Comparison of Solar Wind Speeds Using Wavelet Transform and Fourier Analysis in IPS Data

Solar Physics ◽  
2015 ◽  
Vol 290 (9) ◽  
pp. 2507-2518 ◽  
Author(s):  
E. Aguilar-Rodriguez ◽  
J. C. Mejia-Ambriz ◽  
B. V. Jackson ◽  
A. Buffington ◽  
E. Romero-Hernandez ◽  
...  
Keyword(s):  
Solar Wind ◽  
Wavelet Transform ◽  
Fourier Analysis ◽  
Wind Speeds

The Radial Evolution of Solar Wind Speeds (Postprint)

2012 ◽  
Author(s):  
S. L. McGregor ◽  
W. J. Hughes ◽  
C. N. Arge ◽  
D. Odstreil ◽  
N. A. Schwadron
Keyword(s):  
Solar Wind ◽  
Wind Speeds ◽  
Radial Evolution

scholarly journals Solar Wind Helium Abundance Heralds Solar Cycle Onset

2021 ◽  
Author(s):  
Benjamin L Alterman ◽  
Justin C Kasper ◽  
Robert J Leamon ◽  
Scott W McIntosh
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Sunspot Number ◽  
Cycle Length ◽  
Phase Lag ◽  
Helium Abundance ◽  
Solar Cycles ◽  
Wind Speeds ◽  
Solar Wind Acceleration ◽  
Solar Cycle Length

Abstract We study the solar wind helium-to-hydrogen abundance's ( A He ) relationship to solar cycle onset. Using OMNI/Lo data, we show that A He increases prior to sunspot number (SSN) minima. We also identify a rapid depletion and recovery in A He that occurs directly prior to cycle onset. This A He Shutoff happens at approximately the same time across solar wind speeds ( v sw ) and the time between successive A He shutoffs is typically on the order of the corresponding solar cycle length. In contrast to A He 's v sw -dependent phase lag with respect to SSN (Alterman and Kasper, 2019), A He Shutoff's concurrence across v sw likely implies it is independent of solar wind acceleration and driven by a mechanism near or below the photosphere. Using Brightpoint (BP) measurements to provide context, we infer that this shutoff is likely related to the overlap of adjacent solar cycles and the equatorial flux cancelation of the older, extended solar cycle during solar minima.

Galactic cosmic-ray modulation effect by solar-wind streams

1995 ◽  
Vol 73 (9-10) ◽  
pp. 642-646 ◽  
Author(s):  
M. A. El-Borie
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Cosmic Rays ◽  
Solar Wind Speed ◽  
Cosmic Ray ◽  
Diurnal Variations ◽  
Solar Cycles ◽  
Mean Values ◽  
Wind Speeds ◽  
Cosmic Ray Modulation

Data, from the worldwide network of neutron monitors, recorded at Deep River, Hermanus, Rome, Tokyo, and Huancayo, over two solar cycles (Nos. 20 and 21) are analyzed to study the long-term variations of the solar diurnal variations as they relate to solar-wind speed. The median primary rigidities of response (Rm) for these detectors cover the range 16 GV ≤ Rm ≤ 33 GV. We discuss the solar diurnal variations (amplitude and phase) of cosmic rays as a function of solar activity. The behavior of solar diurnal phases is completely different for the two epochs of high-wind speed. Data of solar-wind speed from 1966–1986 are classified according to the state of the daily mean values. Variation in the amplitudes of the diurnal variations, as functions of the median primary rigidity of cosmic rays, for the two selected periods (1973–1975 and 1979–1981) of high and low solar-wind speeds were determined at the selected stations. The rigidity dependence of the averaged solar diurnal variations of cosmic rays related to the high solar-wind speed was studied. The most sensitive rigidity of modulation is around 20 and 30 GV during the 1973–1975 and 1979–1981 periods, respectively. Our results also show that there is a significant correlation in the solar diurnal amplitudes between the two divisions of high and low solar-wind speed days.

