Longitudinal distribution of major solar flares during 1975–2005

Zhang, L.; Cui, Yanmei; He, Yulin; He, Han; Du, Zhanle; Li, R.; Wang, H.N.

doi:10.1016/j.asr.2006.12.052

Cited by 17 publications

(12 citation statements)

References 15 publications

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“…This implies that 74% and 78% (N 1 /(N 1 + N 2 )) of the SARs occurred near one of the two active longitudes in the northern and southern hemispheres, respectively. This result is consistent with the results of Zhang et al (2007aZhang et al ( ,b, 2011.…”

Section: Longitudinal Distribution Of Sarssupporting

confidence: 83%

“…The rotation period of SARs in the dynamic reference frame is shorter than the Carrington period in both the northern and southern hemispheres. However, Zhang et al (2007aZhang et al ( , 2011 found that the average flare rotates significantly differently in the two hemispheres, with flares rotating faster and slower than the Carrington rate in the northern and southern hemispheres, respectively.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Usoskin et al (2005) introduced a new method to remove the solar differential rotation of the raw data, which was the same as that used by Berdyugina & Usoskin (2003), without any preprocessing or filtering and confirmed the finding of Berdyugina & Usoskin (2003). Zhang et al (2007aZhang et al ( ,b, 2011 used this method and the improved one to study the distribution of solar X-ray flares, respectively. They also found that there were two persistent active longitudes during the last three solar cycles.…”

Section: Introductionmentioning

confidence: 99%

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Statistical properties of superactive regions during solar cycles 19–23

Chen

Wang

et al. 2011

A&A

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Context. Each solar activity cycle is characterized by a small number of superactive regions (SARs) that produce the most violent of space weather events with the greatest disastrous influence on our living environment. Aims. We aim to re-parameterize the SARs and study the latitudinal and longitudinal distributions of SARs. Methods. We select 45 SARs in solar cycles 21-23, according to the following four parameters: 1) the maximum area of sunspot group, 2) the soft X-ray flare index, 3) the 10.7 cm radio peak flux, and 4) the variation in the total solar irradiance. Another 120 SARs given by previous studies of solar cycles 19-23 are also included. The latitudinal and longitudinal distributions of the 165 SARs in both the Carrington frame and the dynamic reference frame during solar cycles 19-23 are studied statistically. Results. Our results indicate that these 45 SARs produced 44% of all the X class X-ray flares during solar cycles 21-23, and that all the SARs are likely to produce a very fast CME. The latitudinal distributions of SARs display the Maunder butterfly diagrams and SARs occur preferentially in the maximum period of each solar cycle. Northern hemisphere SARs dominated in solar cycles 19 and 20 and southern hemisphere SARs dominated in solar cycles 21 and 22. In solar cycle 23, however, SARs occurred about equally in each hemisphere. There are two active longitudes in both the northern and southern hemispheres, about 160• -200• apart. Applying the improved dynamic reference frame to SARs, we find that SARs rotate faster than the Carrington rate and there is no significant difference between the two hemispheres. The synodic periods are 27.19 days and 27.25 days for the northern and southern hemispheres, respectively. The longitudinal distribution of SARs is significantly non-axisymmetric and about 75% SARs occurred near two active longitudes with half widths of 45• .

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Section: Longitudinal Distribution Of Sarssupporting

confidence: 83%

Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Statistical properties of superactive regions during solar cycles 19–23

Chen

Wang

et al. 2011

A&A

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“…This periodicity is mostly caused by the presence on the Sun surface of two sunspots which rotate with the same period but are separated by about 180° in longitude (e.g. Bai, 2003;Zhang et al, 2007). These findings are in agreement with previous results (Fioletov, 2009).…”

Section: Mls/aura Data (Solar Cycle 23)supporting

confidence: 83%

Sensitivity of tropical stratospheric ozone to rotational UV variations estimated from UARS and Aura MLS observations during the declining phases of solar cycles 22 and 23

