Secular variation
Encyclopedia
The secular variation of a time series
is its long-term non-periodic variation (see Decomposition of time series). Whether something is perceived as a secular variation or not depends on the available timescale: a secular variation over a time scale of centuries
may be part of a periodic variation over a time scale of millions of years. Natural quantities often have both periodic and secular variations. Secular variation is sometimes called secular trend or secular drift when the emphasis is on a linear long-term trend.
, operations research
, biological anthropology
, astronomy
(particularly celestial mechanics
) such as secular variations of the planetary orbits
etc.
, secular phenomena
refers to long-term perturbations in the motion of planets. The precession of the Earth's axis has a period of 25,771.5 years, so on a much shorter time frame it appears to be a "drift" of the position of the equinox
in the plane of the ecliptic
of approximately one degree every 71.6 years.
are classified as secular, primary and secondary for long, medium and short time frames. Traders identify market trends using technical analysis
.
. The field has variations on time scales from milliseconds to millions of years, but rapid changes mostly come from currents in the ionosphere
and magnetosphere
. The secular variation is the changes over periods of a year or more, reflecting changes in the Earth's core. Phenomena associated with this secular variation include geomagnetic jerk
, westward drift and geomagnetic reversals.
Time series
In statistics, signal processing, econometrics and mathematical finance, a time series is a sequence of data points, measured typically at successive times spaced at uniform time intervals. Examples of time series are the daily closing value of the Dow Jones index or the annual flow volume of the...
is its long-term non-periodic variation (see Decomposition of time series). Whether something is perceived as a secular variation or not depends on the available timescale: a secular variation over a time scale of centuries
Century
A century is one hundred consecutive years. Centuries are numbered ordinally in English and many other languages .-Start and end in the Gregorian Calendar:...
may be part of a periodic variation over a time scale of millions of years. Natural quantities often have both periodic and secular variations. Secular variation is sometimes called secular trend or secular drift when the emphasis is on a linear long-term trend.
Examples
The term secular variation is used wherever time series are applicable in economicsEconomics
Economics is the social science that analyzes the production, distribution, and consumption of goods and services. The term economics comes from the Ancient Greek from + , hence "rules of the house"...
, operations research
Operations research
Operations research is an interdisciplinary mathematical science that focuses on the effective use of technology by organizations...
, biological anthropology
Biological anthropology
Biological anthropology is that branch of anthropology that studies the physical development of the human species. It plays an important part in paleoanthropology and in forensic anthropology...
, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
(particularly celestial mechanics
Celestial mechanics
Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects. The field applies principles of physics, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics is a subfield which focuses on...
) such as secular variations of the planetary orbits
Secular variations of the planetary orbits
The secular variations of the planetary orbits is a concept describing long-term changes in the orbits of the planets Mercury to Neptune. If one ignores the gravitational attraction between the planets and only models the attraction between the Sun and the planets, then with some further...
etc.
Astronomy
In astronomyAstronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, secular phenomena
Secular phenomena
In astronomy, secular phenomena are contrasted with phenomena observed to repeat periodically. In particular, astronomical ephemerides use secular to label the longest-lasting or non-oscillatory perturbations in the motion of planets, as opposed to periodic perturbations which exhibit repetition...
refers to long-term perturbations in the motion of planets. The precession of the Earth's axis has a period of 25,771.5 years, so on a much shorter time frame it appears to be a "drift" of the position of the equinox
Equinox
An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator...
in the plane of the ecliptic
Plane of the ecliptic
The plane of the ecliptic is the plane of the Earth's orbit around the Sun. It is the primary reference plane when describing the position of bodies in the Solar System, with celestial latitude being measured relative to the ecliptic plane. In the course of a year, the Sun's apparent path through...
of approximately one degree every 71.6 years.
Market trends
Market trendsMarket trends
A market trend is a putative tendency of a financial market to move in a particular direction over time. These trends are classified as secular for long time frames, primary for medium time frames, and secondary for short time frames...
are classified as secular, primary and secondary for long, medium and short time frames. Traders identify market trends using technical analysis
Technical analysis
In finance, technical analysis is security analysis discipline for forecasting the direction of prices through the study of past market data, primarily price and volume. Behavioral economics and quantitative analysis incorporate technical analysis, which being an aspect of active management stands...
.
Geomagnetic secular variation
Geomagnetic secular variation refers to changes in the Earth's magnetic fieldEarth's magnetic field
Earth's magnetic field is the magnetic field that extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun...
. The field has variations on time scales from milliseconds to millions of years, but rapid changes mostly come from currents in the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...
and magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
. The secular variation is the changes over periods of a year or more, reflecting changes in the Earth's core. Phenomena associated with this secular variation include geomagnetic jerk
Geomagnetic jerk
In geophysics, a geomagnetic jerk or secular geomagnetic variation impulse is a relatively sudden change in the second derivative of the Earth's magnetic field with respect to time....
, westward drift and geomagnetic reversals.