1. LT Ricardo Roman OC3570 March 7, 2006
Differences in “Line 67” between
March 1998 and January 2006
LT Ricardo Roman OC3570 March 7, 2006

2. Outline Introduction Area of interest (“Line 67”) El Nino
El Nino and Line 67
November 1998
March 1998
El Nino Data Set
What is happening today
January 2006
Reference: “Changes in the hydrography of Central California waters associated with the El Nino” (Collins et al. 2002)

3. Introduction Data Sets: March 1998 and January 2006
March 1998: return to normal
January 2006: possible return of La Nina
California Cooperative Fisheries Investigations (CalCOFI) Line 67
Equipment
SeaBird CTD

4. CalCOFI Line 67 (MAR 1998) Line 67
Central California Measurement locations
Solid Blue Dots: Hydrographic Stations
Sea Level Gauge: +
Sea Surface Temp. and Salinity measurements: *
Location of Geostrophic Wind Estimates:

5. El Nino Caused by: Physical effects:
Poleward Advection of Equatorial Waters
Onshore advection of Offshore waters
Decrease in coastal upwelling
Physical effects:
Increased coastal sea levels
Biological changes (e.g. decreased productivity, reduction of fish and marine life)

6. El Nino (NOV 1998) NASA satellite
Peak Sea Levels witnessed in Monterey Bay, November 1998
El Nino not initially predicted by models
Equatorial effects propagate to higher latitudes along eastern boundaries
Stations were set up off Central California

7. El Nino (MAR 1998) Return to near normal state
Lower Temperatures along Central California
Rapid decrease in sea level and freshening of water

8. Monterey Sea Level (1997-1999) Black line: mean sea level 1974-99
Blue line: mean sea level
Dashed line: mean sea level
JUN1997-FEB1998 monthly mean sea level higher than normal
Max mean sea level ~1.15m, November 1997
March 1998, conditions return to normal
FEB 1998
JUN 1997

9. Dynamic Height (dynamic meters)
Variations along CalCOFI Line 67 at surface
JUN-JUL 1997, Initial signs of El Nino
Fall and Early Winter 1997, Peak Sea Level Height
March 1998, Rapid Decrease in Height, Normal Conditions

10. Potential Temperature (1997-1999) at surface
JUN-JUL 1997, Clear Evidence of El Nino
Fall and Early Winter 1997, Temp. max
March SST returned to normal
Salinity ( ) at surface
Increased Salinity in Fall and Early Winter
Rapid Freshening of Coastal Water in March

11. Geostrophic Velocity (MAR 1998) Vertical Profile
Poleward
Flow
Equatorward
Flow
Equatorward
Flow
Land

12. Temperature (MAR 1998) Vertical Profile
Represents
Poleward
Flow

13. Salinity (MAR 1998) Vertical Profile
Observed
Salinities
< 32
Very rapid
freshening

14. What’s happening today
Dec 31, 2005
Possible return of La Nina?
NOAA predicts weak La Nina conditions for Spring (NOAA News, JAN 2006)

15. Geostrophic Velocity (JAN 2006) Vertical Profile
Equatorward
Flow,
Opposite of
March 1998
Poleward
Flow,
Opposite of
March 1998

16. Temperature (JAN 2006) Vertical Profile
Increase in
Temp

17. Salinity (JAN 2006) Vertical Profile
Higher Salinity
Than March 1998