Urban green spaces play an important role for mitigating urban heat island and greenhouse gas emissions. For understanding the role of urban green space, we have conducted the eddy covariance measurements of energy, water vapor, and CO2 fluxes at an urban greenspace. The urban green space is located in a weed field on the site just after a clear cut citrus orchard at Osaka Metropolitan University. The weed field is intensively managed, where period mowing was conducted.