Exploring trends in wet-season precipitation and drought indices in wet, humid and dry regions
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Funk_2019_Environ._Res._Lett._ ...
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Univ Arizona, Dept Hydrol & Atmospher SciIssue Date
2019-10-29Keywords
precipitationprecipitation extremes
climate change
drought
evapotranspiration
global warming
satellite precipitation
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IOP PUBLISHING LTDCitation
Chris Funk et al 2019 Environ. Res. Lett. 14 115002Journal
ENVIRONMENTAL RESEARCH LETTERSRights
Copyright © 2019 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
This study examines wet season droughts using eight products from the Frequent Rainfall Observations on GridS database. The study begins by evaluating wet season precipitation totals and wet day counts at seasonal and decadal time scales. While we find a high level of agreement among the products at a seasonal time scale, evaluations of 10 year variability indicate substantial non-stationary inter-product differences that make the assessment of low-frequency changes difficult, especially in data-sparse regions. Some products, however, appear more reliable than others on decadal time scales. Global time series of dry, middle, and wet region standardized precipitation index time series indicate little coherent change. There is substantial coherence in year-to-year variations in these time series for the better-performing products, likely indicative of skill for monitoring variations at large spatial scales. During the wet season, the data do not appear to indicate widespread global changes in precipitation, reference evapotranspiration (RefET) or Standardized Precipitation Evapotranspiration Index (SPEI) values. These data also do not indicate a global shift towards increasing aridity. Focusing on SPEI values for dry regions during droughts, however, we find modest increases in RefET and decreases in SPEI when wet season precipitation is below normal. Dry region SPEI values during droughts have decreased by −0.2 since the 1990s. The cause of these RefET increases is unclear, and more detailed analysis will be needed to confirm these results. For wet regions, however, the majority of products appear to indicate increases in wet season precipitation, although many products perform poorly in these regions due to limited observation networks, and estimated increases vary substantially. Synopsis: Our analysis indicates a lack of increasing aridity at global scales, issues associated with non-stationary systematic errors, and concerns associated with increases in reference evapotranspiration in global dry regions during droughts.Note
Open access articleISSN
1748-9326Version
Final published versionSponsors
US Geological Survey's Drivers of Drought program; USAID Famine Early Warning Systems Network United States Agency for International Development (USAID); USAID/NASA Harvest program; Australian Research Council [CE170100023, DP160103439]ae974a485f413a2113503eed53cd6c53
10.1088/1748-9326/ab4a6c
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Except where otherwise noted, this item's license is described as Copyright © 2019 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.