Di Kenneth Richard 11 Agosto 2016
Mentre le notizie giornalistiche e dei vari blogger su internet sono occupati a raccontare storie spaventose che invocano il presunto nesso causale tra le emissioni antropiche di CO² correlati alle inondazioni, alla siccità e al riscaldamento globale, forti prove scientifiche del cambiamento climatico naturally-forced, hanno continuato ad accumularsi molto rapidamente.
C’è un “consenso” scientifico ormai molto affermato che i cambiamenti climatici degli ultimi decenni sono solo debolmente influenzati da fattori naturali, mentre sarebbero fautori le emissioni antropogeniche di auto cambiamenti nei modelli delle precipitazioni e delle temperature. Eppure gli scienziati con aria di sfida continuano a pubblicare articoli in riviste peer-reviewed che minano questo parere “consenso”.
Le variazioni nelle precipitazioni e nelle temperature regionali sono stati a lungo determinati essendo fortemente correlati con modelli di circolazione oceanico-atmosferico naturali, o oscillazioni. L’indice amo (AMO), la Pacific Decadal Oscillation (PDO), la North Atlantic Oscillation (NAO), e il El Niño-Southern Oscillation (ENSO) è provato che influenzano in modo significativo cambiamenti della temperatura dell’aria di superficie e le precipitazioni (clima) su scala decadale e scala multi-decennale, e queste oscillazioni oceaniche naturali sono state collegate in modo molto robusto alle variazioni dell’attività solare.
Qui di seguito sono riassunti 35 nuovi studi chiave con articoli scientifici peer-reviewed pubblicati di recente, divisi in due categorie. La prima raccolta di documenti stabilisce che (a) i modelli decadali e multi-decennali di circolazione oceanica (AMO, PDO, NAO, ENSO) hanno modulato in modo significativo le precipitazione e le temperature con talvolta vistosi cambiamenti negli ultimi decenni, e la seconda collezione di documenti confermano che (b) naturali oscillazioni oceaniche sono, a loro volta, modulati dall’attività solare.
Natural Ocean Oscillations Drive Climate
Multiscale evolution of surface air temperature in the arid region of Northwest China [ARNC] and its linkages to ocean oscillations
Compared with the reconstructed interannual variation, the reconstructed interdecadal variability plays a decisive role in the ARNC [northwest China] warming and reveals the climatic pattern transformation from the cold period to the warm period before and after 1987. Additionally, there were also regional differences in the spatial patterns of change trend in the ARNC temperature at a given time. We also found that the AMO and PDO had significant impacts on the ARNC [northwest China] temperature fluctuation at an interdecadal scale
—–
A recent study of instrumental time series revealed NAO [North Atlantic Oscillation] as main factor for a strong relation between winter temperature, precipitation and river discharge in central Norway over the past 50 years. … The [NAO proxy record] shows distinct co-variability with climate changes over Greenland, solar activity and Northern Hemisphere glacier dynamics as well as climatically associated paleo-demographic trends.
—–
Spatial-temporal analysis of United States precipitation data from 1900 to 1999 indicates that the Atlantic Multidecadal Oscillation (AMO) primarily modulates drought frequency. Changes in the extended drought record correspond with timing of the Roman Climate Optimum, Medieval Warm Period, Little Ice Age … AMO modulated drought in southern Texas for the last 3000 years.
—–
Most of flood periods coincided with the warm phase of the Atlantic Multidecadal Oscillation (AMO). … Logistic regression showed that AMO index was the most correlated index with flood events. In fact, the odds ratio showed that floods were 1.90 times more likely to occur when AMO index was positive.
—–
The interannual relationship between North American (NA) winter temperature and large-scale atmospheric circulation anomalies and its decadal variation are analyzed. … NA [North American] temperature is largely controlled by these three large-scale atmospheric patterns, i.e., the PNA [Pacific-North American pattern], ABNA [Asian-Bering-North American pattern] and NAO [North Atlantic Oscillation] .
—–
Tree-ring-based reconstruction of temperature variability (1445–2011) for the upper reaches of the Heihe River Basin, Northwest China
Spectral analyses suggested that the reconstructed annual mean temperature variation may be related to large-scale atmospheric–oceanic variability such as the solar activity, Pacific Decadal Oscillation (PDO) and El Niño–Southern Oscillation (ENSO).
—–
Krishnamurthy and Krishnamurthy, 2016
Introduction: On interannual timescale, El Niño-Southern Oscillation (ENSO) is known to have a major impact on the Indian monsoon (Sikka, 1980; Rasmusson and Carpenter, 1983). … On decadal to multidecadal timescales, the Pacific Decadal Oscillation (PDO), the Atlantic Multidecadal Oscillation, and the Atlantic tripole mode determine the variability of rainfall over India (Sen Roy et al., 2003; Lu et al., 2006; Zhang and Delworth, 2006; Li et al., 2008; Sen Roy, 2011; Krishnamurthy and Krishnamurthy, 2014a, 2014b, 2016b).
