The term "downscaling" and the first examples of using the statistical variant of this approach for the construction of climate change scenarios.
The term "downscaling" was first used in the MPI Report #64 - Hans von Storch, Eduardo Zorita, Ulrich Cubasch (1991): Downscaling of Global Climate Change Estimates to Regional Scales: An Application to Iberian Rainfall in Wintertime. This approach was developped out of a request for elaborating the utility of GCM output, asked by a group of German hydrologists - the details of the meeting are by now forgotten. In this paper, Hans von Storch and Eduardo Zorita applied Canonical Correlation Analysis to derive Iberian Peninsula seasonal rainfall change in winter from global GCM scenarios
The work was inspired by Kim, J.W., J.-T. Chang, N.L. Baker, D.S. Wilks and W.L. Gates, 1984: The statistical problem of climate inversion: Determination of the relationship between local and large-scale climate. Mon. Wea. Rev. 112: 2069-2077, .
A first sketch was presented in
von Storch, H. and E. Zorita, 1990: Assessment of regional climate changes with the help of global GCM's: an example. CAS/JSC Working group on Numerical Experimentation. WMO Report no. 14, 7.30
The spectral nudging technique used in dynamical downscaling for, mainly, reconstructing regional climate extending decades of years but also for scenario construction.
The problem of simulating the regional climate conditional upon the large scale state of a re-analysis or a GCM simulation is no longer formulated as a boundary-value problem but as a data-driven problem, with the known large-scale conditioning the medium- and small scale dynamics. In doing so, it becomes also clear that the expected value added is not in the large scales, which are already described by the global model/analysis but in those scales, which are insufficiently resolved by the global analysis/model.
von Storch, H., H. Langenberg and F. Feser, 2000: A spectral nudging technique for dynamical downscaling purposes. Mon. Wea. Rev. 128: 3664-3673.
Preliminary "grey" versions were
Langenberg, H, and H. von Storch, 1999: Spectral analysis in regionalisation retaining the large scales but adding detail. In H. Ritchie (Ed.): Research Activities in Atmospheric and Oceanic Modelling, WMO/TD No 942, 7.31-32
and von Storch, H., H. Langenberg and F. Feser, 1999: Long-wave forcing for regional atmospheric modelling. GKSS 99/E/46 report
In 2011, the different lines of analysis of the added value generated in this way was described in a review paper Regional climate models add value. in Bull. Amer. Meteor. Soc. (92: 1181–1192) coauthored by F. Feser, B. Rockel, H. von Storch, J. Winterfeldt, and M. Zahn. After having been implemented in limited area software like WRF, the spectral nudging method finds more an more acceptance and is often utilized.
The same terminology and a similar approach had been earlier published by Waldron, K. M., J. Peagle and J.D. Horel, 1996: Sensitivity of a spectrally filtered and nudged limited area model to outer model options. Mon. Wea. Rev. 124, 529-547. At the time of submitting our manuscript, this paper was unknown to Hans von Storch, as it dealt with issues of weather forecasting, and he learned from it during the review process. Earlier a number of authors (Kida, Sasaki, McGregor) had experimented with nudging spatial means.
Need for signal-to-noise analysis for assessing the outcome of numerical experiments with atmospheric limited area models just as with global model experiments.
It was accepted in the early 1970s that ensembles of global model (GCM) simulations, which differ by miniscule details, such as modified initial values or parameters, would show strong variability reflecting internal chaotic dynamics. This observation was important for both validating models, as simple comparisons of observations and a model simulation would not be conclusive becaused the differences may very well be due to ensemble variations, and for doing numerical experiments on the effect of changing parametrizations or boundary conditions (such as sea surface temperature). As a consequence, the concept of using the concept of testing null hypotheses was introduced and became quickly a stand routine in validating of and experimenting with GCMs.
Not so with regional climate models (RCMs). While the situation is in principle the same - the lateral boundary conditions, which are usually stipulated via "sponge zone, are insufficient to enforce a unique solution in the intgerior, and the chaotic dynamics generate - at least sometimes - different circulations in the interior, which are consistent with the lateral boundary conditions. Thus, validation of and experimenting with RCMs needs the same statsitical analysis as for global models. Ioneers in demonstrating the emrgence of ensm,eble variations in RCMs simulations were Ji and Vernekar in 1997 (J. Clim 10), and Annette Rinke and Klaus Dethloff in 2000 (Clim. Res. 14). But even nowadays, in 2012, the statistical challenge of assessing RCM output has not been acknowledged by many in the RCM community.
