Understanding elevated CO concentrations in East Asia relative to the global mean during boreal spring on the slow and interannual timescales.

It is important to examine the physical processes that regulate current CO concentrations in East Asia to understand the global carbon cycle. To do this, we begin by defining the difference between East Asian and global CO concentrations (East Asian CO concentration minus global CO concentration), which is referred to as East Asian local CO concentration (i.e.

Low frequency changes in CO concentration in East Asia related to Pacific decadal oscillation and Atlantic multi-decadal oscillation for mid-summer and early fall.

The climatological seasonal maximum and minimum CO concentrations in East Asia for 1987-2020 have been recorded at April and August, respectively. We found that the CO concentration in East Asia during July, August, and September (JAS) is lower than normal before the late 1990s and after the early 2010s (Low_CO period), and higher than normal from the late 1990s to the early 2010s (High_CO period). The low-frequency variability of CO concentration in East Asia during JAS correlates with both Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO)-related sea surface temperatures (SSTs).