Abstracts for the 5th International GAME Conf.
3-5 October 2001
Aichi Trade Center
Nagoya Japan
FLUX DISTRIBUTIONS OF HEAT AND CARBON DIOXIDE IN THE ATMOSPHERIC BOUNDARY LAYER OVER NON-HOMOGENEOUS SURFACE IN EASTERN SIBERIA
T. Hiyama (1), M. A. Strunin (2), J. Asanuma (3), M. Y. Mezrin (2), R. Suzuki (5), T. Ohata (6)
(1) Hydrospheric Atmospheric Research Center, Nagoya University / Frontier Observational Research System for Global Change
(2) Central Aerological Observatory
(3) Terrestrial Environment Research Center, University of Tsukuba
(5) Frontier Research System for Global Change
(6) Institute of Low Temperature Science, Hokkaido University / Frontier Observational Research System for Global Change
Spatial and seasonal variations of sensible heat, latent heat, and carbon dioxide fluxes were determined using special equipped Russian aircraft over non-homogeneous forest - grass surface in eastern Siberia. The data set was obtained during GAME-Siberia project in April - June 2000.
From the two grid-paths covered 12 x 32 km area of left and right bank sides of the Lena River, clear spatial distributions of sensible heat, latent heat, and carbon dioxide fluxes were obtained. The spatial flux distributions had good consistency with the underlying vegetation cover. Especially in the snowmelt season, relatively larger uptake of carbon dioxide and flux of latent heat were observed over the pine (evergreen) forest area, while larger sensible heat flux was observed over the larch (leafless) forest area. These characteristics were also observed on the flux towers established in different forest ecosystems in the region. Clear spatial distributions of the fluxes were also obtained over forest - grass patch systems during summer flights. Sensible heat flux over the forest was relatively larger than that over the grass field in the season.
Thermally induced internal boundary layers (TIBL) were observed from the 100 km long flight (regional path) within the convective boundary layer (CBL) developed in different thermal and dynamic conditions over the vicinity of the Lena River. Clear horizontal and vertical distributions of sensible and latent heats in the TIBL were consistent with the generation of cumulus, which have appeared only over the forested area but not over the Lena River valley. Large horizontal fluxes of sensible and latent heats were observed in the daytime when the TIBL was appeared. This means that distinctive land cover distributions, e.g. forest - grass (or river) system, might generate TIBL within the CBL and induce the local circulation in strong unstable conditions.
Comparison of fluxes obtained from the aircraft measurements and those derived from the tower-based measurements showed that seasonal changes of the fluxes had good agreement with each other. However underestimation of the fluxes derived from the aircraft was shown in every flight. This underestimation was large in latent heat flux. Horizontal flux components of latent heat caused by the TIBL are considered as the main reason for the underestimation.
Submittal Information
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Hydrospheric Atmospheric Research Center, Nagoya University | |
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Chikusa-ku, Nagoya 464-8601 | |
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hiyama@ihas.nagoya-u.ac.jp | |