However, there is a characteristic difference in the ensemble structure between different trajectories generated by global and regional models. Once two global models trajectories have moved from each other, they will remain at a statistically stationary distance. In case of RCMs, this is different, because the efficiency of lateral boundary conditions vary in enforcing a circulation in the interior. Sometimes they do it really well, and any two trajectories move closer, while in other situations the differences grow, sometimes strongly within a short term and only for a limited time.
At a later time, I coined the term "intermitted divergence in phases space" for this phenomenon. (von Storch., H., 2005: Models of global and regional climate. M.G. Anderson (Ed): Encyclopedia of Hydrological Sciences, Part 3. Meteorology and Climatology, Chapter 32, ISBN: 0 471-49103-9, p 478-490 DOI: 10.1002/0470848944.hsa035) This intermitted divergence in phase space is strongly suppressed, when spectral nudging is employed (see Weisse and Feser, 2003, Coastal Eng. 48.)
Originally introduced by Klaus Hasselmann in a rather general concept, later expanded to Principal Interaction Patterns (PIPs, see Hasselmann, 1988, I derived a simplified but workable version, which nowadays goes with the name of Principal Oscillation Patterns (POPs; see von Storch et al., 1988. The basic idea is to identify a low-dimensional linear subspace, which is dynamically closed (interacting with other dynamcis only through links, which are suitably described by statistical terms). The PIPs represent a very general, and elegant, approach, while the POPs reduced this to the case of 2-dimensional subspace, within which oscillatory modes descrrbe most of the variation. Both, PIPs and POPs incorporate a predictive potential.
PIPs have never been implemented in its full generality; POPs have been successfully applied to the Madden & Julian Oscillation and to ENSO, among other phenomena. A review dates from 1995. The original FORTRAN code from about 1991 has been preserved (thanks to Silvio Gualdi),to gether with the manual (by Fergus Gallagher, Reiner Schnur, Gerhard Hannoschöck and myself) from those days.
The deconstruction of the "hockeystick" methodology
The "hockeystick"-episode was a tough time, also interesting in terms of the social process called science. We have summarized how we perceived this time in a comment on the weblog of nature. The problem was that the scienbtist behind the hockeystick used the unfortunate declaration that the hockeystick would be "it", by the IPCC (TAR) as a tool to block others who would come forward with different results; in particular borehole temperature people suffered.
For the debate about detecting and attributing man-made climate change the hockeystick was unnecessary, as was demonstrated by our later analysis (Rybksi et al.) in 2006, which employed various reconstructions; also formal detection and attribution studies had solved the problem long before (e.g., IDAG, 2005: Detecting and attributing external influences on the climate system. A review of recent advances. J. Climate 18, 1291-1314; or, much earlier Hegerl, G., H. von Storch, K. Hasselmann, B.D. Santer, U. Cubasch, P.D. Jones, 1996: Detecting anthropogenic climate change with an optimal fingerprint method. - J. Climate 9, 2281-2306)
The "skeptics" were keen on deconstructing the hockeystick because they considered it as a key argument "pro" man-made causes. However, it was not, and the fact that the hockeystick methodology was flawed did not imply that the question about man-made causes would be entirely open again. (Of course there is some doubt left, because of significant uncertainty in the level of natural variability - but this doubt is small.) This demonstrates very clearly that overselling does not pay; instead it endangers the credibility of the whole community.
The significance of hockeystick business is illustated by the fact that it brought me an invitation to show up as a witness first at the National Research Council and later at the Subcommittee on Oversight and Investigations of the Committee on Energy and Commerce, U.S. House of Representatives. (Hearing "Questions Surrounding the ‘Hockey Stick’ Temperature Studies: Implications for Climate Change Assessments" on 19. July 2006)
The key-paper of this effort was
von Storch, H., E. Zorita, J. Jones, Y. Dimitriev, F. González-Rouco, and S. Tett, 2004: Reconstructing past climate from noisy data, Science 306, 679-682, 22 October 2004 (Sciencexpress, doi 10.1126/science.1096109)
which was commented to by Osborn and Briffa, and by S. Rahmstorf.
Stehr, N. and H. von Storch, 1994: Climate change, the social construct of climate and climate policy. Proc. of the Fifth Symposium on Global Change Studies, Nashville, Tennessee, January 23-28, 1994, 118-125.
