TY - JOUR
T1 - Intradiurnal and seasonal variability of soil temperature, heat flux, soil moisture content, and thermal properties under forest and pasture in Rondonia.
AU - Alvala, R.C.S.
AU - Gielow, R.
AU - Rocha, H.R.
AU - Freitas, H.C.
AU - Lopes, J.M.
AU - Manzi, A.O.
AU - von Rondow, C.
AU - Dias, M.A.F.S.
AU - Cabral, O.M.R.
AU - Waterloo, M.J.
PY - 2002
Y1 - 2002
N2 - Soil temperatures depend on the soil heat flux, an important parameter in meteorological and plant growth-energy balance models. Thus, they were measured, together with soil moisture contents, within the LBA program at forest (Reserva Jaru) and pasture (Fazenda Nossa Senhora) sites in Rondônia, Brazilian Amazonia during wet (February) and dry (August) periods of 1999. The wet period showed maxima of the heat flux into the soil around five to six times smaller at the forest than at the pasture, except for some spikes that are related to stronger solar forcing, such as those due to sunspecks in the forest. This pattern remained during the dry period, but with doubled maximum values. Also the soil heat flux and the soil temperatures responded very significantly to the passage of cold fronts in both periods at both sites. Temperature profiles measured in the 0.10-0.40 m soil layer showed daily averages and ranges smaller at the forest than at the pasture. The daily average of the soil moisture content in the same layer, during the wet season, increased with depth at both sites, with consistently lower values at the forest. However, their ranges were smaller at the pasture, except for the 0.40 m depth. During the dry period, these ranges were much higher at the pasture, but with nearer average values. Finally, the computed daily apparent soil thermal diffusivities, volumetric heat contents, and thermal conductivities are presented, with the first ones crossed with the measured soil moisture content. Copyright 2002 by the American Geophysical Union.
AB - Soil temperatures depend on the soil heat flux, an important parameter in meteorological and plant growth-energy balance models. Thus, they were measured, together with soil moisture contents, within the LBA program at forest (Reserva Jaru) and pasture (Fazenda Nossa Senhora) sites in Rondônia, Brazilian Amazonia during wet (February) and dry (August) periods of 1999. The wet period showed maxima of the heat flux into the soil around five to six times smaller at the forest than at the pasture, except for some spikes that are related to stronger solar forcing, such as those due to sunspecks in the forest. This pattern remained during the dry period, but with doubled maximum values. Also the soil heat flux and the soil temperatures responded very significantly to the passage of cold fronts in both periods at both sites. Temperature profiles measured in the 0.10-0.40 m soil layer showed daily averages and ranges smaller at the forest than at the pasture. The daily average of the soil moisture content in the same layer, during the wet season, increased with depth at both sites, with consistently lower values at the forest. However, their ranges were smaller at the pasture, except for the 0.40 m depth. During the dry period, these ranges were much higher at the pasture, but with nearer average values. Finally, the computed daily apparent soil thermal diffusivities, volumetric heat contents, and thermal conductivities are presented, with the first ones crossed with the measured soil moisture content. Copyright 2002 by the American Geophysical Union.
U2 - 10.1029/2001JD000599
DO - 10.1029/2001JD000599
M3 - Article
SN - 2169-897X
VL - 107
SP - 2001
JO - Journal of Geophysical Research. Atmospheres
JF - Journal of Geophysical Research. Atmospheres
IS - D20
ER -