Subseasonal prediction with and without a well-represented stratosphere in CESM1

There is a growing demand for understanding sources of predictability on subseasonal to seasonal (S2S) time scales. Predictability at subseasonal time scales is believed to come from processes varying slower than the atmosphere such as soil moisture, snowpack, sea ice, and ocean heat content. The st...

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Bibliographic Details
Published in:Weather and Forecasting
Other Authors: Richter, Jadwiga H. (author), Pegion, Kathy (author), Sun, Lantao (author), Kim, Hyemi (author), Caron, Julie M. (author), Glanville, Anne (author), LaJoie, Emerson (author), Yeager, Stephen (author), Kim, Who M. (author), Tawfik, Ahmed (author), Collins, Dan (author)
Format: Article in Journal/Newspaper
Language:English
Published: 2020
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Online Access:https://doi.org/10.1175/WAF-D-20-0029.1
Description
Summary:There is a growing demand for understanding sources of predictability on subseasonal to seasonal (S2S) time scales. Predictability at subseasonal time scales is believed to come from processes varying slower than the atmosphere such as soil moisture, snowpack, sea ice, and ocean heat content. The stratosphere as well as tropospheric modes of variability can also provide predictability at subseasonal time scales. However, the contributions of the above sources to S2S predictability are not well quantified. Here we evaluate the subseasonal prediction skill of the Community Earth System Model, version 1 (CESM1), in the default version of the model as well as a version with the improved representation of stratospheric variability to assess the role of an improved stratosphere on prediction skill. We demonstrate that the subseasonal skill of CESM1 for surface temperature and precipitation is comparable to that of operational models. We find that a better-resolved stratosphere improves stratospheric but not surface prediction skill for weeks 3-4. 1844590 1852977