Decadal and longer timescale variability in the winter North Atlantic Oscillation (NAO) has considerable impact on regional climate, yet it remains unclear what fraction of this variability is potentially predictable. This study takes a new approach to this question by demonstrating clear physical differences between NAO variability on interannual-decadal (<30 year) and multidecadal (>30 year) timescales. It is shown that on the shorter timescale the NAO is dominated by variations in the latitude of the North Atlantic jet and storm track, whereas on the longer timescale it represents changes in their strength instead. NAO variability on the two timescales is associated with different dynamical behaviour in terms of eddy-mean flow interaction, Rossby wave breaking and blocking. The two timescales also exhibit different regional impacts on temperature and precipitation and different relationships to sea surface temperatures. These results are derived from linear regression analysis of the Twentieth Century and NCEP-NCAR reanalyses and of a high-resolution HiGEM General Circulation Model control simulation, with additional analysis of a long sea level pressure reconstruction. Evidence is presented for an influence of the ocean circulation on the longer timescale variability of the NAO, which is particularly clear in the model data. Finally, as well as providing new evidence of potential predictability, these findings are shown to have implications for the reconstruction and interpretation of long climate records
Woollings, T., Franzke, C., Hodson, D. L. R., Dong, B., Barnes, E. A., Raible, C. C., & Pinto, J. G. (2014). Contrasting interannual and multidecadal NAO variability. Climate Dynamics, 45(1-2). https://doi.org/10.1007/s00382-014-2237-y
Woollings, T., Franzke, C., Hodson, D. L. R., et al., "Contrasting interannual and multidecadal NAO variability," Climate Dynamics 45, no. 1-2 (2014), https://doi.org/10.1007/s00382-014-2237-y
@article{osti_1565279,
author = {Woollings, T. and Franzke, C. and Hodson, D. L. R. and Dong, B. and Barnes, E. A. and Raible, C. C. and Pinto, J. G.},
title = {Contrasting interannual and multidecadal NAO variability},
annote = {Decadal and longer timescale variability in the winter North Atlantic Oscillation (NAO) has considerable impact on regional climate, yet it remains unclear what fraction of this variability is potentially predictable. This study takes a new approach to this question by demonstrating clear physical differences between NAO variability on interannual-decadal (30 year) timescales. It is shown that on the shorter timescale the NAO is dominated by variations in the latitude of the North Atlantic jet and storm track, whereas on the longer timescale it represents changes in their strength instead. NAO variability on the two timescales is associated with different dynamical behaviour in terms of eddy-mean flow interaction, Rossby wave breaking and blocking. The two timescales also exhibit different regional impacts on temperature and precipitation and different relationships to sea surface temperatures. These results are derived from linear regression analysis of the Twentieth Century and NCEP-NCAR reanalyses and of a high-resolution HiGEM General Circulation Model control simulation, with additional analysis of a long sea level pressure reconstruction. Evidence is presented for an influence of the ocean circulation on the longer timescale variability of the NAO, which is particularly clear in the model data. Finally, as well as providing new evidence of potential predictability, these findings are shown to have implications for the reconstruction and interpretation of long climate records},
doi = {10.1007/s00382-014-2237-y},
url = {https://www.osti.gov/biblio/1565279},
journal = {Climate Dynamics},
issn = {ISSN 0930-7575},
number = {1-2},
volume = {45},
place = {United States},
publisher = {Springer-Verlag},
year = {2014},
month = {07}}
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
Sponsoring Organization:
German Federal Ministry of Education and Research (BMBF); National Centre for Atmospheric Science (NCAS); Natural Environmental Research Council (NERC); Swiss National Science Foundation; USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)