Casanueva Vicente, Ana

Feigenwinter, Iris

Kotlarski, Sven

Schwierz, Cornelia

English

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Geophysical Research AbstractsVol. 20, EGU2018-8288-1, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.Spatial artefacts in distributed quantile-mapped climate scenariosSven Kotlarski, Iris Feigenwinter, Ana Casanueva, and Cornelia SchwierzFederal Office of Meteorology and Climatology MeteoSwiss, Zurich Airport, Switzerland (sven.kotlarski@meteoswiss.ch)The provision of user-friendly and directly applicable climate scenarios is an essential part of climate services,but is challenged by a number of well-known limitations of the underlying climate model data. These limitationsespecially relate to the coarse resolution (that does often not match the spatial scale required by climate impactassessments) and to systematic biases of the raw model output (which would be inherited by subsequent impactmodels if not corrected for). Numerous post-processing methodologies have been developed in recent years thattransfer coarse-resolved climate model data to finer spatial scales and/or to bias correct raw model data. In theframe of the upcoming generation of Swiss reference climate scenarios (CH2018; www.climate-scenarios.ch) anempirical quantile mapping (QM) approach is employed to provide transient bias-corrected scenarios of severalmeteorological variables at Swiss stations and on a high-resolution grid based on the EURO-CORDEX regionalclimate projections.QM has previously been shown to perform well compared to other downscaling and bias correction ap-proaches. However, certain caveats and limitations remain that both climate scenario providers and climatescenario users need to be aware of. One of these potentially critical issues concerns the modification of the rawclimate model’s change signal by QM. Such a modification can be meaningful in case of intensity-dependentmodel biases that would lead to different mean biases in a present-day reference and a future scenario period.Here we present an example for a systematic modification of raw temperature change signals by QM that isstrongly connected to the topography of the region of interest. This case potentially reveals a statistical artefactcaused by the purely empirical distribution-based correction approach of QM. The systematic modificationconsists of an elevation-dependent amplification or attenuation of raw climate model temperature changes. Itconcerns both the station-based QM product and the high-resolution QM-based grid and generally lacks a physicalexplanation. The interpretation of QM-based climate scenarios in a spatial context is hampered by these artefacts,and elevation-dependent warming signals in QM-based products need to be carefully evaluated.This contribution presents a summary of the issue, and also discusses potential future adjustments of theQM methodology in order to circumvent the adverse effect on temperature change signals.

Spatial artefacts in distributed quantile-mapped climate scenarios

https://repositorio.unican.es/xmlui/bitstream/10902/18597/3/Spatialartefacts.pdf

Spatial artefacts in distributed quantile-mapped climate scenarios

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