Impacts of the MJO on Winter Rainfall and Circulation in China |
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Authors: | JIA Xiaolong CHEN Lijuan REN Fumin and LI Chongyin |
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Institution: | National Climate Center, China Meteorological Administration, Beijing 100081,National Climate Center, China Meteorological Administration, Beijing 100081,National Climate Center, China Meteorological Administration, Beijing 100081,State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101 |
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Abstract: | Impacts of the MJO on winter rainfall and circulation in China are
investigated using a real-time multivariate MJO index. Composite results
using the daily rainfall anomalies and ``rainy day' anomalies according to
eight different MJO phases show that the MJO has considerable influence on
winter rainfall in China. Rainfall anomalies show systematic and substantial
changes (enhanced/suppressed) in the Yangtze River Basin and South China
with the eastward propagation of the MJO convective center from the Indian
Ocean to the western Pacific. When the MJO is in phase 2 and 3 (MJO
convective center is located over the Indian Ocean), rainfall probability is
significantly enhanced. While in phase 6 and 7 (MJO convective center is
over the western Pacific), rainfall probability is significantly reduced.
MJO in winter influences the rainfall in China mainly through modulating the
circulation in the subtropics and mid-high latitudes. For the subtropics,
MJO influences the northward moisture transport coming from the Bay of
Bengal and the South China Sea by modulating the southern trough of the Bay
of Bengal and the western Pacific subtropical high. For the mid-high
latitudes, the propagation of the low frequency perturbations associated
with the eastward-propagating MJO convection modulate the circulation in the
mid-high latitudes, e.g. the East Asian winter monsoon and the low trough
over central Asia. |
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Keywords: | MJO rainfall anomaly subtropics mid-high latitudes vertical motion |
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