A regional coupled approach to water cycle prediction during winter 2013/14 in the United Kingdom

Abstract

A regional coupled approach to water cycle prediction is demonstrated for the 4-month period from November 2013 to February 2014. This provides the first multicomponent analysis of precipitation, soil moisture, river flow and coastal ocean simulations produced by an atmosphere-land-ocean coupled system focussed on the United Kingdom (UK), running with horizontal grid spacing of around 1.5 km across all components. The Unified Model atmosphere component, in which convection is explicitly simulated, reproduces the observed UK rainfall accumulation (r 2 of 0.95 for water day accumulation), but there is a notable bias in its spatial distribution-too dry over western upland areas and too wet further east. The JULES land surface model soil moisture state is shown to be in broad agreement with a limited number of cosmic-ray neutron probe observations. A comparison of observed and simulated river flow shows

A comprehensive intercomparison study between a lumped and a fully distributed hydrological model across a set of 50 catchments in the United Kingdom

“…Given the flashy nature of these catchments it might be appropriate to model these catchments at sub-daily timesteps with slightly advanced two-dimensional hydraulic routing techniques, for example, two-dimensional diffusive or dynamic overland flow modelling. The loss in model performance for these northern catchments is in line with findings of other researchers(Coxon et al, 2019;Lewis & Dadson 2021). Furthermore, it must be noted that the density of rain gauges that was used to derive the inputs (CEH-GEAR) is comparatively low in this part of the UK leading to greater uncertainty in the rainfall inputs and consequently somewhat diminished model performance.…”

The Regional Coupled Suite (RCS-IND1): application of a flexible regional coupled modelling framework to the Indian region at km-scale

“…In future, it is envisaged that river flows simulated from the land component will feed into the ocean (e.g. Lewis and Dadson, 2021).…”

“…For example, development of a new bimodal diagnostic cloud fraction (Weverberg et al, 2021) and cloud microphysics (e.g., Hill et al, 2015) parameterizations in RAL offer pathways towards improving the frequency distribution of simulated precipitation. Improving the representation of precipitation in RCS-IND1 is a key priority in the context of coupled prediction given the opportunity to further assess and develop the land surface model component to enable a more integrated approach to simulating the terrestrial water cycle (e.g., Lewis and Dadson, 2021). This is of particular importance in the Bay of Bengal given potential feedbacks through the ocean state (e.g., Krishnamohan et al, 2019).…”

Preface – special issue on “coupled atmosphere‐hydrological processes: Novel system developments and cross‐compartment evaluations”

“…Indirectly, indications of possible hydrological impact produced by larger-scale (continental) application of a fully coupled approach were provided by Arnault et al (2021), who, however, detected a slight precipitation increase. The atmosphere-land-ocean coupled system applied by Lewis and Dadson (2021) over the whole United Kingdom showed its ability to predict broad-scale features of river streamflow even without using proper calibration procedures.…”