南方濤動(dòng)指數(shù)的計(jì)算說明

1、南方濤動(dòng)指數(shù)的計(jì)算說明(中英文對(duì)照)計(jì)算南方濤動(dòng)指數(shù)(SOI)所使用的氣候基礎(chǔ)數(shù)據(jù)分為1887-1989以 及1933 - 1992兩種，對(duì)應(yīng)著兩種不同的計(jì)算方法。1、Troup的計(jì)算方法：SOI=10 x PA(塔希提島)-PA(達(dá)爾文)/氣壓差異標(biāo)準(zhǔn)差* Note跖必 些虹竺W尊口LW .Dev. Diff其中:PA()力異常=每月平均值-長期(1887-1989)平均值氣壓差異的標(biāo)準(zhǔn)差=基期(1887-1989)的氣壓差異標(biāo)準(zhǔn)差。(應(yīng)該指達(dá) 爾文和塔希提兩地的氣壓差異標(biāo)準(zhǔn)差)Troup的SOI值為-10意味著該月SOI的偏差為長期氣壓差異標(biāo)準(zhǔn)差的 負(fù)1倍。Troup從1876年起計(jì)算的月

2、度SOI推導(dǎo)自正?；Ｌ釐u- 達(dá)爾文平均海平面壓力(mslp)。2、NCC的計(jì)算方法：國家氣候中心(NCC)基于Troup的公式對(duì)SOI的方法進(jìn)行了修改，其基期為1933 - 1992年的SOI計(jì)算公式為：SOI=10 x PA塔希提島)-PA(達(dá)爾文)/氣壓差異標(biāo)準(zhǔn)差其中:?入()=壓力異常=每月平均值-長期(1933 - 1992)平均值氣壓差異標(biāo)準(zhǔn)差=基期(1933-1992)的氣壓差異標(biāo)準(zhǔn)差。根據(jù)推算，1887-1989年的氣壓差異標(biāo)準(zhǔn)差(St.Dev.Diff.)值約為1.57，塔希提的長期平均大氣壓減去達(dá)爾文的長期平均大氣壓值約為 2.88，通過這兩個(gè)參數(shù)以及達(dá)爾文和塔希提兩地的

3、實(shí)際大氣壓即可算 出此時(shí)的SOI！SOI可反映厄爾尼諾現(xiàn)象的活躍程度，當(dāng)南方濤動(dòng)指數(shù)出現(xiàn)持續(xù) 性的負(fù)值，該年有厄爾尼諾現(xiàn)象。相反地,如果南方濤動(dòng)指數(shù)出現(xiàn)持續(xù) 性的正值，該年有反厄爾尼諾現(xiàn)象也就是拉尼娜現(xiàn)象。The Southern Oscillation Index (SOI) used by this site is calculated using a climatic base period of 1887 to 1989. The National Climate Centre (NCC) has made a number of changes to the way the SOI

4、is calculated, in particular changing the climatic base period to 1933-1992. Long Paddock will continue to provide the original SOI data (1887 to 1989 base period) as the SOI phase maps on Long Paddock are based on this data.The file called MonthlySOIPhase1887-1989Base contains a column of numbers u

5、nder the heading Phase. The five Phases of the SOI are as follows:consistently negativeconsistently positiverapidly fallingrapidly risingconsistently near zeroTroups SOI Calculation (used on this site)10 x PA (Tahiti) - PA (Darwin) / Std Dev Diff* Note5=y 偌fSOI Calculation formula: 10 x PA (Tahiti)

6、- PA (Darwin) / Std Dev Diffwhere: PA() = the Pressure Anomaly = monthly mean minus long-term mean (1887-1989 base period)St.Dev.Diff. = Standard Deviation of the Difference (1887-1989 base period)A Troup SOI of -10 means the SOI is 1 standard deviation on the negative side of the long-term mean for

7、 that month. Troups monthly SOI from 1876 onwards is derived from normalised Tahiti minus Darwin mean sea level pressure (mslp)NCC SOI CalculationThe National Climate Centre (NCC) have a revised SOI calculation although still based on the Troup formula.The formula for calculating the NCC 1933-92 bas

8、e period SOI is:10 x PA (Tahiti)- PA (Darwin) / Std Dev Diffwhere: PA() = the Pressure Anomaly=monthly mean minus long-term mean (1933-1992 base period)St.Dev.Diff. = Standard deviation of the difference (1933-1992 base period)ReferenceA.J. Troup (1965) The Southern Oscillation. Quarterly Journel of Royal Meteorological Society. 91, 490-506.Note: These calculatio