PNNL

The Science

At low latitudes near North America, summer rainfall is strongly influenced by the position of the North Atlantic subtropical high (NASH) pressure system, whose winds dictate moisture pathways. Earth system models project a westward displacement of the NASH and drying near North America in response to increased atmospheric carbon dioxide. Similar effects have been documented in response to increased sunlight during the mid-Holocene period 6,000 years ago.

Through novel modeling experiments, researchers at the U.S. Department of Energy's Pacific Northwest National Laboratory built a unified understanding of these rainfall changes near North America in a warmer world.

The Impact

Distilling the effects of global change scenarios down to regional scales is a significant yet high-priority challenge within the atmospheric science community. At these scales, the direct socioeconomic effects of Earth system changes occur, and rainfall is a key variable when interpreting such scenarios.

By highlighting common physical linkages of the Earth system, this study helps to unify interpretations of regional rainfall changes across a variety of constraints.

User Facility: This research used computational resources from the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science user facility.

Reference: P. Kelly, B. Kravitz, J. Lu, L.R. Leung, "Remote Drying in the North Atlantic as a Common Response to Precessional Changes and CO₂ Increase Over Land." Geophysical Research Letters 45 (2018). [DOI: 10.1002/2017GL076669]