Exploring the relationships between precipitation and surface temperature using satellite-based observations

How the global hydrological cycle, generally denoted by precipitation, may respond to surface temperature changes has been debated for decades. This debate is crucial to correctly assessing the global warming-related climatic variability/change, and also reflects our limited present understanding of what relationship exists between precipitation and surface temperature on various spatial and temporal scales. Using satellite-based global precipitation measurements (1979-present) from the Global Precipitation Climatology Project (GPCP) and the SSM/I-based (1988-present) tropospheric water vapor data, we find that the (intrinsic) correlations between oceanic mean precipitation and surface temperature anomalies are very weak once the effects of ENSO and volcano are removed, whereas oceanic mean tropospheric water vapor content varies with surface temperature no matter whether the ENSO and volcanic effects are included or not. We hence conclude that precipitation variability averaged over large-domains in which the large-scale dynamical processes become weak does not need to directly follow surface temperature variations at least on the interannual time scale. This tends to be consistent with the fact that ENSO precipitation signals are usually very weak over combined land plus ocean areas for both tropical and global regimes. This finding may also be applied to improve our understanding of the weak global-mean precipitation responses under the global warming scenario that have been shown based on both model simulations and observations.