Abstracts for the 5th International GAME Conf.
3-5 October 2001
Aichi Trade Center
Nagoya Japan
Surface energy/water balance in the tundra region estimated by a one-dimensional land surface model ---An examination of transpiration by CO2 flux
Kumiko TAKATA (1), Hironori YABUKI (2), Toshiyuki SATO (3), Manfred BOELTER (4), Seita EMORI (5), Yuji KODAMA (6), Tetsuo OHATA (7)
(1) Frontier Research System for Global Change, Japan
(2) Frontier Observational Research System for Global Change, Japan
(3) Shinshu Univ., Japan
(4) Kiel Univ., Germany
(5) National Institute for Environmental Studies, Japan
(6) Hokkaido Univ., Japan
(7) Hokkaido Univ./Frontier Observational Research System for Global Change, Japan
The surface energy/water balance at Tiksi in the tundra region is
calculated for 1998-2000 using a one-dimensional land surface model,
MATSIRO, and compared with the observed seasonal cycle. The calculated
snow-covered duration agrees well with the observation, and the observed
variation in radiation components are reproduced including the
day-to-day variations.
The calculated latent heat flux is lower than those estimated by
Bowen ratio method, while the calculated sensible heat flux is higher
than that. 78 % of the total evapotranspiration averaged for two years
is ground evaporation, 2 % is interception evaporation, 1 % is
transpiration, and 19 % is sublimation from snow surface.
Transpiration is calculated from the stomatal resistance estimated
by photosynthetic processes in MATSIRO. The CO2 assimilation rate of
photosynthesis is 112 gCO2/m^2/year in this experiment. On the other
hand, CO2 flux by soil respiration estimated from soil temperature data
at Tiksi is 273 gCO2/m^2/summer (Boelter et al., 2000). Assuming that
CO2 assimilation rate by vegetation equilibrates with CO2 release due to
soil respiration, the CO2 assimilation rate calculated by MATSIRO is
low. It is also lower than the net primary production (NPP) estimated
from the satellite observation in Tundra regions, 350 gCO2/m^2/year.
We are going to estimate the CO2 assimilation rate from measured dry
weight of vegetation, and examine the calculated and observed latent and
sensible heat fluxes.
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Frontier Research System for Global Change | |
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