Study On Comparison Of The Interdecadal Variability Of The Upper Pacific Between Low And Mid-Latitudes And The Interaction With West Pacific Subtropical High

The interdecadal variability of the upper Pacific between low and mid-latitudes and the interaction with west Pacific subtropical high have been analyzed here on the basis of some variable data from JEDAC, NCEP and SODA. Results show that:The different interdecadal variability characteristics of sea temperature anomaly fields at upper-ocean standard levels between the mid and low latitudes are performed in this passage.The analysis detects that decadal variability characteristics in the low latitudes are more complex than that in the mid altitudes because in the low latitudes there existed 4 types of abrupt change modes, while the mid latitudes only 2 types. It is also found-that there was a significant decadal abrupt change of temperature from surface to different depth in the subsurface layer around 1980 in both mid and low latitudes. The 80 meter layer is the transition zone of generating firstly decadal abrupt change in the mid or low latitudes.Diagnostic analysis and contrast are performed in the interatction between the low or mid-latitude pacific and west Pacific subtropical high by means of SVD. The results show that the main differences in the two areas are as follows: both in low and in mid-latitude pacific, the west Pacific subtropical high is more important during the interaction with west Pacific subtropical high in the interdecadal scale. The area of passing significance level in the sea temperature anomaly gradually decrease and scatter while the west Pacific subtropical high hardly change. It is also found that there was a significant decadal abrupt change of temperature both the west Pacific subtropical high and the sea temperature in both mid and low latitudes around 1976 and west Pacific subtropical high had happened more quickly. The interdecadal change of the Pacific temperature results from the interdecadal change of the west Pacific subtropical high and the change intensity is reducing with the depth.According to the key areas of interaction between the low or mid-latitude sea temperature and west Pacific subtropical high, the temperature anomaly index is definited. We find the temperature difference big and small year. In the big year, west Pacific subtropical high is stonger, the area is larger, it moves west prominently, the sinking movement speed in the subtropical is larger and the Hadley circulation is stronger while the case is on the contrary in the small year. It shows that there is a very good relation between the Pacific temperature anomaly of the low and mid latitudes and the west Pacific subtropical high.Numerical experiment results which are done to further study the relation between sea temperature anomaly and west Pacific subtropical high shows: the results of numerical experiment is in coincidence with the diagnosis resulst. The Pacific temperature anomaly of the mid and low-latitude is one reason which affects Hadley circulation and then has influence with west Pacific subtropical high.