HR: 08:30h
AN: B31C-03    [Abstracts]
TI: Carbon Budget in High-Arctic Greenland Analyzed by a Cascade System Approach
AU: * Soegaard, H
EM: hs@Geogr.ku.dk
AF: Institute of Geogrpahy, Oster Voldgace 10, Copenhagen, DK1350 Denmark
AU: Friborg, T
EM: tfj@geogr.ku.dk
AF: Institute of Geogrpahy, Oster Voldgace 10, Copenhagen, DK1350 Denmark
AU: Rysgaard, S
EM: sr@dmu.dk
AF: NERI, Frederiksborgvej, Roskilde, DK4000 Denmark
AU: Geern, L
EM: Lotte.Geern@risoe.dk
AF: Risoe National Laboratory, Frederiksborgvej, Roskilde, DK4000 Denmark
AU: Elberling, B
EM: Be@geogr.ku.dk
AF: Institute of Geogrpahy, Oster Voldgace 10, Copenhagen, DK1350 Denmark
AU: Groendahl, L
EM: lg@dmu.dk
AF: NERI, Frederiksborgvej, Roskilde, DK4000 Denmark
AU: Pedersen, L T
EM: ltp@oersted.dtu.dk
AF: DTU, Anker Engelundsvej 1, Kgs Lynby, DK2800 Denmark
AB: The High Arctic is considered one of the most vulnerable climatic zones with respect to the potential effect of a global warming. To be able to monitor this development, the carbon budget has for the last decade been observed at Zackenberg research station of NE Greenland (74.5 oN, 20.5 oW). The CO2 flux measurements has comprised terrestrial (wetlands and dwarf shrub heaths), fluvial and coastal ecosystems and this is supplemented by CO2 exchange measurements over the Greenlandic sea. Rather than a detailed study of the individual components a cascade system approach is used starting with the fixation of CO2 by the vegetation and the sea, followed by carbon release through dissolution and erosion, and lateral transport by rivers and currents until a final sedimentation takes place in the fjord system. The results show that the High Arctic is an important carbon sink also when the methane emission is taken into account. It is found that there is large diversity in the CO2 exchange rates among the terrestrial ecosystem which may be scaled by use of the leaf area index and the snow cover. This is verified by comparison with fluxes derived by planetarian boundary layer budgets. The largest CO2 uptake rates are measured in the wetlands during July and August (2 g C m-2 d-1) but due to the net CO2 emission simulated for the rest of the year the annual NEE is only around 18 g C m-2 yr-1 This is only one third of the annual carbon uptake in the open Greenlandic Sea because the carbon uptake is nearly constant throughout the year, only in case of sea ice the CO2 uptake is reduced to near zero. Finally, climatic feedback couplings are discussed. For the land surface increasing summertime temperatures leads to an increase in carbon uptake which more than compensates for an increased CO2 emission during wintertime. A negative feedback coupling with temperature is also found for the sea, because the observed decrease in sea ice will also imply an increase in the CO2 uptake rate.
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting