Date of Graduation

5-2011

Document Type

Thesis

Degree Name

Master of Science in Geography (MS)

Degree Level

Graduate

Department

Geosciences

Advisor

David W. Stahle

Committee Member

Van Brahana

Second Committee Member

Falko Fye

Keywords

Earth sciences, Douglas fir, Earlywood, Latewood, Mexico

Abstract

Problems with instrumental climate data and difficulties arising from the distribution of sensitive, long-term tree-ring chronologies across Mexico's complex terrain have made it difficult to model the climate signal of tree-rings in Mexico. The objective of this research is to utilize the improved long-term, high-resolution, gridded instrumental climate dataset for Mexico recently developed by Zhu and Lettenmaier (2007) to document the climate signal of Douglas-fir in central Mexico. Through correlation analysis between five Douglas-fir tree-ring chronologies created by the University of Arkansas-Fayetteville Tree-Ring Laboratory and Zhu and Lettenmaier's (2007) gridded historical climate dataset, this research aims to define the regional and seasonal precipitation signal of earlywood (EW) and latewood (LW) tree-ring chronologies and to create a regionally averaged time series that could be considered as a proxy of seasonal climate for specific regions of central Mexico. Monthly and seasonal analyses between the gridded data and the EW and LW tree-ring chronologies show that spring precipitation signal in EW is the strongest, especially at Cuauhtémoc la Fragua. Summer precipitation signal in LW is apparent, though the region of strong signal is smaller than for EW and spring. Cuauhtémoc la Fragua again displayed the best results for modeling regional climate signal in the LW. There was a modest amount of seasonal overlap in climate signal between EW and LW. Also, because the tree-ring chronologies come from sites at remote, high elevations, more high-elevation climate data might contribute to better overall modeling of precipitation signal in the Douglas-fir of central Mexico.

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