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Radiative Transfer Modelling for the characterisation of natural burnt surfaces AO/1-5526/07/NL/HE Recommendations #2a P. LEWIS 1, T. QUAIFE 5, J. GOMEZ-DANS.

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Presentation on theme: "Radiative Transfer Modelling for the characterisation of natural burnt surfaces AO/1-5526/07/NL/HE Recommendations #2a P. LEWIS 1, T. QUAIFE 5, J. GOMEZ-DANS."— Presentation transcript:

1 Radiative Transfer Modelling for the characterisation of natural burnt surfaces AO/1-5526/07/NL/HE Recommendations #2a P. LEWIS 1, T. QUAIFE 5, J. GOMEZ-DANS 1,2, M. DISNEY 1, M. WOOSTER 2, D. ROY 3, B. PINTY 4 1. NCEO/DEPT. GEOGRAPHY, UNIVERSITY COLLEGE LONDON, GOWER ST., LONDON WC1E 6BT, UK 2. NCEO/DEPT. GEOGRAPHY, KING'S COLLEGE LONDON, STRAND, LONDON WC2R 2LS, UK 3. GEOGRAPHIC INFORMATION SCIENCE CENTER OF EXCELLENCE, SOUTH DAKOTA STATE UNIVERSITY, WECOTA HALL, BOX 506B, BROOKINGS, SD , USA 4. INSTITUTE FOR ENVIRONMENT AND SUSTAINABILITY (IES), EC JOINT RESEARCH CENTRE, VIA E. FERMI 1, TP 440, ISPRA (VA), ITALY 5. NCEO/DEPT. GEOGRAPHY, EXETER UNIVERSITY,

2 Overview  EO technology overview (talk 1) – Wildfire detection and quantification – Brief summary of relevant results – ESA and related missions  Modelling fire impacts (talk 2) – Semi-analytical – 3D – Thermal – Linear modelling

3 Semi-analytical modelling  Models need to have at least 3 layers – Soil, grass/understorey, tree/overstorey – Number of state variables then quite high  Semi-analytical models model average radiation fields – Not directly relevant to high spatial resolution – can’t easily model some fire effects  E.g. lower (or in some cases higher) density of grass below trees – Difficult to include anything but simplest fire impact model  e.g. assume linear mixture of grass/char here  BUT this is same as linear model being tested, so not a full test  BUT can learn about overall behaviour of algorithm  AND simpler to set up/run than 3D models

4 Recommendations: semi-analytical models  rather simplistic and at times circular for testing algorithms: more complex mechanisms for the description of fire impacts might be considered if such models are to play a significant role in algorithm testing. – Probably best to learn about these from 3D modelling and apply understanding gained to these models

5 3D Numerical modelling  3 components: – Collection and generation of 3D structure – Simulating fire impacts in 3D models – Testing and validation 3D models

6 Collection and generation of 3D structure  3D information from: – ‘models’ (e.g. L-systems etc.) – Measurement (e.g. lidar)  Here, have partially calibrated library models (simple grass model) against field obs. – Practical approach in absence of other information to enable scene generation

7 Collection and generation of 3D structure  Library approach proved useful – Each tree not ‘grown’ as such – But can represent density effects etc.  Rapidly advancing measurement method: lidar – Particularly attractive waveform lidar  E.g. CSIRO Echidna  Esp. multi-spectral lidars under development –NIR + SWIR –Possibility of fuel moisture mapping  Incidently, librat s/w delivered capable of simulating these

8 Validating/testing models  Here, compared with range of field measurements – Manual/photographic … quite time consuming – Airborne/ground lidar would be advantageous for scene development and validation of structure  Compared here with limited range of EO measures – Limited by cloud cover during campaign … – Wider range necessary  E.g. BRDF … CHRIS-PROBA of value, but …

9 Simulating fire impacts in 3D models  Simple but effective model of fire impact here – Replace grass by patchy char around plants and ‘burned grass’ model  Can conceptualize how to extend to tree impact – But not done here (time)

10 Recommendations  Build 3D model database of pre-post fire vegetation – Need to consider validation data  range of EO airborne/spaceborne – Develop coordinated field campaigns to achieve this  Develop measurement technologies/algorithms – Lidar  Develop more sophisticated fire impact models  Build linkages to 3D thermal models – Fire impact on 3D model


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