1. SAR-derived Sea Surface Winds in the Seas around Korea and Air-Sea Interaction Kyung-AePark and Tae-Sung Kim Department of Earth Science Education / Research Institute of Oceanography, Seoul National University, KOREA SEOUL(Satellite Earth/Ocean Sciences & EdUcationLab.)

3. Ocean surface circulation

4. Modification of vertical thermal structure, MLD variability

5. Air-sea gas exchange through sea surface

6. Key environmental factor of Ocean Ecosystem

8. Severe weather disasters

9. Human-related activities

10. …Role of Sea Surface Wind

12. Relatively low spatial resolution : 25km × 25km

13. Unable to observe winds in the near-shore region

14. Limitation of understanding coastal phenomenaScatterometer Winds

16. Insufficient in-situ wind measurements (5 ocean buoys)

17. Need for monitoring sea surface winds at the Korean coast

18. Understanding of coastal wind variability

19. Korean Coastal regions : Unpredictable Natural Disasters (severe fog, heavy rainfall, swell, …)

21. Comparison of the high-resolution SAR-derived wind vectors with wind measurements and other satellite winds to assess the accuracy

22. Attempted to eliminate noise problems in ALOS PALSAR data

23. Understanding air-sea interactions through wind field modification over a variety of complex oceanographic phenomena, frequently apparent along the Korean coast.

25. L-band SAR-derivedSea Surface Wind Retrieval

26. Estimation of Wind Direction Wind measurement data (in situ, other satellite sensor data, reanalysis data, etc) ECMWF Interim Reanalysis Winds Interpolation 2 1 3 Incidence Angle Wind Direction Normalized Radar Cross Section(σ0) Algorithms L-band HH GMF Distribution of interpolated near surface wind vectors from ECMWF reanalysis data on 18 Jul 2007 Wind Speed

31. Backscattering Coefficient (σ0) (a) DN (b) σ0 Yellow Sea Dark and Bright Stripe- and Band-like Features Irregularity Animation of DN and NRCS values All images reveal the same issues Also found on Land !

33. Careful landuses are neededMaps of (a) NRCS(σ0) and (b) Gradient values of ALOS PALSAR ScanSAR (2007. 07. 18 02:15:15 (UTC))

34. Wind Field from ALOS PALSAR Observing Direction Low Incidence Angle Images of (a) NRCS and (b) retrieved wind field off the east coast of Korea from ALOS PALSAR image (2007/08/11 02:56:56 (UTC))

36. The noises are not limited in the Yellow Sea

38. Non-local, but Universal problem

39. The different noise patterns seems to depend on regional characteristicsRADARSAT-1 (Southeast Alaska coast)

40. Error Characteristics of SAR-derived Sea Surface Wind

42. Large RMS errors (3~7m/s)

46. Wind Field from PALSAR

47. Subsampled PALSAR winds at QuikSCAT WVC

48. Similar wind speed range (~6m/s)

50. Fairly good rms errors (<2m/s)

51. Detailed patial structure of wind speeds(a) Location of SIR-C SAR image on the SST map and (b) distribution of wind field off the east coast of Korea from SIR-C SAR data by using CMOD4 algorithm (m/s).

53. Difference of wind direction between coastal and outsea regions

54. MBL stability change-induced deflection of the wind directione.g. V > 10m/s, Maximum of wind speed error induced by wind direction : 6.09 m/s

55. How to eliminate the noises on SAR Images ?

57. Stripe- and Band-like Features

58. Irregularity

61. Determination of the frequency for band-pass filtering Clear image after noise reduction

63. Ships and Small scale oceanic features still remainedSubimagewith band-like noises, (b) the mean image of extracted noises from the spectrum, and (c) the filtered ScanSARsubimage

65. However, discontinuity between the scans were still apparent.

69. Land-Air-Sea Interactionsfrom Scatterometer and SARIntensification of Winds throughLand OrographyCharacteristic Ekman Pumping Structure

70. Schematic of air flow over coastal ranges cold-air outbreak in winter Role of Wind Field has been paid no attention Beardsley et al.(2000), The mountain ranges along the North Korean and Russian coasts reach heights of 1000m or higher, and are separated by an orographic gap at Vladivostok The wintertime synoptic weather pattern is dominated by the Siberian high, which forces northerly or northwesterly winds(cold-air outbreak) from the Asian continent over the JES 36

72. Characteristic EKP structure

73. Hypothesis on air-sea-land interaction Fig. (a) Land topography,and (b) mean of Ekman pumping. Contour overlaid in (a) is mean of EKP. Contours with zero EKP corresponds to the enter of strong winds along the wind direction, which seem to be affected by intensified winds through shallow trough of land orography. 37

74. Evidence of Orography-Induced Ekman Pumping Structure VladivostokGap Fig. Land topography, wind speed, and EKP along the Russian and North Korean coast. Zero value of EKP corresponds to the center of strong winds along the wind direction, which is produced by intensified winds through a shallow trough of land orography. 38

77. QuikSCAT winds : Similar to SAR Wind, low resolution No observation along the coast.

79. Negative Relationship

80. As land elevations are lower, so the wind speeds tend to increase

82. Thank You !