Southern Oscillation extremes reconstructed from tree rings of the Sierra Madre Occidental and southern Great Plains
- Univ. of Arkansas, Fayetteville (United States)
The El Nino-Southern Oscillation (ENSO) is correlated with climate and tree growth over northern Mexico and the southern Great Plains of the US. Warm events favor moist-cool conditions from October through March (event years 0 and +1), and subsequent tree growth (year +1) in the region tends to be above average. The opposite climate and tree growth conditions prevail with less consistency during cold events. ENSO-sensitive tree-ring chronologies from this region were selected to develop two reconstructions of the Southern Oscillation index (SOI) back to 1699. The calibration and validation results suggest that the 56 climate extremes classified from 1699 to 1965 represent about half of the true number of extremes during this 267-year period, and that each reconstructed extreme has up to a 70% chance of representing a true winter SOI extreme. The most accurate estimates of past winter SOI extremes may be achieved in those years when the regression and classification methods of reconstruction agree, but comparisons with the instrumental data indicate that evidence for a past extreme cannot be disregarded when based on only one method. Both reconstructions indicate an increase in the frequency of winter SOI extremes after ca. 1850. Because the regression and classification errors are randomly distributed through time, these and other reconstructed changes in event frequency may reflect real changes in the extratropical influence of the SO over Mexico and the southern United States, if not in the SO itself. 50 refs., 5 figs., 3 tabs.
- OSTI ID:
- 6648234
- Journal Information:
- Journal of Climate; (United States), Vol. 6:1; ISSN 0894-8755
- Country of Publication:
- United States
- Language:
- English
Similar Records
The hydroclimatology of the United States during El Nino/Southern Oscillation
Prediction and assessment of impacts on Asian river deltas by extreme climate events and their association with El Nino and Southern Oscillation (ENSO)