Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters
Abstract
:1. Introduction
2. Methods
2.1. In situ Measurements and Synthetic Aperture Radar (SAR) Images
2.2. C-Band Geophysical Model Function (GMF)
2.3. Height Correction of In situ Wind Speed
2.4. Conversion from ENW to SDW
3. Results and Discussion
3.1. Accuracies of Wind Speed Retrieval Using Four GMFs
3.2. Effect of Short Fetch on Wind Speed Retrieval
3.3. Effectiveness of Atmospheric Stability Correction with CMOD5.N
4. Conclusions
- Of all the GMFs, the stability-dependent wind speed (SDW) retrieved with CMOD5.N and corrected for atmospheric stability with the LKB code (CMOD5.N_SDW) has the smallest root mean square error (RMSE) and the smallest bias at both Hiratsuka and Shirahama. The RMSEs are 2.03 m/s at Hiratsuka and 1.76 m/s at Shirahama, and the biases are −0.77 m/s at Hiratsuka and −0.42 m/s at Shirahama.
- All of the GMFs exhibit a negative bias in the retrieved wind speed at both validation sites. By contrasting winds blowing onshore and offshore, only offshore winds were found to have a large negative bias. This indicates that the negative bias is primarily caused by short fetches from a coastline.
- Atmospheric stability can cause an error of about −1 to +1 m/s in the SAR retrieved wind speed at Shirahama when using the GMFs that do not take the effect of atmospheric stability into account. CMOD5.N can reduce this error especially in non-neutral conditions, indicating that the use of CMOD5.N is effective for the atmospheric stability correction.
Acknowledgments
References
- APDRC. Available online: http://apdrc.soest.hawaii.edu/data/data.php (accessed on 10 October 2012).
- Stoffelen, A.; Anderson, D. Scatterometer data interpretation: Estimation and validation of the transfer function CMOD-4. J. Geophys. Res 1997, 102, 5767–5780. [Google Scholar]
- Lehner, S.; Horstmann, J.; Koch, W.; Rosenthal, W. Mesoscale wind measurements using recalibrated ERS SAR images. J. Geophys. Res 1998, 103, 7847–7856. [Google Scholar]
- Horstmann, J.; Koch, W.; Lehner, S.; Tonboe, R. Ocean winds from RADARSAT-1 ScanSAR. Can. J. Remote Sens 2002, 28, 524–533. [Google Scholar]
- Hasager, C.B.; Dellwik, E.; Nielsen, M.; Furevik, B.R. Validation of ERS-2 SAR offshore wind-speed maps in the North Sea. Int. J. Remote Sen 2004, 25, 3817–3841. [Google Scholar]
- Stoffelen, A. Toward the true near-surface wind speed: Error modeling and calibration using triple collocation. J. Geophys. Res 1998, 103, 7755–7766. [Google Scholar]
- Quilfen, Y.; Chapron, B.; Elfouhaily, T.; Katsaros, K.; Tournadre, J. Observation of tropical cyclones by high-resolution scatterometry. J. Geophys. Res 1998, 103, 7767–7786. [Google Scholar]
- Hasager, C.B.; Badger, M.; Peña, A.; Larsén, X.G.; Bingöl, F. SAR-based wind resource statistics in the Baltic Sea. Remote Sens 2011, 3, 117–144. [Google Scholar]
- Hersbach, H.; Stoffelen, A.; Haan, S. An improved C-band scatterometer ocean geophysical model function: CMOD5. J. Geophys. Res 2007, 112, 1–18. [Google Scholar]
- Hersbach, H. Comparison of C-band scatterometer CMOD5.N equivalent neutral winds with ECMWF. J. Atm. Oceanic Tech 2010, 27, 721–736. [Google Scholar]
- Liu, W.T.; Tang, W. Equivalent Neutral Wind. 1996, pp. 96–178. Available online: http://airsea-www.jpl.nasa.gov/data (accessed on 10 October 2012).
