Links between tropical energy budget variability and the diurnal cycle

Periodic variations of a geophysical variable (e.g. temperature, water vapor, clouds, and precipitation) caused by only the daily variation of solar insolation are referred to as the diurnal cycle. Precise representation of fundamental earth system variability in climate models is required for accurate climate simulation and is extremely important for climate change attribution; the diurnal cycle represents such a fundamental variability. Previous work has demonstrated the importance of temperature, water vapor, and cloud diurnal cycles to the mean radiation budget. However, little work has been done to elucidate the influence of diurnal cycle on radiation budget variability. The Clouds and Earth's Radiant Energy System (CERES) top of atmosphere radiative flux and Tropical Rainfall Measuring Mission 3B42 precipitation products are used to investigate links between energy budget and water cycle variability and the diurnal cycle. A covariability is found where positive (negative) outgoing longwave anomalies over land are associated with a stronger (weaker) diurnal cycle amplitude. In addition, the analysis reveals that the effect of diurnal cycle on inter-annual variability is minimal over tropical ocean regions but can be significant in land convective regions (e.g, central Africa and central South America). The drivers and implications of these relationships are discussed.