1. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Frost mapping with NOAA- AVHRR data G. Antolini, V. Marletto ISTITUTO DI BIOMETEOROLOGIA CONSIGLIO NAZIONALE DELLE RICERCHE Meteorological Service – Enviromental Protection and Prevention Agency Remote Sensing Laboratory With the collaboration of: M. Menenti, Z.L. Li, F. Becker Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection Université Louis Pasteur Strasbourg

2. 15 June 2005 Workshop on climatic analysis and mapping for agriculture What we needed… We need to assess the spatial variability of frost, in order to: - Validate our interpolation models and improve them - Realize a frost risk map for Emilia-Romagna - Assess the simulation of frost events with numerical meteorological models By frost maps we mean night Land Surface Temperature (LST) maps, during a frost event

3. 15 June 2005 Workshop on climatic analysis and mapping for agriculture What is frost… Physical meaning: a phase change in water (from liquid or vapor to solid) We want to know where frost is more likely to occur in order to plan crop protection (radiative frost). Agrometeorological meaning: low temperatures that causes ice formation in crop cells

4. 15 June 2005 Workshop on climatic analysis and mapping for agriculture What is frost… Typical synoptic situation Typical micrometeorological conditions

5. 15 June 2005 Workshop on climatic analysis and mapping for agriculture What we used… NOAA Polar orbiter satellite AVHRR sensor

6. 15 June 2005 Workshop on climatic analysis and mapping for agriculture What we used…

7. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Planck blackbody law: A few words on theory… Problems: Land surface is not a perfect blackbody. The emitted radiance depends on spectral emissivity and land surface temperature. We cannot assume homogenous emissivity. There are always one more missing variable than equations (N channel emissivities + surface temperature). Atmospheric correction

8. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Processing of NOAA-AVHRR data Pre-processing of raw data - Calibration - Navigation (manual or automatic) Processing of calibrated data - Cloud detection and maskingCloud detection and masking - Atmospheric correction Atmospheric correction - Surface emissivity retrieval Surface emissivity retrieval - Land surface temperature retrieval Land surface temperature retrieval

9. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Pre-processing…

10. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Cloud detection Saunder and Kriebel (1988, IJRS, 9: 123-150) Gesell (1989, IJRS,10: 897-905) for ice/snow detection

11. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Atmospheric correction Atmospheric water vapor retrieval Ch. 4Ch. 5 MODTRAN Radiosounds Radiative transfer modelling to compute unknown atmospheric radiative quantities Computation of night and day surface brightness temperature Atmospheric quantities

12. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Surface emissivity retrieval TISI (Temperature-Independent Spectral Indices) Day surface brightness temperature Ch. 3, 4, 5 March 17th 2003, 04:25 UTC Night surface brightness temperature Ch. 4, 5 March 19th 2003, 15:01 UTC Emissivity depends on: Composition of surface Roughness of surface Other physical parameters (soil moisture…) Wavelength

13. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Land surface temperature retrieval Surface emissivity Atmospheric quantities maps (atmospheric correction results) Split window algorythm

14. 15 June 2005 Workshop on climatic analysis and mapping for agriculture March 17th 2003 04:25 UTC

15. 15 June 2005 Workshop on climatic analysis and mapping for agriculture March 23th 2003 03:39 UTC

16. 15 June 2005 Workshop on climatic analysis and mapping for agriculture April 9th 1997 02:04 UTC

17. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Comparison with observations (spatial interpolation methods) Some considerations: - thermodynamique vs radiometric temperatures - time lag - spatial resolution - surface vs air temperature

18. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Frost risk mapping LATE FROST RISK low medium high very high

19. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Numerical weather simulations RAMS (Regional Atmospheric Modeling System)

20. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Thanks for your attention

21. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Satellite Atmosphere Outer of atmosphere Sun Surface A few words on theory…

22. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Effects on LST of atmosphere (transmissivity) and emissivity

23. 15 June 2005 Workshop on climatic analysis and mapping for agriculture Becker F., Li Z. L., 1995. Surface temperature and emissivity at various scales: definition, measurement and related problems. Remote Sensing Reviews, vol. 12, 225-253. Gesell, G., 1989. An Algorithm for Snow and Ice Detection Using AVHRR Data: An Extension to the APOLLO Software Package. Int. J. Remote Sensing 10, 897-905. Li Z.L., Becker F., Stoll M.P., Wan Z., 1999. Evaluation of six methods for extracting relative emissivity spectra from thermal infrared images. Remote Sens. Environ. 69, 197-214. Nerry F., Petitcolin F., Stoll M.P., 1998. Bidirectional reflectivity in AVHRR channel 3: application to a region in Northern Africa. Remote Sens. Environ. 66, 298-316. Saunders R.W., 1986. An Automated Scheme for the Removal of Cloud Contamination from AVHRR Radiances over Western Europe. Int. J. Remote Sensing 7, 867-886. Saunders, R.W., Kriebel, K.T., 1988. An Improved Method of Detecting Clear Sky and Cloudy Radiances from AVHRR Data. International Journal of Remote Sensing 9: 123-150. Sobrino J.A. (ed.), 2000. Teledetección. Servicio de Publicaciones, Universidad de Valencia, ISBN 84-370-4220-8, 467 pp. Sobrino J.A., Raissouni N., Li Z.L., 2001. A comparative study of land surface emissivity retrieval from NOAA data. Remote Sens. Environ. 75, 256-266. BIBLIOGRAPHY