Zonally Averaged Wind Zonal DJFZonal JJA Meridional JJA

V and Omega V (DJF)  (JJA)  (DJF) V (JJA)

T and  T (DJF)  (JJA)  (DJF) T (JJA)

Sea Surface Temperature (SST) Annual Average

Zonal wind and  (2-d) Zonal Wind Speed (400mb-600mb) Omega (400mb-600mb) DJF JJA

DJF Zonal Wind Speed (400 mb mb) Tropical Westerlies!

Omega in the tropics (400mb mb) 30S-30N 2.5N-30N 2.5S-30S

Helmholtz Decomposition of a Velocity Field has all the vorticity, no divergence has all the divergence, no vorticity

1000 mb Velocity Potential (Annual)

Velocity Potentials (Annual) 1000 mb 200 mb

Velocity Potentials (Seasonal) DJF JJA

The “Walker Circulation” (

Seasonal Cycle of Sea Level Pressure

Pressure at the Surface (Data) P at surface (annual) SLP (annual) SLP (DJF) SLP (JJA)

SLP, Winds (DJF) Sketch The real world is not covered by a series of belts that completely encircle the globe. Instead, we find a number of alternating semi-permanent cells of high and low pressure. Among the most prominent features in the Northern Hemisphere during winter are the Aleutian and Icelandic Lows over the Pacific and Atlantic Oceans, and the Siberian High over central Asia.

SLP, Winds (JJA) Sketch In summer, the best-developed semi-permanent cells are the Hawaiian and Bermuda-Azores Highs of the Pacific and Atlantic Oceans and the Tibetan Low of southern Asia.

Ocean Currents Ocean currents are horizontal movements of surface water that have an impact on the exchange of energy and moisture between the oceans and the lower atmosphere. Among these are the North Equatorial Current and the South Equatorial Current, which converge, creating the Equatorial Countercurrent. The warm Gulf Stream flows northeast to become the North Atlantic Drift and later the cold Canary Current as it turns southward. The cold Labrador Current flows south along the east coast of Canada fed by the East and West Greenland Drift.

“Skin” Temperature (Annual) “Skin” temperature is an analysis product corresponding to the temperature of an “infinitely thin” layer of surface material (land or water).

Skin Temperature Annual DJF JJA

Sea Surface Temperature Annual DJF JJA

Water-related variables mixing ratio specific humidity relative humidity partial pressure of water vapor

Specific Humidity (g/kg) Annual Mean Annual

Specific Humidity (Seasonal) Annual DJF JJA

1000 mb Specific Humidity Annual DJF JJA

850 mb Specific Humidity Annual DJF JJA

Specific Humidity by Level (Annual) 500 mb 700 mb 850 mb 1000 mb

850 mb Specific Humidity (Latitude, time)

Seasonal Cycle: Zonally Averaged Specific Humidity

Precipitation Rate (Annual)

Precipitation Rate (NCEP) JJASON MAM DJF JJA

Seasonal Cycle of Precipitable Water