—–
Drought variations in the study area significantly correlated with sea surface temperatures (SSTs) in North Pacific Ocean, suggesting a possible connection of regional hydroclimatic variations to the Pacific Decadal Oscillation (PDO).
—–
Hawaiian Islands rainfall exhibits strong modulation by El Niño–Southern Oscillation (ENSO), as well as in relation to Pacific decadal oscillation (PDO)-like variability. For significant periods of time, the reconstructed large-scale changes in the North Pacific SLP field described here and by construction the long-term decline in Hawaiian winter rainfall are broadly consistent with long-term changes in tropical Pacific sea surface temperature (SST) based on ENSO reconstructions documented in several other studies, particularly over the last two centuries.
—–
Century-scale causal relationships between global drought conditions and the state of the Pacific and Atlantic Oceans
In this study, the Granger causality test is used to examine the effects of ENSO, PDO, and NAO on global drought conditions. The results show robust relationships between drought conditions and the ocean states …ENSO and PDO may reinforce each other to dominate climate variability over North America and northern South America. Climate variability in southern Europe and northern Africa may be forced by the concurrence of ENSO and NAO.
—–
Decadal variability is a notable feature of the Atlantic Ocean and the climate of the regions it influences. Prominently, this is manifested in the Atlantic Multidecadal Oscillation (AMO) in sea surface temperatures. Positive (negative) phases of the AMO coincide with warmer (colder) North Atlantic sea surface temperatures. The AMO is linked with decadal climate fluctuations, such as Indian and Sahel rainfall, European summer precipitation, Atlantic hurricanes and variations in global temperatures. It is widely believed that ocean circulation drives the phase changes of the AMO by controlling ocean heat content.
—–
Multi-decadal and centennial variability in flood activity is recorded in extended series of discharge data, historical information and sedimentary records. Over the last six centuries that variability correlates with components of the Atlantic climate system such as the North Atlantic Oscillation (NAO) and Atlantic Multi-decadal Oscillation (AMO).
—–
Results from a multiregression analysis of the global and sea surface temperature anomalies for the period 1950–2011 are presented where among the independent variables multidecade oscillation signals over various oceanic areas are included. These indices are defined in analogy with the Atlantic Multidecadal Oscillation (AMO) index. Unexpectedly we find that a strong multidecade oscillation signal echoing the AMO is also present in the Western and Northwestern Pacific region. The results indicate that naturally induced climate variations seem to be dominated by two internal variability modes of the ocean–atmosphere system: AMO and El Niño Southern Oscillation
—–
When seasonal restrictions were added the results were similar, however, we found one clearly significant result: an increase in southerly flow of 2.6±0.8 days/month (p=1.9×10−4) during boreal summertime in association with El Niño. This result supports the existence of a robust teleconnection between the ENSO and European weather.
—–
Investigating the relationship between North Atlantic Oscillation and flood losses at the European scale
The North Atlantic Oscillation (NAO) is Europe’s dominant mode of climate variability. … We found significant correlations between the NAO signal and both the average annual loss (AAL) and the average seasonal loss (ASL) [due to floods], for all the countries analysed.
—–
García-García and Ummenhofer, 2015
Multidecadal variability of the continental precipitation annual amplitude driven by AMO and ENSO
Here we show that continental precipitation annual amplitude, which represents the annual range between minimum and maximum (monthly) rainfall, covaries with a linear combination of the Atlantic Multidecadal Oscillation and low-frequency variations in the El Niño–Southern Oscillation on a decadal to multidecadal scale with a correlation coefficient of 0.92 (P < 0.01).
—–
Furthermore, since the end of the 19th century, we find an increasing variance in multidecadal hydroclimatic winter and spring, and this coincides with an increase in the multidecadal North Atlantic Oscillation (NAO) variability, suggesting a significant influence of large-scale atmospheric circulation patterns. However, multidecadal NAO variability has decreased in summer. Using Empirical Orthogonal Function analysis,we detect multidecadal North Atlantic sea-level pressure anomalies, which are significantly linked to the NAO during the Modern period.
—–
The ENSO phenomenon is one of the key factors that influence the interannual variability of precipitation over Southern South America. The aim of this study is to identify the regional response of precipitation to El Niño/La Niña events [during 1961-2008], with emphasis in drought conditions. [W]e calculated the mean SPI [standardized precipitation index] values for the El Niño and La Niña years and assessed its significance through bootstrap analysis. We found coherent and significant SPI [standardized precipitation index] responses to ENSO phases in most of the seven regions considered
—–
Gastineau and Frankignoul, 2015
The SST [sea surface temperature] influence is dominated by the Atlantic multidecadal oscillation (AMO), which also has a horseshoe shape, but with larger amplitude in the subpolar basin. A warm AMO phase leads to an atmospheric warming limited to the lower troposphere in summer, while it leads to a negative phase of the NAO in winter.
