1 / 17

Monitoring and Retrieving Rice Phenology by means of Satellite SAR Polarimetry at X-band

Monitoring and Retrieving Rice Phenology by means of Satellite SAR Polarimetry at X-band. Juan M. Lopez-Sanchez J. David Ballester-Berman. Shane R. Cloude. AEL Consultants. Signals, Systems & Telecommunications Group University of Alicante. Motivation.

dorjan
Download Presentation

Monitoring and Retrieving Rice Phenology by means of Satellite SAR Polarimetry at X-band

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Monitoring and Retrieving Rice Phenology by means of Satellite SAR Polarimetry at X-band Juan M. Lopez-Sanchez J. David Ballester-Berman Shane R. Cloude AEL Consultants Signals, Systems & Telecommunications Group University of Alicante

  2. Motivation • Motivation: examples of known demands from rice farmers in Spain • Timely information for: • Effective germination measurements • When all plants have emerged they count their number. If low, more seeds are added • Nitrogen fertillization stop • Once all panicles in a field have appeared, fertilization is not longer needed • Excessive fertilization may cause an increase in pests • Detection of cultivation problems due to water salinity: areas with delayed development • Objective: Is it possible to retrieve the current phenological stage from a single acquisition? • Approach: • Analysis and interpretation of the polarimetric behavior of rice at different phenological stages • If possible, proposal of a retrieval approach based on scattering properties

  3. Site • Mouth of the Guadalquivir river, Sevilla (SW Spain) 30km x 30km

  4. Ground campaign • Campaigns: 2008 and 2009 • Ground measurements over 5-8 parcels provided by the local association of rice farmers (Federación de Arroceros de Sevilla) • Weekly (defined at field level): • Phenology: BBCH stage (0-99) • Vegetation height • Additional information: • Sowing and harvest dates • Plantation density: plants/m2, panicles/m2 • Yield (kg/ha) • Important: • A water layer is always present at ground during the campaign • Sowing is carried out by spreading seeds (from a plane) randomly over flooded fields

  5. Satellite data 2008 2009 Failed orders Available images TerraSAR-X images provided by DLR in the framework of projects LAN0021 and LAN0234

  6. Analysis of observations • TerraSAR-X, 30 deg, 2009: Temporal evolution HH VV HH-VV

  7. Analysis of observations TerraSAR-X HHVV dual-pol images: List of observables Backscattering coefficients and HH/VV ratio Backscattering coefficients at the Pauli basis (HH+VV, HH-VV) Correlation between HH and VV: magnitude and phase (PPD) Correlation between 1st and 2nd Pauli channels: mag. and phase Eigenvector decomposition (H2a): Entropy and alpha Model-based decomposition: Random volume + polarized term (rank1) Coherent acquisition of co-pol channels

  8. Analysis of observations vs phenology HH and VV power • Power Nearly random volume Wind induced roughness Increasing randomness Development Vegetative phase Reproductive phase Maturation Double-bounce Vertical orientation: differential extinction

  9. Analysis of observations vs phenology • Correlation between HH and VV Magnitude Phase (PPD) Vegetative phase Vegetative phase Reproductive phase Reproductive phase Maturation Maturation

  10. Analysis of observations vs phenology • Eigenvalue decomposition Entropy Alpha (dominant) Vegetative phase Reproductive phase Maturation + Double-bounce Wind induced roughness

  11. Retrieval of phenology from TSX data • Basic retrieval approach with a single acquisition (TSX) • Four parameters • HHVV coherence and phase difference • Entropy and alpha1

  12. Retrieval of phenology from TSX data • Basic retrieval approach with a single acquisition (TSX) • Five phenological intervals • Decision plane

  13. Retrieval of phenology from TSX data • Retrieval results (parcel F)

  14. Retrieval of phenology from TSX data • Retrieval results: Comparison against ground data • Percentage of pixels assigned to each stage within a parcel Parcel B Parcel C

  15. Retrieval of phenology from TSX data • Comments on the approach • Useful tracking of phenology: • At parcel level: BBCH agrees with the stage assigned to the majority of pixels inside the parcels (with some exceptions) • At (multi-looked) pixel level: parts with different development within a parcel are well identified • But not perfect.. • The algorithm is very ‘simple’: parameters and thresholds have been selected manually (it could be optimized) • An ambiguity between plant emergence (BBCH 18-21) and last stages (BBCH +50) is still present at some areas. Both are characterized by high entropies

  16. Conclusions • Coherent dual-pol data provided by TerraSAR-X have been useful for retrieving phenology of rice fields with a single acquisition • Advantages when compared to other possible approaches: • 11-days revisit rate with the same sensor & mode • High spatial resolution • Retrieval with a single pass is possible (single-pol and incoherent dual-pol are not enough) • Limitations: • There remain some ambiguities that might be solved with full-pol data (e.g. using anisotropy), but not in operational mode with TSX • Low coverage: TSX dual-pol swath is 15 km on ground • Some measurements are below or close to the noise level of TSX (-19 dB)

  17. Future lines of research • Multi-temporal approaches (time series) • Time coordinate provides extra information • Multi-angular (and multi-temporal) integration • Ideal to reduce refresh time or increase spatial coverage • Development of an operational scheme with farmers • Pending issues: • Presence of rain • Other species within the rice fields (mixture) • Application to rice under different farming practices: • Plantation procedures and arrangements • Dry ground at some moments

More Related