Preprints
https://doi.org/10.5194/egusphere-2022-890
https://doi.org/10.5194/egusphere-2022-890
19 Sep 2022
 | 19 Sep 2022

How does the explicit treatment of convection alter the precipitation-soil hydrology interaction in the Holocene African humid period?

Leonore Jungandreas, Cathy Hohenegger, and Martin Claussen

Abstract. Global climate models with coarse horizontal resolution are largely unable to reproduce the monsoonal precipitation pattern over North Africa during the mid-Holocene. Here we present the first regional, storm-resolving simulations with an idealized but reasonable mid-Holocene vegetation cover. In these simulations, the West African monsoon expand farther north by about 4–5° and the precipitation gradient between the Guinea coast and the Sahara decreases in comparison to simulations with a barren Sahara as it is today. The northward shift of monsoonal precipitation is caused by land surface – atmosphere interaction, i.e. the coupling of soil moisture and precipitation as well as interactions of the land surface with the large-scale monsoon circulation (e.g. the African easterly jet).

We find a similar response of the monsoon circulation to an increase in vegetation cover in simulations with parameterized convection. Moreover, changes are even larger than in simulations with explicitly resolved convection (i.e. the storm-resolving simulations). We attribute the differences in monsoonal precipitation to differences in soil moisture that are strongly controlled by runoff and the precipitation characteristics as previously shown in Jungandreas et al. (2021).

We confirm this by performing simulations with a constant soil moisture field in both explicitly resolved and parameterized convection simulations. In these simulations, explicitly resolved convection simulations expand precipitation as far north as parameterized convection simulations. This study thus highlights the importance of the type of rainfall in modulating land- atmosphere feedbacks, instead of only considering the amount of rainfall. Moreover, this study suggests that comprehensive land-surface schemes, which properly respond to varying precipitation characteristics, are needed for studying land-surface – atmosphere interaction

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

21 Mar 2023
How does the explicit treatment of convection alter the precipitation–soil hydrology interaction in the mid-Holocene African humid period?
Leonore Jungandreas, Cathy Hohenegger, and Martin Claussen
Clim. Past, 19, 637–664, https://doi.org/10.5194/cp-19-637-2023,https://doi.org/10.5194/cp-19-637-2023, 2023
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Increasing the vegetation cover over mid-Holcocene North Africa expands the West African Monsoon...
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