Water cycle changes characterised from atmospheric moisture recycling (WEATHER)

Living Planet Fellowship research project carried out by Tim Trent.

Water vapour is an essential greenhouse gas in the Earth climate system, acting as a natural feedback mechanism for carbon dioxide forcing. Critical to the development of cloud and precipitation, water vapour also has a significant influence and impact on surface fluxes and radiative balance. Water vapour is considered to be under natural control as it is sufficiently abundant and short‐lived. On global scales the mean residency time (the time between evaporation and precipitation) of water vapour is roughly 10 days. Under climate change, water vapour is expected to increase at a rate of 6%/K/decade (under constant relative humidity) in line with the Clausius-Clapeyron relationship. However, when it comes to precipitation, there is no simple global correlation with changes in temperature. Therefore, understanding the links between the residence time of water vapour in relationship to trends in global precipitation has great importance for climate studies.

The work proposed in this fellowship looks to address this gap by bringing together satellite and reanalysis datasets that represent water in different phases or stages within the hydrological cycle. Through the combination of multiple datasets, I will investigate how well satellite datasets capture the moisture recycling process and the surface-atmosphere interactions relative to modern reanalysis. From a climate perspective, these data can also then be used to asses/Test model data from the recent Coupled Model Intercomparison Project Phase 6 (CMIP6).