Wavelet Analysis of Several Important Periodic Properties in the Relative Sunspot Numbers

Le, G. M.; Wang, Jia-Long

doi:10.1088/1009-9271/3/5/391

Cited by 37 publications

(30 citation statements)

References 13 publications

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“…Equation (4) is similar to the equation proposed by Le and Wang [21]. However, the difference here is that the variances (σ w and σ T ) are considered explicitly.…”

Section: Methodsmentioning

confidence: 97%

Wavelet analysis of the wind velocity and temperature variability in the Amazon Forest

Bolzan

Vieira

2006

Braz. J. Phys.

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We studied the turbulent interactions among vertical wind velocity and temperature time-series measured in the Amazonian forest, during the wet season campaign of Large Biophere-Atmosphere Experiment in Amazonia (LBA) in 1999. The approach is based on the estimation of the correlation coefficient between the different scales in turbulent fields and Cross Wavelet Power (XWP). The results suggest that the correlations among scales of the vertical wind velocity are due to the Coherent Structures (CS), a large scale signature in the thermal profile. These coherent structures, kind of ramps, promoted an increase in the interaction among both variables, vertical wind velocity and temperature, and also depends on the atmospheric stability conditions. Furthermore, these coherent structures may explain the higher values of the correlation coefficient found in the large scales during the diurnal period compared with the nocturnal period, for the vertical wind velocity.

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“…Equation (4) is similar to the equation proposed by Le and Wang [21]. However, the difference here is that the variances (σ w and σ T ) are considered explicitly.…”

Section: Methodsmentioning

confidence: 97%

Wavelet analysis of the wind velocity and temperature variability in the Amazon Forest

Bolzan

Vieira

2006

Braz. J. Phys.

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“…The use of the Morlet wavelet (with ω 0 = 6), as a filter, is justified by the fact that it provides a good balance between time and frequency localization (Grinsted et al 2004). The square module of the wavelet transform integrated in the time provides the energy contained in all wavelet coefficients of the same scale s (Le & Wang 2003). This function is called global wavelet power spectrum (GWPS) and can be computed as:…”

Section: The Continuous Wavelet Transformmentioning

confidence: 99%

Wavelet analysis of CME, X-ray flare, and sunspot series

Guedes

Pereira

Cecatto

2014

A&A

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Context. Coronal mass ejections (CMEs) and solar flares are the most energetic transient phenomena taking place at the Sun. Together they are principally responsible for disturbances in outer geospace. Coronal mass ejections and solar flares are believed to be correlated with the solar cycle, which is mainly characterized by sunspot numbers. Aims. Here, we search for pattern identification in CMEs, X-ray solar flares, and sunspot number time series using a new data mining process and a quantitative procedure to correlate these series. Methods. This new process consists of the combination of a decomposition method with the wavelet transform technique applied to the series ranging from 2000 until 2012. A simple moving average is used for the time-series decomposition as a high-pass filter. A continuous wavelet transform is applied to the series in sequence, which permits us to uncover signals previously masked by the original time series. We made use of the wavelet coherence to find some correlation between the data. Results. The results have shown the existence of periodic and intermittent signals in the CMEs, flares, and sunspot time series. For the CME and flare series, few and relatively short time intervals without any signal were observed. Signals with an intermittent character take place during some epochs of the maximum and descending phases of the solar cycle 23 and rising phase of solar cycle 24. A comparison among X-ray flares, sunspots, and CME time series shows a stronger relation between flare and CMEs, although during some short intervals (four-eight months) and in a relatively narrow band. Yet, in contrast we have obtained a fainter or even absent relation between the X-ray flares and sunspot number series as well as between the CMEs and sunspot number series.

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“…Damon and Sonnett (1991) identify cycles in radiocarbon production of 105 and 131 yr which they relate to solar variability. The Gleissburg solar cycle is typically thought to be between 80 and 90 yr in length, but Le and Wang (2003) argue that it has a dominant 101 yr period based on their wavelet analysis of the sunspot number series between A.D. 1700 and 2002. Fig.…”

Section: Solar Influence On Gulf Sstmentioning

confidence: 99%

Solar forcing of Gulf of California climate during the past 2000 yr suggested by diatoms and silicoflagellates

Barron

Bukry

2007

Marine Micropaleontology

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High-resolution records of the past 2000 yr are compared in a north-south transect (28°N to 24°N) of three cores from the eastern slopes of the Guaymas, Carmen, and Pescadero Basins of the Gulf of California (hereafter referred to as the "Gulf"). Evenly-spaced samples from the varved sediments in each core allow sample resolution ranging from ∼ 16 to ∼ 37 yr.Diatoms and silicoflagellates capture the seasonal variation between a late fall to early spring period of high biosiliceous productivity, that is driven by northwest winds, and a summer period of warmer, more stratified waters during which these winds slacken and/or reverse direction (monsoonal flow). As these winds decrease, tropical waters enter the Gulf and spread northward. Individual samples represent a composite of 7 to 23 yr of deposition and are assumed to record the relative dominance of the winter vs. summer floral components.Intervals of enhanced summer incursion of tropical waters, alternating with periods of increased late fall to early spring biosiliceous productivity are recorded in all three cores. Regularly spaced cycles (∼ 100 yr duration) of Octactis pulchra, a silicoflagellate proxy for lower SST and high productivity, and Azpeitia nodulifera, a tropical diatom, occur between ∼ A.D. 400 and ∼ 1700 in the more nearshore Carmen Basin core, NH01-21 (26.3°N), suggesting a possible solar influence on coastal upwelling.Cores BAM80 E-17 (27.9°N) and NH01-26 (24.3°N) contain longer-duration cycles of diatoms and silicoflagellates. The early part of Medieval Climate Anomaly (∼ A.D. 900 to 1200) is characterized by two periods of reduced productivity (warmer SST) with an intervening high productivity (cool) interval centered at ∼ A.D. 1050. Reduced productivity and higher SST also characterize the record of the last ∼ 100 to 200 yr in these cores. Solar variability appears to be driving productivity cycles, as intervals of increased radiocarbon production (sunspot minima) correlate with intervals of enhanced productivity. It is proposed that increased winter cooling of the atmosphere above southwest U.S. during sunspot minima causes intensification of the northwest winds that blow down the Gulf during the late fall to early spring, leading to intensified overturn of surface waters and enhanced productivity.A new silicoflagellate species, Dictyocha franshepardii Bukry, is described and illustrated.

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Wavelet Analysis of Several Important Periodic Properties in the Relative Sunspot Numbers

Cited by 37 publications

References 13 publications

Wavelet analysis of the wind velocity and temperature variability in the Amazon Forest

Wavelet analysis of the wind velocity and temperature variability in the Amazon Forest

Wavelet analysis of CME, X-ray flare, and sunspot series

Solar forcing of Gulf of California climate during the past 2000 yr suggested by diatoms and silicoflagellates

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