TITLE:
Calculation of Forest Potential Evapotranspiration of Okinawa in Japan Using the Penman Equation
AUTHORS:
Takuya Arakaki, Akira Shimizu, Naoki Kabeya, Hitoshi Ikuzawa, Takanori Shimizu, Shin’ichi Iida, Hiroshi Furugen
KEYWORDS:
Potential Evapotranspiration, Penman Equation, Weather Station, Subtropical Region, Evergreen Forest
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.9,
June
26,
2014
ABSTRACT:
The northern area of Okinawa Island is a unique forest area in Japan,
with a distinctive ecosystem and subtropical climate. The area is a central
region of forestry in Okinawa Prefecture. However, quantitative evaluation of
the effects of the forest environment is inadequate. The authors began
meteorological observation of this forested area to address this situation by
setting up a weather station in 2009. In this study, we performed research on
one of the major factors of the water cycle in forest ecosystems,
evapotranspiration. We calculate seasonal changes in potential
evapotranspiration through analysis of data from our weather station in 2013,
because all measurement elements were assembled. To calculate potential
evapotranspiration, we used the Penman equation. We found that the potential
evapotranspiration in this forest area was 1170.5 mm in 2013. The mean
temperature in 2013 was 20.7°C, yearly average relative humidity was 84.7%, and
average wind speed was 1.40 m/s. Regarding the amount of evapotranspiration in
the forests of northern Okinawa Island, which has not been previously obtained,
it has become possible to calculate the amount of potential evapotranspiration
using the Penman equation.