Hilal Özen1, Nigel Fox2, Uğur Murat Leloğlu1, Irina Behnert2, Andrew Deadman2

1 TUBITAK UZAY, METU Campus, 06531 Ankara, Turkey

(hilal.ozen, leloglu)@uzay.tubitak.gov.tr2 NPL, TW11 0LW Teddington Middlesex, UK

(nigel.fox, irina.behnert, andrew.deadman)@npl.co.uk

THE 2010 TUZ GÖLÜ FIELD THE 2010 TUZ GÖLÜ FIELD CAMPAIGN—AN OVERVIEWCAMPAIGN—AN OVERVIEW

CEOS Land Comparison 2010

• Introduction

• Objectives

• Tuz Gölü Calibration Test Site

• Pre-campaign at Tuz Gölü

• Laboratory measurements at METU

• Logistics at CEOS Land Comparison 2010

• Measurements at Tuz Gölü

• Conclusions

CEOS Land Comparison 2010This study provides an overview of the CEOS international comparison carried out at Tuz Gölü in 13 - 27 August 2010.

The CEOS international comparison, infrastructure, analysis etc was largely funded by ESA with additional support from TUBITAK UZAY (Turkey) and NPL (UK) .

All participants were self-funded.

NPL was responsible for the cross-comparison of instrumentation and reference panels in the laboratory and at the site. Additionally, NPL was responsible for the land protocol for field measurements.

TUBITAK UZAY was responsible for the coordination, local support and logistics.

CEOS Land Comparison 2010

Objectives

1. Cross-comparison of field instrumentation used (radiometer and reference panel)- Traceability through NPL standards

2. Evaluate differences in methods for characterising a site

– Small areas (100 m x 300 m) for high and medium resolution imagers

– Large area (1 km x 1 km) for low resolution imagers

3. Establish traceability of Tuz Gölü calibration site

CEOS Land Comparison 2010

Objectives

4. Development of “best practice” guidance

5. A multi-sensor comparison linked to ground calibration derived from multi-team comparison

6. Identify the minimum and ideal specifications for characterisation/instrumentation for a CEOS “reference standard”

Tuz Gölü Calibration Test SiteLocation: 38 50’N, 33 20’E Central Anatolia, Turkey Elevation: 907 mTotal area: 1964 km²Surface type: Salt lake

Tuz Gölü Calibration Test Site

•Tuz Gölü, the second biggest lake of Turkey. •It is a bright natural target, free of vegetation. •It is extremely saline.

•In summer, up to 95% of water in the lake evaporates and exposes an average of 30-80 cm thick salt crust.

•It is in a sparsely populated region with low aerosol content.

Tuz Gölü Calibration Test Site

The Tuz Gölü test site is temporarily instrumented during field campaigns and maintained by TUBITAK UZAY.

The site is open to access to international scientific teams provided they are accompanied by TUBITAK UZAY researchers.

DMC-UK image (24.08.2008)

CEOS Land Comparison 2010

Schedule:

Ankara

13 August 2010 Kick off meeting

14-15 August 2010 Laboratory measurements

Tuz Gölü

16 August 2010 Moving to site and instrumentation instalition

17 - 25 August 2010 Site measurements

Ankara

26 August 2010 Laboratory measurements

27 August 2010 Final meeting

CEOS Land Comparison 2010Participants1. TUBITAK UZAY (Space Technologies Research Institute of The

Scientific and Technological Research Council of Turkey, Turkey)2. NPL (National Physical Laboratory, United Kingdom) 3. ONERA / CNES (French Aerospace Laboratory/French Space

Agency, France)4. VITO (Flemish Institute for Technological Research, Belgium) 5. GISTDA (Thailand Geo-Informatics and Space Technology

Development Agency, Thailand)6. NASA (National Aeronautics and Space Administration, United

States) 7. KARI (Korean Aerospace Research Institute, South Korea)8. CSIR (South Africa Council for Scientific and Industrial Research,

South Africa) 9. NSMC/CMA (Chinese National Satellite Metrological Centre, China)10. SDSU (South Dakota State University, United States)11. INPE (Brazilian National Institute for Space Research, Brazil)

Pre-Campaign at Tuz Gölü by

TUBITAK UZAY

CEOS LAND COMPARİSON 2010

Pre-Campaign at Tuz Gölü The decision on the location of the measurement and camping areas was based on:– surface homogeneity from Terra Modis satellite images (WIST -

https://wist.echo.nasa.gov)– site survey– ease of access to the measurement site

Pre-Campaign at Tuz Gölü Measurement Site Setup – TUBITAK UZAY

Laboratory Measurements at Middle East Technical

University, Ankara

CEOS LAND COMPARİSON 2010

Logistics at Ankara Optical Laboratory at Physics Department, METU

45°/0° Lamp-panel and detector-panel geometry - 45º illumination angle is the sun zenith angle for approximately 07:00 UTC at Tuz Gölü in Aug 2010.

Laboratory Study at Ankara

1 kW FEL lamp

Reflectance panel

ASD radiometerwith a 5º FOV

Reflectance panel cross-comparison

NPL calibrated PTFE reference panel (spectralon like) manufactured by Gigahertz Optik (Optical Diffuser Material)

Reference panel characterisations

Laboratory Study at Ankara

Panel calibrations will be used to normalize participants site reflectance values.

