HR: 17:15h
AN: A44A-06    [Abstracts]
TI: Understanding Formation and Maintenance of Mixed-Phase Arctic Stratus Through Long- Term Observation at two Arctic Locations
AU: * de Boer, G
EM: gdeboer@wisc.edu
AF: The University of Wisconsin - Madison, 1225 W. Dayton Street, Madison, WI 53706, United States
AU: Eloranta, E W
EM: eloranta@lidar.ssec.wisc.edu
AF: The University of Wisconsin - Madison, 1225 W. Dayton Street, Madison, WI 53706, United States
AU: Tripoli, G J
EM: tripoli@aos.wisc.edu
AF: The University of Wisconsin - Madison, 1225 W. Dayton Street, Madison, WI 53706, United States
AB: Mixed-phase stratus clouds are commonly found in the Arctic, and have a strong effect on the radiation budget of this region. However, because of the unstable nature of mixed-phase systems, climate and even cloud-resolving models have difficulty accurately representing them and the radiative effects that they provide. In order to accurately predict climate scenarios for the future, a better representation of these prevalent structures must be implemented into current forecasting tools. The University of Wisconsin Arctic High Spectral Resolution Lidar (AHSRL) has been deployed to Barrow, Alaska and Eureka, Canada to gather long-term data sets of clouds at high latitudes. Together with a NOAA Millimeter Cloud Radar (MMCR), University of Idaho Polar Atmospheric Emitted Radiance Interferometer (PAERI) and NOAA Microwave Radiometer (MWR), the AHSRL has been collecting data at Eureka for over two years as a part of the Study of Environmental Arctic Change (SEARCH) program. In addition to these instruments there are twice-daily radiosonde launches as well as relatively frequent A-Train overpasses. A similar set of instruments, in conjunction with aircraft in-situ measurements recorded nearly two months worth of data at Barrow in 2004 for the Mixed-Phase Arctic Clouds Experiment (M-PACE). This data set for 2005 and 2006 alone contains over 1700 half-hour cases of mixed-phase stratus. Using direct measurements and retrieval algorithms, these cases along with those from 2004 and 2007 are being analyzed for long-term statistics on properties such as cloud top and cloud base heights, cloud thickness, cloud water content, ice water content, particle size, and particle number density. Additionally effects of temperature, pressure, wind speed and wind direction on the presence of these cloud structures are being analyzed. Also, observations from CloudSat and CALIPSO are being used to study the spatial extent of these cloud systems as well as to detect aerosol layers that may be aiding in the maintenance of the mixed-phase scenario. We will present results from these observations and introduce theories on the formation of these cloud systems based on these results. Additionally, comparison of observations with numerical simulations of specific cases will be shown, and future pathways for model improvement will be presented.
UR: http://lidar.ssec.wisc.edu
DE: 0319 Cloud optics
DE: 0320 Cloud physics and chemistry
DE: 0321 Cloud/radiation interaction
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting