| Despite their importance in Earth's radiation budget and atmospheric models, Arctic clouds remain poorly documented and understood. The deployment of a cloud radar and a high spectral resolution lidar at Eureka (80°N) in August 2005 offers a unique data set for the study of Arctic clouds. In this project, synergetic retrievals were developed and applied to two years of data in order to provide a first climatology of the clouds and their microphysics at this remote location. Results show an annual cycle in cloud coverage. They are mostly detected in the low levels or in single-layer, especially in winter due to a temperature inversion and cloud top radiative cooling. An analysis of the winds also demonstrated that different wind directions relate to different cloudiness conditions, while a strong channelling from the topography is present in the low levels. Moreover, liquid phase particles were detected all year round, with a minimum occurrence in winter due to colder temperatures. Turbulence and high relative humidity seem to maintain supercooled liquid, especially when ice crystals were also present. Precipitation was mostly identified during summer months, often in the form of virga, although falling snow might have been missed due to the difficulty to distinguish it from glaciated clouds. Finally, results show that satellite validation is possible using Eureka's data, but only under homogeneous conditions and when the instruments characteristics (like the sampling and sensitivity) are taken into account. |
