The asymmetry of the solar cycle: A result of non-linearity

Rusu, Mircea

doi:10.1016/j.asr.2007.02.098

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…Furthermore, although WTC can be used to detect correlation between two time series in the frequency domain, if one of the time series has varying skewness, the correlation in the temporal domain would be weak [84]. Many geophysical time series are nonlinear [84][85][86] and exhibit skewness and kurtosis; thus, it is important to determine whether such characteristics also exist in GST, SAT, and SATD time series. Moreover, owing to large errors in GST before 1980, we selected the higher quality GST data of 1980-2019 and revealed the WTC between GST, SAT, SATD, and the large-scale indexes for the period 1980-2019.…”

Section: Uncertainties and Limitationsmentioning

confidence: 99%

Three-Dimensional Dynamic Variations of Ground/Air Surface Temperatures and Their Correlation with Large-Scale Circulation Indexes in Southwest China (1980–2019)

2022

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Air/soil temperatures play important roles in land–atmosphere interactions. The three-dimensional (temporal, spatial, and vertical) variations of maximum, mean, and minimum ground soil temperature at 0 cm (GSTx, GSTm, and GSTn, respectively), surface air temperature at 2 m (SATx, SATm, and SATn, respectively), and soil–air temperature difference (SATDx, SATDm, and SATDn, respectively) and their potential linkages with large-scale indexes in Southwest China during 1980–2019 were analyzed. Variations of GST and SAT at the majority of stations (pixels) exhibited significant (p ≤ 0.05) warming, albeit at different rates; consequently, SATD exhibited different variation. Moreover, the period of GST, SAT, and SATD was similar in intra-annual and interannual oscillation but was different in interdecadal oscillation. The variation rate of GST, SAT, and SATD exhibited significant (p ≤ 0.05) correlation with elevation, but with different variation gradient. Notably, asymmetric variation of SATDx (downward trend) and of SATDn (upward trend) with elevation was found at elevations >3 km. Wavelet coherence showed that the Atlantic Multidecadal Oscillation is the dominant factor affecting GST and SAT, whereas the Pacific Decadal Oscillation and the North Atlantic Oscillation make the greatest contributions to SATD. It was found that GST, SAT, and SATD exhibit different variations under the effects of global warming, the driving mechanism of which requires further study.

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Section: Uncertainties and Limitationsmentioning

confidence: 99%

Three-Dimensional Dynamic Variations of Ground/Air Surface Temperatures and Their Correlation with Large-Scale Circulation Indexes in Southwest China (1980–2019)

2022

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“…As in the last section we can't describe here and discuse extensively all the problems we examined and in which we have notable results. I leave for reader to have the pleasure to run through references from [143] to [176] to find the spectrum of our activities. Once again, it is necessary to recognize that without computers was not possible to cover all the topics.…”

Section: Astronomy and Astrophysicsmentioning

confidence: 99%

A short history of computer use at Faculty of Physics – University of Bucharest

Rusu

2018

Studia Digitalia

Self Cite

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For physicists computing is a main activity. Starting from devising an experiment to problem solving with computer, from using mathematical tables to other aids to computation, physics has grown its strength by using each step the numerical computation. So, computing for researches as well as education was used and steadily improved by us, starting from first minicomputers to the last generation of computers and algorithms. In this presentation we will follow, in short, the evolution of computing, hard and soft, in physics at our faculty. We selected here the main field of interests that was connected with problems showing: programmed solutions, simulations and modeling, computer application and software during the time. Such a time recollection is interesting and surprises me as how diverse and far such activity was done. Examples will be from computation in tradition physics, to biology, chemistry, astronomy, medicine to data processing and visualization, data management, to create our own educational software and so on. The fields as nonlinear dynamics, complexity, chaos and fractals, as well as fluid dynamics, atomic, molecular or nuclear physics, earth or stellar physics, connected to improvement of the experiments and devices via artificial intelligence are some of our topics which will be exemplified here.

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“…Many geophysical time series such as the solar cycle (Rusu, 2007), Quasi-biennial Oscillation (QBO; Hamilton and Hsieh, 2002;Lu et al, 2009), and El Niño-Southern Oscillation (ENSO; Timmermann, 2003) are nonlinear. From a time series analysis perspective, the nonlinearities in the time series manifest as the tendency for the time series to rise more quickly than they fall or as the propensity for positive deviations above a horizonal axis (zero axis in the case of zero-mean time series) to be greater than negative deviations below the same horizonal axis.…”

Section: Introductionmentioning

confidence: 99%

A waveform skewness index for measuring time series nonlinearity and its applications to the ENSO–Indian monsoon relationship

Schulte

Policelli

Zaitchik

2022

Nonlin. Processes Geophys.

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Abstract. Many geophysical time series possess nonlinear characteristics that reflect the underlying physics of the phenomena the time series describe. The nonlinear character of times series can change with time, so it is important to quantify time series nonlinearity without assuming stationarity. A common way of quantifying the time evolution of time series nonlinearity is to compute sliding skewness time series, but it is shown here that such an approach can be misleading when time series contain periodicities. To remedy this deficiency of skewness, a new waveform skewness index is proposed for quantifying local nonlinearities embedded in time series. A waveform skewness spectrum is proposed for determining the frequency components that are contributing to time series waveform skewness. The new methods are applied to the El Niño–Southern Oscillation (ENSO) and the Indian monsoon to test a recently proposed hypothesis that states that changes in the ENSO–Indian monsoon relationship are related to ENSO nonlinearity. We show that the ENSO–Indian rainfall relationship weakens during time periods of high ENSO waveform skewness. The results from two different analyses suggest that the breakdown of the ENSO–Indian monsoon relationship during time periods of high ENSO waveform skewness is related to the more frequent occurrence of strong central Pacific El Niño events, supporting arguments that changes in the ENSO–Indian rainfall relationship are not solely related to noise.

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The asymmetry of the solar cycle: A result of non-linearity

Cited by 6 publications

References 14 publications

Three-Dimensional Dynamic Variations of Ground/Air Surface Temperatures and Their Correlation with Large-Scale Circulation Indexes in Southwest China (1980–2019)

Three-Dimensional Dynamic Variations of Ground/Air Surface Temperatures and Their Correlation with Large-Scale Circulation Indexes in Southwest China (1980–2019)

A short history of computer use at Faculty of Physics – University of Bucharest

A waveform skewness index for measuring time series nonlinearity and its applications to the ENSO–Indian monsoon relationship

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