Space environment (natural and artificial) -- Operational estimation of the solar wind energy input into the Earth's magnetosphere by means of the ground-based magnetic polar cap (PC) index

This document provides guidelines for specifying the qualitative estimation of the solar wind energy input into the magnetosphere with use of operative ground-based information on the polar cap magnetic activity (PC index). The solar wind energy incoming into the magnetosphere predetermines development of the magnetospheric disturbances: magnetic storms and substorms. Magnetospheric disturbances include a wide range of phenomena and processes directly affecting human activity, such as satellite damage, radiation hazards for astronauts and airline passengers, telecommunication problems, outrages of power and electronic systems, effects in the atmospheric processes, and impact on human health. This document is intended for on-line monitoring the magnetosphere state and nowcasting the intensity and extent of magnetic disturbances as well as parameters of the high-latitude ionosphere. The method and accuracy of estimating is ascertained by close relationship between the PC index and interplanetary electric field (as the most geoeffective solar wind parameter), on the one hand, and between the PC index and magnetoshpheric disturbances, on the other hand.

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ISO/TR 23989:2020 - Space environment (natural and artificial) -- Operational estimation of the solar wind energy input into the Earth's magnetosphere by means of the ground-based magnetic polar cap (PC) index
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TECHNICAL ISO/TR
REPORT 23989
First edition
2020-01
Space environment (natural and
artificial) — Operational estimation
of the solar wind energy input into the
Earth's magnetosphere by means of
the ground-based magnetic polar cap
(PC) index
Reference number
ISO/TR 23989:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO/TR 23989:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 23989:2020(E)
Contents  Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2  Normative references ...................................................................................................................................................................................... 1

3  Terms and definitions ..................................................................................................................................................................................... 1

4  Symbols and abbreviated terms ........................................................................................................................................................... 2

5  General parameters ........................................................................................................................................................................................... 3

5.1 Solar wind parameters determining the magnetosphere state .................................................................... 3

5.2 Magnetic activity in the polar cap and its relation to the solar wind parameters ........................ 3

5.3 The PC-index: method of derivation..................................................................................................................................... 4

5.4 Relationship between the PC index and magnetic substorms and storms ......................................... 4

5.5 Relation of the PC index to the interplanetary electric field, E ............................................................... 5

5.6 PC index as a verifier of the solar wind parameters presented at OMNI website......................... 5

5.7 PC index as a proxy of the solar wind energy input into the magnetosphere .................................. 6

5.8 PC index as a standard for calibration of the magnetospheric disturbances power .................. 6

6  Availability of the PC index ........................................................................................................................................................................ 6

6.1 Production of the PC index ........................................................................................................................................................... 6

6.2 Access to the PC data ......................................................................................................................................................................... 6

7  Compliance criteria for use of the PC index as a calibrator of the magnetospheric

disturbance ................................................................................................................................................................................................................ 7

7.1 Rationale....................................................................................................................................................................................................... 7

7.2 Reporting ..................................................................................................................................................................................................... 7

7.3 Documenting............................................................................................................................................................................................. 7

7.4 Publishing .................................................................................................................................................................................................... 7

7.5 Archiving ...................................................................................................................................................................................................... 7

Annex A (informative) Resolution No. 3 of XXII Scientific Assembly of International

Geomagnetism and Aeronomy Association (12th IAGA), Merida, Меxico, August

2013: PC index ......................................................................................................................................................................................................... 8

Annex B (informative) Map of spreading of the auroral absorption calibrated by the PC

index value .................................................................................................................................................................................................................. 9

Bibliography .............................................................................................................................................................................................................................10

© ISO 2020 – All rights reserved iii
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ISO/TR 23989:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

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expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,

Subcommittee SC 14, Space systems and operations.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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ISO/TR 23989:2020(E)
Introduction

The polar cap magnetic activity PC index was introduced as a measure of the magnetic activity generated

in the Earth’s polar caps by interplanetary electric field and is regarded at present as a proxy of the

solar wind energy input into the magnetosphere in course of solar wind – magnetosphere coupling.

The PC index can be required as input parameter for monitoring and nowcasting the space weather

influence on various characteristics of magnetosphere and high-latitude ionosphere.

