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Details

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General

Meta data ID	{A7231C06-4DAC-4808-8B7A-5EE49FA70CFB}
Last modified	2019-05-14T14:26:08

Dataset creators

Contact person

First name	Kirsikka
Last name	Heinilä
Email	kirsikka.heinila@syke.fi
Organisation	Finnish Environment Institute

Dataset creators

First name	Kirsikka
Last name	Heinilä
Organisation	kirsikka.heinila@syke.fi

Description

Basic information

Dataset title	Airborne spectrometer data from patchy snow cover measured on May 2011
Theme	Environment and Conservation
Description	The dataset contains 10 meter resolution reflectance data from boreal and tundra sites during spring snow melt. The purpose of the airborne measurements was to investigate the effect of forest canopy and snow melting on optical remote sensing signals at the very end of melting period. The hyperspectral airborne data was acquired with an AisaDUAL imaging spectrometer on 5 May 2011 in Sodankylä and in Saariselkä, Finland. Saariselkä is a fell region and partly represents open tundra. The image swath was 240 meters and flight lines were several kilometers long. The original spatial resolution of the data is 80 cm x 80 cm, but it was resampled to pixel size of 10 m. Snow depth was between 0 cm and 30 cm at the Sodankylä site and between 0 cm and 60 cm at the Saariselkä site implying that the spring melt was clearly more advanced in Sodankylä. Additionally, more snow-free pixels were found at Sodankylä than Saariselkä. During the measurements the sky was cloudless in Sodankylä (cloud cover 0/8) and cloudy (cloud cover 7/8) in Saariselkä. The data contains mosaics of the flight lines for the bands 555 nm, 645 nm, 858.5 nm and 1640 nm as well as for the Normalized Difference Snow Index (NDSI) and Normalized Difference Vegetation Index (NDVI) for both study sites.
Language (dataset)	English
Keyword	spectrometer, airborne, reflectance, snow, NDSI, NDVI

Data processing steps

sampling

Description

The airborne hyperspectral data were acquired with an AisaDUAL imaging spectrometer manufactured by Spectral Imaging Ltd (SPECIM). The airborne spectral measurements were made from airoplane at an altitude of 800 m offering a spatial resolution of 0.8 m and a swath of 240 m. Flight lines were several kilometers long. The instrument foreoptic unit was set to look at nadir (0 degrees) and the field of view (FOV) was 17 degrees. The Oxford Technical Solutions RT4000 GPS/INS was utilized to provide high accuracy position measurements with low drift rates. The reflectance level was obtained by applying a real-time fibre optic downwelling irradiance sensor (FODIS). The measurements from Sodankylä were carried out in direct illumination (i.e. clear sky: 0/8) and the measurements from Saariselkä were carried out in diffuse illumination (i.e. cloudy sky: 7/8).

Data processing steps

processing

Description

The AisaDUAL spectrometer data was radiometrically and geometrically corrected by using the SPECIM’s CaliGeo tool in the ENVI software. Measurements from Saariselkä are additionally corrected with the digital elevation model KM10 with a pixel size of 10 m × 10 m and elevation resolution of 1.4 m. The original spectral resolution for the VNIR bands was 5 nm and for SWIR bands 6 nm totaling to 359 spectral bands. The original spatial resolution of the data is 80 cm x 80 cm. From this data the bands 555 nm, 645 nm, 858.5 nm and 1640 nm were extracted from the spectra by using the band specific FWHM criterion (Full width at half maximum) corresponding to MODIS bands. For these bands the data was filtered with mean filter using 12x12 window corresponding to pixel size of 10 meter.

Material time period

Start date	2011-05-05
End date	2011-05-05

Area

West Bounding Longitude	25.7472
East Bounding Longitude	28.926
South Bounding Latitude	66.6063
North Bounding Latitude	67.5598

Distribution

Contact person

First name	Kirsikka
Last name	Heinilä
Email	kirsikka.heinila@syke.fi
Organisation	Finnish Environment Institute

Resources

Resource content description

Data is available on request.

Resources

Resource content description

Data is available on request.

Reference publications

Reference

Heinilä, K., Salminen, M., Metsämäki, S., Pellikka, P., Koponen, S., & Pulliainen, J. (2019). Reflectance variation in boreal landscape during the snow melting period using airborne imaging spectroscopy. International Journal of Applied Earth Observation and Geoinformation, 76, 66-76.

The license for open SYKE's open datasets is Creative Commons Attribution 4.0 International.

The data described here can be freely used to all purposes, provided that the source of the data is mentioned.

The citation for the dataset as given above.

Further information on the license:
https://creativecommons.org/licenses/by/4.0/legalcode (English)
https://creativecommons.org/licenses/by/4.0/legalcode.fi (Finnish)

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