RT Journal Article
T1 Internal variability and external forcings in the ocean–atmosphere multidecadal oscillator over the North Atlantic
A1 Ribera Rodríguez, Pedro
A1 Ordónez, Paulina
A1 Gallego Puyol, David
A1 Peña Ortiz, Cristina
K1 Atlantic multidecadal oscillation (AMO)
K1 SST reanalyses
K1 Twentieth century reanalysis
K1 Internal climate variability
K1 Blocking
K1 NAO
K1 MTM-SVD
K1 External forcings
AB In this paper, we generalize the concept of “external forcing” to include any mechanism that modulates the long-term evolution of a meteorological variable but is not directly related to the internal variability of the climate system. Applying this concept, the corresponding ‘external forcings’ are removed from several long record datasets of oceanic and atmosphericvariables at the surface in the North Atlantic. We perform a multivariate analysis in the frequency domain over both the original data felds and the new ‘internal variability’ felds. This multivariate analysis is based on a MultiTaper Method-Singular Value Decomposition (MTM-SVD). It is noteworthy that, after the removal of the external forcings, there is an almost perfect alignment of the main multidecadal oscillatory band (f=0.21 cycles/decade) with all the spectra of the analysed felds. This alignment was not observed before the external forcings were removed. Particularly striking is the case of the sea level pressure (SLP), which shows a notable variation in its oscillation period despite the fact that this variable has traditionally been considered to be unafected, at global scale, by any external forcing. The external forcing in the SLP records is very probably caused by the scarcity of the observed data during the frst hundred years of the record (most evident, during the earliest decades), by the spatial distribution of those observations and, possibly, by the assimilation model employed to build those long record datasets. When we analysed the relationship between the ocean and the atmosphere using this approach, we found strong evidence of a cyclic behaviour in which oceanic conditions modulate the atmospheric variability, with a lead time of up to about 10 years.
PB Springer Link
YR 2020
FD 2020-05-23
LK https://hdl.handle.net/10433/20055
UL https://hdl.handle.net/10433/20055
LA en
NO Ribera, P., Ordoñez, P., Gallego, D. et al. Internal variability and external forcings in the ocean–atmosphere multidecadal oscillator over the North Atlantic. Clim Dyn 55, 909–923 (2020). https://doi.org/10.1007/s00382-020-05300-8
NO Departamento de Sistemas Físicos, Químicos y Naturales
DS RIO
RD May 9, 2026