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

Outline Introduction Area of interest (“Line 67”) El Nino 1997-1998 El Nino and Line 67 November 1998 March 1998 1997-1998 El Nino Data Set What is happening today January 2006 Reference: “Changes in the hydrography of Central California waters associated with the 1997-98 El Nino” (Collins et al. 2002)

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

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:

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)

El Nino (NOV 1998) NASA satellite Peak Sea Levels witnessed in Monterey Bay, November 1998 1997-1998 El Nino not initially predicted by models Equatorial effects propagate to higher latitudes along eastern boundaries Stations were set up off Central California

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

Monterey Sea Level (1997-1999) Black line: mean sea level 1974-99 Blue line: mean sea level 1997-98 Dashed line: mean sea level 1982-83 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

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

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 (1997-1999) at surface Increased Salinity in Fall and Early Winter Rapid Freshening of Coastal Water in March

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

Temperature (MAR 1998) Vertical Profile Represents Poleward Flow

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

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

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

Temperature (JAN 2006) Vertical Profile Increase in Temp

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