Archives par mot-clé : AMO/PDO

Climate change might not slow ocean circulation as much as thought

by Carolyn Grambling, January 31, 2019 in ScienceNews

New findings from an international ocean observing network are calling into question the long-standing idea that global warming might slow down a big chunk of the ocean’s “conveyor belt.” The first 21 months of data from sensors moored across much of the North Atlantic are giving new insight into what controls the strength of the Atlantic Meridional Overturning Circulation, a system of currents that redistributes heat around much of the Western Hemisphere.

Modern Climate Wavelet Patterns

by Renee Hannon, December 17, 2018 in WUWT

Wavelet analyses of modern global temperature anomalies provides an excellent visualization tool of temperature signal characteristics and patterns over the past 150 years. Scafetta recognized key temperature oscillations of about 9, 20 and 60-years using power spectra of global surface temperature anomalies. There has been much discussion about the 60-year quasi-oscillation both in WUWT and publications.

Detrending the temperature time series and removing the 60-year underlying trend enables insights into the interplay of interannual and decadal scales. Wavelet analyses reveals these periodic signals have distinguished patterns and characteristics that repeat over time suggesting natural external and internal influences. Interannual wavelet patterns that consist of 9-year and 3 to 5-year quasi-oscillations are repeated and dominate over 70% of the instrumental record. The 3 to 5-year discontinuous breakouts are coincident to El Niño and La Niña events of the El Niño-Southern Oscillation (ENSO). A period of quiescence from 1925 to 1960 is devoid of most wavelet signals suggesting different or transitional climate processes.