Long-term evolution of nighttime turbulent carbon flux at the LBA pasture/agricultural site
Acevedo, UFSM, email@example.com
Moraes, UFSM, firstname.lastname@example.org
Fitzjarrald, SUNY, email@example.com
Sakai, SUNY, firstname.lastname@example.org
Czicowski, SUNY, email@example.com
Campos, UFSM, firstname.lastname@example.org
The LBA deforested site at km 77 is characterized by strong stable stratification at night. It determines a large reduction of the nocturnal turbulent mixing, making it difficult to apply filtering techniques, such as the u* correction to the analysis of the nocturnal data. A number of recent studies have shown that the temporal scales of the turbulent exchange under very stable conditions can be properly identified by the multiresolution decomposition. In a previous work, we showed that this process can be applied to the very stable conditions of km 77, leading to the determination of the amount of carbon dioxide transferred by turbulent exchange from the surface to the atmosphere. Consequences of this result are that a larger portion of the eddy correlation data can be used for the determination of the nocturnal respiration rates, and that the amount transferred by other processes, such as drainage flows can be quantified.
Now, we apply this technique to the long-term observations conducted at the site. The main purpose is to determine the seasonal and year-to-year evolution of the turbulent carbon exchange under very stable conditions. The physical processes responsible for the nocturnal transfer of carbon at the site and their temporal evolution along the 7 years of observations will be discussed.