Climagrams

Climagrams show the distributions of area average anomalies for broad-scale indices (e.g. sea temperatures across a region, teleconnection indices, standard 'monsoon' indices, etc.).  They are produced for a number of defined areas across the globe (Fig.8.3.4.2-1, Fig.8.3.4.2-2).  

Climagram areas

Fig8.3.4.2-1: Areas used for 2m temperature and rainfall anomaly climagrams.

Fig8.3.4.2-2: Areas used for sea surface temperature anomaly climagrams.

Climagram explanation

The climagram shows the range of anomalies of the forecast monthly mean values of several forecast variables in box and whisker format.   These may be directly compared with seasonal model climate (shorter S-M-climate) and reanalysis climatology.

In the climagram:

• the purple boxes and whiskers indicate the seasonal forecast.
• the grey boxes and whiskers indicate the seasonal model climatology (shorter S-M-climate) derived from the re-forecasts using SEAS5 (i.e. for the period 1993-2016).
• the yellow and orange bands indicate the reanalysis climatology during the same 1993-2016 period.

• the limits of the purple and grey whiskers and the limits of the yellow band correspond to the 5th and 95th percentiles.
• the limits of the purple and grey boxes and the limits of the orange band correspond to the lower and upper terciles,
• the lines within the purple and grey boxes and the red line within the orange band correspond to median values.

Climagram examples

Fig8.3.4.2-3: Sea surface temperature anomaly over the Western Tropical Indian Ocean area.  

The seasonal (SEAS5) forecast of the anomaly (purple) lies well above above upper terciles of the seasonal model climatologies (yellow and grey).

Red dots are verification values from observations.

Fig8.3.4.2-4: Sea surface temperature anomaly over the Eastern Tropical Indian Ocean area.  

The seasonal (SEAS5) forecast of the anomaly (purple) lies:

• in September to November below the mean but within the lower terciles of the seasonal model climatologies (yellow and grey).
• in January and February above the mean but rising above upper terciles of the seasonal model climatologies (yellow and grey).

 Red dots are verification values from observations.

Fig8.3.4.2-5: Sea surface temperature anomaly over the Nino 3.4 area.

The seasonal (SEAS5) forecast of the anomaly (purple) lies:

• above upper terciles of the seasonal reanalysis climatology (yellow).
• within the upper terciles of the seasonal model climatology (shorter S-M-climate) (grey).

The red dots show the observed anomalies.

Fig8.3.4.2-6: North Atlantic Oscillation.  Positive values correspond to an intensification of westerly winds over the North Atlantic.

The seasonal (SEAS5) forecast of the anomaly (purple) lies near to the model climate values but some indication of negative values in January and February suggesting a weakening of the westerly wind regime across the Atlantic.

The red dots show the observed anomalies.

Fig8.3.4.2-7: Precipitation anomaly over southern Europe. 

The seasonal (SEAS5) forecast of the anomaly (purple) lies:

• above the model climate values in October, November and December suggesting a wetter spell.
• below the model climate values in February suggesting drier weather.

Fig8.3.4.2-8: Temperature anomaly over Northern Europe.

Sequence of seasonal (SEAS5) forecasts of the anomaly (purple) over Northern Europe.  The pecked red box encloses forecasts verifying November and December.

SEAS5 forecasts for November and December predict above normal temperatures in Northern Europe.  The SEAS5 forecasts remain within the box and whisker symbols of both the reanalysis climatology and seasonal model climatology (shorter S-M-climate).

The red dots show the observed anomalies.  The observed anomaly September lies above the SEAS5 forecast, the reanalysis climatology and the seasonal model climatology (shorter S-M-climate).

Fig8.3.4.2-9: Precipitation anomaly over Southern Europe. 

Sequence of seasonal (SEAS5) forecasts of the anomaly (purple) over Southern Europe.  The pecked red box encloses forecasts verifying October and November.

SEAS5 forecasts for October and November predict above normal precipitation in Southern Europe.  However, the SEAS5 forecast run DT 1st Oct shows a negative anomaly for that month.  Here the extended range forecast might be more appropriate to use.  The SEAS5 forecasts remain within the box and whisker symbols of both the reanalysis climatology and seasonal model climatology (shorter S-M-climate).

SEAS5 forecasts for February suggest the precipitation anomaly rises from below reanalysis mean climatology from the Aug forecast to above reanalysis mean climatology.