Monday, January 30, 2012

Starting a bestiary of oscillations and cycles

A bestiary originally was originally a book of pictures and descriptions, often with morals attached, of animals.  Well, that was the middle ages.  The version I've got in mind is one describing the more or less regular oscillations or cycles in the earth system, its orbit, and the sun.  For now, I'll describe just the period and its name and invite you to add to the list.  Also, I won't worry about whether the named thing is a proper oscillation (such as tides) or more of an index that may not have any particular period (PNA).  The later rendition will have some discussion of what happens in each and concern about whether the variation is a real thing or just an artefact of how people looked at the data.  For those who'd like to jump straight to discussion of weather cycles directly, I'll suggest William Burroughs' Weather Cycles, Real or Imaginary

As always, you're encouraged to add your own suggestions!
Around a day

12h 25 min (12:25) -- Lunar semidiurnal tide
23:56 -- Sidereal day
24:00 -- Mean Solar day (1 dy)
24:50 -- Lunar diurnal tide

Around a month
13.66 dy -- Lunar fortnightly tide
27.32 dy -- Lunar monthly tide
40-60 dy -- Madden-Julian Oscillation (MJO)

Around a year
365.2422 dy --  Tropical Year (equinox to equinox) (1 year for later)
365.2564 dy -- Sidereal year [see comment]
365.259 dy -- Anomalistic Year (perihelion to perihelion)
~433 dy -- Chandler Wobble

A few years
~26 months -- Quasi-biennial Oscillation (QBO)
2-7 years -- El-Nino/Southern Oscillation (ENSO), Southern Oscillation Index (SOI)
~4 years  -- Antarctic Circumpolar Wave
~3.75 years -- Rossby-Kelvin wave in North Pacific [see comment]
8.85 years -- Lunar perigee
18.6 years -- Precession of the Lunar Node

Many years
(See http://http://www.arctic.noaa.gov/essay_bond.html for some discussion)
--- -- Arctic Oscillation (AO)
--- -- Antarctic Oscillation (AAO)
--- -- North Atlantic Oscillation (NAO)
--- -- Pacific/North America Pattern (PNA)
20-30 years -- Pacific Decadal Oscillation (PDO)

~11 years -- Sunspot cycle
~22 years -- Solar cycle (each sunspot cycle is opposite magnetic polarity)
~88 years -- Gleissberg cycle (clumping of solar cycles)


Long period
19-23,000 years -- Milankovitch Cycle -- Precession of the equinoxes
~41,000 years --Milankovitch Cycle -- Tilt of the earth
~100,000 years -- Milankovitch Cycle -- Eccentricity of the earth's orbit
~400,000 years -- Milankovitch Cycle -- Eccentricity of the earth's orbit

Very long period
30 million years --  Oscillation of solar system above/below the plane of the galaxy
230 million years -- Solar system orbit of the galaxy [see comment]
400 Million years -- Supercontinent cycle

3 comments:

Alastair said...

Another very long cycle is the 230M years that the Earth takes to orbit the Milky way galaxy.

See http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question18.html

Anonymous said...

Sidereal year: 365.2564 days

David B. Benson said...

Unnamed Rossby/Kelvin wave in the North Pacific Ocean: ~3.75 years.

There are others with different periods in both the North Pacific and North Atlantic but the 3.75 year period wave is the best studied.