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Inner Shelf Circulation Near Point Conception, California C. Cudaback, L. Washburn, E. Dever Inner-shelf circulation affects larval transport and species distributions. What drives inner-shelf circulation near Point Conception? I will discuss responses of inner-shelf:
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Inner Shelf Circulation Near Point Conception, California • C. Cudaback, L. Washburn, E. Dever • Inner-shelf circulation affects larval transport and species distributions. • What drives inner-shelf circulation near Point Conception? • I will discuss responses of inner-shelf: • currents to seasonal flow patterns on outer shelf • currents to meteorologic-scale variability in winds • temperature to different winds and flow patterns
Monterey Bay Pt Conception June 14, 1996 at local mid-afternoon Temperature, Circulation and Ecology change at Pt Conception
35.2 35 34.8 34.6 34.4 34.2 34 33.8 -121.5 -121 -120.5 -120 -119.5 -119 data collection sites for PISCO study Pt Sal Purisima Arguello Jalama Alegria Ellwood 62 SIO moorings NDBC Buoys CODAR Stations SAMI 23 SMIN 54 53 SMOF ANMI
35 34.8 34.6 34.4 34.2 34 33.8 -121 -120.5 -120 -119.5 -119 Conditionally-Averaged Near Surface Currents reverse outside channel, only rotate inside Equatorward Convergent Poleward
Inner shelf follows similar patterns to mid-shelf 34.9 Equatorward Convergent Poleward 34.8 Purisima 34.7 34.6 Alegria 34.5 Ellwood 34.4 34.3 34.2 -120.8 -120.3 -119.8
along shore currents cross shore curents 34.9 0.2 m/s 34.85 34.8 34.75 34.7 34.65 Purisima, in upwelling zone Along shore currents fit winds winter & spring Cross shore currents fit winds spring only X-shelf transport ~1/3 Ekman 34.6 34.55 34.5 -121.2 -121.1 -121 -120.9 -120.8 -120.7 -120.6 -120.5
along shore currents cross shore curents 34.6 0.2 m/s 34.55 34.5 34.45 Alegria, in western SB channel: Along shore and cross shore currents fit wind only in winter. Hints of direct wind forcing. 34.4 34.35 34.3 -120.5 -120.45 -120.4 -120.35 -120.3 -120.25 -120.2 -120.15 -120.1
along shore currents cross shore curents 34.5 34.48 34.46 34.44 34.42 34.4 34.38 34.36 Ellwood, in channel: Long shore currents fit wind only in winter. Unclear what drives circulation. 34.34 0.2 m/s 34.32 34.3 -120.05 -120 -119.95 -119.9 -119.85 -119.8 -119.75
Wind Speed, Circulation State, Inner Shelf Temperature 1999 2000
Large Scale Circulation Patterns: • Equatorward flow dominates in spring. • Convergent flow is common in late summer and fall. • Poleward flow is most common during winter storms. • Inner shelf currents follow same patterns, but much slower. • Meteorologic Scale Variability • Purisima: classic upwelling, transport ~ 1/3 Ekman • Alegria: cross-shore currents driven by local cross-shore winds • Ellwood: forcing uncertain • Inner shelf temperature responds to flow pattern.