How well is water vapour turnover time (TUT) and vertical mixing represented by satellite records, reanalysis and climate models, how will this change under climate warming?

Tim is currently a research fellow working within the National Centre for Earth Observation (NCEO) based at the University of Leicester. In addition to his research role, he also co-chairs the international GEWEX Water Vapour Assessment (G-VAP) working group. Output from this group features in the Sixth Assessment Report (AR6) the Intergovernmental Panel on Climate Change (IPCC).

To date, most of his research focuses on the moisture in our atmosphere, but he also has experience working with surface temperatures, aerosol, trace gases and night-time light data. Before receiving his fellowship from the European Space Agency (ESA), he worked on many projects revolving around satellite remote sensing to the Earth’s surface and atmosphere over decadal time scales.

As part of his PhD, he also produced characterised ground-based reference datasets and applied them to validation activities. He also has experience developing algorithms used to retrieve water vapour from the shortwave and thermal infrared satellite instruments.

Research objectives

His project will initially use ensembles of long-term satellite observations, reanalysis, and climate model output from the recent Atmospheric Model Intercomparison Project (AMIP) to investigate our current understanding and provide a comprehensive overview of water vapour residence time. This objective is supported by a secondary task that reviews the datasets’ performance using the framework developed within the GEWEX Water Vapour Assessment (G-VAP). This approach examines trends, stability and percentiles to provide insight into consistency and differences within each ensemble. Finally, climate projections from the Scenario Model Intercomparison Project (ScenarioMIP) are used by this study to infer how future warming will impact residency times.

The second key objective of the fellowship focuses on investigating water vapour in the planetary boundary layer (PBL) as a source term in atmospheric moisture pathways. Water vapour residency times in the tropics dominate the global total. However, there are still biases related to known issues for climate models, such as convective mixing and precipitation. This work takes developments from the ESA S5p-I stable water vapour isotopologue project and applies them to the GOSAT PBL product developed at the University of Leicester. By combining PBL water vapour and isotopologue pairs, free tropospheric (FT) water vapour, surface temperature, precipitation and soil moisture datasets, this fellowship will develop a new framework to characterise changes in vertical mixing between the PBL and the FT. This approach aims to establish emergent constraints on the vertical transport of moisture, which will help reduce uncertainties in atmospheric moisture pathways.

Read more on the research project sheet.