CalCOFI Reports, Vol. 11, 1967 - California Cooperative Oceanic ...

REPORTS VOLUME XI, 1 JULY 1963 TO 30 JUNE 1966 173in fall and, hence, its position correlates with thestrength of the California Current. The coastal regimeis complex and some difficulty results from thestation spacing and sampling frequency. The stationregression curves for stations near San FranciscoBay show marginal significance. The low-salinityeffluent from the bay is greatest in the spring coincidentwith upwelling of high-salinity water north andsouth of the bay. A pattern of isohalines, broken atSan Francisco Bay, is shown in charts for Aprilthrough August. The pattern is simpler for the remainderof the year although the data for January,February, and March are not clear.South of Monterey Bay water with salinity > 33.40/,0is always present in the mean. This salinity is greaterthan that found farther from the coast. The coastalhigh salinity is maintained by upwelling in the springand summer and by the high salinity of the countercurrent(either directly by the advection or by verticalmixing with submerged countercurrent waters) inautumn and winter.Upwelling regions have high-salinity water inspring and summer. Beginning in March and carryingthrough until July an isolated high-salinity regiondevelops along the coast north and south of PointConception and among the Channel Islands. In Augustthrough October the isolated high-salinity regionis found only among the islands having successivelysmaller extent. The large temperature gradient (6'C. in 120 miles in June) occurs within this body ofwater. In part, the high salinities are formed byupwelling in the vicinity of Point Conception andthe distribution is further influenced by the circuitousflow of the large eddy. The mass distribution associatedwith geostro,phic balance requires that denserwater, in this instance the higher salinity water, befound at shoaler depths to the left of the directionof flow (in the northern hemisphere). The springincreases in current flow amplifies this effect. Thereestablishment of the large eddy in June centersthe denser water in the island region and causesthe mixed layer to be thin. In the Channel Islandregion, at depth, there is a greater percentage ofwater of southern origin than offshore (Sverdrupand Fleming, 1941). This water has a higher salinityat a given density than water of northern origin. Allof these facts favor high salinities in the island region.The seasonal variation of salinity off southern BajaCalifornia is markedly affected by advection. Startingin spring and developing into early summer theisohalines bend sharply towards the southeast. Thelower salinities form a tongue-like distribution. Thehigher salinities along the coast must in part bemaintained by upwelling. The northwestward projectionof high salinity water near Punta Eugenia inSeptember indicates an influx of more southerlywater and corresponds to a cyclonic eddy sometimesfound there in this season.7-9 5 75 7NEW CHARTS COMPARED TO PREVIOUS CHARTSThe mean (monthly) temperature and salinitycharts of CalCOFI Atlas No. 1 were constructed fromstation averages with a base period of 1950-59. Stationaverages based on fewer than five observations(for each month) were not used. Consequently, thedistributions for some months have large gaps. Thedistributions of properties in the Atlas No. 1 chartsand these newer charts are closely similar. The largerdifferences are in the salinity charts and in the areasof limited sampling. No attempt is made to providerepresentative differences because in some areas smalldifferences may mean a large displacement of anisopleth whereas in other areas the opposite is true.The change in base period has an uneven effect dependingupon sampling frequency and its change.The addition of the 33.5%0 isohaline (half of thestandard interval) in the newer charts adds importantdefinition.ACKNOWLEDGMENTSI thank Joseph L. Reid, Jr., and Gunnar I. Rodenfor guidance and many helpful suggestions. MarvinCline did the computer programming.REFERENCESCalifornia Marine Research Committee. 1963. CalCOFI atlasof 10-meter temperatures and salinities 1949 through 1959.Calif. Coop. Ocean. Fish. Invest. Atlas, no. 1.Conrad, V., and L. W. Pollak. 1950. Methods in climatology. 2nded. Harvard Univ. Press, Cambridge, Mass. 459 p.Griffiths. R. C. 1965. A study of ocean fronts off Cane San Lucas.Lower California. U.S. -Fish Wild. Serv. Speo. Sci. Rept..:Fish., (499) :1-54.Ministerstvo Oborony Soiuza SSR. 1950. Morskoi Atlas. Moscow,Glaynyi shtab Voenno-Morskikh Sil, 11.Montgomery, R. B., and W. S. Wooster. 1954. Thermostericanomaly and the analysis of serial oceanographic data.Deep-Sea Res., 2:63-70.Norpac Committee. 1960. Oceanic observations of the Pacific :1955, the Norpac Atlas. Univ. Calif. Press, Berkeley ; Univ.Tokyo Press, Japan. 123 maps.Reid, J. L., Jr. 1960. Oceanography of the northeastern PacificOcean during the last ten years. Calif. Coop. Ocean. Fish.Invest. Rept., 8 :91-95.-1962. Distribution of dissolved oxygen in the summerthermocline. J. Mar. Res., 20(2) :138-148.-1965. Physical oceanography of the region near PointArguello. Univ. Calif. Inst. Mar. Resour., IMR Ref. 6519 :1-39.Reid, J. L., Jr., G. I. Roden and J. G. Wyllie. 1958. Studiesof the California Current system. Calif. Coop. Ocean. Fish.Invest. Prog. Rept. 1 July 1956-1 Jan. 1958, :29-57.Reid, J. L., Jr., R. A. Schwarzlose and D. M. Brown. 1963.Direct measurements of a small surface eddy off northernBaja California. J. Mar. Res., 21 (3) :205-218.Reid, J. L., Jr., C. G. Worrall and E. H. Coughran. 1964.Detailed measurements of a shallow salinity minimum inthe thermocline. J. Geophys. Res., 69(22) :4767-4771.Reid, J. L., Jr., R. S. Arthur and E. B. Bennett (Ed.). 1957-1965. Oceanic observations of the Pacific : 1949-1959. Univ.Calif. Press, Berkeley. (11 vols.)Robinson, M. K. 1957. Sea temperature in the Gulf of Alaskaand the northeast Pacific Ocean, 1941-1052. Scripps Inst.Oceanogr. Bull., 7( 1) :1-98.