Global Atmospheric Circulation
This series of maps depict various aspects of the atmospheric
circulation both near the surface and at upper levels. Select
desired field from menu at left or the drop-down menu above.
These maps are based on the NCEP Reanalysis data. NCEP is an acronym
for the US National Centers for Environmental Prediction.
Aids to interpreting plots:
||The long-term average of a given variable, often
the 30-year period 1971-2000.
||The difference between the observed value of a variable and its climatological
||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
||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" the pressure units
also displayed on some plots.