Monsoon criteria
The term monsoon criteria describes the totality of the meteorological criteria according to which a monsoon is defined and demarcated from monsoon- like weather phenomena.
Monsoon criteria according to Chromov
Monsoon criteria according to SP Chromov (1957):
- Monsoon angle criterion : Wind phenomenon in which there is a change in the direction of the prevailing wind directions ( monsoon angle ) of at least 120 ° between January and July
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Monsoon resistance criterion : wind directions in January and July certain averaged frequencies:
- over 60% = monsoon
- 40% to 60% = Monsoon low resistance
- below 40% = monsoon tendency
Ramage monsoon criteria
Another restriction of the monsoon climates took place in 1971 by CS Ramage, which is why the resulting criteria of the monsoon definition are also known as the Ramage-Chromow criteria, or Ramage criteria for short . In addition to the Chromov criteria, the following therefore applies:
- Monsoon intensity criterion : wind speed of at least 3 m / s in the resulting wind direction in January or July
- Tropical monsoon criterion : only one cyclone - anticyclone change per two years on an area of five degrees of latitude times five degrees of longitude in January and July
consequences
The comparatively strict definition ensures that many extra-tropical weather and climate phenomena are not counted among the monsoons, as their monsoon-like phenomena, such as a wind reversal or seasonal drought, usually have causes alien to the monsoon. The article monsoon made classification of different monsoon phenomena refers to this definition, and thus only the Indian , Southeast Asian, and African monsoon nordaustralische phenomenon are also classified as monsoons.
literature
- Chromov, SP (1957): The geographical distribution of the monsoons. Peterm. Geogr. Mitt. 1957, pp. 234-237.
- Ramage, CS (1971): Monsoon Meteorology. International Geophysic Series, vol. 15. San Diego, CA: Academic Press.