- Monin, A.S.; Obukhov, A.M. Basic laws of turbulent mixing in the surface layer of the atmosphere. Tr. Akad. Nauk SSSR Geophiz. Inst 1954, 24, 164–187. [Google Scholar]
- Cressman, G.P. An operational objective analysis system. Mon. Wea. Rev 1959, 87, 67–374. [Google Scholar]
- Takeyama, Y.; Ohsawa, T.; Kozai, K.; Hasager, C.B.; Badger, M. Error Factors in SAR Wind Retrieval for Inshore Areas. Proceedings of European Offshore Wind 2009 Conference & Exhibition, Stockholm, Sweden, 14–16 September 2009; PO. 136. p. 10.
- Shankaranarayanan, K.; Donelan, M.A. A probabilistic approach to scatterometer model function verification. J. Geophys. Res 2001, 106, 19969–19990. [Google Scholar]
- Vachon, P.W.; Dobson, F.W. Wind retrieval from radarsat sar images: Selection of a suitable C-band HH polarization wind retrieval model. Can. J. Rem. Sens 2000, 26, 306–313. [Google Scholar]
- ASCAT Wind Product User Manual, Version 1.12; 2012, p. 27. Available online: http://www.knmi.nl/scatterometer/publications/pdf/ASCAT_Product_Manual.pdf (accessed on 10 October 2012).
- Vachon, P.W.; Dobson, F.W. Validation of wind vector retrieval from ERS-1 SAR images over the ocean. Glob. Atmos. Ocean Syst 1996, 5, 177–187. [Google Scholar]
- Wackerman, C.; Rufenach, C.L.; Shuchman, R.A.; Johannessen, J.A.; Davidson, K.L. Wind vector retrieval using ERS-1 synthetic aperture radar imagery. IEEE Trans. Geosci. Remote Sens 1996, 34, 1343–1352. [Google Scholar]
- Takeyama, Y.; Ohsawa, T.; Kozai, K.; Hasager, C.B.; Badger, M. Effectiveness of weather research and forecasting wind direction for retrieving coastal sea surface wind from synthetic aperture radar. Wind Energy, 2013; in press. [Google Scholar]
- Mouche, A.A.; Hauser, D.; Daloze, J.; Gueri, C. Dual-Polarization measurements at C-Band over the ocean: Result from airborne radar observations and comparison with ENVISAT ASAR data. IEEE Trans. Geosci. Remote Sens 2005, 43, 753–769. [Google Scholar]
- Liu, W.T.; Katsaros, K.B.; Businger, J.A. Bulk parameterization of air-sea exchanges of heat and water vapor including the molecular constraints at the interface. J. Atmos. Sci 1979, 36, 1722–1735. [Google Scholar]
- The Weather Research and Forecasting Model. Available online: http://wrf-model.org/index.php (accessed on 10 October 2012).
- Charnock, H. Wind stress on a water surface. Q. J. Roy. Meteor. Soc 1955, 81, 639–640. [Google Scholar]
- Abdalla, S.; Hersbach, H. The Technical Support for Global Validation of ERS Wind and Wave Products at ECMWF. Final Report for ESA Contract 15988/02/I-LG. 2004, p. 59. Available online: http://www.ecmwf.int/publications/library/ecpublications/_pdf/esa/ESA_abdalla_hersbach.pdf (accessed on 10 October 2012).
- Portabella, M.; Stoffelen, A. On scatterometer ocean stress. J. Atm. Oceanic Tech 2009, 26, 368–382. [Google Scholar]
- Shimada, T.; Kawamura, H.; Shimada, M. Evaluation of JERS-1 SAR images from a coastal wind retrieval point of view. IEEE Trans. Geosci. Remote Sens 2004, 42, 491–500. [Google Scholar]
Appendix
Appendix 1. List of 33 ENVISAT Advanced SAR images with corresponding in situ measurements at Hiratsuka.
