The channel specifications of the Global Imager onboard the Advanced Earth Observing Satellite II have been determined by extensive numerical experiments. The results show that there is an optimum feasible position for each ocean color channel. The bandwidth of the 0.763-microm channel should be less than 10 nm for good sensitivity to the cloud top height and geometric thickness of the cloud layer; a 40-nm bandwidth is suitable for the 1.38-microm channel to have the strongest contrast between cloudy and clear radiance with a sufficient radiant energy; and a 3.7-microm channel is better than a 3.95-microm channel for estimation of the sea surface temperature (SST) and determination of the cloud particle size when the bandwidth of the channel is 0.33 microm. A three-wavelength combination of 6.7, 7.3, and 7.5 microm is an optimized choice for water vapor profiling. The combination of 8.6, 10.8, and 12.0 microm is suitable for cloud microphysics and SST retrievals with the split-window technique.

No abstract

It is of great interest to investigate the properties on the cloud optical, microphysical, and geometrical parameters, in particular, of low-level marine clouds which play crucial influence on the global climate system. Top height, base height, and geometrical thickness of cloud layer are considered here as cloud geometrical parameters. These parameters are very important to retrieve, because top and base heights are the factors which govern the strength of greenhouse effect through the thermal radiation from / to cloud layer, whereas the geometrical thickness is the key parameter for the estimation of gaseous absorption in cloud layer where multiple scattering process dominates. In this study, an algorithm was developed to retrieve simultaneously cloud optical thickness, effective particle radius, top height, and geometrical thickness of cloud layer from the spectral information of visible, near infrared, thermal infrared, and oxygen A band channels. This algorithm was applied to FIRE (First ISCCP Regional Experiment, 1987) airborne data which included the above four channels and targeted at the lowlevel marine clouds off the coast of California in summer. The retrieved results seems to be comparable to the in situ microphysical observation although further validation studies are required for the cloud geometrical parameters in particular.

No abstract

Shipboard observations of cloud fraction were performed along the round-trip research cruise between Japan and Antarctica from November 2013 to April 2014 using both a whole-sky camera and a ceilometer onboard the Research Vessel (R/V) Shirase. Based on the results of the comparison of these cloud fractions, it was found that the correlation coefficient was 0.86 for the 2024 observations acquired between Australia and Antarctica from 27 November to 9 December 2013. Overall, the results were consistent between the two observation methods; however, some underestimation by the whole-sky camera was determined in comparison with the ceilometer. It is intended that shipboard observations will continue onboard the R/V Shirase over subsequent every years in order to improve the retrieval of cloud fractions for the validation of satellite observations.