The intraseasonal oscillation （ISO; 14 97-day ocean was studied based on Argo observations periods） of temperature in the upper 2000 m of the global from 20052008. It is shown that near the surface the ISO existed mainly in a band east of 60°E, between 10°S and 10°N, and the region around the Antarctic Circumpolar Current （ACC）. At other levels analyzed, the ISOs also existed in the regions of the Kuroshio, the Gulf Stream, the Indonesian throughflow, the Somalia current, and the subtropical eountercurrent （STCC） of the North Pacific. The intraseasonal signals can be seen even at depths of about 2000 m in some regions of the global ocean. The largest amplitude of ISO appeared at the thermocline of the equatorial Pacific, Atlantic and Indian Ocean, with maximum standard deviation （STD） exceeding 1.2°C. The ACC, the Kuroshio, and the Gulf Stream regions all exhibited large STD for all levels analyzed. Especially at 1000 m, the largest STD appeared in the south and southeast of South Africa a part of the ACC, with a maximum value that reached 0.5°C. The ratios of the intraseasonal temperature variance to the total variance at 1000 m and at the equator indicated that, in a considerable part of the global deep ocean, the ISO was dominant in the variations of temperature, since such a ratio exceeded even 50% there. A case study also confirmed the existence of the ISO in the deep ocean. These results provide useful information for the design of field observations in the global ocean. Analysis and discussion are also given for the mechanism of the ISO.
In this study,monthly NCEP/NCAR reanalysis data and NOAA ERSST as well as observed precipitation data from 160 stations in China were used to investigate coupled modes affecting the rainfall over China and sea surface temperature （SST） in the Pacific during boreal summertime based on singular value decomposition （SVD） method.The SVD analysis revealed three remarkable coupled modes：rainfall over North China associated with an ENSO-like SST pattern （ENSO-NC）,rainfall over the Yangtze River valley associated with SST anomalies in the western tropical Pacific （WTP-YRV）,and rainfall over the Yellow River loop valley associated with tropical Pacific meridional mode-like SST pattern （TPMM-YRLV）.These coupled SVD modes appear robust and closely correlated with the single field.Furthermore,the covariabilities among of the three coupled modes have different characteristics at the decadal time scale.In addition,the possible atmospheric teleconnections of the coupled rainfall and SST modes were discussed.For the ENSO-NC mode,anomalous low-pressure and high-pressure over the Asian continent induces moisture divergence over North China and reduces summer rainfall there.For the WTP-YRV mode,East Asia-Pacific teleconnection induces moisture convergence over the Yangtze River valley and enhances the summer rainfall there.The TPMM SST and the summer rainfall anomalies over the YRVL are linked by a circumglobal,wave-train-like,atmospheric teleconnection.
Long-term change of sea surface temperature （SST） in the China Seas from 1900 to 2006 is examined based on two different observation datasets （HadlSSTI and HadSST3）. Similar to the Atlantic, SST in the China Seas has been well observed during the past 107 years. A comparison between the reconstructed （HadISSTI） and un-interpolated （HadSST3） datasets shows that the SST wanning trends from both datasets are consistent with each other in most of the China Seas. The warming trends are stronger in winter than in summer, with a maximum rate of SST increase exceeding 2.7℃ （100year）-I in the East China Sea and the Taiwan Strait during winter based on HadISSTI. However, the SST from both datasets experienced a sudden decrease after 1999 in the China Seas. The estimated trend from HadlSSTI is stronger than that fi＇om HadSST3 in the East China Sea and the east of Taiwan Island, where the difference in the linear SST warming trends are as large as about 1℃ （100year）-I when using respectively HadISST1 and HadSST3 datasets. When compared to the linear winter warnling trend of the land surface air temperature （1.6℃ （100 year）-1）, HadSST3 shows a more reasonable trend of less than 2.1℃（ 100 year）-1 than HadISST 1 ＇s trend of larger than 2.7℃ （ 100 year）-1 at the mouth of the Yangtze River. The restllts also indicate large uncertainties in the estimate of SST warming patterns.
In this study, the relationship between El Nifio-Southern Oscillation （ENSO） and winter rainfall over Southeast China （SC） is demonstrated based on instrumental and reanalysis data. The results show that ENSO and SC winter rainfall （ENSO-SC rainfall） are highly correlated and intimately coupled through an anomalous high pressure over the northwestern Pacific. In mature phase, El Nifio （La Nina） events can cause more （less） rainfall over SC in winter. Due to the persistence and spring barrier of ENSO, SC winter rainfall has potential predictability of about half a year ahead with ENSO as a predictor.
