EFFECT OF GREEN STRATEGY PROPOSED IN THE HANOI MASTER PLAN ON ITS URBAN CLIMATE Andhang Rakhmat Trihamdani 1 , Han Soo Lee 2 , Tran Thi Thu Phuong 4 , Tetsu Kubota 1 , Takahiro Tanaka 3 , Kaoru Matsuo 3 1 Graduate School for International Development and Cooperation, Hiroshima University, 739-8529 Japan 2 Graduate School of Science and Engineering, Saitama University, 338-8570 Japan 3 Graduate School of Engineering, Hiroshima University, 739-8527 Japan 4 Vietnam Institute of Architecture Urban and Rural Planning, Vietnam This study aims to assess the impact of land use changes brought by the Hanoi Master Plan on its urban climate, using the Weather Research and Forecasting (WRF), focusing on the effect of the green strategies proposed in the master plan. The results showed that even after implementing the master plan, the peak air temperature remained at the same level. However, the expansion of urban area largely increased the UHI intensity, especially in the nighttime by up to 3-4°C over the expanded built-up areas. The proposed green strategies are seen to be ineffective to mitigate UHIs in the existing urban areas. Keywords: urban heat island, Hanoi, tropics, sustainable development, WRF INTRODUCTION Emerging economies in Southeast Asia are likely to see serious energy shortages, especially in terms of electricity, due to the recent rapid economic growth. Most of the cities in this region have a hot and humid climate during the summer months, and the growing energy consumption caused by air-conditioning in buildings is, therefore, a major concern. Meanwhile, these cities are suspected of already experiencing urban heat islands (UHIs) as a result of the rapid urbanization. The further rise of urban temperature would lead to a significant increase in energy demand for cooling. Currently, these Southeast Asian cities tend to propose large-scale master plans and increase their urban population. This would result in a dramatic change in land use and therefore the urban climate. In Hanoi, a long-term urban development plan, namely the Hanoi Master Plan 2030, was implemented in 2011 with the aim of developing the city into a more sustainable capital [1]. One of the key concepts of the master plan is to maintain abundant green coverage in the city by developing a systematic green network, including green buffers and green belts, for example. Although the master plan had considered various environmental issues such as soil pollution, air pollution, water quality and eco- system, this assessment did not take into account the impact of this development on the urban climate and UHIs in the city. Therefore, the objective of this study is to investigate the UHI effects in Hanoi under the present land use conditions as well as under those conditions proposed by the master plan, focusing especially on the cooling effects of the green strategies. Numerical simulations, specifically meso-scale urban climate modelling using Weather Research and Forecasting (WRF) are performed for this purpose. HANOI MASTER PLAN 2030 The Vietnam government officially implemented the Hanoi Master Plan 2030 in 2011. The main target of the master plan is to develop Hanoi as a green-cultured and civilized-modern city. In order to achieve that target, the master plan proposes a series of spatial development strategies for the capital city. One of them is, as described before, the green network consisting of two major green strategies which are the green belts and the green buffers. As shown in Fig. 1b, the green belts are the large green spaces located inside the urban development area with the aim of improving the microclimate conditions, while the green buffers are the boundary space between the existing urban areas and expanded urban clusters. As a result, the green coverage in the master plan would account for about 52% of the total land of the city. Fig. 1 shows the land use changes before and after the implementation of the master plan. To meet the demand of expanding urban development, 28% of the city’s natural land will be allocated for urban construction land. In total, the built-up land will rise sharply by almost three times, from 46,340 ha (14%) to more than 129,500 ha (39%). METHODOLOGY Meteorological modelling is performed to obtain basic weather elements such as air temperature, humidity, and surface wind, using the Advanced Research Weather Research and Forecasting (WRF-ARW) model (version 3.5) [2]. WRF is a three dimensional non-hydrostatic meso- scale meteorological model developed at the National Center for Atmospheric Research (NCAR) based on the non-hydrostatic compressible form of the governing equations in spherical and sigma coordinates with physical processes, such as cumulus clouds, microphysics, planetary boundary layer (PBL) processes and atmospheric radiation processes, incorporated into a number of physics parameterizations. This model has