ICON-NWP simulations of the mid-Holocene West African Monsoon using parameterized and explicit convection and mid-Holocene land surface

Link:
Autor/in:
Beteiligte Person:
  • Jungandreas, Leonore
Verlag/Körperschaft:
World Data Center for Climate (WDCC) at DKRZ
Erscheinungsjahr:
2023
Medientyp:
Datensatz
Schlagworte:
  • Climate
  • Conv_mH_WAM
  • ICON
  • Precipitation
  • West Africa
  • convection-permitting
  • explicitly resolved convection
  • midHolocene
  • resolved deep convection
Beschreibung:
  • Project: Simulations of land-atmosphere feedback during the mid-Holocene West African Monsoon with resolved deep convection - Global climate models have difficulties to simulate the northward extension of the monsoonal precipitation over north Africa during the mid-Holocene as revealed by proxy data. A common feature of these models is that they usually operate on too coarse grids to explicitly resolve convection, but convection is the most essential mechanism leading to precipitation in the West African monsoon region. Here, we investigate how the representation of tropical deep convection in the ICON climate model affects the meridional distribution of monsoonal precipitation during the mid-Holocene, by comparing regional simulations of the summer monsoon season (July to September, JAS) with parameterized (40km-P) and resolved deep convection (5km-E). Simulations with parameterized convection produce generally more rain and extend precipitation further north than simulations with resolved deep convection. The most striking difference between these simulations is the difference in the probability distribution function of precipitation and its resulting interactions with the land surface. The convective parametrization produces light and large-scale precipitation, keeping the soils moist and supporting the development of convection. In contrast, less frequent but locally intense precipitation events lead to high amounts of runoff in simulations with resolved deep convection. Hence, the stronger runoff inhibits the moistening of the soil during the monsoon season and limits the amount of water available to evaporation. This is true for simulations with present-day land surface cover and for simulations where we prescribe a higher mid-Holocene-like vegetation cover. However, in experiments with the same constant soil moisture field, precipitation expands equally far north in resolved deep convection and parameterized convection simulations. This highlights the importance of the type of rainfall in modulating land-atmosphere feedbacks, instead of only considering the amount of rainfall. Summary: The experiment aims to investigate how the representation of convection influences the West African Monsoon during the mid-Holocene. Atmospheric and SST input data originate from the MPI-ESM Holocene simulations reflecting Holocene condition. External Parameters (surface condition) were adjusted to reflect mid-Holocene vegetation conditions. We prescribe an idealized, denser vegetation cover based on the simulated desert fraction (1-vegetation fraction) of the transient mid-Holocene MPI-ESM simulations (Dallmeyer et al., 2020). We use the ICON (ICOsahedral Nonhydrostatic) model framework version 2.5.0 (see Zängl et al. (2014) for more details). The provided data covers one simulation from June to October (JJASO) for the year 7024 before present (BP) with the year 2000 as the reference year.
relatedIdentifier:
DOI 10.1002/qj.2378 DOI 10.5194/cp-16-117-2020
Lizenz:
  • CC BY 4.0
Quellsystem:
Forschungsdaten DKRZ

Interne Metadaten
Quelldatensatz
oai:wdcc.dkrz.de:Datacite4_3965486_20230302