SAR | In situ | WRF | |||||
---|---|---|---|---|---|---|---|
Date (year/month/day) | Time (hr:min:sec) | Polarization | Observation Mode | Wind Direction (°C) | Wind Speed (m·s−1) at 10 m | Sea Temp. (°C) | Air Temp. (°C) |
2003/02/01 | 00:54:51 | VV | IMP | 3 | 6.1 | 17.8 | 8.6 |
2003/02/17 | 00:51:57 | VV | IMP | 350 | 3.7 | 18.1 | 11.6 |
2003/06/21 | 00:54:56 | VV | IMP | 213 | 3.8 | 23.8 | 25.3 |
2003/07/26 | 00:55:00 | VV | IMP | 5 | 5.8 | 24.3 | 25.5 |
2003/08/30 | 00:55:04 | VV | IMP | 19 | 3.6 | 26.5 | 28.0 |
2003/10/04 | 00:55:00 | VV | IMP | 38 | 3.4 | 26.0 | 21.0 |
2003/10/20 | 00:52:06 | VV | IMP | 1 | 8.4 | 24.2 | 18.5 |
2003/11/08 | 00:54:56 | VV | IMP | 117 | 3.0 | 24.4 | 20.9 |
2003/12/25 | 12:31:35 | VV | IMP | 233 | 17.2 | 20.2 | 15.7 |
2003/12/29 | 00:52:09 | VV | IMP | 259 | 9.4 | 20.1 | 13.4 |
2005/10/05 | 00:49:22 | HH | IMP | 40 | 3.0 | 22.6 | 22.0 |
2005/11/25 | 00:46:29 | HH | IMP | 24 | 4.7 | 22.9 | 14.8 |
2005/12/30 | 00:46:22 | HH | IMP | 18 | 2.4 | 16.9 | 7.2 |
2006/03/10 | 00:46:20 | HH | IMP | 357 | 10.2 | 17.1 | 10.2 |
2006/05/19 | 00:46:26 | HH | IMP | 17 | 4.4 | 20.5 | 21.5 |
2006/06/23 | 00:46:31 | HH | IMP | 298 | 2.0 | 22.6 | 22.4 |
2006/07/28 | 00:46:32 | HH | IMP | 168 | 4.3 | 24.4 | 25.4 |
2007/01/22 | 00:52:02 | VV | IMP | 352 | 7.5 | 18.7 | 9.7 |
2007/05/04 | 00:46:26 | HH | IMP | 121 | 3.6 | 21.6 | 20.2 |
2007/05/07 | 00:52:06 | HH | IMP | 174 | 3.0 | 21.1 | 19.8 |
2007/06/08 | 00:46:28 | VV | IMP | 146 | 4.2 | 21.7 | 21.2 |
2007/08/17 | 00:46:28 | HH | IMP | 146 | 2.8 | 29.4 | 30.7 |
2007/09/21 | 00:46:23 | VV | IMP | 183 | 1.2 | 25.9 | 25.7 |
2007/11/17 | 00:54:53 | VV | IMP | 3 | 5.8 | 22.8 | 13.7 |
2007/11/30 | 00:46:19 | HH | IMP | 353 | 6.4 | 20.2 | 13.3 |
2007/12/03 | 00:51:59 | HH | IMP | 212 | 7.2 | 19.6 | 15.3 |
2008/04/21 | 00:52:00 | VV | IMP | 8 | 6.9 | 19.3 | 19.7 |
2008/06/27 | 00:46:22 | HH | IMP | 83 | 3.1 | 21.0 | 22.2 |
2008/08/01 | 00:46:22 | HH | IMP | 165 | 2.9 | 22.2 | 20.9 |
2008/10/13 | 00:52:00 | VV | IMP | 113 | 4.8 | 27.6 | 27.1 |
2008/11/14 | 00:46:23 | HH | IMP | 23 | 6.1 | 24.6 | 21.5 |
2008/11/17 | 00:51:57 | VV | IMP | 354 | 6.5 | 21.4 | 17.5 |
2008/12/22 | 00:51:59 | VV | IMP | 91 | 2.0 | 22.6 | 17.9 |
Appendix 2. Same as Appendix 1, but for 73 images and in situ measurements at Shirahama.
