TAILIEUCHUNG - Definition of new summer monsoon index for Vietnam region

In this study, we define a new summer monsoon index for Vietnam region (VSMI) by averaging 850hPa zonal wind (U850hPa) over the area of 5-15o N and 100-110o E using the 1981-2010 CFSR reanalysis data. The evaluation results show that VSMI index can reflect well the interannual variability of both low and high broad-scale circulation of the summer monsoon. On the intraseasonal timescale, the pentad-to-pentad VSMI index has a close relationship to the local summer monsoon rainfall observed. The correlation coefficients between VSMI index and rainfall are at 95% confidence level and show clearly effects of summer monsoon on the local rainfall due to terrain. The comparison results among three indices show that the VSMI index is the most suitable index in the term of describing summer monsoon for Vietnam region. In addition, features of summer monsoon as intensity, onset and withdrawal date as well as break event can be defined by the VSMI index. | ENVIRONMENTAL SCIENCES CLIMATOLOGY Definition of new summer monsoon index for Vietnam region Dang Mau Nguyen Van Thang Nguyen Vietnam Institute of Meteorology Hydrology and Climate change Received 20 September 2017 accepted 12 February 2018 Abstract In this study we define a new summer monsoon index for Vietnam region VSMI by averaging 850hPa zonal wind U850hPa over the area of 5-15oN and 100-110oE using the 1981-2010 CFSR reanalysis data. The evaluation results show that VSMI index can reflect well the interannual variability of both low and high broad-scale circulation of the summer monsoon. On the intraseasonal timescale the pentad-to-pentad VSMI index has a close relationship to the local summer monsoon rainfall observed. The correlation coefficients between VSMI index and rainfall are at 95 confidence level and show clearly effects of summer monsoon on the local rainfall due to terrain. The comparison results among three indices show that the VSMI index is the most suitable index in the term of describing summer monsoon for Vietnam region. In addition features of summer monsoon as intensity onset and withdrawal date as well as break event can be defined by the VSMI index. Keywords OLR U850hPa rainfall summer monsoon VSMI Classification number Introduction Vietnam is located in the affected area of the Asian monsoon system collided by a lot of monsoon systems like Southern Asia Eastern Asia as well as North-Western Pacific monsoons. Besides monsoon circulations are also significantly influenced by topography specifically Truong Son Mountains lying along Vietnam and Laos boundary 1 . Therefore it is hard to predict the seasonal monsoons over Vietnam due to typical and immensely complex. On the other hand Vietnam has high mountains in the Northeastern zone and high-narrow Truong Son Mountains along the border of Vietnam-Laos. On the side adjacent to the sea a fertile and narrow coastal lowland extends south from the Red River Delta to the Mekong Delta Fig. 1

• Năng lượng
• Summer monsoon
• New summer monsoon index
• CFSR reanalysis data
• VSMI index
• Local summer monsoon rainfall
• Rainfall indices
• Drastic changes
• Extreme rainfall phenomena
• Rainfall index
• Climate Change Realities
• Its Evidences
• Climate Change
• Water Resources
• Queretaro River
• Its Hydrological Effects