Sort Options:

• Sort By Last Name
• Sort By Title

Other:

• Print All

Sort by time-scale:

• Short
• Intermediate
• Long
• SHOW ALL

The Effects of Solar Radiation on the Daily Mean Heat Flux in Canopy Model

Diurnal Variation of Rain and Cloudiness

Junko NKATA
Climate Physics Lab., Div. Earth and Planetary Sci.
Graduate School of Science, Kyoto University
Sakyo, Kyoto 606-8502, JAPAN
Tel & FAX: +81-75-753-4272
e-mail: nakataj@kugi.kyoto-u.ac.jp

Prediction of diurnal variation of rain and cloudiness by GCMs is not well correspond to that of observation. These errors may produce the errors of solar radiation budget, which potentially influence long time energy budget. In this study, we did numerical experiment in order to examine the influence of diurnal variation of shortwave radiation on the energy flux from land and vegetation. We use the multilayer canopy model !HMINCER!I (Watanabe et. al., 2006). The model is driven with two atmospheric data set: one is the averaged three typical sunny days in August 1987 at the middle of Japan (case 1), and the other is the average of the data in case 1 (case 2). In the case 1, the variables in the data set have a diurnal variation, whereas they are constant in time in case 2. The integrated shortwave radiation in two cases is the same. The integration time in both cases is 7 days.

In case 1, the 7-days averaged sensible heat flux is larger than that in case 2. The increase of turbulent viscosity in case 1 owing to the imbalance in daytime causes large sensible heat flux. As a result, the total energy flux from the canopy top in case 1 is 5 to 6 W m-2 larger than that in case 2. Considering that the radiation forcing by CO2 is estimated as only 1 to 2 W m-2, our result suggests that the diurnal variation of solar radiation may produce the remarkable error of energy flux from canopy model.