ENSO Monitoring - LONGITUDE-TIME PLOTS

A series of analyses indicating the time evolution of different atmospheric and oceanic variables.  Select desired field from the menu at left.

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Aids to interpreting plots:

Definitions
Climatology The long-term average of a given variable, often a 30-year period.
Anomaly The difference between the observed value of a variable and its climatological value.
Standardized Anomaly An anomaly of a given variable that has been divided by its standard deviation over the base period considered.
OLR An abbreviastion for "Outgoing Longwave Radiation".  Anomalies in OLR can be related to cloud cover and precipitation.  Negative OLR anomalies generally indicate increased cloudiness and likelihood of precipitation while positive anomalies imply decreased cloudiness.   The relationship between OLR anomalies and precipitation holds most strongly in tropical regions.
Pentad A 5-day average of a variable, starting from 1-5 Jan, 6-10 Jan, ..., 27-31 Dec.  On plots using pentad data, the date for the "middle" of the pentad is displayed: 3 Jan, 8 Jan, ... , 29 Dec.
hPa The abbreviation for "hectopascal", a unit of atmospheric pressure.  For comaprison, the atmospheric pressure near the earth's surface is roughly 1000 hPa (its less at higher elevations).  The 250 hPa level in the atmosphere is roughly 10 km above the earth's surface.  One hPa equals one "millibar" or "mb", these pressure units are also displayed on some plots.