Influence Of Tropical Oceans On Middle And High Latitudes Of Atmospheric Circulation Anomalies

In this paper, using outgoing Long-wave radiation data during 1974～2006 (Hereinafter referred to OLR) from NOAA and monthly mean reanalysis wind data of NCEP from 1948～2006, composite character of anomalous atmospheric circulation during El Ni?o years, La Ni?a years, normal years(neither El Ni?o and La Ni?a) and El Ni?o and Indian Ocean dipole jointly years are investigated. Abnormal OLR over the tropical western Pacific Ocean(20°S-20°N) is also analyzed corresponding with the wind fields.It is found that, the difference between distribution of abnormal OLR in tropical western Pacific region and corresponding distribution of abnormal wind is obvious under different circumstances. Whether El Ni?o or La Ni?a years, the excitation of PJ (or WP) teleconnection pattern wave train is depended on seasons. In August of El Ni?o year, in July and October of La Ni?a, especially in July and September of El Ni?o and Indian Ocean dipole jointly year, PJ (or WP) teleconnection pattern wave train are always obvious. The profound convection beyond the area of Philippine and South Sea is most effective to the excitation of PJ teleconnection pattern wave train. The abnormal convection of the Bay of Bengal appears little relation with teleconnection pattern wave train on the coastal region of eastern Pacific.In the La Ni?a year, from spring to autumn, an obviously abnormal cyclone circulation can be observed over the coastal region of eastern Asia. By numerical model experiment, the happening of abnormal circulation pattern is found closely related with abnormal convection heating over the tropical northwestern Pacific east of Philippine.SVD method was used to analyze the possible relation between the abnormal OLR field over the tropical western Pacific and abnormal wind field over coastal region of eastern Asia. It is found that the contribution of quadratic sum of total covariance of the first three modals had reached 95% and basically reflected the covariation between sea and atmosphere, and the influence of the atmosphere to the sea reflected in the first and the second modal, but the influence of the sea to the atmosphere was in the first mode; in the first three modes, the correlation of OLR was high in area of 0o～14oN,110o～130oE . We found that, in the two areas, there was intimate relation between abnormal heating field and abnormal wind field. When the SST of the tropical western Pacific was high, then the valuation of OLR was low and the cloud cover was more, and when the convection was intense, then exciting the teleconnection wave train to influence the circulation over the eastern Asia marginal seas. Also, the variety of the circulation on the offshore of east China and north-east Asia influenced the sea of tropical west Pacific by monsoon wind circulation to do changes of SST and convection, hence formed a potentially positive feedback.The paper also proceeded SVD analysis between interannual time scale, decadal time scale of OLR field over the tropical region with the synoptic time scale, intraseasonal time scale perturbation wind field, as well as geopotential height field. It is found that interannual time scale, decadal time scale of anomalous OLR over the tropical region had intimate relation with synoptic time scale, intraseasonal time scale perturbation wind field over coastal eastern Asia; The interannual scale abnormal convection had intimate relation with weather scale perturbation geopotential height field of eastern Asia seashore. The reason may probably be that interannual scale abnormal convection was propitious to the development of weather scale system, and weather scale system on middle latitude was related with Rossby waves in the westerly. The energy of Rossby wave could transmit southeastwardly, then favoring the convection over the tropical western Pacific.