The MJO Index. 10N-10S 200hPa 6-hourly zonal mean - zonal wind filtered with a 90-30 day band pass filter - squared and passed through a 90 day running mean

Time series
The SAO. The climatological annual cycle of the monthly mean - zonal mean equatorial zonal wind m/s 1958-1978 and 1979-2001
The QBO. Monthly mean - zonal mean - equatorial zonal wind m/s and 48-9 month band pass filtered anomalies
The QBO at 50hPa. Monthly mean - zonal mean equatorial zonal wind anomalies m/s [blue] and filtered with a 48-9 month band pass filter [red]
The MJO Index. 10N-10S 200hPa 6-hourly zonal mean - zonal wind filtered with a 90-30 day band pass filter - squared and passed through a 90 day running mean
The SOI. Tahiti minus Darwin monthly mean - mean sea level pressure anomalies hPa [blue] and normalised by their 45-year monthly standard deviation [red]
The NAO Index. Azores minus Iceland monthly mean - mean sea level pressure anomalies hPa [blue] and normalised by their 45-year monthly standard deviation [red]
The PNA Index. A linear combination of 500hPa geopotential height anomalies m [blue] and normalised by their 45-year monthly standard deviation [red]