Lifetime of soil moisture perturbations in a coupled land–atmosphere simulation
<p class="p">In order to evaluate whether the initialization of soil moisture has the potential to improve the prediction skill of earth system models (ESMs) on seasonal to decadal timescales, an elaborate experiment was conducted. For this task a coupled land–atmosphere model with p...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-01-01
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| Series: | Earth System Dynamics |
| Online Access: | http://www.earth-syst-dynam.net/7/1/2016/esd-7-1-2016.pdf |
| Summary: | <p class="p">In order to evaluate whether the initialization of soil moisture has the potential to improve the prediction
skill of earth system models (ESMs) on seasonal to decadal timescales,
an elaborate experiment was conducted. For this task a coupled
land–atmosphere model with prescribed ocean was utilized. The experiment
design considered soil moisture initialization in different seasons and years
and yielded information about the lifetime (memory) of extreme yet realistic
soil moisture perturbations. Our analyses were focused on root zone soil moisture (RootSM) as it
comprises the part of the soil that directly interacts with the atmosphere
via bare-soil evaporation and transpiration. We found that RootSM memory
differs not only spatially but also depends on the time of initialization. A
long memory of up to 1 year is evident mostly for dry soil moisture regimes
after heavy precipitation periods or prior to snow covered conditions. Short
memory below 2 weeks prevails in wet soil moisture regimes and prior to
distinct precipitation periods or snowmelt. Furthermore, RootSM perturbations
affect other land surface states, e.g. soil temperature and leaf carbon
content, and even induce anomalies with specific memory in these variables.
Especially for deep-layer soil temperature, these anomalies can last for up
to several years. As long as RootSM memory is evident, we found that
anomalies occur periodically in other land surface states whenever climate
conditions allow for interactions between that state and RootSM.
Additionally, anomaly recurrence is visible for RootSM itself. This
recurrence is related to the thickness of the soil layer below the root zone
and can affect RootSM for several years. From our findings we conclude that
soil moisture initialization has the potential to improve the predictive
skill of climate models on seasonal scales and beyond. However, a
sophisticated, multilayered soil hydrology scheme is necessary to allow for
the interactions between RootSM and the deep-soil layer reservoir.</p> |
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| ISSN: | 2190-4979 2190-4987 |