Influence of Nonseasonal River Discharge on Sea Surface Salinity and Height

Abstract River discharge influences ocean dynamics and biogeochemistry. Due to the lack of a systematic, up‐to‐date global measurement network for river discharge, global ocean models typically use seasonal discharge climatology as forcing. This compromises the simulated nonseasonal variation (the d...

Full description

Bibliographic Details
Published in:Journal of Advances in Modeling Earth Systems
Main Authors: Hrishikesh A. Chandanpurkar, Tong Lee, Xiaochun Wang, Hong Zhang, Severine Fournier, Ian Fenty, Ichiro Fukumori, Dimitris Menemenlis, Christopher G. Piecuch, John T. Reager, Ou Wang, John Worden
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union (AGU) 2022
Subjects:
river discharge
sea surface salinity
sea surface height
Physical geography
GB3-5030
Oceanography
GC1-1581
Arctic
Arctic Ocean
Online Access:https://doi.org/10.1029/2021MS002715
https://doaj.org/article/6ce1c61f851746faa62419442d37ada1
Description
Summary:Abstract River discharge influences ocean dynamics and biogeochemistry. Due to the lack of a systematic, up‐to‐date global measurement network for river discharge, global ocean models typically use seasonal discharge climatology as forcing. This compromises the simulated nonseasonal variation (the deviation from seasonal climatology) of the ocean near river plumes and undermines their usefulness for interdisciplinary research. Recently, a reanalysis‐based daily varying global discharge data set was developed, providing the first opportunity to quantify nonseasonal discharge effects on global ocean models. Here we use this data set to force a global ocean model for the 1992–2017 period. We contrast this experiment with another experiment (with identical atmospheric forcings) forced by seasonal climatology from the same discharge data set to isolate nonseasonal discharge effects, focusing on sea surface salinity (SSS) and sea surface height (SSH). Near major river mouths, nonseasonal discharge causes standard deviations in SSS (SSH) of 1.3–3 practical salinity unit (1–2.7 cm). The inclusion of nonseasonal discharge results in notable improvement of model SSS against satellite SSS near most of the tropical‐to‐midlatitude river mouths and minor improvement of model SSH against satellite or in‐situ SSH near some of the river mouths. SSH changes associated with nonseasonal discharge can be explained by salinity effects on halosteric height and estimated accurately through the associated SSS changes. A recent theory predicting river discharge impact on SSH is found to perform reasonably well overall but underestimates the impact on SSH around the global ocean and has limited skill when applied to rivers near the equator and in the Arctic Ocean.

Similar Items