1. Change of Microwave Radiation under Different Oceanic Conditions
- Results from Comparison between AMSR and SeaWinds on ADEOS-II -
Akira Shibata
EORC / JAXA
NOAA-NASA Workshop, Feb.8-10, 2005, at FIU

2. Research Purpose
Under what kind of parameters does the ocean microwave emission change ?
SST
Wind speed and direction
Air-Sea temperature difference
Swells
Examples of anomalous emission, which may be due to air-sea temperature difference
Arabian Sea in summer
Off California coast

3. Sensors
AMSR and SeaWinds on ADEOS-II
Launched on Dec. 14, 2002
Stopped on Oct. 25, 2003
Data from Apr. to Oct., 2003

4. AMSR’s Two Parameters for Ocean Wind
1. S36 from 36GHz
S36=(T36H – s*T36V + k ) / atmos_corr
s & k : constants
2. 6H from 6GHz
6H=T6H_obs – atmos_effect - T6H_calm

5. Graphical explanation of S36

6. Anisotropic feature of S36 for relative wind direction
SeaWinds
Wind speed
S36 (K)
Relative wind direction (degree)

7. Anisotropic feature of 6H for relative wind direction
6H (K)
Relative wind direction (degree)

8. Relation between 6H and S36 for various relative wind directions
Ascending orbit in S.H
16m/s
upwind
downwind
7m/s
7m/s

9. Comparison of ascending and descending orbit data
May, 2003 in S.H.

10. Comparison of ascending and descending orbit data
June, 2003 in S.H.

11. Comparison of ascending and descending orbit data
July, 2003 in S.H.

12. Geometry of AMSR looking direction and wind direction in S.H.
Descending orbit
Ascending orbit
Upwind Southern wind
(cold air)
Downwind Northern wind
(warm air)
Upwind Northern wind
(warm air)
Downwind Southern wind
(cold air)

13. Next Slides
April versus October in S.H.

14. Comparison of ascending and descending orbit data
April, 2003 in S.H.

15. Comparison of ascending and descending orbit data
October, 2003 in S.H.

16. Comparison of significant wave height between April and October
(From ERA)

17. Comparison of air-sea temperature difference
between April and October 2003
April
October

18. Next Slides
S.H. versus N.H. in April

19. Comparison of ascending and descending orbit data
April, 2003 in S.H.

20. Comparison of ascending and descending orbit data
April, 2003 in N.H.

21. Summary
•Two parameters (6H and S36) of AMSR are different between ascending and descending orbits under strong wind.
• Those parameters are also different among seasons, and also between southern and northern hemispheres.
• An order of the difference at 16m/s is 1K or so.
• One explanation of the difference is air-sea temperature difference.