seasonal values appear earliest to the south, i.e., in April at 

 lat. 21°N, and appear progressively later to the north. 

 Maxima are in May off southern California and in June and 

 July from central California to the northern extremity of the 

 Gulf of Alaska. Minimum mean seasonal values appear 

 during winter as strong negatives (intense downwelling) in 

 the north and as weak positives (relaxed upwelling) toward 

 the south. At the southern extreme the seasonal minimum is 

 in the fall, indicating downwelling conditions on the average 

 during September and October at lat. 21°N. In general, the 

 timing and duration of the upwelling seasons indicated by 

 these series differ very little from those reported by Bakun 

 (1973). 



The seasonal distributions of variance in the daily and 

 weekly values are tabulated in terms of standard deviations 

 in Tables 5 and 6. High variances in the daily means are 

 indicated during the winter downwelling season in the Gulf 

 of Alaska. The coast of northern California appears as a 

 region of high variability throughout the year. The most 

 stable situation appears to be the summer season in the 

 north. The distributions of variance of the weekly values 

 tend to be similar to those of the daily values. However, the 

 numerical values are markedly lower, indicating major 

 contributions by shorter term fluctuations in all seasons and 

 locations. 



As mentioned in the introduction, the very short-term 

 variability may not be of great concern in many applications. 

 Many of the processes involved are probably sufficiently 

 linear that averages over weekly periods and perhaps 

 monthly periods will provide relevant information. The daily 

 and weekly indices presented in this report, and the month- 

 ly, quarterly, and yearly indices presented by Bakun (1973) 

 are intended to provide a choice of scales to users, which 

 may enhance the usefulness and ease of application of 

 this information to fishery problems. 



ACKNOWLEDGMENT 



Atmospheric pressure analyses and electronic computing 

 and plotting facilities were provided by the U.S. Navy, Fleet 

 Numerical Weather Central. 



LITERATURE CITED 



BAKUN. A, 



1973. Coastal upwelling indices, west coast of North America, 

 1946-71. U.S. Dep. Commer., NOAA Tech, Rep. NMFS SSRF- 

 671. 103 p. 



1974. Properties of 6 hourly upwelling index series off western 

 North America. (Ab.stract) (03), Fall Annu. Meet. 74, EeS. 

 Trans., Am. Geophys. Union 55:1132. 



BAKUN. A.. D. R. McLAIN, and F. V. MAYO. 



1974. The mean annual cycle of coastal upwelling off western 

 North America as observed from surface measurements. Fish. 

 Bull., U.S. 72:843-844. 



DAVIDSON, K. L. 



1974. Observational results on the influence of stability and wind- 

 wave coupling on momentum transfer and turbulent fluctuations 

 over ocean waves. Boundary-Layer Meteorol. 6:305-331. 



DeLEONIBUS, P. S. 



1971. Momentum flux and wave spectra observations from an 

 ocean tower. J. Geophys. Res. 76:6506-6527. 



DENMAN, K. L., and M. MIYAKE. 



1973. Behavior of the mean wind, the drag coefficient, and the 

 wave field in the open ocean. J. Geophys. Res. 78:1917-1931. 



HOLL. M. M., and B. R. MENDENHALL. 



1972. Fields by information blending, sea-level pressure version. 

 Fleet Numerical Weather Central Tech. Note 72-2, 66 p. 



O'BRIEN. J. J., and R. L. SMITH. 



1971. CUE- A Coastal Upwelling Experiment. (Abstract) (032), 

 1971 Fall Annu. Meet.. E©S Trans.. Am. Geophys. Union 52:851. 



Table 5. — Standard deviatione of daily means of 6-hourly upwelling indices grouped by long- 

 term (1967-73) month. Units are cubic meters per second per 100 m of coastline. 



