| Sea surface temperature (SST) in the North Pacific is changing remakablely with theglobal warming during last several decades. In this paper, we used some datasets like: SSTdataset from Hadley center, reanalysis data from NCEP/NCAR and JRA-25, and TO-PEX/Poseidon sea surface height (SSH) data from Aviso center. Some statistical methods areused in this study including: two-dimensional finite impulse response filter, Empirical Ortho-gonal Function (EOF), correlation analysis, composite analysis and singular value decomposi-tion (SVD). We analysed the spatial and time distributions of standard deviation of sea surfacetemperature anomalies (SSTA) in the North Pacific during1949-2012, and got two aspects ofcontents from these conclusions: one was the relationships between SSTA and SSH, as well asdifferent components from two-dimensional FIR filter; the other one was the dramatic varia-tions of winter SSTA may be related to winter Aleutian Low, thus, we studied the impact ofvariations of Aleutian Low and SSTA on the summer SAT over the Arctic. Main conclusionswere including:1. The TOPEX/Poseidon SSH data were decomposed into several thermal signal andwave signals which were on different time scales and spatial scales through two-dimensionalFIR filter. The relationship between SSH including different components and SSTA in theNorth Pacific Ocean during recently20years were studied. The SSH of observation (zori) andSSTA had a high correlation coefficient in the almost whole Pacific Ocean, SSTA and biannualRossby waves (z24) had a tight relationship in the low latitudes, and in the middle latitudesbasin-scale thermal signal which was non-propagating (zt) and SSTA had a high correlation.Using Empirical orthogonal function (EOF) and correlation analysis, the relationship betweenSSTA and three variables above wre further examined: EOF1mode of SSTA, EOF2mode ofzori, EOF2mode of zt and EOF1mode of z24all had tight linkages with ENSO. Among them,EOF1mode of z24might have the best relationship with ENSO from the whole trends and details of its time series. The correlation coefficient of Ni o3.4index and time series of z24EOF1mode was-0.71, this can also prove the above results. The conclusions of our studycould reveal the closely connection between SSH and SSTA in the North Pacific Ocean further,and stable biannual Rossby wave signal might be more beneficial to monitor the ENSO sig-nal,as well as prediction, than atmospheric and oceanic variables.2. The variations of surface air temperature (SAT) over the Arctic were closely related toglobal climate change. Based on reanalysis datasets and a newly defined Aleutian Low inten-sity index (ALI), we found a good correlation between intensity of winter Aleutian Low andthe SAT over the Arctic during the subsequent summer. Explanations were given using corre-lation analysis, composite analysis and singular value decomposition (SVD) methods. Whenintensity of winter Aleutian Low was weaker, sea surface temperature (SST) appeared higherin the North Pacific in the subsequent spring and summer, resulting in mean meridional circu-lation anomalies and500hPa geopotential height anomalies in spring and summer. Anomalousupward motion in mid-latitudes and downward motion in high latitudes (Ferrel cell weakening)transported the warmer air to the north from lower layer to the upper layer followed by in-creases in the SAT over the Arctic. Anomalous downward motion over about75°N also causedconsequent adiabatic warming and contributed to inhibit the heat transportation from surfaceto upper layer. Negative500hPa geopotential height anomalies existed in mid-latitudes andpositive anomalies existed in high latitudes. The pattern (low-in-south and high-in-north) be-nefited from increasing the inflow volume flux of the Bering Strait, which also made the SATover the Arctic increase. The results of this study reveal the process that the summer SAT overthe Arctic was modulated by interannual variability of intensity of winter Aleutian Low. |
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