27 March 2019

Circumglobal Response to Prescribed Soil Moisture over North America

Science

  

Impact

  

Summary

A series of idealized prescribed soil moisture experiments are performed with the atmosphere/land stand-alone configuration of the Community Earth System Model, version1, in an effort to find sources of predictability for high-impact stationary wave anomalies observed in recent boreal summers. We arbitrarily prescribe soil water to have a zero value at selected domains in the continental U.S. and run 100-member ensembles to examine the monthly and seasonal mean response. Contrary to the lack of a substantial response in the boreal winter, the summertime circulation response is robust, consistent and circumglobal.  While the stationary wave response over the North America and North Atlantic sectors can be well explained by the reaction of a linear dynamical system to heating anomalies caused by the imposed dry land surface, nonlinear processes involving synoptic eddies play a crucial role in forming the remote response in Eurasia and the North Pacific Ocean.   A number of other possible factors contributing to the circulation responses are also discussed.  Overall, the experiments suggest that, in the boreal summer, soil moisture may contribute to the predictability of high-impact stationary wave events, which can impact regions that are great distances from these sources regions.

Contact
Haiyan Teng
National Center for Atmospheric Research (NCAR)
Publications
Teng, H, G Branstator, A Tawfik, and P Callaghan.  2019.  "Circumglobal Response to Prescribed Soil Moisture over North America."  Journal of Climate.  https://doi.org/10.1175/jcli-d-18-0823.1.