Process‐Level Assessment of the Iris Effect Over Tropical Oceans

The iris hypothesis suggests a cloud feedback mechanism that reduction in the tropical anvil fraction (CF) warmer climate may act to mitigate warming by enhanced outgoing longwave radiation. Two different physical processes, one involving precipitation efficiency and other focusing on upper-tropospheric stability, have been argued literature be responsible for effect. In this study, A-Train observations reanalysis data are analyzed assess these two processes. Major findings as follows: (a) CF changes evidently with stability expected from theory, (b) is unlikely control but related mid- low-level CFs, (c) day nighttime radiative effects largely cancel out when integrated over diurnal cycle, suggesting neutral feedback.