Cirrus cloud macrophysical and optical properties over North China from CALIOP measurements

Abstract

Two years of mid-latitude cirrus cloud macrophysical and optical properties over North China are described from Earth-orbiting Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite measurements. Global cloud climatological studies based on active remote sensing data sets benefit from more accurate resolution of vertical structure and more reliable detection of optically thin layers. The mean values for cirrus cases over North China are 0.19±0.18 for infrared emittance, 0.41±0.68 for visible optical depth, 0.26±0.12 for integrated depolarization ratio, and 0.72±0.22 for integrated color ratio. When studied using reasonable assumptions for the relationship between extinction and ice crystal backscatter coefficients, our results show that most of the cirrus clouds profiled using the 0.532 μm channel data stream correspond with an optical depth of less than 1.0. The dependence of cirrus cloud properties on cirrus cloud mid-cloud temperature and geometry thickness are generally similar to the results derived from the ground-based lidar, which are mainly impacted by the adiabatic process on the ice cloud content. However, the differences in macrophysical parameter variability indicate the limits of spaceborne-lidar and dissimilarities in regional climate variability and the nature and source of cloud nuclei in different geographical regions.

Depolarization Property of Cirrus Clouds Over Hanoi

“…They suggest that the trend appears as a result of the occurrence of complex ice crystal aggregates at low temperatures. The high depolarization values, up to 80%, for cirrus clouds over Hanoi as measured by our polarization lidar system are entirely consistent with the results reported earlier for other regions of the world such as Taiwan [8], China [9], India [10], and North America [11].…”

Cloud-base distribution and cirrus properties based on micropulse lidar measurements at a site in southeastern China

“…The mean τ for all cirrus clouds in this study is 0.34 ± 0.33, which is consistent with the mean values of 0.31 reported by Giannakaki et al (2007) and 0.28 reported by Immler and Schrems (2002). However, the mean value found in this study is significantly larger than the value of 0.16 ± 0.27 reported by Das et al (2009) and slightly smaller than the value of 0.41 ± 0.68 reported by Min et al (2011). The mean value of τ c is much smaller than that of 0.75 ± 0.91 reported by Sassen and Campbell (2001).…”

“…A maximum cirrus occurrence in summer and a minimum in winter were also found from two years' worth of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data over northern China (Min et al, 2011). The summertime maximum happens because there is a relatively abundant supply of upper-tropospheric water vapor introduced by regional convective activity influenced by the western tropical Pacific and because of the seasonal meridional displacement of subtropical cirrus bands (Sassen et al, 2008;Min et al, 2011). The annual mean cirrus occurrence in our study is similar to that (37%) calculated from an eight-year cirrus climatology generated by Das et al (2009) over Chung-Li, a site in East Asia.…”

A decadal cirrus clouds climatology from ground-based and spaceborne lidars above the south of France (43.9° N–5.7° E)

“…Similar results have been retrieved regarding the variability of Cloud Mean Height which keeps quite constant from one month to another. A mean monthly variation of ∼ 0.15 km around the total mean value has been observed (Sassen and Comstock, 2001), G07 (Giannakaki et al, 2007) and M11 (Min et al, 2011 9.28 ± 1.77 9.4 ± 1.76 8.85 ± 1.95 9.35 ± 1.47 8.17 ± 1.95 9 ± 1.1 9.16 ± 1.83 CTH [km] 10.94 ± 1.68 11.03 ± 1.84 10.4 ± 1.62 10.91 ± 1.48 10.97 ± 1.92 11.7 ± 0.9 10.77 ± 0.9 CT [km] 1.64 ± 1.1 1.64 ± 1.1 1.56 ± 1 1.56 ± 1 2.79 ± 1.38 2.7 ± 0.9 1.6 ± 1.15 for the class 1 and 3 from both CALIOP and the OHP lidar, and of ∼ 0.3 km for the class 2. Parameters for class 2 cirrus clouds agree well with results from G07.…”