1. 1997-98 EL NINO EFFECTS ON SOUND SPEED IN THE SOUTH CHINA SEA BASIN
LT Adria Schneck-Scott
SEP 2004
OC3570 Cruise Project

2. Contents Introduction/Navy Relevance Data Collection Background
Data Processing
Analysis and Findings
Recommendations

3. Introduction Why? Political/Strategic Sea Power 21
Quantification/Prediction Ocean Variability
Current Databases Good Enough
Thesis Work
Sea Poer 21 - information superiority and accurate battle space characterization provide “unprecedented offensive power, defensive assurance, and operational independence”
quantification and prediction of spatial and temporal ocean variability becomes more valuable
These products do not always provide sufficient prediction of the acoustic environment. Resolution of these models is equally inadequate to meet the high spatially sensitive needs of today’s operations; however, with scarce computing resources and the demands of the right information at the right time, we must ask ourselves what is good enough.

4. Data Collection 2 USNS Silas Bent cruises (Prof. Steve Ramp)
April 28-May 17, 1997
April 4-18, 1998
CTD data
Limited to Deep Basin
Thesis Work

5. Background - El Niño
displays the development of the El Niño. In April, during the 1997 data collection, an oceanic Kelvin wave reached South America (topex.com) approximately one month after being triggered by east-blowing winds near Australia.
The El Niño peak is seen in November at about 35 centimeters above average in the eastern Pacific, near the Galapagos Islands. In May 1998, just after the second Silas Bent China Sea cruise, typical conditions of a decaying El Niño are exhibited.
What is El Niño? Characterized by sustained warming over a large part of the central and eastern tropical Pacific Ocean .

6. Background - El Niño Global Impacts

7. Data Processing Convert CTD data Used MATLAB GDEM from NAVO
Depth into pressure (db)
SSP for station
GDEM from NAVO
April, May
MATLAB – SSP

8. Results – SSP GDEM “good enough” very deep water?

9. Results - SSP db
GDEM 5m/s faster than mean

10. Upper 100db of SSP

11. Temperature Cross Section

12. 50db Temperature Contour

13. 50db Salinity Contour

14. 50db Salinity Contour

15. Ship UDAS Readings

16. Recommendations Explanation for: Deeper MLD in 1998
Stronger seasonal thermocline in 1998
Increase sound speed in upper 20db 1997
Verify cause of fresh waters of 1997
Sea Poer 21 - information superiority and accurate battle space characterization provide “unprecedented offensive power, defensive assurance, and operational independence”
quantification and prediction of spatial and temporal ocean variability becomes more valuable
These products do not always provide sufficient prediction of the acoustic environment. Resolution of these models is equally inadequate to meet the high spatially sensitive needs of today’s operations; however, with scarce computing resources and the demands of the right information at the right time, we must ask ourselves what is good enough.

17. Conclusion El Niño did impact South China Sea
1998 SSP:
Deeper isospeed layer
Deeper isothermal layer (mixed layer depth)
Stronger seasonal thermoclines
1997 SSP marked by increase in upper 20db
METOC needs to understand and develop tools to predict temporal and spatial variations
Information Superiority and Battle Space Characterization
Sea Poer 21 - information superiority and accurate battle space characterization provide “unprecedented offensive power, defensive assurance, and operational independence”
quantification and prediction of spatial and temporal ocean variability becomes more valuable
These products do not always provide sufficient prediction of the acoustic environment. Resolution of these models is equally inadequate to meet the high spatially sensitive needs of today’s operations; however, with scarce computing resources and the demands of the right information at the right time, we must ask ourselves what is good enough.