On the connection between AMOC and observed land precipitation in Northern Hemisphere: a comparison of the AMOC indicators

摘要

Decadal climate prediction has been one of the most popular topics in recent climate change studies. It is closely linked to our daily life, deeply affecting the wellbeing of people and global economic growth. Among those climate variables, precipitation is essential for industrial and agricultural productions but it's also hard to precisely predict. In this study, we provide observational evidence for the relationship of mean precipitation in the Northern Hemisphere (NH), NH tropics and Sahel with the five Atlantic Meridional Overturning Circulation (AMOC) indicators on the multidecadal time scale. We conclude that precipitation in those three regions exhibits a consistent multidecadal variability from 1901 to 2015. The correlations between NH precipitation and AMOC indicators are strong and significant. The NAO-based AMOC indicator leads the precipitation by 8 years and the correlation coefficient reaches 0.9 higher than other oceanic indicators. It is the NAO that forces the AMOC transporting heat to the North Atlantic and induces sea surface temperature (SST) dipole which eventually affects the multidecadal precipitation change in NH. As the AMOC_NAO indicator leads the precipitation, we employ it as a predictor and construct a linear model to make a future prediction based on historical data. It indicates that the precipitation will decrease in the following few years, and then will rise again.