2:15 PM - 2:30 PM
[ACG41-21] Microphysical properties of marine fog retrieved from a geostationary satellite, Himawari-8/9
Fogs, especially marine sky-obscuring fogs, can significantly affect the Earth’s radiation budget owing to the wide coverage area of the earth surface. The radiation properties of fogs are largely dependent upon the microphysical prosperities of the fogs, and therefore, understanding their microphysical properties is required to estimate their radiative impacts accurately. The continuous observations at same area during long period by geostationary satellites are required to more sophisticated understanding of the microphysical properties of fogs. Recent advance in the spatiotemporal resolution of the measurement by the satellite enables us to estimate fogs’ microphysical properties from geostationary satellites. In this study, we estimated the microphysical properties of fogs off the coast of Hokkaido and Sanriku region in Japan using data from a geostationary satellite, Himawari-8/9. A retrieval algorithm for estimating cloud microphysical properties (Comprehensive Analysis Program for Cloud Optical Measurements, CAPCOM: Nakajima and Nakajima, 1995, Kawamoto et al., 2001) was applied for the Himawari-8/9 data. An approach that calculates cloud base height was introduced to distinguish between fogs and low clouds. Using this approach, 70 % of fog events reported at the Kushiro site in Hokkaido with precision rate was captured, with miss rate and overlook rate as 29 %, and 38 %, respectively. The approach also enabled us to estimate 9 years climatology of the optical thickness, effective radius, and liquid water path of fogs over the wide area of the target regions. The estimated effective radius over the land qualitatively agreed with the ground-based measurement even though the available literature of ground-based measurement of fog’s microphysical properties is limited. The results also clarified that the microphysical properties of fog over the sea and land vary around the coastline.