Contemporary changes in the pan-Arctic river flow and analysis of their potential causes
Abstract
The Arctic freshwater cycle, and river flow in particular, are changing rapidly. Multiple observations have shown a significant increase in total annual river discharge to the Arctic Ocean as well as significant spatial and seasonal changes in pan-Arctic river runoff over the last several decades. Most recent estimates of combined river discharge from the six largest Russian pan-Arctic rivers show an annual discharge increase of 2.9 km3/year over 1936-2015 and 10 km3/year over 1980-2015. Since 1989 a significant 15% increase in river flow is observed in North American pan-Arctic. However, there was a robust decline in the linear trend in regional river flow during 1964-1988. Thus, the total river discharge from North America to the Arctic Ocean over the entire observational period (1964-2015) has increased less significantly than from Eurasia.
The observed reduction of Arctic sea ice and later freeze-up in the Arctic Ocean are likely to enhance moisture transport into the pan-Arctic with concomitant increases in precipitation and intensification of the land surface hydrological cycle. This is usually considered as the main cause of the observed increase in pan-Arctic river flow. We analyzed the annual and seasonal observed river flow records along with several available precipitation data and evapotranspiration (ET) estimates to better understand and quantify changes in the pan-Arctic hydrological cycle. Preliminary results show that regional precipitation and ET have not significantly changed to fully support the observed increase in river flow. To identify and quantify contributions of individual drivers and factors to river flow we made a set of modeling experiments on Water Balance Model (WBM), developed at the University of New Hampshire, with the capability to track changes in individual storages (e.g. soil, ground water, reservoirs) and fluxes (e.g. rain flow, snowmelt flow, glacier runoff, baseflow). By comparing the water component fraction differences in water storages and fluxes resulting from base line runs and prescribed forcing experiments we quantified responses of each water source to the changes in climatic drivers.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C53A..01S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0710 Periglacial processes;
- CRYOSPHEREDE: 1625 Geomorphology and weathering;
- GLOBAL CHANGEDE: 1807 Climate impacts;
- HYDROLOGY