Reply to comment on five decades of observed daily precipitation reveal longer and more variable drought events across much of the western United States

Authors: Biederman, Joel; ZHANG, F.Y. - University Of Arizona; DANNENBERG, M.P. - University Of Iowa; YAN, D. - University Of Arizona; REED, S.C. - Us Geological Survey (USGS); SMITH, W.K. - University Of Arizona

Submitted to: Geophysical Research Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2023
Publication Date: 1/4/2024
Citation: Biederman, J.A., Zhang, F., Dannenberg, M., Yan, D., Reed, S., Smith, W. 2024. Reply to comment on five decades of observed daily precipitation reveal longer and more variable drought events across much of the western United States. Geophysical Research Letters. 51(1). Article e2023GL105124. https://doi.org/10.1029/2023GL105124.
DOI: https://doi.org/10.1029/2023GL105124

Interpretive Summary: Here the authors respond to a comment on their 2021 publication “Five decades of observed daily precipitation reveal longer and more variable drought events across much of the western United States.” The comment suggests that our choice to smooth precipitation data using five-year moving windows inflated the preponderance of statistically significant trends reported. Here we respond that A) we agree this was not best practice and that the number of stations with significant p-values was thereby inflated; B) however, the trend magnitudes and the regional patterns of trends was relatively unchanged across the 350 weather stations, meaning the main conclusions of the paper stand; C) this is another example of why p-values should not be the sole arbiter of what is and is not real; D) environmental science needs new approaches to test whether spatial patterns in large numbers of observation locations constitute a trend.

Technical Abstract: Here the authors respond to a comment on their 2021 publication “Five decades of observed daily precipitation reveal longer and more variable drought events across much of the western United States.” The comment suggests that our choice to smooth precipitation data using five-year moving windows inflated the preponderance of statistically significant trends reported. Here we respond that A) we agree this was not best practice and that the number of stations with significant p-values was thereby inflated; B) however, the trend magnitudes and the regional patterns of trends was relatively unchanged across the 350 weather stations, meaning the main conclusions of the paper stand; C) this is another example of why p-values should not be the sole arbiter of what is and is not real; D) environmental science needs new approaches to test whether spatial patterns in large numbers of observation locations constitute a trend.