A model for the diurnal universal time variation of the Dst index

Takalo, Jouni; Мурсула, К.

doi:10.1029/2000ja000231

Cited by 28 publications

(33 citation statements)

References 14 publications

(2 reference statements)

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“…Takalo et al, 1995) (Cliver et al, 2001;Saroso et al, 1993), and explanations have been proposed for their presence (e.g. Takalo and Mursula, 2001;Mursula et al, 2008). We believe that the actual explanation is very mundane: stationary solar-quiet variation has not been effectively subtracted from the disturbance time series during calculation of the Kyoto D st .…”

Section: -4shmentioning

confidence: 99%

Revised Dst and the epicycles of magnetic disturbance: 1958–2007

Love

Gannon

2009

Ann. Geophys.

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Abstract.A revised version of the storm-time disturbance index D st is calculated using hourly-mean magneticobservatory data from four standard observatories and collected over the years . The calculation algorithm is a revision of that established by Sugiura et al., and which is now used by the Kyoto World Data Center for routine production of D st . The most important new development is for the removal of solar-quiet variation. This is done through time and frequency-domain band-stop filtering -selectively removing specific Fourier terms approximating stationary periodic variation driven by the Earth's rotation, the Moon's orbit, the Earth's orbit around the Sun, and their mutual coupling. The resulting non-stationary disturbance time series are weighted by observatory-site geomagnetic latitude and then averaged together across longitudes to give what we call D , storms are ranked for maximum storm-time intensity, and we show that storm-occurrence frequency follows a power-law distribution with an exponential cutoff. The epicycles of magnetic disturbance are explored: we (1) map low-latitude local-time disturbance asymmetry, (2) confirm the 27-day storm-recurrence phenomenon using autocorrelation, (3) investigate the coupled semi-annual-diurnal variation of magnetic activity and the proposed explanatory equinoctial and Russell-McPherron hypotheses, and (4) illustrate the well-known solar-cycle modulation of stormoccurrence likelihood. Since D 5807−4SH st is useful for a variety of space physics and solid-Earth applications, it is made freely available to the scientific community.

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Section: -4shmentioning

confidence: 99%

Revised Dst and the epicycles of magnetic disturbance: 1958–2007

Love

Gannon

2009

Ann. Geophys.

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“…The D st index is known to depict a small but persistent diurnal UT variation (Mayaud, 1978;Saroso et al, 1993;Siscoe and Crooker, 1996;Cliver et al, 2000) which mainly results from the asymmetric distribution of the D st stations (Takalo and Mursula, 2001a). Figure 4 shows the annual averages of the diurnal UT variation in the original and reconstructed indices using all hourly values.…”

Section: Problems In the Original D St Indexmentioning

confidence: 99%

A new reconstruction of the Dst index for 1932-2002

Karinen

Мурсула

2005

Ann. Geophys.

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Abstract. We have reconstructed a new, homogeneous geomagnetic D st index for , thus extending the original D st index by 25 years, i.e. by more than one full solar magnetic cycle. The extension was done by using data from the original set of four low-latitude stations for [1941][1942][1943][1944][1945][1946][1947][1948][1949][1950][1951][1952][1953][1954][1955][1956], and by using the nearby CTO station as a predecessor of the HER station for [1932][1933][1934][1935][1936][1937][1938][1939][1940]. Despite some open questions related to the composition of the original D st index, the reconstructed index is quite similar to the original one during the overlapping time interval . However, the reconstructed D st index corrects for some known errors in the original D st index, such as the erroneously large daily UT variation in 1971. Also, despite the overall agreement, the reconstructed index deviates from the original index even on the level of annual averages for several years. For instance, all annual averages of the reconstructed index are negative, and for 1962-1966 they are systematically lower (more stormy) than those of the original index. Accordingly, we disagree with the uniquely positive annual average of the original index in 1965, which most likely is erroneous. We also find somewhat higher (less stormy) values than in the original D st index for the three lowest annual averages in 1960, 1989 and 1991, out of which the lowest annual average is found in 1989 rather than in 1991. The annual averages of the geomagnetic A p index and the reconstructed D st index correlate very well over this time interval, except in the beginning of the series in 1932-1940 and in the declining phase of solar cycles 18, 20 and 21, where high speed solar wind streams cause enhanced geomagnetic activity. Using the superposed epoch method we also find that, on average, the storms in the early extended period are less intense but tend to have a longer recovery phase, suggesting that there are more HILDCAA-type medium activity intervals during the early period than more recently. We also study the annually averaged storm structure over the 71-year time interval and find that the most stormy years occur during the declining phase of solar cycles 17 and 21 and around the solar maxima of cycles 19 and 22.

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“…However, O'Brien and McPherron (2002) state that this mechanism would give only 17% of observed asymmetry. Takalo and Mursula (2001) connected the diurnal variations of Dst with an uneven distribution of Dst network stations. Let us use this known effect to validate our method.…”

Section: Identification Of New Geoeffective Parametersmentioning

confidence: 98%

Regression modeling method of space weather prediction

Parnowski

2009

Astrophys Space Sci

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A regression modeling method of space weather prediction is proposed. It allows forecasting Dst index up to 6 hours ahead with about 90% correlation. It can also be used for constructing phenomenological models of interaction between the solar wind and the magnetosphere. With its help two new geoeffective parameters were found: latitudinal and longitudinal flow angles of the solar wind. It was shown that Dst index remembers its previous values for 2000 hours.Comment: 13 pages, 19 figures, 2 table

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A model for the diurnal universal time variation of the Dst index

Cited by 28 publications

References 14 publications

Revised <I>D<sub>st</sub></I> and the epicycles of magnetic disturbance: 1958–2007

Revised <I>D<sub>st</sub></I> and the epicycles of magnetic disturbance: 1958–2007

A new reconstruction of the <i>D<sub>st</sub></i> index for 1932-2002

Regression modeling method of space weather prediction

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A model for the diurnal universal time variation of the Dst index

Cited by 28 publications

References 14 publications

Revised &lt;I&gt;D&lt;sub&gt;st&lt;/sub&gt;&lt;/I&gt; and the epicycles of magnetic disturbance: 1958–2007

Revised &lt;I&gt;D&lt;sub&gt;st&lt;/sub&gt;&lt;/I&gt; and the epicycles of magnetic disturbance: 1958–2007

A new reconstruction of the &lt;i&gt;D&lt;sub&gt;st&lt;/sub&gt;&lt;/i&gt; index for 1932-2002

Regression modeling method of space weather prediction

Contact Info

Product

Resources

About

Revised <I>D<sub>st</sub></I> and the epicycles of magnetic disturbance: 1958–2007

Revised <I>D<sub>st</sub></I> and the epicycles of magnetic disturbance: 1958–2007

A new reconstruction of the <i>D<sub>st</sub></i> index for 1932-2002