25 



30 



35 



25 



30 



35 



15 



10 



e o 



1971 



J L 



e o o 



J I I L 



J I 



25 



30 



35 



Figure 2.-Temperature-salinity diagrams for NH 1, NH 3, and 

 NH 5 in 1969, 1970, and 1971 between April and September. 



seasons are seen. About 26% of the 1969 and 1970 

 data fell within the limits of the modal cell (8.1°- 

 9.0°C and 33.1-34.0 °/oo). Only 6% of the 1971 data 

 fell within the limits. Water was generally 

 warmer and of a lower salinity during most of the 

 1971 upwelling season. Higher temperatures and 

 lower salinities indicate the presence of mixed 

 Columbia River plume water and surface oceanic 

 water. Both the modal cell and surface tempera- 

 ture observations indicate that upwelling was 

 weaker in 1971 than in 1969 or 1970. 



Wind data supports the conclusion that the up- 

 welling season of 1971 was a weak one. The PVD's 

 (Figure 3) illustrate the pattern of the wind from 1 

 May through 30 September for the years 1969-71. 

 They give an indication of amounts of upwelling- 

 inducing northerly winds during a given season, 

 and are useful for comparing different seasons. 

 The axes of the PVD's are wind-miles (i.e., miles 

 per hour multiplied by hours). The northerly com- 

 ponent of the wind extends positively down the 

 ordinate and westerly component extends posi- 



tively along the abscissa. The seasonal pattern for 

 1971 is quite different from 1969 and 1970. 

 Northerly wind miles are low while westerly wind 

 miles are exceptionally high. Therefore, upwelling 

 should have been relatively weak. This explains 

 the low frequency of temperature and salinity ob- 

 servations in the modal cell in 1971, compared to 

 1969 or 1970. The 1969 and 1970 wind patterns are 

 similar; 1969 had about 2V2 mo of persistent 

 northerlies, while 1970 had about 4 mo of persis- 

 tent northerlies. A higher total northerly com- 

 ponent was achieved in 1970 than in 1969. 



The upwelling index data of Bakun (1973) show 

 1969 and 1970 to have been close to average years 

 compared with the years 1946 to 1971, while 1971 

 was far below average. These monthly indices es- 

 timate the magnitude of the offshore component 

 of the Ekman transport and are calculated from an 

 estimate of the mean monthly sea surface wind 

 stress, which is based in turn on a geostrophic wind 

 calculation from pressure field data. The 

 anomalies of the index at lat. 45°N, long. 125°W 

 for the periods of interest in our study are: 



Total 



+ 7 



+ 12 



-48 



Bakun's indices were derived from different data 

 than the PVD's and comparisons between years 

 would not be expected to be in exact agreement. 



Total Zoopiankton 



Table 1 is a list of the sampling dates and total 

 zoopiankton abundance at stations NH 1, 3, 5, and 

 10. The 1972 data set is shown, but since so few 

 samples were taken relative to the number 

 gathered in other years, we have eliminated these 

 data from comparative discussions. One can see 

 several patterns in Table 1. Abundances are 

 usually highest at the station nearest the shore (2 

 km from the beach). Abundances grade to lows at 

 the station 18 km from shore. They continue to 

 decrease farther from shore (Cross 1964). There is 



645 



