MEAN

Bimonthly means for temperature, along each line, are calculated using the raw XBT data, in latitude/longitude bins ( Table 1 ) and decimated every 20m in depth. Mean values are given for January/February, February /March, and so on, through the year.

Bimonthly mean salinity values are obtained from the bimonthly mean XBT temperatures and from the Levitus annual mean T/S relationship, ( Levitus,1982 ) using linear interpolation in the vertical plane.

 If the range of Levitus temperature values is smaller then the range of XBT temperature values, in a particular bin, the interpolation ( at either end of the T/S relation ) cannot be performed. In this case, the last Levitus salinity value, at either end of the TS relationship, is used to extrapolate to the highest or lowest XBT temperature.

Figures 3 and 4.1 - 4.12 illustrate the annual and bimonthly mean temperature sections. Figures 11 and 12.1 - 12.12 illustrate the annual and bimonthly mean salinity sections.
 
 
 

ANALYSIS OF VARIANCE

The following variance calculations of the temperature section were performed  :
 
  • The  Standard Deviation ( s ) of all the raw XBT temperatures collected during the period
  • The  Standard Deviation  of the seasonal cycle  ( ss )
  • The  Standard Deviation  of the interannual temperature anomalies  ( si  )
  • The ratio of seasonal to interannual standard deviations,  (  ss / si  )
  •  The noise standard deviation ( sn  ) .   Noise variance  was estimated by the residual  after subtracting seasonal and interannual variance :  (  sn   )2  =  ( s  )2  - ( ss )2  - ( si )2 .
  • The ratio of  the  standard deviations of noise and signal :  (  sn  ) / sqrt( ( ss )2 +( si )2 )

    •  
    The  above results  are  illustrated in   Figures 5 to 10 :
     

    REFERENCES:

    Levitus, S. (1982) :
    'Climatological Atlas of the World Ocean', NOAA Professional Paper 13, Rochville, MD, 173 pp.