Relation Between Coronal Hole Areas and Solar Wind Speeds Derived from Interplanetary Scintillation Measurements

Solar Physics ◽  
2017 ◽  
Vol 292 (3) ◽  
Author(s):  
Munetoshi Tokumaru ◽  
Daiki Satonaka ◽  
Ken’ichi Fujiki ◽  
Keiji Hayashi ◽  
Kazuyuki Hakamada
Keyword(s):  
Solar Wind ◽  
Coronal Hole ◽  
Interplanetary Scintillation ◽  
Wind Speeds

Forecasting the Dst index from L5 in-situ data using PREDSTORM: accuracy and applicability

2020 ◽  
Author(s):  
Rachel Bailey ◽  
Christian Moestl ◽  
Martin Reiss ◽  
Andreas Weiss ◽  
Ute Amerstorfer ◽  
...  
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Dst Index ◽  
Wind Speeds ◽  
In Situ Data ◽  
L1 Data ◽  
Earth Environment ◽  
Speed Solar Wind ◽  
Using Data

<p>STEREO-B and STEREO-A are both important proxies for potential solar wind monitors at the Sun-Earth L5 point. In this study, measurements from STEREO-B are used to determine how well the Dst index in particular can be predicted using data measured near the L5 point. This is useful for determining the geoeffectivity of storms resulting from high-speed solar wind streams. Observed solar wind speeds are first mapped to the near-Earth environment as if they had been measured at L1, and the Dst is predicted from the data using a solar wind-to-Dst model. We find that Dst predicted from L5 data performs better than a recurrence model assuming the solar wind conditions repeat every 27 days, although not as well as when predicted from L1 data. The newly developed approach is currently implemented in the PREDSTORM software package to provide a real-time Dst forecast using STEREO-A data.</p>

scholarly journals Advantages Of A Time Series Analysis Using Wavelet Transform As Compared With A Fourier Analysis

2015 ◽  
Vol 23 (2) ◽  
pp. 30-36 ◽  
Author(s):  
Patrik Sleziak ◽  
Kamila Hlavčová ◽  
Ján Szolgay
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
Time Series Analysis ◽  
Fourier Analysis ◽  
Stationary Time Series ◽  
Precipitation Time Series ◽  
Software Environment ◽  
R Software ◽  
Series Analysis ◽  
Average Annual Precipitation

Abstract The paper presents an analysis of changes in the structure of the average annual discharges, average annual air temperature, and average annual precipitation time series in Slovakia. Three time series with lengths of observation from 1961 to 2006 were analyzed. An introduction to spectral analysis with Fourier analysis (FA) is given. This method is used to determine significant periods of a time series. Later in this article a description of a wavelet transform (WT) is reviewed. This method is able to work with non-stationary time series and detect when significant periods are presented. Subsequently, models for the detection of potential changes in the structure of the time series analyzed were created with the aim of capturing changes in the cyclical components and the multiannual variability of the time series selected for Slovakia. Finally, some of the comparisons of the time series analyzed are discussed. The aim of the paper is to show the advantages of time series analysis using WT compared with FT. The results were processed in the R software environment.

scholarly journals The radial evolution of solar wind speeds

2011 ◽  
Vol 116 (A3) ◽  
Author(s):  
S. L. McGregor ◽  
W. J. Hughes ◽  
C. N. Arge ◽  
D. Odstrcil ◽  
N. A. Schwadron
Keyword(s):  
Solar Wind ◽  
Wind Speeds ◽  
Radial Evolution

scholarly journals Two-Dimensional Solar Wind Speeds from 6 to 26 Solar Radii in Solar Cycle 24 by Using Fourier Filtering

2018 ◽  
Vol 121 (7) ◽  
Author(s):  
Il-Hyun Cho ◽  
Yong-Jae Moon ◽  
Valery M. Nakariakov ◽  
Su-Chan Bong ◽  
Jin-Yi Lee ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Two Dimensional ◽  
Wind Speeds ◽  
Fourier Filtering ◽  
Solar Cycle 24 ◽  
Cycle 24

scholarly journals Cosmic Ray Signatures of Different Types of Solar Wind Streams

1990 ◽  
Vol 142 ◽  
pp. 259-260
Author(s):  
P.K. Shrivastava ◽  
S.P. Agrawal
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Solar Wind Speed ◽  
Coronal Holes ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Wind Speeds ◽  
Different Types ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

The earlier concept of average solar wind speed has changed with time. Besides quiet periods of low/average solar wind speeds, two different kinds of solar sources (solar flares and coronal holes) have been identified to produce high speed solar wind streams. In an earlier investigation, it was reported that the high speed streams associated to these sources produce distinctly different effects on the cosmic ray intensity (Venkatesan, et. al., 1982).

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