HR: 0800h
AN: H41A-0395    [Abstracts]
TI: Measurement and Simulation of the Dew Profile in the Plant Canopy
AU: * Maruyama, A
EM: maruyama@affrc.go.jp
AF: National Agricultural Research Center for Kyushu Okinawa Region, 2421, Suya, Nishigoshi, Kumamoto, 8611192 Japan
AU: Kuwagata, T
EM: kuwa@affrc.go.jp
AF: National Institute for Agro-Environmental Sciences, 3-1-3, Kannondai, Tsukuba, 3058604 Japan
AU: Watanabe, T
EM: twata@ffpri.affrc.go.jp
AF: Forestry and Forest Products Research Institute, 1, Matsunosato, Tsukuba, 3058687 Japan
AU: Ohba, K
EM: kohba@affrc.go.jp
AF: National Agricultural Research Center for Kyushu Okinawa Region, 2421, Suya, Nishigoshi, Kumamoto, 8611192 Japan
AB: Dew on the leaves of the plant plays an important role not only on nocturnal local climate but also on the evapotranspiration on next daytime and the outbreaks of plant diseases. Most of disease germs colonize at particular sites of the plant, so that the dew distribution in the plant canopy is important factor that affect the germ development. We measured vertical variation of the dew in the rice plant canopy on summer season under warm temperate climate, and simulate it by using mechanistic micrometeorological model to study the relationship between dew formation and canopy structure. Dew on the leaves and panicles were measured with two hours intervals during the nighttime at clear sky days on mid-stage (August 19, 21 and 24) and late-stage (October 1) of 2005 rice growing season in Kumamoto plain, Japan. Vertical one-dimensional Double Source Model (DSM) and Multi Layer Model (MLM) were used as the simulation model, which based on the radiation transfer, heat budget and mass diffusion theories on soil-plant-atmosphere. DSM separates the land surface for soil layer and plant layer, and solves the heat budget equations of both layers to calculate the dew formation flux. MLM additionally separates the plant layer for vertical multi layer, and solves the heat budget equations to calculate the dew formation flux on each layer. Maximum values of measured total weight of the dew in the plant on unit ground area were 0.14 kg m^-2 on August 19, 0.09 kg m^-2 on August 21, 0.18 kg m^-2 on August 24 and 0.38 kg m^-2 on October 1. These maximum values were observed at 6:00 am on every case. Simulated values of total dew weight using DSM were smaller than measured values, whereas that using MLM showed good agreement with measured values. The reason could be comes from the difference between two models that MLM calculate the temperature and humidity profile of the atmosphere in the canopy that was not calculated in DSM. Since the atmospheric humidity in the canopy was higher than above the canopy, MLM could accurately simulate the actual process of dew formation. Dew profile on every case showed common trend that the dew weight on unit leaf area was larger in upper plant layer and smaller in lower layer. This trend could be explained by the differences of long-wave radiation and leaf temperature between upper and lower layers that simulated using MLM. It is expected to understand the dew distribution in the various plant canopies using MLM.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0402 Agricultural systems
DE: 0466 Modeling
DE: 1818 Evapotranspiration
DE: 1876 Water budgets
SC: Hydrology [H]
MN: Fall Meeting 2005