The 18.6‐year nodal tidal cycle and the bi‐decadal precipitation oscillation over the plains to the east of subtropical Andes, South America

Agosta, Eduardo A.

doi:10.1002/joc.3787

Cited by 17 publications

(10 citation statements)

References 32 publications

(68 reference statements)

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“…Finally, since subregion V presents quasi‐cycles close to the bidecadal band, it would be interesting to explore in future works if precipitation in the subregion could be influenced by the moon nodal 18‐year cycle. In this sense, Agosta () found a bidecadal oscillation in CWA precipitation that is present all along over a 100 years of records, and the author related it with the influence of the lunar nodal cycle on the mid‐latitude lower tropospheric circulation.…”

Section: Resultsmentioning

confidence: 99%

Climate change and precipitation variability over the western ‘Pampas’ in Argentina

Maenza

Agosta

Bettolli

2017

Intl Journal of Climatology

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This work focuses on the analysis of spatial and temporal variability of precipitation in the central region of southern Central Argentina (SCA), a climate transition area which has experienced an important agricultural expansion. For this purpose, gauge station precipitation datasets available in the area were extensively used. The annual cycle shows a defined dry season (May–August) and wet season (September–April). Wet season represents over 85% of annual totals. A regionalization analysis of wet‐season precipitation suggests five subregions with spatially homogeneous precipitation variability in SCA. Three out the five subregions are located in central SCA. Conveniently devised precipitation indices for the latter subregions show the presence of significant precipitation jumps by the early 1970s, and to a minor extent, the mid‐1960s. Precipitation jumps are responsible for the observed long‐term trends in central SCA, which explain positive precipitation changes over 30–40% of regional averages in the period 1922–2012. The presence of stationary and non‐stationary components in SCA precipitation variability remotely connects the region mainly with variations in equatorial Pacific SSTs. The assessment of greenhouse gases concentration effects on future projections of wet‐season precipitation over central SCA is investigated by means of multi‐model analysis of historical experiment, and the representative concentration pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5), provided by the Coupled Model Intercomparison Project Phase 5. Results suggest an overall increased precipitation, roughly 15% respect to present climate, under most severe future scenario.

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Section: Resultsmentioning

confidence: 99%

Climate change and precipitation variability over the western ‘Pampas’ in Argentina

Maenza

Agosta

Bettolli

2017

Intl Journal of Climatology

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“…Lower (higher) SSTs over the middle (high) latitudes will weaken the SST gradient, which should result in a weakening and northward displacement of storm tracks in the westerlies as well as the midlatitude jet. Moreover, lower SSTs over the midlatitudes, associated with larger mixing in the ocean due to larger diurnal tides, may result in negative 850 hPa heights at the midlatitudes, as demonstrated for the southwestern Atlantic [ Agosta , ]. Conversely, the SST pattern (Figure ) also resembles the response to the (negative) SAM, shown to occur with a lag of 1 week with respect to atmospheric anomalies [ Ciasto and Thompson , ].…”

Section: Resultsmentioning

confidence: 99%

Response of the Southern Annular Mode to tidal forcing and the bidecadal rainfall cycle over subtropical southern Africa

2014

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Synoptic weather data and rainfall records are used to support previous suggestions that the decadal-scale cycle in certain climate records may be attributed to the modulation in tidal forcing related to the 18.6 year lunar nodal cycle. The Southern Annular Mode (SAM) is shown to be sensitive to tidal forcing on a daily time scale. It is subsequently shown that the late-summer SAM can be predicted by consideration of tidal potential. The seasonal response in the SAM is also reflected in sea surface temperatures. Observed behavior of the atmosphere suggests that changing tidal potential over the lower versus higher latitudinal regions plays a role. The atmospheric response as reflected in the changing SAM affects the daily rainfall variation in certain subtropical parts of southern Africa where rainfall correlates positively with the SAM. The daily rainfall response subsequently accumulates in a bidecadal rainfall cycle, known over southern Africa as the Dyer-Tyson cycle.

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“…Using long‐term runs of two climate models (HadCM3 and GFDL CM2.1), they found that the 20‐year variability in the Arctic could be related to the Atlantic Multidecadal Oscillation (AMO). Agosta () found a quasi 20‐year oscillation in the summer rainfall of subtropical South America on the lee side of the Andes. Agosta () argued that this scale of variability could be linked to the lunar nodal cycle influence on the amplitude of the solar tides.…”

Section: Discussionmentioning

confidence: 99%

“…Agosta () found a quasi 20‐year oscillation in the summer rainfall of subtropical South America on the lee side of the Andes. Agosta () argued that this scale of variability could be linked to the lunar nodal cycle influence on the amplitude of the solar tides. He found a statistically significant correlation with SST variability in the vicinity of the Malvinas (Falkland) Islands.…”

Section: Discussionmentioning

confidence: 99%

110 years of temperature observations at Orcadas Antarctic Station: multidecadal variability

Zitto

Barrucand

Piotrkowski

et al. 2015

Intl Journal of Climatology

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ABSTRACT:There is growing evidence of significant changes in components of the Antarctic climate system, an important issue given the influence Antarctica has on global climate. It is important to infer to what extent these regional changes could be attributed to human-induced processes and to what extent to natural variability. Standard methods such as linear trend estimates or piecewise linear trends can be inadequate because they may result in erratic, non-systematic results, particularly if different scales of variability are present in each record and various records are to be compared. The Orcadas Antarctic Station (Argentina), with daily surface meteorological observations since April 1903, provides Antarctica's longest observational record. This study analyses the Orcadas seasonal surface temperature variability. Multidecadal variability and short-term trends are studied to provide an improved assessment of climate evolution and necessary information for the determination of mechanisms driving regional/local change. A combined method using wavelet transform (WT), non-linear statistical model approaches and derivative of fits is developed. This methodology is also applied for validation and comparison to the Gomez ice core oxygen isotope record for the 1857-2006 and 1903-2006 time intervals. Significant quasi 50-year and quasi 20-year variability bands were obtained, both for the quarterly and seasonal Orcadas temperature records, with warming (cooling) periods detected between 1903-1912, 1927-1961 and 1972-2004 (1912-1927 and 1962-1972). If seasons are considered, the only one with a fairly sustained warming is summer, where actual cooling is observed only at the beginning, prior to the early 1930s. Quasi 50-year variability was also detected in the Gomez record. Long periods are obtained in the model fits, longer than the time series, which varied with window length. Although not representing variability cycles, they could represent the best fit of the non-linear, non oscillating asymptotic stationary component of the series, i.e. a non-linear trend.

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The 18.6‐year nodal tidal cycle and the bi‐decadal precipitation oscillation over the plains to the east of subtropical Andes, South America

Cited by 17 publications

References 32 publications

Climate change and precipitation variability over the western ‘Pampas’ in Argentina

Climate change and precipitation variability over the western ‘Pampas’ in Argentina

Response of the Southern Annular Mode to tidal forcing and the bidecadal rainfall cycle over subtropical southern Africa

110 years of temperature observations at Orcadas Antarctic Station: multidecadal variability

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