Deng, L., Li, T., Liu, J., & Peng, M. (2016). Factors controlling the interannual variations of MJO intensity. Journal of Meteorological Research, 30(3), 328-340.
Factors Controlling the Interannual Variations of MJO Intensity
DENG Li 1(邓莉), LI Tim1;2*(李天明), LIU Jia1(刘佳), and PENG Melinda3
1 Key Laboratory of Meteorological Disaster, Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China
2 International Pacific Research Center and Department of Atmospheric Sciences, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
3 Naval Research Laboratory, Monterey, California 93943, USA
(Received December 16, 2015; in final form March 11, 2016)
The interannual variations of intensity of the Madden-Julian Oscillation (MJO) during boreal winter are investigated by using the observed outgoing longwave radiation (OLR) and the reanalysis data of ECMWF and NCEP. The standard deviation of 20-80-day filtered OLR anomaly is used to measure the MJO intensity. The dominant spatial structure of the interannual variability is revealed by an EOF analysis of the MJO intensity field. It is found that the leading mode is associated with eastern Pacific type ENSO, whereas the second mode is related to central Pacific type ENSO. A simple atmospheric model is used to investigate the relative roles of background moisture and wind changes in affecting the overall strength of MJO. The numerical experiments indicate that the background moisture effect is dominant while the background wind change has a minor effect.
Key words: MJO, interannual variation, ENSO, background mean state