NUMERICAL EXPERIMENT ON THE SEASONAL VARIATION OF GLOBAL OCEAN AND THE EL NINO PROCESS——PART Ⅱ:NUMERICAL EXPERIMENT ON THE 1972-1973 EL NINO PROCESS*

In Part Ⅰ,the climatological state of the ocean has been simulated by integrating a 6-layer,4°×5°grid global ocean model up to 100 years.In this part,the forcing in 1971-1973 is calculated by COADS,and using the integrated result of the 100th year as the initial state,we simulated the El Nino process in 1972-1973.The results are as follows:(1)We have reproduced the 1972-1973 El Nino process and its cooling process in the equatorial eastern Pacific.The simulated distribution of SST and the intensity of El Nino are similar to the observations.(2)The results show that there are two kinds of processes in El Nino formation:(i)the warming occurs in the equatorial western Pacific,then propagates eastward to the central Pacific;(ii)the warm water forms near the coast of the South America and then,propagates westward along the equator.Observation indicates that the two processes were included in the El Nino in 1972.Our numerical experiment can simulate out both of them,although the first process is stronger than the second.In observation,the intensities of both processes are similar.(3)The El Nino process in 1972 can be simulated by running the model with the wind stress forcing,but its intensity is 1/2 the magnitude of observation.Only after adding the forcing of heat flux to run the model,its intensity can coincide with the observation.So the forcing effect of heat flux should not be ignored in the formation of El Nino,especially in the study of El Nino intensity.