Seasonality of water and heat fluxes over a tropical forest in eastern Amazonia.

Humberto R. da Rocha*, Leandro D.V.O. Pinto, Helber C. Freitas, Adelaine M.S.FigueiraDepartment of Atmospheric Sciences, IAG/University of Sao Paulo

Michael L. Goulden, Scott D. Miller, Mary C. MentonDepartment of Earth System Science, University of California Irvine

The experimental site - Floresta Nacional do Tapajos, km 83 of the Santarem-Cuiba highway (BR-163)

Energy balance

energy stored in the canopy 0.0 to 0.15 MJm-2day-1

biomass storage, 0.1 MJm-2day-1 larger in absolute values

The seasonality of storage terms appear similar to the variation of air temperature daily amplitude, that is, decreasing in wet season and increasing towards the dry season.

fluxes underestimate the available energy by 22% (Y=0.78x+4.29, R20.86,N=7943

the closure’s deviation was 22%, and when including those therms, it decreased to 21%.

Conductances of water vapour

Significant differences Dry season Wet season All year

E (mm day-1) 3.7 0.6 2.8 0.9 3.2 0.8Rn (MJm-2day-1) 12.8 1.9 10.1 2.6 11.4 2.5

H (MJm-2day-1) 2.3 0.8 2.1 0.9 2.2 0.9Bowen ratio 0.33 0.09 0.41 0.10 0.37 0.11

Dry to wetseason Wet to dry season

Bowen ratio 0.28 0.10 0.40 0.10H (MJm-2day-1) 1,8 0.7 2.4 0.9

Table 1. Average daily rates and standard deviation of evaporation (E), net radiation (Rn), sensible heat flux (H) and Bowen ratio, in the dry and wet season, in the entire period and in transition periods (see text for periods specification).