and main features of the wavenumber spectrum. As concerns the azimuthal distribution, two methods are tested to remove the 180° ambiguity of the radar derived directional spectrum. The first method is based on the correlation between the modulations of σ° and Doppler velocity, which reflects the correlation between sea surface slope and orbital velocity. The second method does not use the Doppler velocity, but computes the cross-spectrum between the modulations of σ° between two power profiles separated by some time lag ΔT, from which the phase velocity of sea waves is deduced. Comparing the sea wave directional spectra disambiguated by both methods, with the directional spectrum given by the wave rider, we conclude that the first method (using Doppler velocity) is more efficient to remove the 180° ambiguity, and should be preferred to the second method.3