Teleconnection Pattern Between IOD And Northern Tropospheric Atmosphere With The Corresponding Dynamic View

Recently a coupled mode of air-sea variability was documented for the tropical IndianOcean. This mode, referred here as the Indian Ocean Dipole (IOD) events involves largevariations in zonal SST (Sea Surface Temperature) gradient and explains about 12％of the totalvariance of anomalous Indian Ocean SST. Ever since the discovery of IOD, extensive studies onimpact of IOD on the local and remote climate suggested that IOD plays an active role inaffecting the global climate system. In Northern Hemisphere,it is well known that significantlow-frequency fluctuations—NPO(North Pacific Oscillation), NAO(North AtlanticOscillation) and the AO (Arctic Oscillation) have been identified. Accordingly, local and remoteforcing factors of these climate anomalies attract a great lot of attentions. To our knowledge,studies to the impact of IOD on the climate anomalies in Northern Hemisphere has just beenstarted in the literature although enough has been said on their teleconnections withElNino-Southern Oscillation. All these illumite us to investigate if IOD is a probably signalinvolving in Northern Hemisphere climate anomalies.Using the NCEP/NCAR reanalysis atmosphere data along with SST data of GISST in thepresent thesis, the teleconnection pattern and the corresponding mechanism between IOD andnorthern tropospheric climate anomalies are investigated. Firstly, the spatial teleconnectionpattern between IOD index time series and SLP (Sea Level Pressure) anomaly, SAT (Surface AirTemperature) anomaly and geopotential height anomaly at upper, middle and lower tropospherein the Northern Hemisphere is studied. Secondly, the dynamic view is given from the point viewof the energy propagation of the stationary planetary wave associated with IOD. Finally, usingCAM/NCAR model,a series of experiments are designed to investigate the northern troposphericatmospheric response to the IOD.The results indicate: In boreal autumn, the SST Dipole Mode signal (IOD) in the tropicalIndian Ocean exists in the northern tropospheric atmosphere.The action centers are identified in the Arctic area, northern high latitudes, Egypt and India et al. The intensity of the teleconnectionis stronger in high latitudes than low latitudes. IOD has close correlation with northerntropospheric geopotential height ,and its variation can excitated a Rossby wave train which startsfrom north-east of India and finally reaches east of Canada in northern geopotential height field.The teleconnection pattern has equivalent barotropic structure in whole troposphere. Lead-lagcorrelation analysis shows that there are about 1-3 months of geopotential height anomalies inNorthern Hemisphere lagging IOD.The possible mechanism is proposed to explain to the teleconnection pattern. The energypropagation of the atmosphere stationary planetary wave which wavenumble is 1-3 could beresponsible for the teleconnection between IOD and northern climate anomalies.Using CAM/NCAR model, a series of experiments are designed to investigate the northerntropospheric atmospheric response to the IOD.The model results indicate that the SST DipoleMode signal in the tropical Indian Ocean exists in northern tropospheric atmosphere.