LOD (AAM) and Land Surface Temperatures in California

The following discussion is based upon a WUWT post
that highlighted a paper called:

Persistence in California Weather Patterns
by Jim Goodridge - State Climatologist (Retired)

which can obtained from:

http://wattsupwiththat.com/2007/10/07/california-climate-pdo-lod-and-sunspot-departure/

In this paper, Goodridge notes that the accumulated departure 

from average of 47 Californian de-trended temperature records

(figure 1) shows a remarkable similarity with the accumulated 

departure from the average Pacific Decadal Oscillation (PDO)

(figure 2).

Figure 1:

Figure 2:

Goodridge notes that link between the PDO and Californian

land surface temperatures is provided by the prevailing coastal

wind directions on the Californian coast that are associated 

with the rising and declining phases in the accumulated departure 

from the average PDO. 

"The accumulated departure from average plot of the PDO 

index has a peak in about 1944 as well as during the current 

period of heating starting in 1975. The rising limb of this 

PDO index represents a warming period of SST on the 

West Coast coast, where as a declining trend represents 

a time of cooling. In general, cooling on the US Pacific 

Coast occurs when coastal North winds induce offshore 

coriolis force that result in off shore winds that lower tides 

that induce cold-water upwelling. This reflects the delicate 

hydrostatic balance of the oceans. Warming SST is associated 

with South winds that induce an onshore coriolis force with 

higher tides, which suppress cold-water upwelling."

In addition, Goodridge notes that the variations in the Earth's 

Length-of-Day (LOD), a quantity that is inversely related

to the Earth rotation rate, appears to closely match the 

observed changes in the accumulated departure from the 

average PDO (compare figure3 with figures 1 & 2):

Figure 3:

The remarkable thing is that the changes in the LOD appear to

preceed those observed in the accumulated departure from the 

average PDO [and the accumulated departure from average of 

47 Californian de-trended temperature records] by about seven

to 10 years! This means that the latter are causally linked to the

former.

Goodridge provides a possible explanation for this causal link: 

"The PDO index is a measure of the East West sea surface 

temperature difference in the North Pacific Ocean. The 

AAM index [closley linked to the LOD] is a measure of the 

ratio of East West vs. North-South winds on the planet 

that affect the earth rotation rate.