—–
The twentieth century Northern Hemisphere mean surface temperature (NHT) is characterized by a multidecadal warming-cooling-warming pattern followed by a flat trend since about 2000 (recent warming hiatus). Here we demonstrate that the multidcadal variability in NHT including the recent warming hiatus is tied to the NAT-NAO-AMO-AMOC coupled mode and the NAO is implicated as a useful predictor of NHT multidecadal variability. An NAO-based linear model is therefore established to predict the NHT, which gives an excellent hindcast for NHT in 1971-2011 with the recent flat trend well predicted.
Solar Activity Drives Ocean Oscillations
This study attempted to determine the relationships between solar activity and SST [sea surface temperature]. Instrumental data from 1901 to 2011 revealed a significant positive relationship on a global basis.
Conclusion: The analysis of the relationship between variations in solar activity and SST from 1901 to 2011 indicated that sunspot numbers and SST were positively correlated in wide areas, with statistically significant positive correlations in many regions. … It is worthy of note that the highest coefficients at a 29-month lag were found in the relationships both between SSN [sunspot number] and PDO [Pacific Decadal Oscillation], and SSN and CP El Niño with statistical significance at the 99% confidence level, respectively.
—–
Discussion of the Results: The results show that there is good connection between ENSO events and the changes in the background temperature and the precipitation in Nigeria. … Overall, the investigation shows a linear relationship between the solar radiation and the induced temperature, thus indicating that the observed variations in the temperature are mainly controlled by the insolation forcing
Conclusion: The outcome shows good link between the ENSO events and the Nigerian climate with the strongest agreement coming from the Niño 3 region of the Tropical Pacific. … The finding indicates that the primary driver of climate like the south-westerlies that brings monsoon into the country from South Atlantic Ocean, the north-easterlies that lead to Tropical dry climate in the North and the ITCZ, which is sandwiched between the air masses, could be affected by changes in ENSO events. According to the results, the major link between an ENSO event and changes in the temperature and rainfall in Nigeria is associated with shifts in the ITCZ position.
—–
Modulation of decadal ENSO-like variation by effective solar radiation
Here, we show that the effective solar radiation (ESR), which includes the net solar radiation and the effects of volcanic eruption, has modulated this decadal ENSO-like oscillation. The eastern Pacific warming (cooling) associated with this decadal ENSO-like oscillation over the past 139 years is significantly related to weak (strong) ESR [effective solar radiation].
—–
[W]e reconstructed the history of typhoon and storm-rain activity only for the interval AD 1400–1900. The record indicates that typhoon frequency throughout the Korean Peninsula varied in response to the state of the El Niño/Southern Oscillation. Typhoon variability was likely modulated further by the state of the East Asia summer monsoon (EASM) pattern, associated with variation in the magnitude of solar irradiance. During periods of minimum solar activity, such as the early Maunder Minimum (AD 1650–1675), typhoons struck the east China coast and Korean Peninsula more frequently because of a strengthened EASM.
—–
Flood frequency in the River Ammer discharge record is significantly correlated to changes in solar activity when the flood record lags the solar signal by 2–3 years (2-year lag: r = −0.375, p = 0.01; 3-year lag: r = −0.371, p = 0.03). Flood layer frequency in the Ammersee sediment record depicts distinct multi-decadal variations and significant correlations to a total solar irradiance reconstruction (r = −0.4, p < 0.0001) and 14C production rates (r = 0.37, p < 0.0001), reflecting changes in solar activity. On all timescales, flood frequency is higher when solar activity is reduced. … [T]he significant correlations as well as similar atmospheric circulation patterns might provide empirical support for a solar influence on hydroclimate extremes in central Europe during spring and summer by the so-called solar top-down mechanism.
—–
We conclude that the positive relation between AISMR [All Indian Summer Monsoon Rainfall] and solar activity, as found by other authors, is due to the combined effect of AMO, PDO and multi-decadal ENSO variability on AISMR. The solar activity influences the ICFs [internal climate forcings] and this influence is then transmitted to AISMR. … We also find that there is statistical significant negative relationship between AISMR and ENSO on inter-annual to centennial time scale and the strength of this relationship is modulated by solar activity from 3 to 40 year time scale.