The PC index can be applicable for a variety of engineering and scientific domains and can be used to

monitor the state of the magnetosphere and high-latitude ionosphere to solve the problems of navigation,

radio-connection and induced currents typical of high-latitude regions during magnetospheric

disturbances.
© ISO 2020 – All rights reserved v
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TECHNICAL REPORT  ISO/TR 23989:2020(E)
Space environment (natural and artificial) — Operational
estimation of the solar wind energy input into the Earth's
magnetosphere by means of the ground-based magnetic
polar cap (PC) index
1 Scope

This document provides guidelines for specifying the qualitative estimation of the solar wind energy

input into the magnetosphere with use of operative ground-based information on the polar cap

magnetic activity (PC index).

The solar wind energy incoming into the magnetosphere predetermines development of the

magnetospheric disturbances: magnetic storms and substorms. Magnetospheric disturbances include

a wide range of phenomena and processes directly affecting human activity, such as satellite damage,

radiation hazards for astronauts and airline passengers, telecommunication problems, outrages of

power and electronic systems, effects in the atmospheric processes, and impact on human health.

This document is intended for on-line monitoring the magnetosphere state and nowcasting the

intensity and extent of magnetic disturbances as well as parameters of the high-latitude ionosphere.

The method and accuracy of estimating is ascertained by close relationship between the PC index and

interplanetary electric field (as the most geoeffective solar wind parameter), on the one hand, and

between the PC index and magnetoshpheric disturbances, on the other hand.
2  Normative references
There are no normative references in this document.
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
solar wind

fully ionized, electrically neutral plasma that carries a magnetic field, B, and streams outward from the

inner solar corona at all times
3.2
interplanetary electric field

electric field, affecting the magnetosphere in course of the solar wind (3.1) – magnetosphere coupling,

calculated according to formula of Kan and Lee [1979]
E = vB sin θ/2
KL T
where
© ISO 2020 – All rights reserved 1
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ISO/TR 23989:2020(E)
v is the solar wind speed;
B is tangential component of the interplanetary magnetic field (3.3);

θ is clock angle between the IMF tangential (B ) component and the geomagnetic dipole

3.3
interplanetary magnetic field
IMF
magnetic field of solar origin transmitted by solar wind (3.1)
3.4
magnetic storm

combination of strong negative geomagnetic disturbances, which are produced over the entire planet

by ring currents flowing around the Earth in the inner magnetosphere

Note 1 to entry: The maximal geomagnetic field depression in the equatorial region (estimated by 1-hour Dst

index or 1-min SymH index) is regarded as a storm intensity.
Note 2 to entry: Definition inspired by Chapman and Ferraro, 1932.
3.5
magnetic substorm
magnetic disturbances typical of the auroral zone

Note 1 to entry: Their distinctive feature is formation of the westward and eastward ionospheric currents

(electrojets) and development of corresponding negative and positive magnetic disturbances on the ground

surface, which intensity is estimated by the 1-min AL and AU indices [Davis and Sugiura, 1966]. The “substorm”

includes a lot of accompanying phenomena in the auroral zone, such as sudden auroral brightening (produced by

precipitation of the auroral particles), its poleward expansion, simultaneous sudden increase of the westward

electrojet intensity and others.
Note 2 to entry: Definition inspired by Akasofu, 1964.
3.6
polar cap magnetic activity

magnetic short-term (minutes or tens of minutes) variations generated in the near-pole region by

interplanetary electric field (3.2)

Note 1 to entry: Value of the polar cap magnetic activity is estimated by the 1-min PC index [Troshichev et al.,

1988; Troshichev, 2018].
4  Symbols and abbreviated terms

AL 1-min index of intensity of negative magnetic disturbances in the auroral zone

AU 1-min index of intensity of positive magnetic disturbances in the auroral zone

AE 1-min index characterizing the magnetic substorm intensity (AE = AU-AL)
B azimuthal component of the interplanetary magnetic field
B vertical component of the interplanetary magnetic field
B southward component of the interplanetary magnetic field
2 2 1/2
B tangential component of the IMF; B = (B + B )
T T Z Y
DR ring magnetospheric currents flowing around the Earth
2 © ISO 2020 – All rights reserved
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ISO/TR 23989:2020(E)
Dst 1-hour index characterizing the magnetic storm intensity

