Stochastic simulations of the Madden-Julian oscillation activity
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
19/10/2012
19/10/2012
2011
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Resumo |
The Madden-Julian oscillation (MJO) is the most prominent form of tropical intraseasonal variability. This study investigated the following questions. Do inter-annual-to-decadal variations in tropical sea surface temperature (SST) lead to substantial changes in MJO activity? Was there a change in the MJO in the 1970s? Can this change be associated to SST anomalies? What was the level of MJO activity in the pre-reanalysis era? These questions were investigated with a stochastic model of the MJO. Reanalysis data (1948-2008) were used to develop a nine-state first order Markov model capable to simulate the non-stationarity of the MJO. The model is driven by observed SST anomalies and a large ensemble of simulations was performed to infer the activity of the MJO in the instrumental period (1880-2008). The model is capable to reproduce the activity of the MJO during the reanalysis period. The simulations indicate that the MJO exhibited a regime of near normal activity in 1948-1972 (3.4 events year(-1)) and two regimes of high activity in 1973-1989 (3.9 events) and 1990-2008 (4.6 events). Stochastic simulations indicate decadal shifts with near normal levels in 1880-1895 (3.4 events), low activity in 1896 1917 (2.6 events) and a return to near normal levels during 1918-1947 (3.3 events). The results also point out to significant decadal changes in probabilities of very active years (5 or more MJO events): 0.214 (1880-1895), 0.076 (1896-1917), 0.197 (1918-1947) and 0.193 (1948-1972). After a change in behavior in the 1970s, this probability has increased to 0.329 (1973-1989) and 0.510 (1990-2008). The observational and stochastic simulations presented here call attention to the need to further understand the variability of the MJO on a wide range of time scales. NOAA Office of Global Programs[NOAA/NA05OAR4311129] NOAA Office of Global Programs[NA07OAR4310211] NOAA Office of Global Programs[NA08OAR4310698] |
Identificador |
CLIMATE DYNAMICS, v.36, n.1/Fev, p.229-246, 2011 0930-7575 http://producao.usp.br/handle/BDPI/26948 10.1007/s00382-009-0660-2 |
Idioma(s) |
eng |
Publicador |
SPRINGER |
Relação |
Climate Dynamics |
Direitos |
closedAccess Copyright SPRINGER |
Palavras-Chave | #Madden-Julian oscillation #Tropical intraseasonal variations #Stochastic simulation #Climate change #Global warming #SEA-SURFACE TEMPERATURE #EXTREME PRECIPITATION EVENTS #AMERICAN-MONSOON-SYSTEM #INTRASEASONAL VARIABILITY #NORTH PACIFIC #REGIME SHIFTS #EL-NINO #ENSO #PREDICTABILITY #PERSISTENCE #Meteorology & Atmospheric Sciences |
Tipo |
article original article publishedVersion |