Stehr, N., H. von Storch and M. Flügel, 1996: The 19th century discussion of climate variability and climate change: analogies for present day debate? World Res. Rev. 7, 589-604
von Storch, H., and N. Stehr, 1997: The case for the social sciences in climate research. - Ambio 26, 66-71 (also in: H. Rodhe and R. Charlson (Eds), 1998: The legacy of Svante Arrhenius. Understanding the greenhouse effect. Royal Swedish Academy of Sciences, Stockholm, ISBN 91-7190-0284, 143-153)
Stehr, N. and H. von Storch, 1997: Das soziale Konstrukt des Klimas. In: VDI-Gesellschaft Energietechnik (Ed): Umwelt- und Klimabeeinflussung durch den Menschen IV, VDI Berichte 1330, 187-197 (ISBN 3-18-0913304)
Stehr, N. and H. von Storch, 1997: Rückkehr des Klimadeterminismus? Merkur 51, 560-562
Stehr, N., und H. von Storch, 1998: Soziale Naturwissenschaft oder die Zukunft der Wissenschaftskulturen. Vorgänge 37, 8-12
Stehr, N., and H. von Storch, 1999: An anatomy of climate determinism. In: H. Kaupen-Haas (Ed.): Wissenschaftlicher Rassismus - Analysen einer Kontinuität in den Human- und Naturwissenschaften. Campus-Verlag Frankfurt.a.M. - New York (1999), 137-185, ISBN 3-593-36228-7
Stehr, N. and H. von Storch, 2000: Klima und Kultur.Vorgänge 39, 100-104
von Storch, H. and N. Stehr 2002: Das Klima in den Köpfen der Menschen. In: Walter Hauser (Ed.): Klima. Das Experiment mit dem Planeten Erde Deutsches Museum. Begleitband und Katalog zur Sonderausstellung des Deutschen Museums vom 7.11.02-15.06.2003, 280-291 (also Velbrueck on-line Magazin 2/2002)
Stehr, N. and H. von Storch, 2002: Die Meinungssache namens Wetter, Frankfurter Allgemeine Zeitung, 14.8.2002, (nr 187), p. 38
von Storch, H., und N. Stehr, 2007: Der öffentliche Diskurs über das Klima oder – die politische Macht der Klimaforschung. In Philipp Mißfelder (Hrsg.): Umdenken. Für eine nachhaltige Klimapolitik, 14-21
von Storch, H., 2010: Klimaforschung - zwischen akademischer Neugier und kultureller Konditionierung. In Philipp Wolf und Dietmar Herdt (Hrsg.): Global Warming. Ethische und technologische Perspektiven des Klimawandels, Leipziger Universitätsverlag GmbH 2009, ISBN 978-3-86583-427-0, 47-58 (Buchbesprechungen: Umweltdialog, )
von Storch, H., A. Bunde and N. Stehr, 2011: The Physical Sciences and Climate Politics In J.S. Dyzek, D. Schlosberg, and R. B. Norgaard (eds): The Oxford Handbook of Climate Change and Society. Oxford University Press. Oxford UK. (in press)
The ongoing trans-disciplinary cooperation between the theoretical sociologist Nico Stehr and the climate scientist Hans von Storch has also resulted in a joint book, a first issue published in German in 1999 (and later in Chinese), and a second in 2010 in English, German, Slowenian, Russian, and Tchechian:
Assessment reports such as BACC und Hamburg-report
So far such reports on the scientifically legitimate knowledge about climate, climate change and climate impact have been published:
von Storch, H., M. Claussen and KlimaCampus Autoren Team, 2010: Klimabericht für die Metropolregion Hamburg, Springer Verlag Heidelberg Dordrecht London New York, DOI 10.1007/978-3-642-16035-6, 321 pp
The Hamburg community is presently preparing an updated, due in 2017, under the auspices of the Hamburg KlimaCampus. A similar effort is presently underway for the North Sea region, see NOSCCA.
Döring, M., W. Settekorn and H. von Storch, 1999: Grenzen und Chancen der Wissenschaftskommunikation. Die Havarie der "Pallas" als Symbol. Vorgänge 148, 4: 13-16
Stehr, N. and H. von Storch, 2010: Climate and Society. Climate as a Resource, Climate as a Risk World Scientific
Stehr, N., in H. von Storch, 2010: Podnebje in Druzba; Podnebje kot vor, podnebje kot tveganje, Zalozba Sophia, Ljubljana (210 pp)
Stehr, N., in H. von Storch, 2011: Wetter, Klima, Mensch (in Russisch), Aletheia, Sankt Petersburg (172 pp), ISBN 978-5-91419-525-7
Stehr, N., and H. von Storch, 2014: Klima a spolecnost, Univerzita Karlova v Praze, Nakladatelství Karolinum, 2014, ISBN 978-80-246-2847-9, 157 s
Stehr, N., und H. von Storch, 1999: Wetter, Klima, Mensch. Beck Verlag München, ISBN 3-406-44613-2, 128 pp.
Complex Chinese translation, 149 pp, Morning Star Publishing Inc., Taiwan, ISBN 957-455-835-5
The BACC author team, 2008: 
The BACC-II author team, 2015: 
