The spatio-temporal influence of atmospheric circulations on hydroclimate in Great Britain

West, Harry

Abstract

Atmospheric circulations have an important influence on regional climate. Understanding the relationships between circulations, rainfall and streamflow at a regional and catchment scale is therefore of interest to water and environmental managers. However previous work exploring circulation-climate relationships across Great Britain have been limited spatially and temporally or have been restricted by data availability and in the number of circulations assessed.

This PhD research aims to address these limitations and contribute to our understanding of the relationship between atmospheric circulations and British hydroclimate at a high spatio-temporal resolution over long (50-100 years) historic time periods. This research finds that strong rainfall and flow relationships are present with the North Atlantic Oscillation (NAO), in particular in the north-west where strong positive correlations (r=0.6-0.9) and spatially significant precipitation hotspots persist during winter (e.g. there is a >70% likelihood of significant wet/dry conditions in some NW areas related to the phase of the NAO). However, the strength and consistency of the NAO-rainfall-flow relationship varies spatially and temporally, and in some regions the occurrence of significant wet/dry conditions is almost equally likely under both NAO+ and NAO- phases. In response, this research explores the combined influence of various other atmospheric circulations, revealing the role of circulations such as the East Atlantic Pattern (EA) in influencing hydroclimate in particular across the southern, central and eastern regions (R2=0.6-0.8). This research presents a new high spatio-temporal resolution understanding of the effect of atmospheric circulations and how they influence rainfall and streamflow both individually and in combination (e.g. in some catchments concurrent NAO+/EA- conditions are associated with >50% of severe meteorological drought events).

This research has implications for the inclusion of circulation indices in water and environmental management practice. NAO forecasting work has developed in recent years, and the findings of this research suggest there is potential to factor these forecasts into water management planning in the north-western region which has strong NAO-rainfall-flow relationships. However even accurate NAO forecasts may have a limited role in management in the southern and central regions, where this research shows the EA and other circulations may be more influential. If (improved) monthly forecasts of these circulations were possible, then these indices would potentially have value for water/environmental managers across Great Britain.

Citation

West, H. The spatio-temporal influence of atmospheric circulations on hydroclimate in Great Britain. (Thesis). University of the West of England. Retrieved from https://uwe-repository.worktribe.com/output/9700950

• Thesis Type: Thesis
• Deposit Date: Jul 15, 2022
• Publicly Available Date: May 5, 2023
• Public URL: https://uwe-repository.worktribe.com/output/9700950
• Award Date: May 5, 2023