The relationship between the outgoing long-wave radiation (OLR) field
over the tropical Pacific and wintertime monthly precipitation for the
western U. S. is investigated, using the mid-latitude upper-air circulation
as an intermediary. Principal components (PC's) of the 500mb monthly
averaged height field over the NE Pacific and western North America are
compared with those of the monthly tropical Pacific OLR field. It is found
that, of the first 6 PC's of the height field, five are correlated significantly
with the first 3 OLR field PC's at lags of between two and six months.
Canonical correlations between the two sets of PC's are greatest at a lag of
four months and are highly significant. When stratified by different levels
of the OLR field PC's, the separations between means of the height field
PC's are highly significant as well. Differing distributions of the height
field PC ensemble are also found to be associated with different OLR field
PC levels.
The relationship between the 500mb height field and concurrent
western district precipitation is examined. Using a hybrid model
including both linear statistical and non-linear physical components it is
found that considerably more of the variance in the precipitation can be
explained by that of the height field alone than when the precipitation is
inferred directly from a linear statistical model.
A set of reconstructed height field PC's is predicted from OLR values
based on the height field/OLR stratification associations compiled for a
period separate from that of the forecast. Applied to the precipitation
model, this results in predicted western district precipitation which is
better correlated with the observations than is the equivalent precipitation
forecast from the linear statistical relationship of precipitation to the
Southern Oscillation Index. / Graduation date: 1995
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28674 |
| Date | 24 February 1995 |
| Creators | Twining, David S. |
| Contributors | Esbensen, Steven K, |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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