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Lucas-Picher, Philippe
Publications (3 of 3) Show all publications
Kumar, P., Wiltshire, A., Mathison, C., Asharaf, S., Ahrens, B., Lucas-Picher, P., . . . Jacob, D. (2013). Downscaled climate change projections with uncertainty assessment over India using a high resolution multi-model approach. Science of the Total Environment, 468, S18-S30
Open this publication in new window or tab >>Downscaled climate change projections with uncertainty assessment over India using a high resolution multi-model approach
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2013 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 468, p. S18-S30Article in journal (Refereed) Published
Abstract [en]

This study presents the possible regional climate change over South Asia with a focus over India as simulated by three very high resolution regional climate models (RCMs). One of the most striking results is a robust increase in monsoon precipitation by the end of the 21st century but regional differences in strength. First the ability of RCMs to simulate the monsoon climate is analyzed. For this purpose all three RCMs are forced with ECMWF reanalysis data for the period 1989-2008 at a horizontal resolution of similar to 25 km. The results are compared against independent observations. In order to simulate future climate the models are driven by lateral boundary conditions from two global climate models (GCMs: ECHAM5-MPIOM and HadCM3) using the SRES A1B scenario, except for one RCM, which only used data from one GCM. The results are presented for the full transient simulation period 1970-2099 and also for several time slices. The analysis concentrates on precipitation and temperature over land. All models show a clear signal of gradually wide-spread warming throughout the 21st century. The ensemble-mean warming over India is 1.5 degrees C at the end of 2050, whereas it is 3.9 degrees C at the end of century with respect to 1970-1999. The pattern of projected precipitation changes shows considerable spatial variability, with an increase in precipitation over the peninsular of India and coastal areas and, either no change or decrease further inland. From the analysis of a larger ensemble of global climate models using the A1B scenario a wide spread warming (similar to 3.2 degrees C) and an overall increase (similar to 8.5%) in mean monsoon precipitation by the end of the 21st century is very likely. The influence of the driving GCM on the projected precipitation change simulated with each RCM is as strong as the variability among the RCMs driven with one. (C) 2013 Elsevier B.V. All rights reserved.

Keywords
Climate change, HighNoon, Regional model, Indian summer monsoon, Indices
National Category
Climate Science
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-335 (URN)10.1016/j.scitotenv.2013.01.051 (DOI)000331022000003 ()23541400 (PubMedID)
Available from: 2015-04-14 Created: 2015-03-31 Last updated: 2025-02-07Bibliographically approved
Lucas-Picher, P., Boberg, F., Christensen, J. H. & Berg, P. (2013). Dynamical Downscaling with Reinitializations: A Method to Generate Finescale Climate Datasets Suitable for Impact Studies. Journal of Hydrometeorology, 14(4), 1159-1174
Open this publication in new window or tab >>Dynamical Downscaling with Reinitializations: A Method to Generate Finescale Climate Datasets Suitable for Impact Studies
2013 (English)In: Journal of Hydrometeorology, ISSN 1525-755X, E-ISSN 1525-7541, Vol. 14, no 4, p. 1159-1174Article in journal (Refereed) Published
Abstract [en]

To retain the sequence of events of a regional climate model (RCM) simulation driven by a reanalysis, a method that has not been widely adopted uses an RCM with frequent reinitializations toward its driving field. In this regard, this study highlights the benefits of an RCM simulation with frequent (daily) reinitializations compared to a standard continuous RCM simulation. Both simulations are carried out with the RCM HIRHAM5, driven with the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) data, over the 12-km-resolution European Coordinated Regional Climate Downscaling Experiment (CORDEX) domain covering the period 1989-2009. The analysis of daily precipitation shows improvements in the sequence of events and the maintenance of the added value from the standard continuous RCM simulation. The validation of the two RCM simulations with observations reveals that the simulation with reinitializations indeed improves the temporal correlation. Furthermore, the RCM simulation with reinitializations has lower systematic errors compared to the continuous simulation, which has a tendency to be too wet. A comparison of the distribution of wet day precipitation intensities shows similar added value in the continuous and reinitialized simulations with higher variability and extremes compared to the driving field ERA-Interim. Overall, the results suggest that the finescale climate dataset of the RCM simulation with reinitializations better suits the needs of impact studies by providing a sequence of events matching closely the observations, while limiting systematic errors and generating reliable added value. Downsides of the method with reinitializations are increased computational costs and the introduction of temporal discontinuities that are similar to those of a reanalysis.

Keywords
Europe, Climate models, Reanalysis data, Regional models
National Category
Climate Science
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-352 (URN)10.1175/JHM-D-12-063.1 (DOI)000326079300008 ()
Available from: 2015-04-14 Created: 2015-03-31 Last updated: 2025-02-07Bibliographically approved
Lucas-Picher, P., Somot, S., Deque, M., Decharme, B. & Alias, A. (2013). Evaluation of the regional climate model ALADIN to simulate the climate over North America in the CORDEX framework. Climate Dynamics, 41(5-6), 1117-1137
Open this publication in new window or tab >>Evaluation of the regional climate model ALADIN to simulate the climate over North America in the CORDEX framework
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2013 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 41, no 5-6, p. 1117-1137Article in journal (Refereed) Published
Abstract [en]

In this study, an ensemble of four multi-year climate simulations is performed with the regional climate model ALADIN to evaluate its ability to simulate the climate over North America in the CORDEX framework. The simulations differ in their driving fields (ERA-40 or ERA-Interim) and the nudging technique (with or without large-scale nudging). The validation of the simulated 2-m temperature and precipitation with observationally-based gridded data sets shows that ALADIN performs similarly to other regional climate models that are commonly used over North America. Large-scale nudging improves the temporal correlation of the atmospheric circulation between ALADIN and its driving field, and also reduces the warm and dry summer biases in central North America. The differences between the simulations driven with different reanalyses are small and are likely related to the regional climate model's induced internal variability. In general, the impact of different driving fields on ALADIN is smaller than that of large-scale nudging. The analysis of the multi-year simulations over the prairie and the east taiga indicates that the ALADIN 2-m temperature and precipitation interannual variability is similar or larger than that observed. Finally, a comparison of the simulations with observations for the summer 1993 shows that ALADIN underestimates the flood in central North America mainly due to its systematic dry bias in this region. Overall, the results indicate that ALADIN can produce a valuable contribution to CORDEX over North America.

Keywords
Regional climate model, CORDEX framework, North America, Multi-year climate simulations, Large-scale nudging, Flood
National Category
Climate Science
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-350 (URN)10.1007/s00382-012-1613-8 (DOI)000325073700001 ()
Available from: 2015-04-14 Created: 2015-03-31 Last updated: 2025-02-07Bibliographically approved
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