SAR | In situ | ||||||
---|---|---|---|---|---|---|---|
Date (year/month/day) | Time (hr:min:sec) | Polarization | Observation Mode | Wind Direction (°C) | Wind Speed (m/s) at 10 m | Sea Temp. (°C) | Air Temp. (°C) |
2003/05/07 | 01:09:47 | VV | IMP | 114 | 3.6 | 22.1 | 22.4 |
2003/07/16 | 01:09:53 | VV | IMP | 296 | 6.6 | 25.2 | 23.6 |
2003/09/24 | 01:09:56 | VV | IMP | 59 | 11.2 | 26.2 | 22.4 |
2003/10/29 | 01:09:50 | VV | IMP | 347 | 10.3 | 24.2 | 16.8 |
2003/12/19 | 01:07:03 | VV | IMP | 347 | 15.1 | 20.2 | 8.3 |
2004/01/23 | 01:07:00 | VV | IMP | 322 | 7.8 | 16.9 | 4.0 |
2004/02/11 | 01:09:51 | VV | IMP | 320 | 3.9 | 17.0 | 8.3 |
2004/02/27 | 01:07:00 | VV | IMP | 308 | 9.9 | 16.4 | 6.9 |
2004/05/07 | 01:07:00 | VV | IMP | 268 | 4.5 | 20.5 | 20.7 |
2004/06/30 | 01:09:55 | VV | IMP | 64 | 5.3 | 25.6 | 24.7 |
2004/07/31 | 12:48:26 | VV | IMP | 115 | 11.3 | 27.0 | 28.6 |
2004/08/20 | 01:07:04 | VV | IMP | 259 | 5.1 | 27.7 | 27.6 |
2004/09/08 | 01:09:55 | VV | IMP | 286 | 2.5 | 27.2 | 26.1 |
2004/10/13 | 01:09:56 | VV | IMP | 20 | 8.9 | 24.8 | 21.8 |
2004/10/29 | 01:07:06 | VV | IMP | 93 | 5.7 | 22.8 | 19.6 |
2005/01/07 | 01:06:58 | VV | IMP | 10 | 7.3 | 16.2 | 10.7 |
2005/02/11 | 01:07:01 | VV | IMP | 331 | 6.1 | 15.8 | 5.8 |
2005/05/11 | 01:09:59 | VV | IMP | 247 | 3.5 | 17.6 | 18.2 |
2005/05/27 | 01:07:07 | VV | IMP | 176 | 3.8 | 19.0 | 23.1 |
2005/10/14 | 01:07:05 | VV | IMP | 96 | 5.0 | 25.7 | 24.7 |
2005/11/18 | 01:07:03 | VV | IMP | 6 | 6.8 | 22.0 | 13.2 |
2005/12/23 | 01:06:57 | VV | IMP | 326 | 9.6 | 15.4 | 6.8 |
2006/01/11 | 01:09:42 | VV | IMP | 358 | 5.9 | 18.2 | 8.5 |
2006/03/03 | 01:06:54 | VV | IMP | 317 | 9.1 | 15.1 | 5.9 |
2007/08/29 | 01:09:47 | VV | IMP | 244 | 2.4 | 29.1 | 28.5 |
2007/11/07 | 01:09:43 | VV | IMP | 16 | 4.0 | 23.9 | 18.0 |
2007/11/23 | 01:06:48 | VV | IMP | 352 | 9.9 | 21.8 | 10.3 |
2007/12/08 | 12:48:10 | VV | IMP | 176 | 5.7 | 20.5 | 11.1 |
2007/12/09 | 01:03:59 | VV | IMP | 340 | 8.3 | 20.4 | 10.4 |
2008/01/12 | 12:48:12 | VV | IMP | 348 | 8.8 | 20.3 | 9.8 |
2008/01/13 | 01:04:01 | VV | IMP | 347 | 9.2 | 20.0 | 6.5 |
2008/01/16 | 01:09:43 | VV | IMP | 349 | 7.1 | 18.4 | 7.9 |
2008/01/31 | 12:51:01 | VV | IMP | 7 | 6.6 | 17.6 | 6.0 |
2008/02/01 | 01:06:50 | VV | IMP | 355 | 5.5 | 17.5 | 5.7 |
2008/02/16 | 12:48:09 | VV | IMP | 323 | 10.8 | 15.3 | 4.7 |
