Articles | Volume 10, issue 4
Geosci. Model Dev., 10, 1665–1677, 2017
Geosci. Model Dev., 10, 1665–1677, 2017

Model experiment description paper 20 Apr 2017

Model experiment description paper | 20 Apr 2017

Investigating soil moisture–climate interactions with prescribed soil moisture experiments: an assessment with the Community Earth System Model (version 1.2)

Mathias Hauser, René Orth, and Sonia I. Seneviratne Mathias Hauser et al.
  • Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland

Abstract. Land surface hydrology is an important control of surface weather and climate. A valuable technique to investigate this link is the prescription of soil moisture in land surface models, which leads to a decoupling of the atmosphere and land processes. Diverse approaches to prescribe soil moisture, as well as different prescribed soil moisture conditions have been used in previous studies. Here, we compare and assess four methodologies to prescribe soil moisture and investigate the impact of two different estimates of the climatological seasonal cycle used to prescribe soil moisture. Our analysis shows that, though in appearance similar, the different approaches require substantially different long-term moisture inputs and lead to different temperature signals. The smallest influence on temperature and the water balance is found when prescribing the median seasonal cycle of deep soil liquid water, whereas the strongest signal is found when prescribing soil liquid and soil ice using the mean seasonal cycle. These results indicate that induced net water-balance perturbations in experiments investigating soil moisture–climate coupling are important contributors to the climate response, in addition to the intended impact of the decoupling. These results help to guide the set-up of future experiments prescribing soil moisture, as for instance planned within the Land Surface, Snow and Soil Moisture Model Intercomparison Project (LS3MIP).

Short summary
Water in the soil can influence temperature and precipitation of the atmosphere. However, the atmosphere also alters the soil moisture content. Climate model simulations prescribing soil moisture are a means to decouple these relationships. We find that the atmospheric response depends strongly on the method used to fix the soil moisture, as well as on the employed soil moisture data set.