Participants reflectance panels were compared to the NPL panel under stable illumination conditions.

Transfer Standard Absolute Radiance Source (TSARS)

Radiometer cross-comparison against TSAR - NPL

Laboratory Study at Ankara

TSARS

ASD radiometer

Logistics at CEOS 2010 Land Comparison

CEOS 2010 LAND COMPARİSON

Logistics at Ankara and Tuz Gölü

Logistics at Tuz Gölü

UKDMC-2 image (08:03:00 UTC, 17/08/10)

Location of site 3.5 km from entrance

Logistics at Tuz Gölü

Transportation of the equipments to the measurement site by an all-terrain vehicle with trailer

Transportation to the hotels by air conditioned minibuses

Transportation

Logistics at Tuz GölüCamping Area

Logistics at Tuz Gölü

NN

Measurement Site

Measurements at Tuz Gölü

CEOS 2010 LAND COMPARİSON

Spectral Measurements at Tuz Gölü

8 different teams multiple different measurement strategies

Spectral Measurements at Tuz Gölü17 - 25 August 2010 Site Measurements

1km x 1km site

Spectral Measurements at Tuz GölüAll teams measured the Thome strip – 3 m x 50 m for a rapid short-term comparison study

Spectral Measurements at Tuz Gölü

Comparison study – Measuring NPL’s reference panel with own radiometers

Spectral Measurements at Tuz Gölü

Comparison study - Measuring own reference panel with own radiometers

BRDF Measurements at Tuz GölüNPL performed a BRDF characterization of the site near the measurement sites using the Gonio RAdiometric Spectrometer System (GRASS) instrument.

GRASS has been designed to measure the Earth’s reflected sunlight over half a hemisphere, at 30° degree intervals.

GRASS – NPL

BRDF Measurements at Tuz Gölü

Is the BRDF same under fixed illumination conditions?

NPL measured the BRDF of the site under fixed illumination angle of 45 degrees using a calibrated light source provided by ONERA at night time .

GRASS – NPL

Atmospheric Measurements at Tuz Gölü

AERONET Direct Sun Products

Data Format

Aerosol Optical Depth (AOD)with Precipitable Water and Angstrom Parameter

Level 1.0 Level 1.5 Level 2.0

Total Optical Depth Level 1.0Level 1.5Level 2.0

http://aeronet.gsfc.nasa.gov/new_web/photo_db/Tuz_Golu.html

Sunphotometer – TUBITAK UZAY

CIMEL CE318

Atmospheric Measurements at Tuz Gölü

Yankee Environmental Systems Multifilter Rotating Radiometer (YES MFR) - SDSU

Through the process of shadowing the detector with the band, the instrument is capable of measuring total, and diffuse irradiance at six different wavelengths, and calculating direct irradiance. This provides optical depth measurements for water vapor, aerosols, and ozone.

Meteorological Measurements at Tuz GölüWeather Station – TUBITAK UZAY

Davis Vantage Pro2 Wireless Weather Station:•Temperature•Surface pressure•Humidity•Wind speed and direction•Precipitation•Radiation

ConclusionsCEOS Land Comparison 2010 during 13 - 27 August 2010 consisted of both laboratory studies in Ankara and ground measurements at Tuz Gölü test site with the international participation of 11 different scientific teams.

CEOS 2010 Land Comparison

•Development of “best practice” guidance

Characterisation of the calibration test site

Atmospheric characterisation

Satellite sensor radiometric calibration and/or validation

CEOS 2010 Land Comparison

•Traceability through NPL standards

Calibration of instruments against a Transfer Standard Absolute Radiance Source (TSARS) developed by NPL

Correction of bidirectional effects of the target using GRASS developed by NPL

Calibration of reference panel using a 1 kW FEL lamp and NPL calibrated PTFE reference panel (spectralon like) manufactured by Gigahertz Optik (Optical Diffuser Material)

CEOS 2010 Land Comparison•Cross-comparison of instrumentation

Cross-comparison of radiometers at the site

Cross-comparison of radiometers at the laboratory

Cross-comparison of reference panels at the site

Cross-comparison of reference panels at the laboratory

CEOS 2010 Land Comparison•Cross-comparison of ground measurements made by different teams

FY3A, Beijing1, DEIMOS1, UKDMC2, SPOT 4-5, LANDSAT 5-7, MERIS, ALOS Avnir-2, RAPIDEYE constellation, MODIS, THEOS, Worldview2, EO-1 Hyperion and ALI satellite overpasses

•Cross-comparison of Top-of-Atmosphere measurements made from different satellite sensors

Uncertainty analyses, repeatability, reproducibility.

For more information about Tuz Gölü radiometric calibration test site:1.Cal/Val Portal; http://calvalportal.ceos.org/cvp/web/guest/tuz-golu2.USGS test site catalog; http://calval.cr.usgs.gov/sites_catalog_template.php?site=tuzg3.Hilal Özen, TUBITAK UZAY; hilal.ozen@uzay.tubitak.gov.tr

at Tuz Gölü