The seasonality of precipitation signals embedded within the North American Drought Atlas
- 7 July 2010
- journal article
- Published by SAGE Publications in The Holocene
- Vol. 20 (6), 983-988
- https://doi.org/10.1177/0959683610365937
Abstract
We examine how the seasonality of precipitation signals embedded within the North American Drought Atlas varies across the continent. Instrumental records of average summer (JJA) Palmer Drought Severity Index (PDSI) are characterized by major regional differences in the relative importance of precipitation during summer and winter (DJF). The Atlas, which is based on a network of drought-sensitive tree-ring records, is able to reproduce the main geographic patterns of these biases, but tree-ring reconstructions exaggerate the influence of seasonal precipitation anomalies in the southwestern United States and northern Mexico (towards a stronger winter signal) and western Canada (towards a stronger summer signal). Drought reconstructions from the Southwest and Tex-Mex regions are tuned mainly to winter precipitation and display strong teleconnections to both El Niño and La Niña. In contrast, winter precipitation signals are either weak or absent in drought reconstructions from northwestern North America, and tree-ring estimates of PDSI show a much less robust association with the El Niño-Southern Oscillation. Geographical differences in the relative strength of seasonal precipitation signals are likely due to (i) local factors that influence tree growth but are not incorporated into the PDSI algorithm and (ii) real differences in regional climatology. These seasonal biases must be taken into account when comparing drought reconstructions across North America, when comparing tree-ring PDSI to drought records developed from other proxies or when attempting to use the Drought Atlas to link past droughts to potential forcing mechanisms.Keywords
This publication has 38 references indexed in Scilit:
- Variable oceanic influences on western North American drought over the last 1200 yearsGeophysical Research Letters, 2009
- North American drought: Reconstructions, causes, and consequencesEarth-Science Reviews, 2007
- Widespread drought episodes in the western Great Lakes region during the past 2000 years: Geographic extent and potential mechanismsEarth and Planetary Science Letters, 2006
- Long-Term Aridity Changes in the Western United StatesScience, 2004
- A 400-year tree-ring chronology from the tropical treeline of North America.AMBIO, 2001
- Drought Reconstructions for the Continental United States*Journal of Climate, 1999
- The changing relationship between ENSO variability and moisture balance in the continental United StatesGeophysical Research Letters, 1998
- Global variations in droughts and wet spells: 1900–1995Geophysical Research Letters, 1998
- Large-Scale Atmospheric Circulation Features of Warm and Cold Episodes in the Tropical PacificJournal of Climate, 1990
- The Palmer Drought Severity Index: Limitations and AssumptionsJournal of Climate and Applied Meteorology, 1984