Abstract:

The Atmosphere Vegetation Interaction Model version 2 (AVIM2) is used to make an offline simulation of terrestrial carbon cycle and its response to climatic variation under the forcing of the meteorological reanalysis data from the National Center for Environmental Prediction. The spatial distribution and its temporal characteristics of global net primary production (NPP) and net ecosystem production (NEP) in the terrestrial ecosystem are simulated from 1953 to 2004. Results show that 52year averaged global NPP and NEP from 1953 to 2004 are 65 Pg/a and 1.2 Pg/a respectively, and reveal that NPP obviously increases with time, while the trend of increase in NEP is not statistically significant. Although the trends of decadal increases in NPP and NEP are different, in the middle of the 1970s their decadal changes all revealed an abrupt change. Their growing trends were all decreased after the abrupt point. This is because the Pacific decadal oscillation (PDO) affected the decadal change of El Nin~oSouthern Oscillation (ENSO), which also affected the decadal variation of NPP and NEP. Before 1976, when PDO was in the cool phase, the strength and frequency of the cool phase of ENSO was increased, which led to the cooler and humid climate in the tropical region so that it was beneficial to the increase in NPP and NEP. On the contrary, while the PDO was in a warm phase after 1976, El Nin~o took place frequently, so that in the equatorial region the drier and warmer climate reduced the increasing trends of NPP and NEP.

Key words: terrestrial ecosystem, AVIM2, NPP, NEP, land carbon flux