2008/02/17 | 01:03:59 | VV | IMP | 342 | 10.6 | 15.1 | 1.7 |
2008/02/20 | 01:09:42 | VV | IMP | 345 | 6.6 | 16.8 | 6.9 |
2008/03/06 | 12:51:02 | VV | IMP | 72 | 4.9 | 16.7 | 7.0 |
2008/03/07 | 01:06:51 | VV | IMP | 337 | 6.7 | 16.6 | 9.0 |
2008/03/22 | 12:48:13 | VV | IMP | 244 | 4.2 | 17.5 | 12.3 |
2008/03/23 | 01:04:02 | VV | IMP | 159 | 7.3 | 18.3 | 13.5 |
2008/03/26 | 01:09:43 | VV | IMP | 354 | 5.1 | 18.2 | 12.9 |
2010/06/25 | 01:01:06 | VV | WSM | 84 | 3.1 | 24.1 | 23.4 |
2010/07/11 | 01:01:03 | VV | WSM | 168 | 7.4 | 24.0 | 26.1 |
2010/07/27 | 01:01:00 | VV | WSM | 184 | 2 | 27.0 | 30.7 |
2010/07/30 | 01:01:06 | VV | WSM | 205 | 2.9 | 26.4 | 27.8 |
2010/08/12 | 00:00:57 | VV | WSM | 218 | 10.6 | 27.8 | 28.2 |
2010/08/15 | 01:01:03 | VV | WSM | 211 | 5.2 | 28.4 | 28.8 |
2010/08/18 | 01:01:09 | VV | WSM | 286 | 4.2 | 28.2 | 28.7 |
2010/08/31 | 01:01:00 | VV | WSM | 223 | 2.4 | 29.0 | 29.3 |
2010/09/03 | 01:01:06 | VV | WSM | 267 | 3 | 29.6 | 28.3 |
2011/10/30 | 01:01:07 | VV | WSM | 30 | 2.8 | 24.2 | 19.8 |
2011/12/07 | 01:01:14 | VV | WSM | 359 | 5.7 | 21.7 | 14.5 |
2011/12/10 | 01:01:04 | VV | WSM | 33 | 4.3 | 21.5 | 9.5 |
2011/12/18 | 01:01:11 | VV | WSM | 3 | 9.1 | 21.2 | 8.4 |
2010/06/27 | 12:12:56 | VV | WSM | 187 | 5 | 24.0 | 25.4 |
2010/07/13 | 12:12:53 | VV | WSM | 164 | 7.6 | 23.9 | 26.1 |
2010/08/14 | 12:12:47 | VV | WSM | 176 | 5.6 | 28.2 | 28.0 |
2010/09/05 | 12:12:56 | VV | WSM | 104 | 2.7 | 29.9 | 27.8 |
2010/09/18 | 12:12:47 | VV | WSM | 95 | 3.2 | 27.7 | 24.0 |
2010/09/21 | 12:12:53 | VV | WSM | 103 | 2.9 | 27.7 | 26.4 |
2011/10/18 | 12:12:58 | VV | WSM | 108 | 3.9 | 25.4 | 18.5 |
2011/10/26 | 13:13:04 | VV | WSM | 29 | 5.2 | 24.5 | 14.6 |
2011/10/29 | 12:12:54 | VV | WSM | 119 | 5.1 | 24.2 | 19.1 |
2011/11/06 | 13:13:01 | VV | WSM | 355 | 5.8 | 23.8 | 21.5 |
2011/11/25 | 13:13:04 | VV | WSM | 18 | 5.9 | 21.8 | 11.0 |
2011/12/06 | 13:13:01 | VV | WSM | 23 | 4.7 | 21.8 | 13.6 |
2011/12/17 | 12:12:58 | VV | WSM | 26 | 5.7 | 20.3 | 7.9 |
2011/12/28 | 12:12:55 | VV | WSM | 71 | 3.2 | 18.9 | 6.5 |
2012/01/06 | 01:01:15 | VV | WSM | 14 | 7.3 | 18.0 | 6.6 |
2012/01/09 | 01:01:05 | VV | WSM | 24 | 7.1 | 17.9 | 9.5 |
2012/01/05 | 13:13:01 | VV | WSM | 27 | 7.2 | 18.3 | 6.3 |
2012/01/16 | 12:12:58 | VV | WSM | 46 | 7 | 18.3 | 6.4 |
Appendix 3. The model configuration used in the WRF simulation is shown.
