North Pacific’s Very Wide Warm Poleward Surface Flow in Summer

Two independent SST atlases are compared for the western tropical North pacific by means of their monthly mean charts. Good agreement is found in three cases involving the 80 F isotherm in the ship-injection temperature atlas and the 25 C isotherm in the BT atlas. From winter to summer the area between the equator and the particular isotherms doubles in size while the SST variation inside the areas is small. Also the average northward speed of the isotherms is the same: about 15 cm/sec. Mixed layer depth charts in the BT atlas strengthen an earlier prediction that in the spring and summer of every year excess absorbed solar radiation is advected out of the tropics toward the sub-polar regions, pushed by a downward slope to the north in sea level set up by thermal expansion in the deep and long surface layer trough described earlier. This is the main result of the paper.