Frost mapping with NOAA- AVHRR data G. Antolini, V. Marletto

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

2. 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 Workshop on climatic analysis and mapping for agriculture

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

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

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

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

7. A few words on theory… Planck blackbody law: 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 Workshop on climatic analysis and mapping for agriculture

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

23. BIBLIOGRAPHY 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. Workshop on climatic analysis and mapping for agriculture