Wednesday, 12 July 2006
Grand Terrace (Monona Terrace Community and Convention Center)
We examined cloud characteristic in Tropics, mid-latitude and polar regions using Research Vessel Mirai since 2001. Main aims of this study are to analyze the macro- and micro physical structure of high, mid-level and low clouds and also validate the representation of clouds in climate models using the observed values. The synergy use of cloud profiling radar and lidar is an ideal approach for above purposes since radar and lidar are complementary sensors to detect clouds and very effective for microphysical retrievals. For the microphysical retrievals, we developed several different algorithms, i.e., (1) single use of lidar (2) single use of radar with multi-parameter functions and (3) radar and lidar method. Lidar algorithm uses the ratio between the backscattering coefficient at 532nm and at 1064nm to derive particle size. The results of the lidar method is compared with the optical thickness derived from infrared radiometer and found that the agreement is achieved unless the optical thickness exceeds 1. Above optical thickness of 1, the single use of lidar method tends to underestimate optical thickness due to the attenuation in lidar signals. It is possible to derive the microphysics of sub visual cirrus (SVC) and compared with those in anvil clouds associated with convective activity in the Tropics case in 2004 -2005. SVC is often found at 16 - 17km and the effective radius and IWC is around 10-20 microns and 0.0025 g/m3, respectively. The relatively thick high-level clouds are frequently observed in the same region where the mean IWC ranges from 0.001 to 0.01 and effective radius is around 30microns. The radar only algorithm utilizes the reflectivity, Doppler velocity and linear depolarization ratio (LDR) (see Sato et al., in this session) to derive cirrus microphysics. The main feature is to correct air motion in Doppler velocity to derive terminal velocity of ice particles. The results of the algorithms are compared and compiled.
The retrieved microphysics are then used to validate the representation of clouds in the SPRINATATARS that is the aerosol transport model based on the CCSR-NIES FRCGC GCM. We report the comparisons of cloud fraction, observables such as radar reflectivity and lidar backscattering coefficient and cloud microphysics between the observations and the SPRINATRS.
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