Spatial distribution of ice and liquid water in Arctic boundary layer clouds and its effects on solar energy budget and remote sensing
Final Report Abstract
The DFG funding enabled us to investigate different methods of the remote sensing of cloud properties. Retrievals of the cloud optical thickness and the effective radius were extended to take multiple wavelength channels into account in order to increase the retrieval accuracy. This was successful in spite of an inconclusive outcome due to a lack of validation. The retrieval of the cloud optical thickness was extended from nadir observations to imaging spectrometry, and two‐dimensional maps of cloud optical thickness were produced. A commercially available digital camera was radiometrically calibrated to produce scientifically usable radiances. The angular dependence of the scattering of visible radiation by the cloud was derived from those camera images. Comparison with model clouds allow conclusions about optical cloud properties such as the effective radius. Measurements were conducted aboard the Polar‐5 aircraft of the Alfred Wegener Institute for Polar and Marine Research out of Longyearbyen airport, Svalbard (Arctic Norway) from 30 April to 20 May 2010. The original target of the project, mixed‐phase clouds, was missed because the measurement campaign was delayed by two weeks as a consequence of the volcanic eruption of the Eyjafjallajökull in Iceland. Upon arrival in Svalbard, spring temperatures had risen too much to leave significant amounts of ice inside the Arctic clouds. Nevertheless, the liquid clouds did provide us with useful experience about cloud retrievals that form the basis for the follow‐up projects in the Arctic. Uni‐Meteorologen über der Arktis unterwegs, Dr. Bärbel Adams, Universitäts‐Zeitung, Universität Leipzig, 14 May 2010 Wie Wolken das Klima beeinflussen, Benedikt Paetzhold, Leipziger Volkszeitung, LVZ‐Online 19 June 2010 Die rätselhafte Welt der Wolken, Tag/Traum Filmproduktion Köln, for ZDF/ARTE, 52 minutes, first aired 24 June 2011 on ARTE
Publications
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Different views on the Arctic surface albedo. At: 2010 AGU Fall Meeting, San Francisco, USA, 13–17 Dec 2010
E. Bierwirth, S. Schmidt, P. Pilewskie, A. Ehrlich, M. Wendisch, H. Stark, A. Bucholtz, C. Schaaf, A. Lyapustin, C. Gatebe, M. Roman, K. Aikin, A. Herber, and G. Birnbaum
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Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera, Atmos. Chem. Phys. 12, 3493‐3510, 2012
A. Ehrlich, E. Bierwirth, M. Wendisch, A. Herber, and J.‐F. Gayet
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Airborne Observation and Characterization of Arctic Boundary‐Layer Clouds. At: 16th International Conference on Clouds and Precipitation (ICCP), Leipzig, Germany, 30 July–3 August 2012
E. Bierwirth, A. Ehrlich, M. Wendisch, A. Herber, A. Lampert, J.‐F. Gayet, R. Dupuy, and C. Gourbeyre
