Cloud variations under subtropical high conditions

摘要: The cloud variations under subtropical high (STH) conditions during summers over a ten-year period are studied using combined data from the International Satellite Cloud Climatology Project and National Centers for Environmental Prediction. results reveal that clouds mainly experience an isolated evolution in STHs, which is designated this study by 1540 gpm geopotential lines at 850 hPa. In STH domain throughout Northern Hemisphere, average amount of total exceeds 30%. Low dominate domain, contributing 60% within Pacific 40% Atlantic high. prevalence low above regions determined circulation pattern around 150°–180°E hPa, suppresses both upward development tops water vapor divergences near surface. Furthermore, present great geographical incoherence domain. eastern middle increases to peak early morning decreases trough afternoon, while remains stable day. Conversely, western diurnal amplitude less than three, dramatically reach maximum afternoon drop minimum evening. Among nine categories, stratocumulus with greater optical thickness account most conditions, no matter their occurrence or amount, causing more shortwave radiative forcing cool local atmosphere surface as consequence.