603 research outputs found
Discussion on common errors in analyzing sea level accelerations, solar trends and global warming
Errors in applying regression models and wavelet filters used to analyze
geophysical signals are discussed: (1) multidecadal natural oscillations (e.g.
the quasi 60-year Atlantic Multidecadal Oscillation (AMO), North Atlantic
Oscillation (NAO) and Pacific Decadal Oscillation (PDO)) need to be taken into
account for properly quantifying anomalous accelerations in tide gauge records
such as in New York City; (2) uncertainties and multicollinearity among climate
forcing functions prevent a proper evaluation of the solar contribution to the
20th century global surface temperature warming using overloaded linear
regression models during the 1900-2000 period alone; (3) when periodic wavelet
filters, which require that a record is pre-processed with a reflection
methodology, are improperly applied to decompose non-stationary solar and
climatic time series, Gibbs boundary artifacts emerge yielding misleading
physical interpretations. By correcting these errors and using optimized
regression models that reduce multicollinearity artifacts, I found the
following results: (1) the sea level in New York City is not accelerating in an
alarming way, and may increase by about 350 mm from 2000 to 2100 instead of the
previously projected values varying from 1130 mm to 1550 mm estimated using the
methods proposed by Sallenger et al. (2012) and Boon (2012), respectively; (2)
the solar activity increase during the 20th century contributed about 50% of
the 0.8 K global warming observed during the 20th century instead of only 7-10%
(IPCC, 2007; Benestad and Schmidt, 2009; Lean and Rind, 2009). These findings
stress the importance of natural oscillations and of the sun to properly
interpret climatic changes.Comment: 21 pages, 10 Figure
Empirical analysis of the solar contribution to global mean air surface temperature change
The solar contribution to global mean air surface temperature change is
analyzed by using an empirical bi-scale climate model characterized by both
fast and slow characteristic time responses to solar forcing: yr, and yr or yr. Since 1980 the solar
contribution to climate change is uncertain because of the severe uncertainty
of the total solar irradiance satellite composites. The sun may have caused
from a slight cooling, if PMOD TSI composite is used, to a significant warming
(up to 65% of the total observed warming) if ACRIM, or other TSI composites are
used. The model is calibrated only on the empirical 11-year solar cycle
signature on the instrumental global surface temperature since 1980. The model
reconstructs the major temperature patterns covering 400 years of solar induced
temperature changes, as shown in recent paleoclimate global temperature
records.Comment: 9 pages, 6 figure
Climate Change and Its Causes, A Discussion About Some Key Issues
This article discusses the limits of the Anthropogenic Global Warming Theory
advocated by the Intergovernmental Panel on Climate Change. A phenomenological
theory of climate change based on the physical properties of the data
themselves is proposed. At least 60% of the warming of the Earth observed since
1970 appears to be induced by natural cycles which are present in the solar
system. A climatic stabilization or cooling until 2030-2040 is forecast by the
phenomenological model.Comment: 26 pages, 15 figure. The full English version with the appendixes can
be downloaded from
http://scienceandpublicpolicy.org/originals/climate_change_causes.htm
Global temperatures and sunspot numbers. Are they related? Yes, but non linearly. A reply to Gil-Alana et al. (2014)
Gil-Alana et al. (Physica A: 396, 42-50, 2014) compared the sunspot number
record and the temperature record and found that they differ: the sunspot
number record is characterized by a dominant 11-year cycle while the
temperature record appears to be characterized by a singularity or pole in the
spectral density function at the zero frequency. Consequently, they claimed
that the two records are characterized by substantially different statistical
fractional models and rejected the hypothesis that sun influences significantly
global temperatures. I show that: (1) the "singularity" or "pole" in the
spectral density function of the global surface temperature at the "zero"
frequency does not exist - it is a typical misinterpretation that discrete
power spectra of non-stationary signals can suggest; (2) appropriate continuous
periodograms clarify the issue and also show a signature of the 11-year solar
cycle (amplitude <0.1 K), which since 1850 has an average period of about 10.4
year, and of many other natural oscillations; (3) the solar signature in the
surface temperature record can be recognized only using specific techniques of
analysis that take into account non-linearity and filtering of the multiple
climate change contributions; (4) the post 1880-year temperature warming trend
cannot be compared or studied against the sunspot record and its 11-year cycle,
but requires solar proxy models showing short and long scale oscillations plus
the contribution of anthropogenic forcings, as done in the literature. Multiple
evidences suggest that global temperatures and sunspot numbers are quite
related to each other at multiple time scales through complex and non-linear
processes. Finally, I show that the prediction of a semi-empirical model for
the global temperature based on astronomical oscillations and anthropogenic
forcing proposed by Scafetta since 2009 has up to date been successful.Comment: 21 pages, 6 figure
Scaling Analysis on Indian Foreign Exchange Market
In this paper we investigate the scaling behavior of the average daily
exchange rate returns of the Indian Rupee against four foreign currencies
namely US Dollar, Euro, Great Britain Pound and Japanese Yen. Average daily
exchange rate return of the Indian Rupee against US Dollar is found to exhibit
a persistent scaling behavior and follow Levy stable distribution. On the
contrary the average daily exchange rate returns of the other three foreign
currencies do not show persistency or antipersistency and follow Gaussian
distribution.Comment: Revised Final Version. In Press Physica
Multi-scale harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle
The sunspot record since 1749 is made of three major cycles (9.98, 10.9 and
11.86 yr). The side frequencies are related to the spring tidal period of
