Analysis of carbon and water fluxes from the NOPEX boreal forest: comment

In a recently published paper on simulation and analyses of water and carbo n fluxes at the NOPEX central site, a modeling exercise indicated a rather strong sink of carbon for the studied forest stand and year (1994). At the 100-m high tower, the eddy-flux measurements stretch out to the present day . They show that the surrounding forest area is a rather weak source of car bon. This note clarifies the previously published numbers in view of severa l new findings at the site since the paper preparation (1995) up to the pub lishing/present date (1998/1999). The key issues that could not be adopted three years ago, were (i) footprint analyses of the eddy-covariance measure ments, (ii) correction of eddy-flux data for night-time, and (iii) informat ion on carbon flux from soil. These complementary findings address the prev ious uncertainties in carbon budget assessment and model parameterization a nd suggest improvements to model application and better match the measured data. (C) 1999 Elsevier Science B.V. All rights reserved.