1. Multiple States in Coastal Lagoons and Estuaries Next Steps Toward Understanding the Lagoons of the Yaqui Valley Arnoldo Valle-LevinsonS. MonismithJuan DelgadoEsther CruzBob Chant Ctr. for Coastal Physical Oceanogr.Stanford UniversityITMAR GuaymasCECARENA Rutgers Ocean, Earth and Atmos. Sci. Dept.GuaymasUniversity Old Dominion UniversityNew Brunswick Norfolk, VirginiaN.J.

2. (From Hearn and Sidhu, 2003) When and how does the system switch? Depends on density contrast

3. Inverse Estuary Classical Estuary Looking into the lagoon Red = outflow Blue = inflow Guaymas Bay OUT IN

4. Mean Flow at Transect 4 red is inflow; blue is outflow (looking seaward) Neap Tides Interface slope, spring tides ~ 2.5e-03 (25 m in 10 km) Interface slope, neap tides ~ 2.0e-03 (18 m in 9 km) Distance from Transect Origin (km) Wet Season: Classical Dry Season: Inverse Importance: Water and Soil(?) Quality Climate Variability OUT IN

5. The Global Heat and Salt Conveyor Belt (From Broecker,1990; in Pinet, 1998)

6. Conservation of Salt and Heat Relative influence of salinity and temperature on density gradients Q Freshwater Precipitation Outflow Inflow S e, T e S o, T o Heating CLASSICAL Q Freshwater Evaporation Outflow Inflow S e, T e S o, T o Cooling INVERSE

7. Relative influence of salinity and temperature on density gradients Salinity influence Temperature influence Net influence Q In reality:

8. Salinity influence Temperature influence Net influence Q T mode S mode Multiple states --- Stommel Transitions

9. Response dominated by salinity Response dominated by temperature

10. Salinity influence Temperature influence Net influence Q Critical response for multiple states Guess for Tobari and Lobos

11. (Indicates Evaporation) (From Hearn and Sidhu, 2003)

12. (Indicates Evaporation) (From Hearn and Sidhu, 2003)

15. (Indicates Evaporation) L = 15 km L = 0.85*15 km (From Hearn and Sidhu, 2003)

16. Shortening basin may prevent it from becoming INVERSE (From Hearn and Sidhu, 2003)

17. Tobari’s causeway

18. Do Yaqui Valley lagoons/estuaries show ‘Stommel Transitions’? Implications for water and soil quality… Does causeway prevent INVERSE conditions? What is the time scale of the Transitions? Natural laboratory to examine climate variations Are the systems in the Yaqui Valley more VULNERABLE to drought?