# Articles on surrogates

In the main work on
surrogate cloud fields
various types of clouds are generated using the IAAFT algorithm and the radiative properties of the surrogates are compared with those of their LES templates. This comparison is satisfactory, thus the amount and quality of the input data is probably the main limitation at the moment. Next to this validation based on LES clouds, Schmidt et. al. (2007) has compared three different cloud generators based on in-situ cloud and radiation measurements using 3D radiative transfer and found the surrogate fields to produce good quality cloud fields. A statistical validation of surrogate time series was performed in Venema et. al. 2006b.

New algoriths have been developed to perform downscaling, as well as interpolation with surrogate clouds

The article on the Stochastic Iterative Amplitude Adjusted Fourier Transform introduces a small variation of the IAAFT algorithm that is more accurate, i.e. the power spectrum of surrogates and template fit better.

## References

Surrogate cloud fields generated with the Iterative Amplitude Adapted Fourier Transform algorithm (color | black/white)*Tellus 58A, no 1, pp. 104-120, 2006a*

Victor Venema, Steffen Meyer, Sebastián Gimeno García, Anke Kniffka, Clemens Simmer, Susanne Crewell, Ulrich Löhnert, Thomas Trautmann, and Andreas Macke

Statistical characteristics of surrogate data based on geophysical measurements

*Nonlinear Processes in Geophysics, 13, p. 449-466, 2006b*

Victor Venema, Susanne Bachner, Henning Rust, and Clemens Simmer

A Stochastic Iterative Amplitude Adapted Fourier Transform Algorithm with improved accuracy

*Nonlinear Processes in Geophysics, 13, no. 3, pp. 247-363, 2006c*

Victor Venema, Felix Ament, Clemens Simmer

Schmidt, K.S., V.K.C. Venema, F. di Giuseppe, R. Scheirer, M. Wendisch, and P. Pilewski.
Reproducing cloud microphysics and irradiance measurements using three 3D cloud generators.
*Q.J.R. Meteorol. Soc.*, **133**, doi: 10.1002/qj.53, pp. 765-780, 2007.

Venema, V.K.C., R. Lindau, T. Varnai, and C. Simmer.
Combining surrogate clouds with geostatistics to ease the comparisons of point radiation measurements with cloud measurements.
(poster | extended abstract)
*ISTP2009*, 18-23 October, 2009, Delft University of Technology, The Netherlands.

Venema, V.K.C., S. Gimeno García, and C. Simmer.
A new algorithm for the downscaling of cloud fields.
*Quart. J. Royal. Meteorol. Soc.*, **136**, no. 646, pp. 91-106, doi: 10.1002/qj.535, 2010.

Venema, V., O. Mestre, E. Aguilar, I. Auer, J.A. Guijarro, P. Domonkos, G. Vertacnik, T. Szentimrey, P. Stepanek, P. Zahradnicek, J. Viarre, G. Müller-Westermeier, M. Lakatos, C.N. Williams,
M.J. Menne, R. Lindau, D. Rasol, E. Rustemeier, K. Kolokythas, T. Marinova, L. Andresen, F. Acquaotta, S. Fratianni, S. Cheval, M. Klancar, M. Brunetti, Ch. Gruber, M. Prohom Duran, T. Likso,
P. Esteban, Th. Brandsma. Benchmarking homogenization algorithms for monthly data. *Climate of the Past*, **8**, pp. 89-115, doi: 10.5194/cp-8-89-2012, 2012.

*Report, 2003*

Victor Venema