Abstract ID: 645

Observation of small scale non-classical thermotopographic flows in Central Amazon Forest

The eddy flux tower measurements over complex topography and dense vegetation have been focus of intense debate due systematic underestimates to nighttime Net ecosystem exchange measurements of CO2. A sub-canopy flow system observation of wind and CO2 was implemented to monitoring and examine a small gully in the vicinity of the eddy flux tower. The flow in slope lee side of the hill was frequently uncoupled with the mean wind aloft, indicating a dynamic thermotopographic upslope flow during nighttime (including geometry, temperature gradient, and net radiation). The nocturnal horizontal gradient of CO2 shows a high correlation and was driven by this small scale subcanopy flow during day and night. The sub-canopy flow was downslope during daytime and upslope during nighttime, indicating a non-classical thermotopographic flow. These results indicate that drainage flow or horizontal advection to correct eddy flux tower measurements above-canopy conditions may be carefully considerer.

Session:  Carbon - What has been learned and what further can be learned from a network of eddy covariance towers in Amazonia?.

Presentation Type:  Oral