Vaisala Energy Support
What Is The Vaisala 1.0 Dataset?
The Vaisala 1.0 dataset is the first dataset created by Vaisala, then 3TIER. It uses the Perez v1.0 clear sky algorithm and monthly average aerosols from a single channel of the MODIS satellites.
The clear sky model used is the Perez SUNY v1.0 methodology, the same as contained in this reference (hereafter referred to as Perez v1.0): R. Perez et al, “A new operational model for satellite-derived irradiances: description and validation”, Solar Energy, Vol. 73, Iss. 5, November 2002, pages 307-317
The primary difference is that the Linke coeffificent used is derived using a Vaisala proprietary method incorporating the MODIS AOD and Water Vapor dataset mentioned above, using Ineichen's “Conversion function between the Linke turbidity and the atmospheric water vapor and aerosol content.” Solar Energy, 82, 1095-1097. Vaisala uses a proprietary Cloud Index calculation methodology.
To derive the Cloud Index the satellite measurements are first processed to account for instrument degradation over time. The proprietary Vaisala cloud algorithm is the main deviation from the Perez SUNY irradiance calculation methodology. It works by dividing the satellite measurements into bins by solar azimuth and zenith angle, and treating each bin independently, for the calculation of a cloud index. The fit between cloud index, clear-sky GHI, and observations is done on a per satellite basis.
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