Luis Brito-Castillo

Reconstruction of long-term winter streamflow in the Gulf of California continental watershed

Abstract Applying multiple regression techniques to tree-ring series from Sierra de la Laguna in Baja California Sur, Mexico and Sierra Madre Occidental in Durango, and Tlaxcala, Mexico (A.D. 1384–1997), reconstruction of winter streamflow was performed for data from the central and southern regions of the Gulf of California continental watershed. Each region was defined after applying Varimax Rotated Empirical Orthogonal Function analysis. Streamflow reconstruction was possible from 1840 to 1992 for the central region and from 1712 to 1993 for the southern region. The power spectrums of the reconstructed streamflow series and the Index of the Pacific Decadal Oscillation series (IPDO) show evidence of low frequency (decadal-scale) variations around 40 and 80 years. Tendencies in reconstructed streamflow series and in the IPDO are analyzed and discussed. We conclude that streamflow reconstruction was attainable on a decadal temporal scale. In this sense, the IPDO may be considered a good indicator of future tendencies (in decades) in winter streamflow in the study zone.

Seasonal Variation of Surface Temperature–Modulating Factors in the Sonoran Desert in Northwestern Mexico

The authors explore a new approach to monitoring of desertification that is based on use of results on the relation between albedo and surface temperature for the Sonoran Desert in northwestern Mexico. The criteria of predominance of radiation by using the threshold value of Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) were determined. The radiation mechanism for regulating the temperature of the surface and the definition of threshold values for AVHRR and MODIS NDVI have an objective justification for the energy budget, which is based on the dominance of radiation surface temperature regulation in relationtoevapotranspiration.Changesin the extentofaridregionswith AVHRRNDVIof ,0.08 andMODIS NDVI of ,0.10 can be considered to be a characteristic in the evolution of desertification in the Sonoran Desert region. This is true because, in a certain year, the time span of the period when radiation factor predominates is important for the desertification process.

Changes in Aridity across Mexico in the Second Half of the Twentieth Century

AbstractSix regions in Mexico, with typical interannual changes in the aridity index, have been defined by the 1951–2001 meteorological dataset. Peak months of rainfall differ within the regions. Most of the land in the Mexican terrain has had a slow aridization since the early 1980s. The decline in the aridity index in the early 1950s and late 1990s was caused by droughts in the area. The distinctive features of the aridization of Mexican dry lands are characterized by steady and extensive droughts during 1948–57, 1960–65, and 1994–2003 in the second half of the twentieth century. During the drought of 1951–57 substantial aridization in most of the dry lands was observed, including the Sierra Madre Occidental, Sierra Madre Oriental, and Mexican Altiplano. Aridization of dry lands during the drought in 1960–65 affected mostly the southern part of the Mexican Altiplano, the Sierra Madre del Sur, and the Yucatan Peninsula. For the drought in the 1990s, one special feature of the aridization was its propagat...

Monsoon region climate applications: Integrating climate science with regional planning and policy

Emerging results climate of research in the monsoon region, including the North American Monsoon Experiment (NAME), have prompted interest in how to integrate climate knowledge with planning and policy to reduce regional climate-related vulnerabilities and enhance sustainability. NAME is a joint process study of the Climate Variability and Predictability Program (CLIVAR) and the Global Energy and Water Cycle Experiment (GEWEX) process study (information online at www.eol.ucar.edu/projects/name). Several climate and society assessment projects are working to understand monsoon-region stakeholder climate sensitivities and decision-making needs. Motivated by these activities, and building other upon bina-tional workshops on climate, environment, and water management,