NAO - North Atlantic Oscillation
North Atlantic Oscillation teleconnection pattern. It can also be viewed as the Atlantic half of the AO (Arctic Oscillation) teleconnection pattern - strongly influences temperatures over europe and much of North America - especially during the cold seasons - and determines the mean latitude of the prevailing storm tracks across the North Atlantic. The phase of the NAO is considered positive when pressures and heights are below normal over Greenland and Iceland (strong icelandic low) and above normal at middle and subtropical latitudes (strong Bermuda-Azores high) - and negative for the reverse anomalies.
AO - Arctic Oscillation
A measure of the difference between the mean mid-tropospheric height or sea level pressure anomaly over the polar basin and the corresponding average anomaly in a ring surrounding the polar basin at middle latitudes. The AO is considered to be the leading mode of climate variability of the extratropical northern hemisphere. The AO can also be considered to include the NAO (North Atlantic Oscillation) with which it is positively correlated - but not identical. The phase of the AO is considered to be positive when heights or pressures are below normal over the arctic basin and above normal over surrounding mid- latitudes - and is negative for the reverse anomaly pattern.
ENSO - ENSO (La Nina/El Nino)
This is the ENSO 3.4 which is the average of SST anomalies over the region 5°N - 5°S and 170° - 120°W region of the Pacific. This tells us whether the ocean is moving to a La Nina (cooler than average) or El Nino (warmer than average) state. A La Nina or El Nino are declared when this index stays more than 0.5° away from the normal value for five consecutive months.
IOD - Indian Dipole Index
The Indian Ocean Dipole is a climate pattern affecting the Indian Ocean. During a positive phase, warm waters are pushed to the Western part of the Indian Ocean, while cold deep waters are brought up to the surface in the Eastern Indian Ocean. This pattern is reversed during the negative phase of the IOD.
PNA - Pacific/North American Teleconnection
Variability in atmospheric pressure over the Northern Pacific and North America is associated with variability in rainfall in the southwestern United States. Wetter summers are associated with PNA phases with strong North to South pressure gradients. Drier summers have tended to follow PNA phases with weak North to South pressure gradients.
SOI - Southern Oscillation
The Southern Oscillation Index is a standardized index based on the observed sea level pressure (SLP) differences between Tahiti and Darwin, Australia. This index gives an indication of the development and intensity of El Nino or La Nina events in the Pacific Ocean.
AAO - Antarctic Oscillation
The Antarctic Oscillation Index is defined as the difference of zonal mean sea level pressure between 40°S and 65°S. The AOI has the potential for clarifying climate regimes in the Southern Hemisphere, similar to how the NAO is used in the Northern Hemisphere.
MJO - Madden-Julian Oscillation
The MJO is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average. There are 8 phases and enhanced rainfall and tropical developments shift into different basins depending on the phase. Atlantic - Phases 1,2,7 and 8. Indian - Phases 2,3 and 4. Pacific - Phases 5,6 and 7.
Phase 1 Phase 2 Phase 3 Phase 4 Phase 5 Phase 6 Phase 7 Phase 8
Foggy and cool, no breeze. ...
Good morning everyone,
Another grey, gloomy start to the day, with spots of light driz...
