The definition of a cloud strongly depends on the individual objectives (i.e., radiative impacts, microphysical processes, precipitation, etc.).
We are examining the issue of cloud identification using surface-base remote sensors in
order to inform our long term records of cloud observations from these sensors.
Figure: Cloud observations by radar (a), lidar (b), and AERI (c) and subsequent cloud fraction
estimates (d) from each during the month of October 2006 in Eureka, Canada. In Panel d, blue is radar,
orange is lidar, red is AERI, and the green symbols are surface observer records.
Figure: Cloud observations by radar (a), lidar (b), and AERI (c) for 26 and 27 October 2006 in Eureka, Canada.
These observations highlight the different perspectives of each instrument. For example, the lidar and AERI observe thin mid-
and high-level cloudiness in the first 10 hours that is partially missed by the radar. On the other hand, the lidar
is occulted and the AERI is saturated during much of 27 Oct, while the radar fully penetrates the cloud layers.
Cloud Occurrence in the Arctic
Objective: Provide cloud macrophysical property data sets for Arctic Atmospheric Observatories. Parameters: Cloud fraction, cloud base, cloud top, total cloud thickness Sites: Barrow, Alaska; Eureka, Canada; Ny'Alesund, Norway; SHEBA Available:CADIS archive
Figure: Total monthly-average cloud fraction at Arctic Atmospheric Observatories.All-site average is given in black.
Objective: Provide cloud microphysical property data sets for Arctic Atmospheric Observatories. Parameters: Condensed water content and particle size for both liquid and ice Sites: Barrow, Alaska; Eureka, Canada; SHEBA Release Date: late-2009