Projected changes in the western North Pacific subtropical high under six global warming targets

Abstract

The summer western North Pacific subtropical high (WNPSH) has large influences on the East Asian summer climate. Many studies have focused on the projected changes in the WNPSH, but little is known about the changes under different global warming targets, such as 1.5°C and 2.0°C. This study investigates the changes in the WNPSH under six global warming targets (1.5°C, 2.0°C, 2.5°C, 3.0°C, 3.5°C, and 4.0°C) in both the mid- and lower troposphere, using the outputs of CMIP5 model in historical simulations and under Representative Concentration Pathway 8.5. The projected changes in the WNPSH, which is measured by multiple variables, show that it changes little under the 1.5°C target in the mid-troposphere, but weakens and retreats approximately 2.5° in longitude under the 2.0°C target. It tends to linearly weaken with warming greater than 2.5°C and shifts eastward by approximately 6.0° in longitude by the 4.0°C target. Meanwhile, the WNPSH intensifies and extends westward under the 1.5°C target in the lower troposphere, but changes little with warming rising from 1.5°C to 2.0°C. It is projected to extend westward by approximately 2.0° in longitude by the 4.0°C target.