Version 2 OI SST Climatology for 1971-2000 ---------------------------------------------------------------------------- NOTE: The Data Support Section maintains an ASCII version of this data. As such, this document has been changed to reflect this ascii format. All other details pertaining to the data are the same as the original version of the data maintianed on the NCEP server listed below ---------------------------------------------------------------------------- A new sea surface temperature (SST) climatology for the 1971-2000 base period was constructed using the method of Reynolds and Smith (1995). The new climatology was built from two intermediate climatologies: a 2 degree SST climatology developed from in situ data for the period 1971-2000, and a 1 degree SST climatology for the period 1982-2000 derived from the revised optimum interpolation (OI) SST analysis. The revised analysis is a major improvement over the original OI SST analysis at high latitudes due to a new ice algorithm (Reynolds et. al. 2001). The revised OI SST analysis was put into operation at the Climate Prediction Center in August 2001. The figures at http://www.cpc.noaa.gov/products/predictions/30day/SSTs/sst_clim.html show the new SST climatology (left column) and the differences between the new climatology and that for the base period 1961-1990 (Smith and Reynolds 1998). The changes in the climatology are caused by changes in the base period as well as changes in the OI analysis. In the tropics and subtropics, the changes in the climatology are largely due to the changes in the base period, while in high latitudes the changes are due to the changes in the OI analysis alone. Because there are insufficient in situ observations at high latitudes prior to 1982, there is no information from the in situ climatology. Thus, the climatology base period is 1982-2000 there. It is seen that the changes in the climatology are generally small with absolute differences usually less than 0.2°C in the tropics and subtropics, while the changes at high latitudes exceed 1°C. The ASCII data file can be read with the following fortran program (file name: readclm.f) real sst(im,jm,12) open (10,file='aoi.71.00.clim.asc',form='formatted') read(10,'(20f7.2)') sst do K=1,12 PRINT 7,K,SST(70,80,K) 7 FORMAT ('MONTH =',I3,3X,'SST (69.5E,10.5S) =',F6.2) enddo stop end c The fortran read gets the SST array degrees Celsius. Missing values over land are set to -999.9 The first dimension (I) of sst is longitude, the second dimension (J) is latitude, the third (K) is month. I = 1 is 0.5E, I = 2 is 1.5E, and so on to I = 360 which is 359.5E. J = 1 is 89.5S, J = 2 is 88.5S, and so on to J = 180 which is 89.5N. K = 1 is January, K= 2 is February, and so on to K = 12 which is December. Output from the above code should be as follows: MONTH = 1 SST (69.5E,10.5S) = 28.33 MONTH = 2 SST (69.5E,10.5S) = 28.39 MONTH = 3 SST (69.5E,10.5S) = 28.72 MONTH = 4 SST (69.5E,10.5S) = 28.70 MONTH = 5 SST (69.5E,10.5S) = 27.96 MONTH = 6 SST (69.5E,10.5S) = 26.83 MONTH = 7 SST (69.5E,10.5S) = 26.12 MONTH = 8 SST (69.5E,10.5S) = 25.71 MONTH = 9 SST (69.5E,10.5S) = 25.93 MONTH = 10 SST (69.5E,10.5S) = 26.47 MONTH = 11 SST (69.5E,10.5S) = 27.33 MONTH = 12 SST (69.5E,10.5S) = 28.13 The user can also check the data if they have grads by entering the following after they have started grads: ga-> open aoi.71.00.clim.ctl ga-> set t 6 ga-> set gxout shaded ga-> d sst ga-> set gxout contour ga-> d sst ga-> draw title June OI.v2 SST climatology for base period 1971-2000 This procedure will generate a plot of the climatology for June (t =6, the sixth month) which should look like the file ftp://ftp.ncep.noaa.gov/pub/cpc/wd52yx/sstclim_71-00/june-clim.gif