Limits...
The Dst index underestimates the solar cycle variation of geomagnetic activity

View Article: PubMed Central - PubMed

ABSTRACT

It is known that the correction of the Kyoto Dst index for the secular variation of the Earth's internal field produces a discontinuity in the Kyoto Dst index at the end of each year. We show that this secular correction also introduces a significant baseline error to the Kyoto Dst index that leads to an underestimate of the solar cycle variation of geomagnetic activity and of the strength of the ring current as measured by the Kyoto Dst index. Thus, the average value of the Kyoto Dst index would be approximately 13 nT more negative for the active year 2003 compared to quiet years 2006 and 2009 if the Kyoto Dst index properly measured the effects of the ring current and other currents that influence the Dst observatories. Discontinuities in the Kyoto Dst index at the end of each year have an average value of about 5 nT, but the discontinuity at the end of year 2002 was approximately 12 nT, and the discontinuity at the end of year 1982 may have been as large as 20 nT.

No MeSH data available.


(top) The difference (i.e., the error) between the model and the Kyoto Dst index when the baseline correction is not applied to the model for the period shown in Figure 2. Note the discontinuity in the difference exactly at the end of the year 2002. (bottom) The difference once the baseline correction is applied to the model. The point of the figure is to demonstrate that the Kyoto Dst index can have significant discontinuities.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5036309&req=5

jgra51951-fig-0003: (top) The difference (i.e., the error) between the model and the Kyoto Dst index when the baseline correction is not applied to the model for the period shown in Figure 2. Note the discontinuity in the difference exactly at the end of the year 2002. (bottom) The difference once the baseline correction is applied to the model. The point of the figure is to demonstrate that the Kyoto Dst index can have significant discontinuities.

Mentions: Figure 3 (top) shows the model error without the baseline correction for the same time period. A large change in the error occurs at midnight on 31 December 2002. Figure 3 (bottom) shows the model error after the baseline correction is applied. Note that now the error has no apparent discontinuity. The error is the difference between model output and the Kyoto Dst index. (The Kyoto Dst index itself changes from −16 nT from the last hour of 2002 to −4 nT for the first hour of 2003.)


The Dst index underestimates the solar cycle variation of geomagnetic activity
(top) The difference (i.e., the error) between the model and the Kyoto Dst index when the baseline correction is not applied to the model for the period shown in Figure 2. Note the discontinuity in the difference exactly at the end of the year 2002. (bottom) The difference once the baseline correction is applied to the model. The point of the figure is to demonstrate that the Kyoto Dst index can have significant discontinuities.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036309&req=5

jgra51951-fig-0003: (top) The difference (i.e., the error) between the model and the Kyoto Dst index when the baseline correction is not applied to the model for the period shown in Figure 2. Note the discontinuity in the difference exactly at the end of the year 2002. (bottom) The difference once the baseline correction is applied to the model. The point of the figure is to demonstrate that the Kyoto Dst index can have significant discontinuities.
Mentions: Figure 3 (top) shows the model error without the baseline correction for the same time period. A large change in the error occurs at midnight on 31 December 2002. Figure 3 (bottom) shows the model error after the baseline correction is applied. Note that now the error has no apparent discontinuity. The error is the difference between model output and the Kyoto Dst index. (The Kyoto Dst index itself changes from −16 nT from the last hour of 2002 to −4 nT for the first hour of 2003.)

View Article: PubMed Central - PubMed

ABSTRACT

It is known that the correction of the Kyoto Dst index for the secular variation of the Earth's internal field produces a discontinuity in the Kyoto Dst index at the end of each year. We show that this secular correction also introduces a significant baseline error to the Kyoto Dst index that leads to an underestimate of the solar cycle variation of geomagnetic activity and of the strength of the ring current as measured by the Kyoto Dst index. Thus, the average value of the Kyoto Dst index would be approximately 13 nT more negative for the active year 2003 compared to quiet years 2006 and 2009 if the Kyoto Dst index properly measured the effects of the ring current and other currents that influence the Dst observatories. Discontinuities in the Kyoto Dst index at the end of each year have an average value of about 5 nT, but the discontinuity at the end of year 2002 was approximately 12 nT, and the discontinuity at the end of year 1982 may have been as large as 20 nT.

No MeSH data available.