The previous sections described the methodology to calculate hourly NEE data
for both the 82 m (large scale) system and the 3 m (local scale) system. The
profile ``tweaking'' methodology together with the empirical NEE-PPFD and
NEE-
functions are powerful tools to estimate NEE when a direct measurement
of NEE is not available. The final step towards the calculation of annual carbon
dioxide exchange is the integration of the hourly data.