milton defra

Calibration of remote sensing systems

• Field measurements to provide data for atmospheric correction.

• Field and laboratory calibration of sensors.

Validation of EO data products

Biomonitoring of Volatile Organic Compounds (VOC)

• Approached by Infoterra Ltd to investigate whether the spectral reflectance of common plant species is affected by exposure to VOCs.

• Client : Astra Zeneca PLC (manuf. plant in Macclesfield).

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Reported results from Astra-Zeneca pilot study

Methods : joint field expt with CEH Edinburgh

• Six Open-Top Chambers (OTC)

• VOC concentrations carefully controlled

• Plants grown in trays• Moved indoors to

measure spectra

• 3 OTC = treatment• 3 OTC = controls• 15 plants per species in each• Measured twice during season

Over 1000 leaf specimens were measured

VOCs : a mixture of Acetone (0.03 mg m-3),Acetonitrile (0.0008 mg m-3), Dichloromethane (0.0008 mg m-3), Ethanol (IMS) (0.004 mg m-3), MTBE (0.025 mg m-3)and Toluene (0.0015 mg m-3).

Large database of high quality reflectance spectra...

Karen at the beginning of the experiment...

and after measuring her 1000th dandelion leaf...

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Mean reflectance of leaves from control and treated Dock plants in July. Samples collected from visually senescent leaves have been omitted to demonstrate that mean reflectance of treated and control green

leaves is very similar across all wavelengths measured.

Treatment Control

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• Stray light error within the spectroradiometer?• Incorrect removal of the dark current?• One for the Journal of Irreproducible Results...

Highlights the need to establish protocols and publicise best practice if remote sensing is to be trusted as a scientific tool.

Network for Calibration and Validation of Earth Observation data

• Knowledge transfer network.• Around 25 partners - universities,

industry and government.• Disseminate best practice through

meetings, website & field experiments.

www.ncaveo.ac.uk

NCAVEO Field Experiment2006

© Ordnance Survey, 2006

Study area for NCAVEO 2006 Field Experiment

Aims of NCAVEO 2006 Experiment• To determine the accuracy and precision of radiance

and reflectance products derived from airborne and satellite sensors (e.g. CASI, CHRIS/PROBA, SPOT).

• To validate examples of three products derived from EO data:• Leaf Area Index map• Vegetation Index map (MTCI)• Land Cover map

• To document and share emergent best practice in EO product validation.

• To consolidate and grow the community of data providers and users interested in quality assurance of EO data products.

• To investigate the feasibility of establishing a long-term calibration & validation site in southern England.

www.ncaveo.ac.uk