River Discharge across Africa under Present-day and Mid-Holocene Conditions
Abstract
It is thought that the regional water budget over parts of Africa is linked to variability in inundated wetlands, the expansion and contraction of which is likely to significantly control regional rainfall. However, the parameterization of lakes and wetlands in current Earth System Models (ESMs) is poorly understood, and therefore needs improvement. Before coupling the land-surface model JULES to the UK Earth System model (UKESM1), the first step was to run and validate a recent version of JULES off-line, with and without incorporating a river routing scheme and an inundation model. JULES (vn4.3) was firstly run several times over Africa, for 30 years each time (1983-2012), forced with different driving data but without river routing. Both of these simulations were compared to satellite-based rainfall and soil moisture estimates. The model was then re-run but with river routing turned on, and the resulting flux density through the grid box was compared to observational river discharge data. Finally, the driving data were modified to represent an idealised version of mid-Holocene conditions ( 6ka), and the simulated flux density through the grid box was compared to the present-day. Preliminary results, presented here, suggest that JULES does a reasonable job at reproducing present-day rainfall and soil moisture patterns. The results also suggest that, when river routing is turned on, simulated flux density for selected African rivers is similar to observed in terms of spatial and temporal patterns. When looking at mid-Holocene conditions, the seasonal cycle of river discharge remains similar to the present-day but the magnitudes differ.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGC44A..01W
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCESDE: 9305 Africa;
- GEOGRAPHIC LOCATIONDE: 1616 Climate variability;
- GLOBAL CHANGEDE: 1878 Water/energy interactions;
- HYDROLOGY