FAC field-aligned currents (currents in the magnetosphere flowing along field lines)

MLat geomagnetic latitude
MLon geomagnetic longitude
QDC geomagnetic field variations under quiet conditions (quiet daily curve)
PC 1-min index characterizing magnetic activity in the Earth’s polar caps
SymH 1-min index characterizing the magnetic storm intensity
SO substorm sudden onset
UT universal time
v solar wind velocity
Θ clock angle between the IMF tangential component and the geomagnetic dipole
5  General parameters
5.1  Solar wind parameters determining the magnetosphere state

The various combinations of the solar wind parameters, providing the best correlation between the

solar wind variations and magnetic activity, were proposed since 2004. About 20 versions of such

combinations, referred as coupling functions, have been examined. All of them include the solar wind

velocity and the IMF B or B components. The comprehensive analysis of Newell et al. [2007, 2008]

ZS T

revealed that different coupling functions demonstrate the good correlation with different variables

characterizing the magnetosphere state; and the unique coupling function, if it exists, should involve

the solar wind velocity, v, to the first (or a little higher) power, the tangential IMF component B to the

first (or a little lower) power, and sine of the IMF clock angle θc to the second (or more) power. One can

see that the interplanetary electric field E answers to the unique coupling function formula in the

best way.

The solar wind parameters determining coupling functions are usually fixed in the Lagrange point

L1, at distance of 1,5 million km far upstream of the Earth. This circumstance determines the most

serious imperfection of all coupling functions because “estimated” characteristics of the solar wind

can be quite distinguished from characteristics of the real solar wind coming into contact with the

magnetosphere. Knowledge of the solar wind affecting the magnetosphere in actuality is necessary to

monitor the magnetosphere state and to forecast the magnetospheric disturbances.

5.2  Magnetic activity in the polar cap and its relation to the solar wind parameters

A special class of the polar cap magnetic activity, identified by Obayashi [1967] as DP2 disturbances,

turned out to be closely related to southward IMF [Nishida, 1968a, b, 1971; Troshichev, 1975]. Statistical

analysis of the relationships between the DP2 disturbances and various 5-min coupling functions

showed [Troshichev and Andrezen, 1985] that the polar cap magnetic activity correlates the best with

interplanetary electric field, E , determined according to formula of Kan and Lee [1979]. Basing on

this result, the PC index, characterizing the polar cap magnetic activity generated by E field, has

been elaborated in Arctic and Antarctic Research Institute (AARI, Saint-Petersburg) [Troshichev and

Andrezen, 1985] and put into practical use in cooperation with the Danish Meteorological Institute

(DMI, Copenhagen) [Troshichev et al., 1988]. The 1-min PC index is calculated independently by magnetic

data from the near-pole stations Qaanaaq in the Northern polar cap (PCN) and Vostok in the Southern

polar cap (PCS) beginning in 1998. The unified method for derivation of the PC index was formulated in

[Troshichev et al., 2006]. Thorough description of the method is given in [Troshichev, 2017].

© ISO 2020 – All rights reserved 3
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ISO/TR 23989:2020(E)
5.3  The PC-index: method of derivation

The unified technique for derivation of the PCN and PCS indices consists of two separate procedures.

The first procedure is determination of the statistically justified regression coefficients α (slope), β

(intersection) and angle φ, defining the relationship between the interplanetary electric field, E , and

the DP2 magnetic disturbance vector, δF [see Formula (1)]
δF = α E + β (1)

This procedure includes determination of the quiet daily curve (QDC), as a level of reference, and

estimation of value δF in reference to QDC according to Formula (2):
δF = δH·sinφ ± δD·cosφ (2)
where

δH and δD are deviations of the geomagnetic field horizontal and declination components from

QDC at the station;

φ is an angle which determines the δF vector arrangement relative to the ionospheric

current system (generated by the E field) during the daily rotation of station under

this current system.
The regression coefficie
...

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