Removing Bad Traces in Shallow Seismic Exploration

The Asian summer monsoon accompanies two systems,the Indianmonsoon and the East Asian monsoon.A major difference between the Asianand the Indian monsoon is that beginning in early May,the Asian monsoontakes about two months,to migrate over an extensive area from southernto northern China.At the same time,the associated heavy rainfall also movesfrom south to north.The monsoon rain-band associated with the Indianmonsoon takes only one to two weeks to migrate from Southern to NorthernIndia.The onset of the Southeast Asian southwest monsoon initiatesthe East Asian monsoon(EASM).Based on the NMC global spectral model,with significant modificationsto virtually all of the physical parameters,we have developed a generalcirculation atmospheric model i.e.NTUGCM.The NTUGCM was usedto perform an AMIP integration from 1 January 1979 to 31 December 1988.For the JJA(June,July,August)climatology,the simulated stream functionat 850 hPa captures most of the major features in the observed climatological-mean fields,e.g.,the subtropical high over the ocean,the cyclonic circulationover South Asia and the eddy straddling the equator in the IndianOcean,as well as the Tibetan high,simulated in the 200 hPa stream function.In general,the NTUGCM gives a better simulation at 850 hPa than at200 hPa and a better simulation around a large forcing region,e.g.SouthAsia,than around a weak forcing region,e.g.the Eastern Pacific and SouthAmerican coast.The best simulation for precipitation is found in the Asianmonsoon region where maximum precipitation occurs.The EASM rainfall distribution is the result of complex interactionsbetween the atmosphere,the earth's surface and the tropical and extra tropicalsystems.The EASM rainfall distribution involves a wide range of spatialand temporal scales from the mesoscale to the planetary scale.TheNTUGCM is able to simulate the large scale features of the EASM and thesudden change of the monsoon rainfall which is associated with abruptchanges in large scale atmospheric circulation.This study also analyzes theonset characteristics of the EASM simulated by the model.The AMIP simulationof the NTUGCM gives the onset date of the EASM as 13 May.The present results are encouraging,however,there are still many obviousissues that remain to be studied,such as the linkage between themonsoon's variation and surface boundaries forcing,the cause of the seasonalnorthward jump of the subtropical high,the dynamic and thermodynamiceffects of the Tibetan Plateau and an improved model representingthe physical parameters.

並列關鍵字

Shallow Seismic ； Noise Reduction ； Least Squares ； Bad Traces

國際替代計量

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