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 15 June 2005 Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection 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 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) 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). 15 June 2005 Workshop on climatic analysis and mapping for agriculture
What is frost… Typical synoptic situation Typical micrometeorological conditions 15 June 2005 Workshop on climatic analysis and mapping for agriculture
What we used… AVHRR sensor NOAA Polar orbiter satellite 15 June 2005 Workshop on climatic analysis and mapping for agriculture
What we used… 15 June 2005 Workshop on climatic analysis and mapping for agriculture
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 always one more missing variable than equations (N channel emissivities + surface temperature). Atmospheric correction 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 masking - Atmospheric correction - Surface emissivity retrieval - Land surface temperature retrieval 15 June 2005 Workshop on climatic analysis and mapping for agriculture
Pre-processing… 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 15 June 2005 Workshop on climatic analysis and mapping for agriculture
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 15 June 2005 Workshop on climatic analysis and mapping for agriculture
Surface emissivity retrieval Day surface brightness temperature March 17 th 2003, 04: 25 UTC Night surface brightness temperature March 19 th 2003, 15: 01 UTC Ch. 4, 5 Ch. 3, 4, 5 TISI (Temperature-Independent Spectral Indices) Emissivity depends on: Composition of surface Roughness of surface Other physical parameters (soil moisture…) Wavelength 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 15 June 2005 Workshop on climatic analysis and mapping for agriculture
March 17 th 2003 04: 25 UTC 15 June 2005 Workshop on climatic analysis and mapping for agriculture
March 23 th 2003 03: 39 UTC 15 June 2005 Workshop on climatic analysis and mapping for agriculture
April 9 th 1997 02: 04 UTC 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 15 June 2005 Workshop on climatic analysis and mapping for agriculture
Frost risk mapping LATE FROST RISK low medium 15 June 2005 high very high Workshop on climatic analysis and mapping for agriculture
Numerical weather simulations RAMS (Regional Atmospheric Modeling System) 15 June 2005 Workshop on climatic analysis and mapping for agriculture
Thanks for your attention 15 June 2005 Workshop on climatic analysis and mapping for agriculture
A few words on theory… Sun Satellite Outer of atmosphere Atmosphere Surface 15 June 2005 Workshop on climatic analysis and mapping for agriculture
Effects on LST of atmosphere (transmissivity) and emissivity 15 June 2005 Workshop on climatic analysis and mapping for agriculture
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. 15 June 2005 Workshop on climatic analysis and mapping for agriculture
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