Comparison of the CALIPSO satellite and ground-based observations of cirrus clouds at the ARM TWP sites

Journal Article · Thu Nov 10 04:00:00 EST 2011 · Journal of Geophysical Research. D. (Atmospheres)

DOI:https://doi.org/10.1029/2011JD015970· OSTI ID:1031431

Thorsen, Tyler J; Fu, Q; Comstock, Jennifer M

Statistics of ice cloud macrophysical and optical properties from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite are compared with those from ground-based lidar observations over a 31 month period. Ground-based lidar observations are taken from the micropulse lidars (MPL) at the three Department of Energy Atmospheric Radiation Measurement (ARM) tropical western pacific (TWP) sites: Manus, Nauru and Darwin. CALIPSO observations show a larger cloud fraction at high altitudes while the ground-based MPLs show a larger cloud fraction at low altitudes. The difference in mean ice cloud top and base heights at the Manus and Nauru sites are all within 0.51 km, although differences are statistically significant. Mean ice cloud geometrical thickness agree to within 0.05 km at the Manus and Nauru sites. Larger differences exist at Darwin due to excessive degradation of the MPL output power during our sampling period. Both sets of observations show thicker clouds during the nighttime which may be real but could also be partially an artifact of the decreased signal-to-noise ratio during the daytime. The number of ice cloud layers per profile are also shown to be consistent after accounting for the difference in spatial resolution. For cloud optical depths, four different retrieval methods are compared, two for each set of observations. All products show that the majority of ice cloud optical depths ({approx}60%) fall below an optical depth of 0.2. For most comparisons all four retrievals agree to within the uncertainty intervals. We find that both CALIPSO retrievals agree best to ground-based optical depths when the lidar ratio in the latter is retrieved instead of set to a fixed value. Also thoroughly compared is the cloud properties for the subset of ice clouds which reside in the tropical tropopause layer (TTL).

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1031431
• Report Number(s): PNNL-SA-84616; KP1701000
• Journal Information: Journal of Geophysical Research. D. (Atmospheres), Journal Name: Journal of Geophysical Research. D. (Atmospheres) Vol. 116
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ARM TWP sites
CALIPSO
CLOUDS
NAURU
OPTICAL PROPERTIES
OPTICAL RADAR
POLARIZATION
RADIATIONS
SAMPLING
SATELLITES
SIGNAL-TO-NOISE RATIO
SPATIAL RESOLUTION
STATISTICS
THICKNESS
TROPOPAUSE
cirrus clouds
ground-based observations
satellite