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Global Scaling of Rainfall With Dewpoint Temperature Reveals Considerable Ocean-Land Difference

Lookup NU author(s): Dr Haider Ali, Professor Hayley Fowler



This is the authors' accepted manuscript of an article that has been published in its final definitive form by John Wiley and Sons Inc, 2021.

For re-use rights please refer to the publisher's terms and conditions.


© 2021. American Geophysical Union. All Rights Reserved.Short-duration rainfall extremes are expected to intensify with warming at around 7%/K, following the Clausius-Clapeyron (CC) relation, causing concomitant increases in flash floods. Observed hourly rainfall extremes show consistent CC-scaling with dewpoint temperature across all land regions. Here, we use two global climate reanalysis products (ERA5 and MERRA-2) to examine consistency in scaling with observations, in ungauged regions and over the oceans. We find that reanalyzes underestimate observed scaling, but ERA5 provides better estimates than MERRA-2. Scaling rates at high latitudes and midlatitudes are similar to observations, at CC, while over the tropics mixed negative- and super-CC scaling rates are seen. We show underestimation of scaling rates over the tropics is related to deficiencies in simulations of extreme rainfall over orographically complex and convection dominated regions. Importantly, both reanalyzes indicate scaling rates over the ocean are substantially higher than over land, with implications for extreme weather events originating over the ocean.

Publication metadata

Author(s): Ali H, Peleg N, Fowler HJ

Publication type: Article

Publication status: Published

Journal: Geophysical Research Letters

Year: 2021

Volume: 48

Issue: 15

Print publication date: 01/08/2021

Online publication date: 02/08/2021

Acceptance date: 27/07/2021

Date deposited: 07/10/2021

ISSN (print): 0094-8276

ISSN (electronic): 1944-8007

Publisher: John Wiley and Sons Inc


DOI: 10.1029/2021GL093798


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Funder referenceFunder name
NE/R01079X/1Natural Environment Research Council (NERC)
WM140025Royal Society