Search

The terrestrial ecosystem in East Asia mainly consists of semi-arid regions that are sensitive to climate change. Therefore, gross primary productivity (GPP) in East Asia could be highly variable and vulnerable to climate change, which can significantly affect the local carbon budget. Here, we examine the spatial and temporal characteristics of GPP variability in East Asia and its relationship with climate factors over the last three decades. We detect an abrupt decrease in GPP over Eastern China-Mongolia region around the year 2000. This is attributed to an abrupt decrease in precipitation associated with the phase shift of the Pacific decadal oscillation (PDO). We also evaluate the reproducibility of offline land surface models to simulate these abrupt changes. Of the twelve models, eight were able to simulate this abrupt response, while the others failed due to the combination of an exaggerated CO2 fertilization effect and an underrated climate impact. For accurate prediction, it is necessary to improve the sensitivity of the GPP to changes in CO2 concentrations and the climate system. [ABSTRACT FROM AUTHOR]

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 m−2 day−1. 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. [ABSTRACT FROM AUTHOR]

Observational evidences are presented to show significant differences in Pacific–East Asian (PEA) teleconnections during the El Niño decaying period depending on the northern off-equatorial sea surface temperature (SST) conditions. On the basis of the northern off-equatorial central Pacific SST (NOCP) index, we separate El Niño events into two groups. Distinctive differences are observed between the two groups not only in tropical features but also in mid-latitude teleconnections. In particular, the NOCP index is closely related to the strength of the local feedback between the SST anomalies and the anticyclonic flow over the western North Pacific (WNP) during the ensuing spring of the El Niño events. Because the WNP anticyclone tends to persist until boreal spring in the case of negative NOCP, diabatic cooling due to the reduced precipitation over the WNP induces anticyclonic flow over the Kuroshio extension region via a Rossby wave response, which leads to warm and wet conditions over East Asia. However, because the WNP anticyclone decays early in the case of positive NOCP, cyclonic circulation exists over the North Pacific, which leads to cold and dry conditions over East Asia. Consequently, the maintenance of the WNP anticyclone during the El Niño decaying period may explain the discrepancy in the PEA teleconnections in various types of El Niño. Accordingly, the NOCP index could be a possible predictor for boreal spring climate conditions over East Asia. [ABSTRACT FROM AUTHOR]