Bossay

Bekki

Marchand

et al. 2015

Journal of Atmospheric and Solar-Terrestrial Physics

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of tropical stratospheric ozone to rotational UV variations estimated from UARS and Aura MLS observations during the declining phases of solar cycles 22 and 23. Journal of Atmospheric and Solar-Terrestrial Physics, Elsevier, 2015, 130-131, pp.96-111. <10.1016/j.jastp.2015 AbstractThe correlation between tropical stratospheric ozone and UV radiation on solar rotational time scales is investigated using daily satellite ozone observations and reconstructed solar spectra.We consider two 3-year periods falling within the descending phases of two 11-year solar cycles 22 (1991-1994) and 23 (2004-2007). The UV rotational cycle is highly irregular and even disappears for half a year during cycle 23. For the 1991-1994 period, ozone and 205 nm UV flux are found to be correlated between about 10 and 1 hPa with a maximum of 0.29 at ~5 2 hPa; ozone sensitivity (percentage change in ozone for 1 percent change in UV) peaks at ~0.4.Correlation during cycle 23 is weaker with a peak ozone sensitivity of 0.2. The correlation is found to vary widely, not only with altitude, but also from one year to the next with a rotational signal in ozone appearing almost intermittent. Unexpectedly, the correlation is not found to bear any relation with the solar rotational forcing. For instance, solar rotational fluctuations are by far the strongest during 1991-1992 whereas the correlation peaks at the end of 1993, a rotationally quiescent period. When calculated over sliding intervals of 1-year, the sensitivity is found to vary very strongly within both 3-year periods; it is almost negligible over the entire vertical profile during some 1-year intervals or reaches close to 1 around 2-5 mb for other intervals. Other sources of variability, presumably of dynamical origin, operate on the rotational spectral range and determine to a large extent the estimated solar rotational signal. Even considering 3 years of observations (corresponding to about 40 solar cycles), the extraction of the rotational solar signal does not appear to be robust during declining phases of 11-year solar cycles. As observational studies cover at best three 11-year solar cycles, it must be challenging to produce a reliable estimation of the 11-year solar cycle signal in stratospheric ozone, especially in the presence of decadal climate variability.Ozone -stratosphere -solar variability -27-days -photochemistry

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“…The broadness of the peaks indicates that the solar rotational cycle is not regular and covers a rather wide frequency domain. A small secondary peak is also found at ∼ 13.5 days, which corresponds to the first harmonic of the rotational cycle and to the presence on the Sun surface of two sunspots which rotate with the same period but are separated by about 180 • in longitude (e.g., Bai, 2003;Zhang et al, 2007). The timeresolved power spectral density derived from the continuous wavelet transforms (CWT; Torrence and Compo, 1998) of the two F205 time series are shown in Fig.…”

Section: The Lmdz-reprobus Modelmentioning

confidence: 99%

Sensitivity of the tropical stratospheric ozone response to the solar rotational cycle in observations and chemistry–climate model simulations

Thiéblemont¹,

Marchand

Bekki

et al. 2017

Atmos. Chem. Phys.

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Abstract. The tropical stratospheric ozone response to solar UV variations associated with the rotational cycle ( ∼ 27 days) is analyzed using MLS satellite observations and numerical simulations from the LMDz-Reprobus chemistry-climate model. The model is used in two configurations, as a chemistry-transport model (CTM) where dynamics are nudged toward ERA-Interim reanalysis and as a chemistry-climate model (free-running) (CCM). An ensemble of five 17-year simulations (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) is performed with the CCM. All simulations are forced by reconstructed time-varying solar spectral irradiance from the Naval Research Laboratory Solar Spectral Irradiance model. We first examine the ozone response to the solar rotational cycle during two 3-year periods which correspond to the declining phases of solar cycle 22 (October 1991-September 1994 and solar cycle 23 (September 2004-August 2007, when the satellite ozone observations of the two Microwave Limb Sounders (UARS MLS and Aura MLS) are available. In the observations, during the first period, ozone and UV flux are found to be correlated between about 10 and 1 hPa with a maximum of 0.29 at ∼ 5 hPa; the ozone sensitivity (% change in ozone for 1 % change in UV) peaks at ∼ 0.4. Correlation during the second period is weaker and has a peak ozone sensitivity of only 0.2, possibly due to the fact that the solar forcing is weaker during that period. The CTM simulation reproduces most of these observed features, including the differences between the two periods. The CCM ensemble mean results comparatively show much smaller differences between the two periods, suggesting that the amplitude of the rotational ozone signal estimated from MLS observations or the CTM simulation is strongly influenced by other (non-solar) sources of variability, notably dynamics. The analysis of the ensemble of CCM simulations shows that the estimation of the ensemble mean ozone sensitivity does not vary significantly either with the amplitude of the solar rotational fluctuations or with the size of the time window used for the ozone sensitivity retrieval. In contrast, the uncertainty of the ozone sensitivity estimate significantly increases during periods of decreasing amplitude of solar rotational fluctuations (also coinciding with minimum phases of the solar cycle), and for decreasing size of the time window analysis. We found that a minimum of 3-and 10-year time window is needed for the 1σ uncertainty to drop below 50 and 20 %, respectively. These uncertainty sources may explain some of the discrepancies found in previous estimates of the ozone response to the solar rotational cycle.

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Longitudinal distribution of major solar flares during 1975–2005

Cited by 17 publications

References 15 publications

Statistical properties of superactive regions during solar cycles 19–23

Statistical properties of superactive regions during solar cycles 19–23

Sensitivity of tropical stratospheric ozone to rotational UV variations estimated from UARS and Aura MLS observations during the declining phases of solar cycles 22 and 23

Sensitivity of the tropical stratospheric ozone response to the solar rotational cycle in observations and chemistry–climate model simulations

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