In situ aircraft observations of one typical stratocumulus cloud process compared with the satellite measurements

The cloud microphysical parameters can be obtained directly by aircraft equipped with the PMS probes, but the measurements made by the in situ probes on aircraft are limited along the flight track. On the other hand, satellite is able to monitor the cloud environment of wide area, but the cloud parameters cannot be obtained directly with inversion needed. The comparisons between aircraft in situ measurements and satellite data are necessary. The cloud microphysical parameters including cloud droplet number concentration, liquid water content and effective radius from the aircraft PMS measurements of 2 flights in Huabei Plain are analyzed in detail. The cloud microphysical parameters from the vertical observation of 5 ascending and descending legs were used in the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) to simulate and compared with the data from the spectral channels of the GMS5/VISSR and the NOAA15/AVHRR. And then a comparison between the simulation and the satellite reflective channel measurements was completed. The in situ measurements show that the depth of stratocumulus cloud is about 1000 m, the maximum cloud droplet concentration is 425 cm-3, and the maximum liquid water content is 0.2 g/m3. During the first flight, the average values of cloud droplet concentration, liquid water content, and effective radius are 225±75 cm -3, 0.08±0.03 g/m 3 and 7.2±1.6цm, respectively. During the second flight, the average values of cloud droplet concentration, liquid water content, and effective radius are 196 73 cm -3, 0.04 0.02 g/m 3 and 4.9 1.4цm, respectively. Based on the calculation of the average value at the vertical interval of 500 m, the average cloud effective radius is 6.1 1.7цm, and the average stratocumulus cloud liquid water content (the cloud layer extends from 1000 to 1500 m) is typically 29.5 17.5 g/m 2. The sensitive analyses indicate that the visible channel reflectance is highly determined by the optical depth in the presence of cloud. In situ aircraft measurements were used to calculate the cloud albedo on the satellite spectral channel, and then the results were compared with the satellite measurements. The comparison shows that the relative bias is 7% with no systemic bias. It can be concluded that it is feasible to use aircraft measurements to calculate the cloud radiative properties. After the comparison with the similar observation in other countries, it indicates that the cloud water content calculated from the PMS data in China is reasonable.