The Relationship Between The Interannual Variability Of The MJO And The Climatology In China During The Winter And Its Influences Under The Global Warming

Based on daily temperature,precipitation observations at 756 Chinese stations archived by the China Meteorological Administration during the period 1951-2011,atmospheric reanalysis datasets from NCEP/NCAR,TRMM satellite precipitation data from 1998 to 2012 and CMIP5 multi-mode output results,main characteristics of MJO and the inter-annual variation of its frequency and intensity are investigated.The relationship between MJO and precipitation as well as temperature during the boreal winter in China has been detected.Furthermore,the possible changes of the MJO under the global warming and the influences on precipitation and temperature during the boreal winter in China are revealed accordingly.The main conclusions are as follows:(1)Influence of Frequency and Intensity of MJO on Temperature and Precipitation in China.Using the RMM index defined by Wheeler and Hendon(2004),the propagation of MJO in winter and the frequency and intensity of each phase were analyzed during the period 1979/1980-2012/2013.It is found that the phase propagation has obvious effect on the precipitation in southern China.When the MJO propagates eastward along the equator,the Yangtze River and South China have experienced a transition from positive to negative anomaly in precipitation.And the national temperature experiences a transition from decrease to increase as well.The interannual variability of MJO frequency is related to winter temperature and precipitation in China.It can be found that the high frequency of convective center in the Indian Ocean region will cause the increase of winter precipitation in South China and the significant decrease of winter temperature.Longer residence in the maritime continent and the equatorial western Pacific will cause decrease of precipitation over part of inland China and significant increase of winter mean temperature in the south.For intensity,the consistent change of each phase has relatively small effect on the winter precipitation and temperature in China.When the intensity of the MJO is enhanced in the western equatorial Pacific and the intensity of the MJO is weakened over the Indian Ocean,the winter precipitation in the Yangtze River basin in China will be significantly reduced,while the winter temperatures in the southwest will also be significantly reduced.(2)The Assessment of Models to Simulate MJO.In order to study the possible changes of MJO under the global warming,we evaluate the simulated capability of 14 models from CMIP5 concerning the period and propagation of MJO in each model.Majority of the 14 models have shown some shortcomings in simulating the characteristics of MJO.Although some models,such as MRI-CGCM3 and GFDL-CM,can reproduce the MJO eastward features in the maritime continent and equatorial western Pacific,the non-propagating features are presented in the Indian Ocean Region.This is probably because that,MJO's eastward propagation process is not related to the propagation of the MJO sourced from the Indian Ocean which is passing through the maritime continent to the West Pacific.The CNRM-CM5 model shows a better performance in simulating the eastward propagation in the Indian Ocean,maritime continent,and the western Pacific.In the analysis of the wavenumber frequency power spectrum,the period,energy and wavenumber are compared between the results of the models and observations.It is found that the energy of the MJO is very weak in the wavenumber spectrum in majority of the modes except CRNM-CM5.Most models can not reflect the high spectrum energy refer to 1-3 wave.(3)Possible Changes of MJO under the Global Warming and Its Impact on China's Winter Climate.By comparing the Pre-industrial experiment in the CMRM-CM5 model with the high-emission scenario RCP85 test,the intensity of the MJO will be significantly enhanced,and the period of propagation will be shortened and the zonal wavenumbers will be reduced under the global warming.By examing the difference in precipitation and temperature between the two experiments,we found that,in the warming climate,the higher frequency of phase 3 and stronger intensity in phase 7 and 8 are clearly investigated.Generally,the changes of the MJO contribute to the increased precipitation in the Yangtze River Basin and the dcreased precipitation in South China.In terms of temperature,the changes of the MJO under global warming may cause the cooling over the mainland China,especially the cooling in the Yangtze River Basin and part of northern China during the winter.