The impact of the 20-50-day atmospheric intraseasonal oscillation on the gross primary productivity between the Yangtze and Yellow rivers

Abstract

Given their high carbon uptake, the terrestrial ecosystems in the East Asia summer monsoon (EASM) region play an irreplaceable role in the global carbon cycle. Because the rich vegetation growth over East Asia benefits mainly from the sufficient water supply brought by the EASM, which is characterized by a strong intraseasonal oscillation (ISO), the intraseasonal spatiotemporal variations and underlying drivers of photosynthesis activity over East Asia have been comprehensively investigated using the daily gross primary productivity (GPP) and meteorological data. Strong intraseasonal fluctuations of GPP have been identified over the area between the Yangtze and Yellow Rivers (YYR) with a magnitude of 0.4 gC m22 day21. The mean power spectrum suggests that 20-50-day variation is the major component of the intraseasonal GPP anomalies over the YYR during the summers of 1980-2013. The 20-50-day ISO of YYR GPP anomalies is modulated by the local 20-50-day precipitation variation via soil moisture, with precipitation (soil moisture) leading GPP by 10 (7) days. The 20-50-day YYR precipitation anomalies are in turn controlled by tropical ISO signals, particularly the convective activity over the western North Pacific. This leading relationship between the 20-50-day atmospheric ISO and GPP suggests a potential for extended-range predictability of vegetation growth.