Abstract
Satellite-based global cloud data records play an essential role in understanding the impact of changing regional weather as well as global climate due to the direct and indirect radiative forcing of clouds. In this research the PATMOS-x Version 6.0 dataset, developed as a collaboration between NOAA National Centers for Environmental Information and the University of Wisconsin-Madison with a focus on providing reliable climate records from NOAA’s POES and EUMETSAT’s MetOp satellite series, is used to investigate long-term changes in maritime clouds from 60°S to 60°N. Monthly mean cloudiness is calculated using generalized additive model backfitting and observational weighting to consider orbital drift and different local overpass times between satellites. Our results show that mean fractional cloudiness is decreasing by 0.86% per decade, with maximums over the central equatorial Pacific Ocean at 3% per decade. Over the western Pacific Ocean and west coast of South America, our record shows increasing trends in ice clouds and water clouds, respectively. Changes in cloud fractions associated with cloud phase are connected to changes in cloud top heights. Cloud top height increases over the western Pacific Ocean at 0.4 km per decade. Decreases in cloud top heights happen near the southeastern Pacific Ocean as well as at other regions where marine stratocumulus clouds are dominant. These changes in cloud fraction and cloud top assignments both contribute to cloud radiative effect so that changes in radiative transfer process and Earth’s radiation budget should be investigated.
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