—–
The 11 years solar cycle acts an important driving force for variations in the space weather, ultimately giving rise to climatic changes. Therefore, it is very important to understand the origin of space climate by analyzing the different proxies of solar magnetic variability. The another most important climate variation is El Niño–Southern Oscillation (ENSO) events, which impact the global oceanic and atmospheric circulations which thereby produce droughts, floods and intense rainfall in certain regions. The strong coupling and interactions between the Tropical Ocean and atmosphere play a major role in the development of global climatic system. … In particular, the El Niño, solar, geomagnetic activities are the major affecting forces on the decadal and interdecadal temperature variability on global and regional scales in a direct/indirect way. …. The 11 year solar cyclic variations observed from the several temperature climate records also suggest the impact of solar irradiance variability on terrestrial temperature …These findings suggest that there is possible strong coupling between temperature–ENSO and solar–geomagnetic signals.
—–
The broad comparability between the HML paleo-proxies, Chinese speleothem δ18Orecords, and the northern hemisphere summer insolation throughout the Holocene, suggests that solar insolation exerts a profound influence on ASM [Asian summer monsoon] changes. These findings reinforce a model of combined insolation and glacial forcing of the ASM.
—–
Invariably the splitting of spectral peaks corresponding to solar signal indicated nonlinear characteristics of the data and; therefore, even small variations in the solar output may help in catalyzing the coupled El Niño-atmospheric ENSO cycles by altering the solar heat input to the oceans. We, therefore, conclude that the Indian temperature variability is probably driven by the nonlinear coupling of ENSO and solar activity.
—–
Water reservoirs in the main aquifer (Section III) and in the Santa Juana dam are highly sensitive to ENSO oscillation climatic patterns. The main climatic events that control this record are the El Niño and La Niña events. In addition, the climatic influence of the westerlies and the SE extratropical moisture were also identified. Spectral analysis identified the presence of a 22.9-year cycle in piezometric levels of the alluvial aquifer of the Huasco River. This cycle is consistent with the 22-year Hale solar cycle, suggesting the existence of a solar forcing controlling the ENSO oscillations.
—–
The various techniques have been used to confer the existence of significant relations between the number of Sunspots and different terrestrial climate parameters such as rainfall, temperature, dewdrops, aerosol and ENSO etc. Improved understanding and modelling of Sunspots variations can explore the information about the related variables. This study uses a Markov chain method to find the relations between monthly Sunspots and ENSO data of two epochs (1996–2009and 1950–2014). … [P]erfect validation of dependency and stationary tests endorses the applicability of the Markov chain analyses on Sunspots and ENSO data. This shows that a significant relation between Sunspots and ENSO data exists.
—–
Understanding the influence of solar variability on the Earth’s climate requires knowledge of solar variability, solar interactions, and the mechanisms explain the response of the Earth’s climate system. The NAO (North Atlantic oscillation) is one of the most dominant modes of global climate variability. Like El Niño, La Niña, and the Southern Oscillation, it is considered as free internal oscillation of the climate system not subjected to external forcing. It is shown, to be linked to energetic solar eruptions. Surprisingly, it turns out that features of solar activity have been related to El Niño and La Niña, also have an significant impact on the NAO. NAO- has a related impacts on winter climate extend from Florida to Greenland and from northwestern Africa over Europe far into northern Asian region.
—–
[A]tmospheric circulation over South America and monsoon intensity have been tightly correlated throughout most of the Holocene, both directly responding to solar precession. … We also detect periods where rainfall amount in northeastern and southeastern Brazil are markedly anti-phased, suggesting a north-south migration of SACZ, which it appears to be mediated by solar irradiance.
—–
In this study, we undertake another effort towards understanding the role of the Sun in changing or varying the Earth’s climate on seasonal to decadal time scale. We focus on effects of varying solar activity on All Indian Summer Monsoon Rainfall (AISMR) and try to investigate how much the prediction of AISMR on a seasonal to decadal time scale can be improved by considering the solar irradiance variability in climate models. … Further, in our analysis we have foundstrong statistical evidence of the influence of solar activity on AMO and AISMR. We have found highly statistically significant evidence that North Atlantic SSTs are positively correlated with TSI on annual (CC 0.46), decadal (CC 0.55) and multidecadal time scales (CC 0.42) during the period 1600-2000. Also AMO influences the Niño3 and AISMR.
—–
Basing on a mathematical idea about the so-called strange nonchaotic attractor (SNA) in the quasi-periodically forced dynamical systems, the currently available re-analyses data are considered. It is found that the El Niño – Southern Oscillation (ENSO) is driven not only by the seasonal heating, but also by three more external periodicities (incommensurate to the annual period) associated with the ~18.6-year lunar-solar nutation of the Earth rotation axis, ~11-year sunspot activity cycle and the ~14-month Chandler wobble in the Earth’s pole motion.
Fonte: notrickszone
Enzo
Attività Solare
