Unforced surface air temperature anomalies and their opposite relationship with the TOA energy imbalance at local and global scales

Abstract:

Unforced global mean surface air temperature (T_global) is stable in the long-term primarily because warm T_global anomalies are associated with enhanced outgoing longwave radiation to space and thus a negative global radiative energy imbalance (N_global, positive downward) at the top of the atmosphere (TOA). However, it is shown here that at the local spatial scale, warm unforced T_local anomalies tend to be associated with anomalously positive N_local imbalances over most of the surface of the planet. It is revealed that this occurs mainly because warm T_local anomalies are accompanied by anomalously low surface albedo near sea ice margins and over high altitudes, anomalously low cloud albedo over much of the mid/low-latitudes and an anomalously large water-vapor greenhouse effect over the deep tropical ocean. During warm T_global years, the largest negative N_local anomalies primarily occur over regions of cool or near-neutral T_local anomalies. These results help explain how TOA energy imbalances can act to damp unforced T_global anomalies while simultaneously amplifying unforced T_local anomalies.