Physical Properties and Forcings in an Estuarine System 2013 PICES Summer School Group 4 Matthew, Daniel, Jingsong, Chorong, Joocheul, Morgaine, Polina, Amy

Topic: Physical Oceanography Question: Describe the time dependence in physical properties (temperature, salinity, dissolved oxygen) and explain what forces these.

Yaquina Bay: 2 Sites, 1.5 Days Mooring w/ CTD CTD casts

Mooring

Winds – upwelling favorable

Y14 Sample Times (m) Aug. 20Aug. 21 Δh = 5cm Δh = 46cm

Y14

Trends Day 1: Day 1: –well-mixed throughout Day 2: Day 2: –well-mixed below 3m –lower T, higher S, lower DO (rel. to day 1) No apparent tidal influence in CTD cast data at Y14 station No apparent tidal influence in CTD cast data at Y14 station –sampling on opposite sides of tidal peak (not at extremes) –Day 2: 2 nd sample in the slack tide

Hypotheses 1: Well-mixed water column due to low summertime river flow relative to tide flow. 1: Well-mixed water column due to low summertime river flow relative to tide flow. 2: Day 2 had more upwelled ocean water at Y14. 2: Day 2 had more upwelled ocean water at Y14. –stronger tide, wind from the N –T decreased, S increased, DO decreased

Vertical velocity differences are small

Potential issues Non-verticality of cast Non-verticality of cast –drift of boat during sampling –strong currents  CTD line angled Non-shared datum Non-shared datum –depth relative to surface –up to 0.5m change in depth (flood vs. ebb)

Conclusions Upwelled water is identifiable at both stations on Day 2 Upwelled water is identifiable at both stations on Day 2 River water is not a strong influence: low flow rates  strong mixing  well-mixed water column (no salt wedge) River water is not a strong influence: low flow rates  strong mixing  well-mixed water column (no salt wedge) CTD sampling must be better spaced along tidal cycle to make conclusions about effects of the tide with only discrete sampling CTD sampling must be better spaced along tidal cycle to make conclusions about effects of the tide with only discrete sampling

Thank you GRACIAS!!!! GRACIAS!!!! GAMSAHAMNIDA!!!! GAMSAHAMNIDA!!!! ARIGATOU!!!! ARIGATOU!!!! DANKE SCHOEN!!!! DANKE SCHOEN!!!! CHEERS MATES!!! CHEERS MATES!!! SHYE SHYE! SHYE SHYE! SPACIBO!!! SPACIBO!!!

Backup Slides

Day 1: Flood tide

Day 1: Ebb tide

Day 2: Flood tide

Day 2: Ebb tide

Tidal cycles in flow-through Temperature decrease & salinity increase as flood tide comes in Temperature decrease & salinity increase as flood tide comes in Temperature & salinity relatively constant for samples around max tide point Temperature & salinity relatively constant for samples around max tide point

Group1

Group2

Group3