1. presented by LCDR Allon Turek, USN 14 March 2008
Comparison of Ocean Station CTD data to the GDEM and SODA Climate Databases
presented by
LCDR Allon Turek, USN
14 March 2008

2. Why is this important to the U.S. Navy?
Purpose:
To test the hypothesis that ocean climatology databases accurately reflect the current ocean environment
Why is this important to the U.S. Navy?
Nearly all tactical decision aids used for under sea warfare (USW) and Mine Warfare (MIW) rely on ocean climatology databases to provide a characterization of the environment. If these databases do not accurately represent the environment then tactical decisions can be impaired.

3. Method:
Compare accurate and detailed temperature and salinity measurements taken from oceanographic stations to various ocean climate databases.
Ocean Station Data
In February 2003 data was collected from 27 ocean stations along the California coast, from Monterey Bay to the southern tip of the Baha peninsula.
Of the data recorded, only temperature and salinity data will be examined in this study
Temperature and salinity were recorded every 2 meters
Only downward measurements were used

4. * 10 station pairs sharing same location
OCEAN STATIONS (Feb. 2003)
27 total stations
(11 shallow [200m])
(16 deep [1000m])
* 10 station pairs sharing same location
* 2 stations with incomplete data
Feb. long term mean climatology sample
Resulting in:
- 15 independent climate comparison locations

5. Ocean Climate Databases
Ocean climate data was extracted using a MatLab GUI interface that provided both graphic and text outputs from the GDEM and SODA data sets.
Station # 19
* Special thanks to Prof. Tom Murphree, NPS Dept. of Meteorology and to Bruce Ford of Clear Science Inc. for providing invaluable service in accessing and processing multiple data sets.
Bruce W. Ford, Clear Science, Inc., Phone/Fax: , 7801 Lonestar Rd. Suite #17, Jacksonville, FL  32211

6. Method (cont.) Ocean Climate Databases
SODA (Simple Ocean Data Assimilation)
Variable grid resolution
approx. 0.3 Degree (depending on latitude)
20 levels
Long term mean (LTM) climatology ( )
GDEM (Generalized Digital Environmental Model)
0.5 Degree grid resolution
41 levels (zero level was discarded to align w/ SODA)
Long term mean (LTM) climatology (70 years)

7. Temperature (C) at Stations
Monthly Mean SST for February
Temperature (C) at Stations
CTD
#15 = #16 =
GDEM
#15 = 15.4
#16 = 16.2
SODA
#15 = 15.2
#16 = 16.6
CTD
GDEM
LTM
Figure from:

8. GDEM and SODA LTM climatologies are smooth and similar
Station # 4
GDEM and SODA LTM climatologies are smooth and similar
Observed CTD data shows sharp changes actually occurring in the environment

9. Station # 9
Depending on location and season GDEM and SODA climatologies can produce a fairly accurate representation of the environment

10. Station # 11
Strong layer

11. Station # 13
Weaker layer

12. Station # 14
Climatologies are similar yet they miss the detail evident in the CTD plot

13. Sharp changes in environment are smoothed out in climo
Station # 15
Sharp changes in environment are smoothed out in climo

14. Station # 16

15. Station # 17

16. Station # 18
Climatology can pick-up on sharp features if they are persistent throughout the population

17. Station # 22

18. Station # 25

19. Station # 27
Sometimes the trend in salinity or temperature can be opposite that of the actual environment

20. Average of Maximum Deviations from CTD Measurements Across Stations
Temperature (C)
Salinity
GDEM
1.533
0.1490
SODA
1.140
0.216

21. Averages of Temperature and Salinity Correlation between CTD and Climatology across Stations
GDEM
.9791
.9192
SODA
.9734
.8866

22. Conclusions:
Current ocean climatology databases such as GDEM and SODA provide a close approximation of the environment offering a good first estimate
Anomalous environmental conditions can cause sizable deviations of T and S from the LTM, especially near the ocean surface.
LTM type climatology tends to smooth T and S profiles causing features such as layers and ducts to be missed

23. Conclusions(cont.):
Comparison of CTD data to climatology within ASPECT (USW tactical decision aid) resulted in noticeably different ranges and sound propagation paths.

24. Future Work:
Investigate if Smart Climatology can provide data that more closely matches observed data from CTD casts.
Document differences in sound propagation based on various types of climatology vs. observed data
Smart Climatology: