CONTENTS 



Page 



Introduction 1 



Data reduction 2 



Dependence of stress estimates on Cn 6 



Effects of averaging 6 



Effect of atmospheric stability 6 



Wind stress distributions 9 



Spatial and temporal variability 12 



Seasonal cycle at the coast 17 



Wind stress curl 19 



Monthly curl distributions 20 



Coastal time series 22 



Discussion 22 



Physical implications 23 



Biological implications 24 



Conclusions 25 



Acknowledgments 25 



Literature cited 25 



Appendix I. Monthly surface wind stress distributions 27 



Charts 1-12. Resultant surface wind stress vectors, January through December 28 



Charts 13-24. East component surface wind stress, January through December 40 



Charts 25-36. North component surface wind stress, January through December 52 



Appendix II. Standard errors of the means 64 



Appendix EI. Monthly wind stress curl distributions 75 



Charts 37-48. Wind stress curl, January through December 76 



Table 



1. Wind speed equivalents of Beaufort force estimates in knots and meters per second 5 



Figures 



1. Chart of the west coast of the United States showing the grid of 1-degree squares used for summaries of 



wind observations 3 



2. Distribution of observations per 1-degree square 4 



3. Equivalent neutral drag coefficient for June 7 



4. Equivalent neutral drag coefficient for December 8 



5. The effect of atmospheric stability on surface wind stress for June 10 



6. The effect of atmospheric stability on surface wind stress for December 11 



7. W T ind stress constancy for June 13 



8. Wind stress constancy for December 14 



9. Relative frequency surfaces and frequency histograms for June . . . . ■ 15 



10. Relative frequency surfaces and frequency histograms for December 16 



11. Relative frequency surfaces and frequency histograms for July 17 



12. Relative frequency surfaces and frequency histograms for January 18 



13. Seasonal cycle of alongshore surface wind stress near the coast 19 



14. Seasonal cycle of onshore surface wind stress near the coast 20 



15. A conceptual diagram of the relationship of wind stress curl to the divergence and convergence of sur- 

 face Ekman transport offshore of the primary coastal upwelling zone 20 



16. Discretization grid used in calculating the wind stress curl 21 



17. Seasonal cycle of wind stress curl near the coast 22 



18. Distributions of: A. wind stress curl, B. surface currents, and C. anchovy subpopulations 24 



in 



