On the global character of overlap between low and high clouds

摘要: [1] The global character of overlap between low and high clouds is examined using active satellite sensors. Low-cloud fraction has a strong land-ocean contrast with oceanic values double those over land. Major low-cloud regimes include not only the eastern ocean boundary stratocumulus shallow cumulus but also associated cold air outbreaks downwind wintertime continents land stratus particular geographic areas. Globally, about 30% are overlapped by clouds. The rate exhibits spatial variability ranging from higher than 90% in tropics to less 5% subsidence areas anticorrelated fraction. zonal mean vertical separation cloud layers never smaller 5 km its variation closely follows that tropopause height, implying tight connection dynamics. Possible impacts on discussed.