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3 - MAC EUROPE CAMPAIGN - FLEVOLAND TEST SITE 
Some of the above principles for linking optical remote sensing with crop growth models will be illustrated with 
results from the European multisensor airborne campaign MAC Europe in 1991. A description will be given of 
the MAC Europe campaign in the Dutch test site Flevoland and of the collected remote sensing and ground truth 
data. In the optical remote sensing domain, NASA executed one overflight with the AVIRIS scanner. In addition, 
the Dutch experimenters flew three flights with the Dutch CAESAR scanner. 
3.1 Test Site 
The test site was located in Southern Flevoland in The Netherlands, an agricultural area with very homogeneous 
soils reclaimed from the lake Usselmeer in 1966. The test site comprised ten different agricultural farms, 45 to 
60 ha in extension. Main crops were sugar beet, potato and winter wheat. Due to hailstorms and night-frost damage 
of the sugar beet in April 1991 some of the sugar beet fields were sown for a second time in late April resulting 
into quite some growth differences between different beet fields. 
3.2 Ground Truth 
Crop parameters concerning acreage, variety, planting date, emergence date, fertilization, harvest date, yield 
and occurring anomalities were collected for the main crops. During the growing season, additional parameters 
were measured in the field. The selected parameters were the estimated soil cover by the canopy, the mean crop 
height, row distance, plants per m 2 , the soil moisture condition and comments about plant development stage. 
3.3 Meteorological Data 
Daily meteorological data are needed as input for crop growth simulation models. For the 1991 growing season 
these were obtained from the Royal Dutch Meteorological Service (KNMI) for the station Lelystad. Data consisted 
of daily minimum and maximum temperature, daily global irradiation and daily precipitation. 
3.4 Spectra of Single Leaves 
Leaf optical properties were investigated with a LI-COR laboratory spectra radiometer at the Centre for Agrobiological 
Research (CABO) in Wageningen. The reflectance or transmittance signature of the upper and lower surface of 
several leaves was recorded continuously from 400 to 1100 nm wavelength in 5 nm steps. The instrument was 
calibrated with a white barium sulphate plate. 
3.5 Groundbased Reflectances 
Field reflectance measurements were obtained during the 1991 growing season with a portable CROPSCAN radiometer. 
Spectral bands were located at 490, 550, 670, 700, 740, 780, 870 and 1090 nm with a bandwidth of 10 nm. The 
sensor head of the radiometer was mounted on top of a long metal pole and positioned three metres above the 
ground surface. 
3.6 CAESAR 
The CAESAR (CCD Airborne Experimental Scanner for Applications in Remote Sensing) has a modular set-up 
and it combines the possiblities of a high spectral resolution with a high spatial resolution. For land applications 
three spectral bands are available in the green, red and NIR part of the EM spectrum. One of the special options 
of CAESAR is the capability of acquiring data according to the so-called dual look concept. This dual look concept 
consists of measurements performed when looking nadir and under the oblique angle of 52°. Combining these 
measurements provides information on the directional reflectance properties of objects. Successful overflights 
over the test site were carried out on July 4th, July 23rd and August 29th, 1991. 
3.7 AVIRIS 
The ER-2 aircraft of NASA, carrying the airborne visible-infrared imaging spectrometer (AVIRIS), performed 
a successful overflight over the Flevoland test site on July 5th, 1991. AVIRIS acquires 224 contiguous spectral 
bands from 0.41 to 2.45 fim. The ground resolution is 20 m as it is flown at 20 km altitude.