Jupiter and Saturn (9.93 yr) and to the tidal sidereal period of Jupiter (11.86
yr). A simplified harmonic constituent model based on the above two planetary
tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal
phases, plus a theoretically deduced 10.87-year central cycle reveals complex
quasi-periodic interference/beat patterns at about 115, 61 and 130 years, plus
a quasi-millennial large beat cycle around 983 years. We show that equivalent
synchronized cycles are found in cosmogenic records used to reconstruct solar
activity and in proxy climate records throughout the Holocene. The
quasi-secular beat oscillations hindcast reasonably well the known prolonged
periods of low solar activity during the last millennium known as Oort, Wolf,
Sporer, Maunder and Dalton minima, as well as 17 115-year long oscillations
found in temperature reconstructions during the last 2000 years. The millennial
three-frequency beat cycle hindcasts equivalent solar and climate cycles for
12,000 years. Prolonged solar minima in 1900-1920 and 1960-1980, the secular
solar maxima around 1870-1890, 1940-1950 and 1995-2005, and a secular upward
trending during the 20th century is recovered: this modulated trending agrees
well with some solar proxy model, with the ACRIM TSI satellite composite and
with the global surface temperature modulation since 1850. The model forecasts
a new prolonged solar grand minimum during 2020-2045, which would be produced
by the minima of both the 61 and 115-year reconstructed cycles. Solar and
climate oscillations are linked to planetary motion and, furthermore, their
timing can be reasonably hindcast and forecast for decades, centuries and
millennia. The critique by Smythe and Eddy (1977) is rebutted.Comment: Journal of Atmospheric and Solar-Terrestrial Physics (2012
Solar and planetary oscillation control on climate change: hind-cast, forecast and a comparison with the CMIP5 GCMs
Global surface temperature records (e.g. HadCRUT4) since 1850 are
characterized by climatic oscillations synchronous with specific solar,
planetary and lunar harmonics superimposed on a background warming modulation.
The latter is related to a long millennial solar oscillation and to changes in
the chemical composition of the atmosphere (e.g. aerosol and greenhouse gases).
However, current general circulation climate models, e.g. the CMIP5 GCMs, to be
used in the AR5 IPCC Report in 2013, fail to reconstruct the observed climatic
oscillations. As an alternate, an empirical model is proposed that uses: (1) a
specific set of decadal, multidecadal, secular and millennial astronomic
harmonics to simulate the observed climatic oscillations; (2) a 0.45
attenuation of the GCM ensemble mean simulations to model the anthropogenic and
volcano forcing effects. The proposed empirical model outperforms the GCMs by
better hind-casting the observed 1850-2012 climatic patterns. It is found that:
(1) about 50-60% of the warming observed since 1850 and since 1970 was induced
by natural oscillations likely resulting from harmonic astronomical forcings
that are not yet included in the GCMs; (2) a 2000-2040 approximately steady
projected temperature; (3) a 2000-2100 projected warming ranging between 0.3
and 1.6 , which is significantly lower than the IPCC GCM
ensemble mean projected warming of 1.1 to 4.1 ; ; (4) an
equilibrium climate sensitivity to doubling centered in 1.35
and varying between 0.9 and 2.0 .Comment: 35 Pages, 18 Figures. General Review in "Mechanisms of Climate Change
and the AGW Concept: a critical review
Empirical evidence for a celestial origin of the climate oscillations and its implications
We investigate whether or not the decadal and multi-decadal climate
oscillations have an astronomical origin. Several global surface temperature
records since 1850 and records deduced from the orbits of the planets present
very similar power spectra. Eleven frequencies with period between 5 and 100
years closely correspond in the two records. Among them, large climate
oscillations with peak-to-trough amplitude of about 0.1 and 0.25 ,
and periods of about 20 and 60 years, respectively, are synchronized to the
orbital periods of Jupiter and Saturn. Schwabe and Hale solar cycles are also
visible in the temperature records. A 9.1-year cycle is synchronized to the
Moon's orbital cycles. A phenomenological model based on these astronomical
cycles can be used to well reconstruct the temperature oscillations since 1850
and to make partial forecasts for the 21 century. It is found that at
least 60\% of the global warming observed since 1970 has been induced by the
combined effect of the above natural climate oscillations. The partial forecast
indicates that climate may stabilize or cool until 2030-2040. Possible physical
mechanisms are qualitatively discussed with an emphasis on the phenomenon of
collective synchronization of coupled oscillators.Comment: 18 pages, 15 figures, 2 table
Understanding the complexity of the L\'evy-walk nature of human mobility with a multi-scale cost/benefit model
Probability distributions of human displacements has been fit with
exponentially truncated L\'evy flights or fat tailed Pareto inverse power law
probability distributions. Thus, people usually stay within a given location
(for example, the city of residence), but with a non-vanishing frequency they
visit nearby or far locations too. Herein, we show that an important empirical
distribution of human displacements (range: from 1 to 1000 km) can be well fit
by three consecutive Pareto distributions with simple integer exponents equal
to 1, 2 and () 3. These three exponents correspond to three
displacement range zones of about 1 km 10 km, 10
km 300 km and 300 km
1000 km, respectively. These three zones can be geographically and physically
well determined as displacements within a city, visits to nearby cities that
may occur within just one-day trips, and visit to far locations that may
require multi-days trips. The incremental integer values of the three exponents
can be easily explained with a three-scale mobility cost/benefit model for
human displacements based on simple geometrical constrains. Essentially, people
would divide the space into three major regions (close, medium and far
distances) and would assume that the travel benefits are randomly/uniformly
distributed mostly only within specific urban-like areas
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