1Centre for Energy and Processes, MINES ParisTech, BP207, 06904, Sophia Antipolis, France
2German Remote Sensing Data Center, German Aerospace Center (DLR), Postfach 1116, 82234 Wessling, Germany
Received: 21 Dec 2010 – Revised: 30 May 2011 – Accepted: 11 Aug 2011 – Published: 29 Aug 2011
Abstract. The MLB parameterisation (Modified Lambert-Beer, Mueller et al., 2004) describes the change in SSI with sun zenith angle (SZA) in clear-sky conditions. It applies to the direct and global SSI as well as their spectral distribution. We assess its performances by comparing its results to the outputs of the radiative transfer model libRadtran and standard interpolation procedures. The standard two-point fitting MLB function performs very well at SZA between 0° and 60° and fairly bad from 60° to 89.9°. A parameterisation made of four MLBs for four intervals (0°, 60°), (60°, 75°), (75°, 85°) and (85°, 89.9°) is also tested. This piecewise MLB parameterisation exhibits satisfactory performances at any SZA and outperforms standard linear interpolation techniques. 95 % of errors in global SSI are less than 1 W m−2 for each band and less than 5 W m−2 for total irradiance.
Qu, Z., Blanc, P., Lefèvre, M., Wald, L., and Oumbe, A.: Study of the MLB parameterisation for change in surface solar irradiance with sun zenith angle in clear sky, Adv. Sci. Res., 6, 233-236, doi:10.5194/asr-6-233-2011, 2011.