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1 Korean Journal of Remote Sensing, Vol.26, No.2, 2010, pp.115~122 Observation of Ridge-Runnel and Ripples in Mongsanpo Intertidal Flat by Satellite SAR Imagery Soyeong Jang, Hyangsun Han, and Hoonyol Lee Department of Geophysics, Kangwon National University Abstract : In this study, we analyzed ridge-runnel structure and ripple marks by using Envisat ASAR, JERS-1 SAR images and in-situ data in Mongsanpo intertidal flat located in Taean-Gun, Korea. A group of light-and-dark lines parallel to the shoreline, alternating 3-5 times, were observed in the intertidal flat in Envisat ASAR images. The patterns are related to ridge-runnel structure in the intertidal flat exposed to air. Well-drained runnels, typically with ripple marks, showed strong backscattering while runnels submerged by surface water or ridges, typically smooth with no ripple, have weak backscattering coefficients in Envisat ASAR images. In JERS-1 SAR images, however, the backscattering was very low on the entire intertidal flat and no ridge-runnel structure could be observed. The wavelengths of ripple marks measured from in-situ observations have ranges from 4 to 10 cm that satisfies the Bragg scattering condition of the 1st-order in Envisat ASAR images operating in C-band, but not in JERS-1 SAR that used L-band. Through this study using SAR images, we could successfully analyze the sedimentary conditions of intertidal flats with ridge-runnel and ripple marks which are not easily observed by optical sensors. It is expected that the results of this study with SAR images will contribute to the sedimentary research over intertidal flats. Key Words : ripple mark, ridge-runnel, intertidal flat, SAR, Bragg scattering. hoonyol@kangwon.ac.kr 115

2 Korean Journal of Remote Sensing, Vol.26, No.2,

Observation of Ridge-Runnel and Ripples in Mongsanpo Intertidal Flat by Satellite SAR Imagery Fig. 1. Study area and examples of SAR images used in this study.

3 Observation of Ridge-Runnel and Ripples in Mongsanpo Intertidal Flat by Satellite SAR Imagery Fig. 1. Study area and examples of SAR images used in this study. (a) Envisat ASAR image (2004/07/02, flow). (b) Envisat ASAR image (2004/08/06, ebb) (c) JERS-1 SAR image (1996/06/20, ebb). (d) JERS-1 SAR image (1997/07/21, flow). Site 1, 2, and 3 are the location of in-situ observation. Yellow lines in each image represent the waterline. Table 1. SAR images and tide information used in this study Satellite Aquisition Date Polarization Orbit Incidence angle Local time Tidal Height Tidal Satellite (yyyymmdd) Polarization Orbit (degree) (hh:mm) (cm) Tidal : flow Envisat VV D : ebb : ebb JERS-1 HH D : flow 117

4 Korean Journal of Remote Sensing, Vol.26, No.2, 2010 m Fig. 2. Landsat-7 ETM+ image (2004/03/23). (a) An RGB image with band-3, 2, 1 composite does not show any pattern of ridge-runnel. (b) The band-5 image (mid-infrared) of ETM+ that faintly shows the ridge-runnel pattern. 118

Observation of Ridge-Runnel and Ripples in Mongsanpo Intertidal Flat by Satellite SAR Imagery Fig. 3. Backscattering coefficient of Envisat ASAR and JERS-1 SAR images.

5 Observation of Ridge-Runnel and Ripples in Mongsanpo Intertidal Flat by Satellite SAR Imagery Fig. 3. Backscattering coefficient of Envisat ASAR and JERS-1 SAR images. (a) Backscattering coefficient lines for the site 1, 2, and 3 shown over the Envisat ASAR image (2004/07/02). Backscattering coefficient profiles of the site 1 (b), site 2 (c). and site 3(d). The solid lines are backscattering coefficient of Envisat ASAR image (2004/07/02) while the dotted lines are those of JERS-1 SAR image. Ridge-runnel structure and ripple marks reside between the two vertical lines. 119

6 Korean Journal of Remote Sensing, Vol.26, No.2, 2010 Fig. 4. Ripples and ridge-runnel structure in Mongsanpo intertidal flat. (a) Runnel in the left of the image with ripples and ridge with no ripple on the right (2007/08/23). (b) Well-drained symmetric ripples on runnel (2007/08/23). (c) Smooth surface of a ridge with no ripple (2009/12/16). (d) Ripples under water (2009/04/24). nl l r = (n = 1, 2, 3,...) (1) 2sinq i n = order number l r = ripple wavelength l = radar wavelength q i = incidence angle n 120

7 Observation of Ridge-Runnel and Ripples in Mongsanpo Intertidal Flat by Satellite SAR Imagery Fig. 5. Histograms of ripple wavelength measured on (a) 23 August 2007 and (b) 9 March The first order Bragg scattering occurs at the ripple wavelength of 7.2 cm for C-band and 18.7 cm for L-band. n n n n n 121

8 Korean Journal of Remote Sensing, Vol.26, No.2, 2010 Allen, J. R. L., A model for the interpretation of wave ripple-marks using their wavelength, textural composition, and shape, Journal of Geological Society, 136: Carling, P. A., J. J. Williams, I. W. Croudace, and C. L. Amos, Formation of mud ridge and runnel in the intertidal zone of the Severn Estuary, UK, Continental Shelf Research, 29: Chauhan, P. P. S., Bedform association on a Ridge and Runnel foreshore: Implications for the hydrography of a macrotidal Estuarine Beach, Journal of Coastal Research, 16(4): King, C. A. M. and W. W. Williams, The formation and movement of sand bars by wave action, The Geographical Journal, 113: Long, M. W., Radar reflectivity of land and sea, 3rd Edition, Artech House, Boston, USA. Moore, J. N., W. J. Fritz, and R. S. Futch, Occurrence of megaripples in a ridge and runnel system, Sapelo Island, Georgia: Morphology and processes, Journal of Sedimentary Petrology, 54(2): Orme, A. R. and A. J. Orme, Ridge-and-runnel enigma, Geographical Review, 78(2): Owens, E. H. and D. H. Frobel, Ridge and runnel systems in the Magdalen Islands, Quebec, Journal of Sedimentary Petrology, 47(1): Park, S. E., W. M. Moon, and D. J. Kim, Estimation of surface roughness parameter in intertidal mudflat using airborne polarimetric SAR data, IEEE Transactions on Geoscience and Remote Sensing, 47(4): Tanner, W. F., Ripple mark indices and their uses, Sedimentology, 9: Van der Wal, D., P. M. J. Herman, and A. W. Dool, Characterisation of surface roughness and sediment texture of intertidal flats using ERS SAR imagery, Remote Sensing of Environment, 98(1): Vincent, C. E., R. C. Kay, C. Chenghui, L. Li, and J. Jarvis, Morphology, sedimentary bedforms and sand transport across a ridgeand-runnel beach under the action of summer waves, Chinese Journal of Oceanology and Limnology, 8(3): Williams, J. J., P. A. Carling, C. L. Amos, and C. Thompson, Field investigation of ridgerunnel dynamics on an intertidal mudflat, Estuarine, Coastal and Shelf Science, 79:

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09È«¼®¿µ5~152s Korean Journal of Remote Sensing, Vol.23, No.2, 2007, pp.45~52 Measurement of Backscattering Coefficients of Rice Canopy Using a Ground Polarimetric Scatterometer System Suk-Young Hong*, Jin-Young Hong**,