2017 ACTS Workshop on Extreme Weather Forecast and Water Resources Management SIMULATION AND PREDICTION OF SUMMER MONSOON CLIMATE OVER THE INDOCHINA PENINSULA BY RSM Presenter: Nguyen Ngoc Bich Phuong Hanoi, 26/9/2017
INTRODUCTION - The Asia summer monsoon is the most complex and characterized by various monsoon systems (Wang and Lin 2002). - Impact of ENSO on ASM - The Indo-china Peninsula The purpose of this study is to examine the performance of Regional Spectral Model (RSM) model in predicting summer monsoon over the Indochina Peninsula (ICP)
DATA AND METHODOLOGY RSM We use the Regional Spectral Model (RSM), which is a non-hydrostatic dynamics RCM, based on the structure of the NCEP Global Spectral Model. Physical parameterizations Long-wave radiation scheme Mlawer et.at.1997 Short-wave radiation scheme The parameterization for deep convection Chou and Suarez,1999. Hou et al, 2002 Pan và Wu 1994, Grell, 1993 Noah land surface model Pan and Mahrt, 1987 Planetary boundary layer processes Troen and Mahrt,1986
DATA AND METHODOLOGY RSM Model We use the Regional Spectral Model (RSM), which is a non-hydrostatic dynamics RCM, based on the structure of the NCEP Global Spectral Model. - A horizontal resolution of 26 km - Cover Indochina Peninsula (ICP) - The number of grid points in Cartesian coordinates is 144 (west east) and 144 (north south) - The domain size is 95E 120E and EQ 25N
DATA AND METHODOLOGY Data Climate Forecast System (CFS) Reforecast - Initial and boundary condition for RSM model - The data were acquired for 6-month re-forecast beginning at March, April, May, and June for three years 1983 (El-Nino), 1984 (non-enso) and 1985 (La Nina). Observation data - APHRODITE data (0.25 ) - Vietnam Gridded Precipitation (VnGP) Dataset data (481 rain gauges, 0.25 ) - CFS reanalysis (CFSR)
Methodology DATA AND METHODOLOGY In this study, we have re-forecasted the summers (JJA) in El Niño (1983), La Niña (1984) and non-enso (1985) condition with 01-month leading forecast. - Empirical orthogonal function EOF analysis (EOF1 and EOF2) detect factors that impact on rainfall regime over this area. x k M m=1 e km u m, k = 1,, K, x k = x k x m: principal component e m : eigenvector u m: linear combination of x - Latitude time outgoing long wave radiation (latitude time OLR) identify the onset of summer monsoon over ICP region. OLR xt = Y y=1 OLR xyt - Average U wind (110 115E, 5 15N) at 850 mb identify the onset of summer monsoon over ICP region. u t = X Y u xyt x=1 y=1
Geopotential height (m) and wind (m/s) 500mb RESULT AND DISCUSS RSM Summer El Niño Summer - ENSO-neutral Summer La Niña - El Nino condition leads to increase the GH increase T over the region - Wind speed seems not change in ENSO summer, but wind in non- ENSO seems weaker.
Geopotential height (m) and wind (m/s) 500mb Summer El Niño RESULT AND DISCUSS RSM 26 km CFS reforecast 100 km - Wind speed and direction of RSM are consist with the ones of CFS reforecast - However, RSM geopotential height values are greater of about 10 m
Geopotential height (m) and wind (m/s) 500mb Summer La Niña RESULT AND DISCUSS RSM 26km CFS reforecast 100 km - Wind speed and direction of RSM are consist with the ones of CFS reforecast - However, RSM geopotential height values are greater of about 10 m
Geopotential height (m) RESULT AND DISCUSS 850mb Summer El Niño Summer - ENSO-neutral Summer La Niña RSM CFS
Air temperature ( 0 C) RESULT AND DISCUSS 500mb Summer El Niño Summer - ENSO-neutral Summer La Niña RSM CFS
RESULT AND DISCUSS 850mb Air temperature ( 0 C) Summer El Niño Summer - ENSO-neutral Summer La Niña RSM CFS
RESULT AND DISCUSS Air temperature ( 0 C) Surface Summer El Niño Summer - ENSO-neutral Summer La Niña RSM APH
Total precipitation in summer (mm) RESULT AND DISCUSS Summer El Niño RSM APH VnGP - Rainfall amount in RSM is lesser than observation of about 200 mm, especially in coastal line and over Thailand, Myanmar
Precipitation (mm) Summer El Niño RESULT AND DISCUSS Summer - ENSO-neutral Summer La Niña RSM APH VnGP
RESULT AND DISCUSS Eigenvector patterns of two leading EOF modes of daily rainfall over ICP Summer El Niño Summer - ENSO-neutral Summer La Niña EOF1 EOF2
Jun. Nov. May Oct. Apr. Sep. Summer El Niño RESULT AND DISCUSS Outgoing Long-wave Radiation (OLR) (W/m 2 ) Summer -non ENSO Summer La Niña
RESULT AND DISCUSS RSM El Nino La Nina Non- ENSO
CONCLUSION Climate variables at 500, 850 mb and surface in summer of ENSO and non-enso condition derived from RSM model has been evaluated. RSM can capture the signals of the impact of ENSO on climate system over the ICP region. RSM does not simulate rainfall well; the rainfall of the model is lower than the observation about 50-100 mm in three summer months. However, the distribution of rainfall is consistent with the observation However, this study only uses the RSM simulations in three summers. Therefore the results are not comprehensive and highly reliable. More assessment for this model is necessary.