Initial data | MANAL NGSST (0.05° × 0.05°, daily) | |||
Vertical resolution | 28 levels (surface to 10 hPa) | |||
Nesting option | two-way nesting | |||
Domain | Domain 1 | Domain 2 | Domain 3 | |
Horizontal | 4.5 km | 1.5 km | 0.5 km | |
Grid points | 100 × 100 | 100 × 100 | 100 × 100 | |
Time step | 27 sec | 9 sec | 3 sec | |
Surface layer | Monin-Obukhov (Janjic Eta) | |||
Planetary Boundary | Mellor-Yamada-Janjic | |||
Layer | (Eta) TKE | |||
Short wave radiation | Dudhia | |||
Physics | Long wave radiation | RRTM | ||
option | Cloud microphysics | WSM3 | ||
Cumulus parameterization | Kain-Fritsch (new Eta) | none | none | |
Land surface | Five-layer soil | |||
4dda option | Enable including PBL | Enable excluding PBL | Enable excluding BL |
CMOD4 | CMOD_IFR2_SDW | CMOD5 | CMOD5.N_SDW | ||
---|---|---|---|---|---|
Hiratsuka | RMSE (m/s) | 2.17 | 2.34 | 2.06 | 2.03 |
Bias (m/s) | −1.15 | −1.31 | −0.98 | −0.77 | |
Correlation coef. | 0.80 | 0.77 | 0.80 | 0.79 | |
Shirahama | RMSE (m/s) | 1.97 | 2.05 | 1.77 | 1.76 |
Bias (m/s) | −1.10 | −1.06 | −0.64 | −0.42 | |
Correlation coef. | 0.80 | 0.79 | 0.81 | 0.79 |
CMOD4 | CMOD_IFR2_SDW | CMOD5 | CMOD5.N_SDW | ||
---|---|---|---|---|---|
Onshore | RMSE (m/s) | 0.74 | 0.86 | 0.64 | 0.88 |
Bias (m/s) | −0.12 | −0.15 | 0.20 | 0.57 | |
Correlation coef. | 0.95 | 0.93 | 0.96 | 0.95 | |
Offshore | RMSE (m/s) | 2.16 | 2.21 | 2.22 | 2.03 |
Bias (m/s) | −1.38 | −1.40 | −0.99 | −0.81 | |
Correlation coef. | 0.79 | 0.77 | 0.80 | 0.78 |
Atmospheric Condition | Unstable (z/L ≤ −1.0) | Neutral (−1.0 < z/L ≤ 0.1) | Stable (0.1 < z/L) | |
---|---|---|---|---|
Bias (m/s) | CMOD5.N_SDW | −0.97 | 0.16 | 0.36 |
CMOD5 | −1.01 | −0.11 | −1.04 | |
RMSE (m/s) | CMOD5.N_SDW | 1.83 | 1.72 | 1.47 |
CMOD5 | 1.85 | 1.70 | 1.62 |
Share and Cite
Takeyama, Y.; Ohsawa, T.; Kozai, K.; Hasager, C.B.; Badger, M. Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters. Remote Sens. 2013, 5, 1956-1973. https://doi.org/10.3390/rs5041956
Takeyama Y, Ohsawa T, Kozai K, Hasager CB, Badger M. Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters. Remote Sensing. 2013; 5(4):1956-1973. https://doi.org/10.3390/rs5041956
Chicago/Turabian StyleTakeyama, Yuko, Teruo Ohsawa, Katsutoshi Kozai, Charlotte Bay Hasager, and Merete Badger. 2013. "Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters" Remote Sensing 5, no. 4: 1956-1973. https://doi.org/10.3390/rs5041956