PI. Masahito UEYAMA

Research background
To accurately estimate global energy, water and carbon exchange, long-term monitoring of those fluxes has been conducted at many terrestrial ecosystems. However, it is still uncertain in the exchange processes in urban landscape due to lack of continuous measurement. In this study, we have conducted the long-term observations of those fluxes in an urban center, to evaluate 1) diurnal, seasonal, and interannual variation of the fluxes, and 2) important processes related to the fluxes.

Field observations
The measurements were conducted at a city center of Sakai (34^o34’25’’N, 135^o28’80’’E), where the area is densely built-up; an industrial and commercial center with heavy traffic since winter in 2008. The measurement height is above the blending height, 112 m above ground. Sakai is a second biggest city in Osaka, and a city designated by ordinance. The population exceeds 800,000.

Environmental Variables	Method	Site
Momentum, sensible heat, and latent heat fluxes	Eddy covariance	SAC, OPU, IZM
CO2 flux	Eddy covariance	SAC, OPU, IZM
air temperature and humidity	Ventilated sensors	SAC, OPU, IZM
solar radiation	Pyrheliometer	SAC, OPU, IZM
Four components of net radiation	Component Net Radiometer	OPU
surface temperature	radiation thermometer	SAC, OPU, IZM
rainfall	rain gauge	OPU
ground heat flux	heat plate	OPU
evaporation	method of weighing	OPU
vertical CO2 profile	4 heights	SAC

* SAC : Sakai City Office

* OPU : root top of Osaka Prefecture University

* IZM : Oizumi Urban park

 

 

 

 

 

 

 

 

Fig. Eddy covariance system over the urban canopy

 

Observation at the roof top of Osaka Prefecture University
To compare the fluxes between the urban center and a surrounding location, we set up another observation system, including closed path eddy covariance system.

 

 

 

 

 

 

 

Fig. observations at the roof top of OPU

 

 

 

 

 

 

 

Fig. observations at Oizumi Urban park.

 

 

 

 

 

 

 

 

 

Fig. An aerial photograph showing our observation point at Sakai Center

Data availability
Observed data can be downloaded from following link.

References

Ueyama, M., Mitake, Y., Yamaguchi, K. and Hamotani, K., 2011: Micrometeorological measurements of heat, water, and CO₂exchanges at an urban landscape in Sakai, Japan. AsiaFlux Newsletter, 32, 9-12.

Ueyama, M., and Ando T. 2016.Diurnal, weekly, seasonal and spatial variabilities in carbon dioxide flux in different urban landscapes in Sakai, Atmos. Chem. Phys., 16, 14727-14740.

Ando T. and Ueyama, M. 2017. Surface energy exchange in a dense urban built-up area based on two-year eddy covariance measurements in Sakai, Japan, Urban Climate, 19, 155-169.