| Title | Benefits from using combined dynamical-statistical downscaling approaches - lessons from a case study in the Mediterranean region |
| Abstract | Various downscaling techniques have been developed
to bridge the scale gap between global climate models
(GCMs) and finer scales required to assess hydrological impacts
of climate change. Such techniques may be grouped
into two downscaling approaches: the deterministic dynamical
downscaling (DD) and the statistical downscaling (SD).
Although SD has been traditionally seen as an alternative to
DD, recent works on statistical downscaling have aimed to
combine the benefits of these two approaches. The overall
objective of this study is to assess whether a DD processing
performed before the SD permits to obtain more suitable
climate scenarios for basin scale hydrological applications
starting from GCM simulations. The case study presented
here focuses on the Apulia region (South East of Italy,
surface area about 20 000 km2), characterised by a typical
Mediterranean climate; the monthly cumulated precipitation
and monthly mean of daily minimum and maximum temperature
distribution were examined for the period 1953-
2000. The fifth-generation ECHAM model from the Max-
Planck-Institute for Meteorology was adopted as GCM. The
DD was carried out with the Protheus system (ENEA), while
the SD was performed through a monthly quantile-quantile
correction. The SD resulted efficient in reducing the mean
bias in the spatial distribution at both annual and seasonal
scales, but it was not able to correct the miss-modelled nonstationary
components of the GCM dynamics. The DD provided
a partial correction by enhancing the spatial heterogeneity
of trends and the long-term time evolution predicted
by the GCM. The best results were obtained through the
combination of both DD and SD approaches. |
| Source | Hydrology and earth system sciences 17 (2), pp. 705–720 |
| Keywords | CLIMATE-CHANGE SCENARIOSSWEDISH PRECIPITATIONUNITED-KINGDOM |
| Journal | Hydrology and earth system sciences |
| Editor | Copernicus Publ., Göttingen, Germania |
| Year | 2013 |
| Type | Articolo in rivista |
| DOI | 10.5194/hess-17-705-2013 |
| Authors | 1)Guyennon N., 1)Romano E., 2)Portoghese I., 3)Salerno F., 4)Calmanti S., 1)Petrangeli A.B., 3)Tartari G., 3)Copetti D. |
| Text | 241715 2013 10.5194/hess 17 705 2013 ISI Web of Science WOS 000316961100003 CLIMATE CHANGE SCENARIOS SWEDISH PRECIPITATION UNITED KINGDOM Benefits from using combined dynamical statistical downscaling approaches lessons from a case study in the Mediterranean region 1 Guyennon N., 1 Romano E., 2 Portoghese I., 3 Salerno F., 4 Calmanti S., 1 Petrangeli A.B., 3 Tartari G., 3 Copetti D. 1National Research Council, Water Research Institute, Roma, Italy 2National Research Council, Water Research Institute, UOS Bari, Bari, Italy 3National Research Council, Water Research Institute, UOS Brugherio, Brugherio, Italy 4ENEA Energy and Environment Modeling Technical Unit, Roma, Italy Various downscaling techniques have been developed to bridge the scale gap between global climate models GCMs and finer scales required to assess hydrological impacts of climate change. Such techniques may be grouped into two downscaling approaches the deterministic dynamical downscaling DD and the statistical downscaling SD . Although SD has been traditionally seen as an alternative to DD, recent works on statistical downscaling have aimed to combine the benefits of these two approaches. The overall objective of this study is to assess whether a DD processing performed before the SD permits to obtain more suitable climate scenarios for basin scale hydrological applications starting from GCM simulations. The case study presented here focuses on the Apulia region South East of Italy, surface area about 20 000 km2 , characterised by a typical Mediterranean climate; the monthly cumulated precipitation and monthly mean of daily minimum and maximum temperature distribution were examined for the period 1953 2000. The fifth generation ECHAM model from the Max Planck Institute for Meteorology was adopted as GCM. The DD was carried out with the Protheus system ENEA , while the SD was performed through a monthly quantile quantile correction. The SD resulted efficient in reducing the mean bias in the spatial distribution at both annual and seasonal scales, but it was not able to correct the miss modelled nonstationary components of the GCM dynamics. The DD provided a partial correction by enhancing the spatial heterogeneity of trends and the long term time evolution predicted by the GCM. The best results were obtained through the combination of both DD and SD approaches. 17 Published version http //www.hydrol earth syst sci.net/17/705/2013/hess 17 705 2013.html Articolo pubblicato Guyennon_benefits.pdf Articolo in rivista Copernicus Publ. 1027 5606 Hydrology and earth system sciences Hydrology and earth system sciences Hydrol. earth syst. sci. Hydrology and earth system sciences. HESS Gottingen. Print Hydrology and earth system sciences Print nicolasdominique.guyennon GUYENNON NICOLAS annabruna.petrangeli PETRANGELI ANNA BRUNA ivan.portoghese PORTOGHESE IVAN franco.salerno SALERNO FRANCO emanuele.romano ROMANO EMANUELE TA.P02.031.002 Impatti dei cambiamenti climatici sugli ecosistemi remoti |
