Unveiling the Indian Ocean forcing on winter eastern warming - western cooling pattern over North America

Area of Science:

• Atmospheric Science
• Climate Dynamics
• Ocean-Atmosphere Interactions

Background:

• The tropical Pacific's influence on North American climate is well-established.
• The Indian Ocean's teleconnections to North America remain less understood.

Purpose of the Study:

• To investigate the Indian Ocean's role in North American winter climate.
• To identify and characterize the Indian Ocean - North America (IONA) teleconnection pattern.

Main Methods:

• Utilized observational data analysis.
• Employed hierarchy atmospheric model simulations of varying complexity.

Main Results:

• Identified the Indian Ocean - North America pattern, a significant teleconnection.
• Warm Indian Ocean phases correlate with colder U.S. West Coast winters (increased snowfall) and warmer Great Lakes regions.
• Snow-albedo feedback amplifies Rossby wave-induced surface temperature anomalies.
• This teleconnection operates on both interannual and multi-decadal timescales.

Conclusions:

• The Indian Ocean is a critical driver of North American winter climate.
• The IONA teleconnection's impact is comparable to, though slightly less pronounced than, tropical Pacific influences.
• Understanding the Indian Ocean's role is vital for improving North American climate prediction and future projections.