Reconciling Precipitation with Runoff: Observed Hydrological Change in the Midlatitudes

Osborne, Joe M.; Lambert, F. Hugo; Groenendijk, Margriet; Harper, Anna B.; Koven, Charles D.; Poulter, Benjamin; Pugh, Thomas A. M.; Sitch, Stephen; Stocker, Benjamin; Wiltshire, Andy; Zaehle, Sönke (2015). Reconciling Precipitation with Runoff: Observed Hydrological Change in the Midlatitudes. Journal of Hydrometeorology, 16(6), pp. 2403-2420. American Meteorological Society 10.1175/JHM-D-15-0055.1

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Century-long observed gridded land precipitation datasets are a cornerstone of hydrometeorological research. But recent work has suggested that observed Northern Hemisphere midlatitude (NHML) land mean precipitation does not show evidence of an expected negative response to mid-twentieth-century aerosol forcing. Utilizing observed river discharges, the observed runoff is calculated and compared with observed land precipitation. The results show a near-zero twentieth-century trendinobserved NHML landmean runoff,in contrast to the significant positive trend in observed NHML land mean precipitation. However, precipitation and runoff share common interannual and decadal variability. An obvious split, or breakpoint, is found in the NHML land mean runoff–precipitation relationship in the 1930s. Using runoff simulated by six land surface models (LSMs), which are driven by the observed precipitation dataset, such breakpoints are absent. These findings support previous hypotheses that inhomogeneities exist in the early-twentieth-century NHML land mean precipitation record. Adjusting the observed precipitation record according to the observed runoff record largely accounts for the departure of the observed precipitation response from that predicted given the real-world aerosol forcing estimate, more than halving the discrepancy from about 6 to around 2 W m 22. Consideration of complementary observed runoff adds support to the suggestion that NHML-wide early-twentieth-century precipitation observations are unsuitable for climate change studies. The agreement between precipitation and runoff over Europe, however, is excellent, supporting the use of whole-twentieth-century observed precipitation datasets here.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Stocker, Benjamin

Subjects:

500 Science > 530 Physics

ISSN:

1525-755X

Publisher:

American Meteorological Society

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

22 Dec 2015 17:01

Last Modified:

22 Dec 2015 17:01

Publisher DOI:

10.1175/JHM-D-15-0055.1

BORIS DOI:

10.7892/boris.74404

URI:

https://boris.unibe.ch/id/eprint/74404

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