Cloud and Radiation Variations Associated with Northern Midlatitude Low and High Sea Level Pressure Regimes

Abstract

Abstract A global meteorological dataset, a global satellite dataset, and a radiative transfer model are combined to map the cloud types in low, near-normal, and high sea level pressure regimes in the northern midlatitudes, and to calculate the radiative balance in those regimes. The prominent cloud feature is a background cloud field that is present most of the time and is modulated by changes in dynamic regime. It consists of a low cloud deck, which becomes optically thicker in the warm seasons over ocean and in the cold seasons over land, and a population of optically thin middle-to-high-top clouds that is mostly middle-top in the cold and mostly high-top in the warm seasons. This background cloud field is modulated by the emergence of a population of optically thick high-top clouds in the low pressure regime and by an increase in the optical thickness of the low clouds in the high pressure regime. The top-of-the-atmosphere (TOA) shortwave flux differences between dynamic regimes show that more sunligh...