Methodology and Results of Calculating Central California Surface Temperature Trends: Evidence of Human-Induced Climate Change?

Authors

John R. Christy, University of Alabama
William B. Norris, University of Alabama
Kelly Redmond, Western Regional Climate Center
Kevin P. Gallo, National Climatic Data CenterFollow

Document Type

Article

Date of this Version

2006

Comments

Published in the Journal of Climate VOLUME 19, 15 FEBRUARY 2006.

Abstract

A procedure is described to construct time series of regional surface temperatures and is then applied to interior central California stations to test the hypothesis that century-scale trend differences between irrigated and non-irrigated regions may be identified. The procedure requires documentation of every point in time at which a discontinuity in a station record may have occurred through (a) the examination of metadata forms (e.g., station moves) and (b) simple statistical tests. From this “homogeneous segments” of temperature records for each station are defined. Biases are determined for each segment relative to all others through a method employing mathematical graph theory. The debiased segments are then merged, forming a complete regional time series.