19 May 2015

The North American Winter ‘Dipole’ and Extremes Activity: A CMIP5 Assessment

Science

The winter season of 2013–2014 in North America was one of the most extreme, with an intense drought in the western United States, California declaring 100% drought, and extremely low temperatures across the central and eastern United States. This climate anomaly started in the early winter of 2013–2014 when the upper-level circulation created a blocking ridge over the Gulf of Alaska accompanied by a deepened trough downwind forming a dipole. A dipole is an amplified upper-level ridge over the West Coast and a deepened trough over the central-eastern United States. A previous study using a single model linked the dipole to the El Niño precursor and found that this link has strengthened in recent years.

Approach

A team of scientists, including a U.S. Department of Energy researcher at Pacific Northwest National Laboratory, used 17 model simulations from the Coupled Model Intercomparison Project Phase 5 to examine dipole activity in the future.

Impact

The research found that most models capture the dipole and its association with the El Niño precursor and project that this association will strengthen as the planet warms.

Summary

The winter season of 2013–2014 in North America was one of the most extreme, with an intense drought in the western United States, California declaring 100% drought, and extremely low temperatures across the central and eastern United States. This climate anomaly started in the early winter of 2013–2014 when the upper-level circulation created a blocking ridge over the Gulf of Alaska accompanied by a deepened trough downwind forming a dipole. A dipole is an amplified upper-level ridge over the West Coast and a deepened trough over the central-eastern United States. A previous study using a single model linked the dipole to the El Niño precursor and found that this link has strengthened in recent years. A team of scientists, including a U.S. Department of Energy researcher at Pacific Northwest National Laboratory, used 17 model simulations from the Coupled Model Intercomparison Project Phase 5 to examine dipole activity in the future. The research found that most models capture the dipole and its association with the El Niño precursor and project that this association will strengthen as the planet warms.

Contact
Jin-Ho Yoon
Pacific Northwest National Laboratory
Publications
, . "The North American Winter ‘Dipole’ and Extremes Activity: A CMIP5 Assessment." Atmospheric Science Letters (2015). [10.1002/asl2.565].
Acknowledgments

This research was supported by grants NNX13AC37G and WaterSMART R13AC80039, and the Utah Agricultural Experiment Station. Jin-Ho Yoon was supported by the Office of Science of the US Department of Energy (DOE) as part of the Earth System Modeling program. Wan-Ru Huang was supported by the Ministry of Science and Technology of Taiwan under MOST 103-2111-M-003-001 and MOST 103-2621-M-492-001.