214-5 



EXAMPLE OF FNWF OCEANOGRAPHIC PRODUCTS 



A. SEA SURFACE TEMPERATURE 



The FNWF Sea Surface Temperature (SST) analysis program uses as input 

 data all ship inflection temperature reports from the previous 3 l/2 days. A 

 median seeking technique is utilized to reduce the influence of erroneous 

 reports. All observations within C.7 niesh lengths (about I50 railes) of each 

 grid point are compared with the previously analyzed value at each ship's 

 position. If a new observation is warmer than the previous analysis, the 

 value at the nearest grid point is raised a fixed amount (O.lC)j similarly, 

 the value is lowered the same sunount if the observation is colder. Areas of 

 no data are modified only by relaxation and smoothing. 



Figure 2 is an example of a numerical analysis of this parameter. 

 Details of this program and error distributions of SST observations have been 

 described by Wolff (l961j-). The SST analyses made at FNWF, Monterey are 

 routinely decomposed into large and small scale patterns (Holl, I963 ) to 

 clarify the results of large-scale circulation changes, fluctuations in 

 upwelling, etc. The large-scale SST pattern derived from Figure 2 is shown 

 in Figure 3. Its similarity to ocean current systems will be pointed out 

 later. 



B. SEA AND SWELL 



The analysis and forecast program for wind waves uses a singular 

 technique to obtain significant wave height and period. Surface geostrophic 

 winds at 3-hourly intervals are the basic input. Duration is determined to 

 the nearest 3 hours and fetch corrections are made in regions of offshore flow. 

 The formulae for wave height and period as functions of duration D^ and 

 geostrophic wind speed Ug used at FNWF are 



H1/3 = a(Ug) D^ +bUg 



^ = (c +dDf.) Ug+e 



A sample wave analysis is shown in Figure k. 



Swell is defined as waves which have traveled more than 2h hours from 

 a generating area. Based on a history tape of wave heights, periods and 

 directions at 12-hourly intervals; travel distance, swell height and swell 

 period are computed from the following equations: 



D = a^^ T^ in" t 



"d. - "f 



T, \ -2.65 

 g 



