North Annular Mode [NAM]



  Teleconnections and long range forecasts  
AAO (Antarctic Oscillation) NAM (North Annular Mode) SCAND (Scandinavia pattern) Stratosphere Analysis
AO (Arctic Oscillation) NAO (North Atlantic Oscillation) SOI (Southern Oscillation) North-Pole Stratosphere Temp
EA (East Atlantic) Polar/Eurasia SST (Sea Surface Temperature) 10 hPa Temp&Geop
EA/WR (East Atl./Western Russia) PNA (Pacific North-America) 100 hPa Temp&Geop
MJO (Madden Julian Oscillation) QBO (Quasi-Biennial Oscillation) Intraseasonal Oscillations


Teleconnective indices - North Annular Mode [NAM]

The North Annular Mode (NAM)) - also Northern Hemisphere annular mode - is a large-scale index of climate variability. The NAM is calculated by projecting the daily geopotential anomalies between 20° N and 90°N to the Arctic oscillation pattern defined by an empirical function of the monthly geopotential averages during the period.
The calculation of the NAM is performed at different pressure levels, starting from the troposphere up to the stratosphere. The NAM at sea level (1000 hPa) coincides with the Arctic Oscillation Index (AO), to which this page is dedicated.
When the NAM is in its positive phase (NAM+), high geopotentials are observed in the mid-latitudes and low in the polar latitudes and very low temperatures in the stratosphere (stratcooling). With this configuration, the stratospheric polar vortex is deep, that is characterized by particularly strong western currents, not very wavy and therefore with consequent reduced heat exchange with the lower latitudes. The colder air therefore remains confined to the polar regions.
In the opposite phase (NAM-), low geopotentials in the mid-latitudes will be observed, while the polar regions will be characterized by high geopotentials. In this situation the stratosphere will register temperatures higher than usual which can also lead to the phenomenon of stratwarming (NAM close to the value -3), that is a rapid and significant warming of the stratosphere.
This page is dedicated to the observation of possible stratwarming events. In a phase of NAM- frequent outbreaks of cold air towards the middle latitudes can be recorded.

NAM North Annular Mode positive phase
North Annular Mode (NAM), positive phase. Credits: wikipedia.org
NAM North Annular Mode phase negative
North Annular Mode (NAM), negative phase. Credits: wikipedia.org

North Annular Mode Diagrams

The NCEP GDAS and CPC temperature and height analyses are used to monitor processes in the Stratosphere and Troposphere. In the table below are zonal mean time series of Temperature, Zonal Wind Component, Normalized Geopotential Height anomalies, amplitude of the height field's Wave 1, Wave 2, and Wave 3.

North Emispheric GDAS-CPC Zonal Temperature Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Temperature Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
Equatorial GDAS-CPC Zonal Temperature Time Series - Zonal Mean: 10S - 10N
Equatorial GDAS-CPC Zonal Temperature Time Series - Zonal Mean: 10S - 10N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Temperature Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Temperature Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Temperature Anomaly Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Temperature Anomaly Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
Equatorial GDAS-CPC Zonal Temperature Anomaly Time Series - Zonal Mean: 10S - 10N
Equatorial GDAS-CPC Zonal Temperature Anomaly Time Series - Zonal Mean: 10S - 10N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Temperature Anomaly Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Temperature Anomaly Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wind Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Wind Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
Equatorial GDAS-CPC Zonal Wind Time Series - Zonal Mean: 10S - 10N
Equatorial GDAS-CPC Zonal Wind Time Series - Zonal Mean: 10S - 10N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wind Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Wind Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wind Anomaly Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Wind Anomaly Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
Equatorial GDAS-CPC Zonal Wind Anomaly Time Series - Zonal Mean: 10S - 10N
Equatorial GDAS-CPC Zonal Wind Anomaly Time Series - Zonal Mean: 10S - 10N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wind Anomaly Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Wind Anomaly Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Normalized Geopotential Heights Anomaly Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Normalized Geopotential Heights Anomaly Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Normalized Geopotential Heights Anomaly Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Normalized Geopotential Heights Anomaly Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wave 1 Amplitude Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Wave 1 Amplitude Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wave 1 Amplitude Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Wave 1 Amplitude Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wave 2 Amplitude Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Wave 2 Amplitude Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wave 2 Amplitude Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Wave 2 Amplitude Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wave 3 Amplitude Time Series - Zonal Mean: 60° N - 90° N
North Emispheric GDAS-CPC Zonal Wave 3 Amplitude Time Series - Zonal Mean: 60N - 90N - Credits: cpc.ncep.noaa.gov
North Emispheric GDAS-CPC Zonal Wave 3 Amplitude Time Series - Zonal Mean: 60S - 90S
South Emispheric GDAS-CPC Zonal Wave 3 Amplitude Time Series - Zonal Mean: 60S - 90S - Credits: cpc.ncep.noaa.gov

North Annular Mode - Past 12 months Values

Diagram of NAM values from sea level to the stratosphere. Stratospheric warming events are highlighted with warm color tones

North Annular Mode (NAM) diagram calculated by GFS, from sea level to the stratosphere. Warm color tones indicate warming of the stratosphere. Credits: lamma.rete.toscana.it

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