Decline in terrestrial moisture sources of the mississippi river basin in a future climate

Benedict, Imme; Van Heerwaarden, Chiel C.; van der Ent, R.J.; Weerts, Albrecht H.; Hazeleger, Wilco

doi:10.1175/JHM-D-19-0094.1

Decline in terrestrial moisture sources of the mississippi river basin in a future climate

Title

Decline in terrestrial moisture sources of the mississippi river basin in a future climate

Author

Benedict, Imme (Wageningen University & Research)
Van Heerwaarden, Chiel C. (Wageningen University & Research)
van der Ent, R.J. (TU Delft Water Resources; Universiteit Utrecht)
Weerts, Albrecht H. (Deltares; Wageningen University & Research)
Hazeleger, Wilco (Wageningen University & Research; Universiteit Utrecht)

Date

2020

Abstract

Assessment of the impact of climate change on water resources over land requires knowledge on the origin of the precipitation and changes therein toward the future. We determine the origin of precipitation over the Mississippi River basin (MRB) using high-resolution (~25 km) climate model simulations for present and future climate (RCP4.5). Moisture resulting in precipitation over the MRB is tracked back in time using Eulerian offline moisture tracking, in order to find out from where this water originally evaporated (i.e., the moisture sources). We find that the most important continental moisture sources are the MRB itself and the area southwest of the basin. The two most relevant oceanic sources are the Gulf of Mexico/Caribbean and the Pacific. The distribution of sources varies per season, with more recycling of moisture within the basin during summer and more transport of moisture from the ocean toward the basin in winter. In future winters, we find an increase in moisture source from the oceans (related to higher sea surface temperatures), resulting in more precipitation over the MRB. In future summers, we find an approximately 5% decrease in moisture source from the basin itself, while the decrease in precipitation is smaller (i.e., lower recycling ratios). The results here are based on one climate model, and we do not study low-frequency climate variability. We conclude that Mis-sissippi’s moisture sources will become less local in a future climate, with more water originating from the oceans.

Subject

North America
Climate change
Hydrologic cycle
General circulation models

To reference this document use:

http://resolver.tudelft.nl/uuid:288d77e2-2d6f-468a-85d5-b7b1c3529f5f

DOI

https://doi.org/10.1175/JHM-D-19-0094.1

ISSN

1525-755X

Source

Journal of Hydrometeorology, 21 (2), 299-316

Part of collection

Institutional Repository