Tracing freshwater anomalies through the air‐land‐ocean system: A case study from the Mackenzie river basin and the Beaufort Gyre

Rawlins, M. A.; Steele, Michael; Vörösmarty, Charles J; Ermold, Wendy; Lammers, R. B.; McDonald, K. C.; Pavelsky, T.; Shiklomanov, A. I.; Zhang, Jinlun

doi:10.3137/oc301.2009

Cited by 19 publications

(11 citation statements)

References 31 publications

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“…Fresh and warm Mackenzie waters reside in the surface layer (Figure ) with the attendant high thermal capacity thus contributing excessive heat to melt sea ice, most effectively when the sea ice cover has been fragmented by the strong BG. This was the case in the 1998 melt season when ice velocity was high in the BG (Figure ), the Mackenzie River had a record discharge [ Rawlins et al ., ], and a record high of open water extent was observed in the decadal satellite data (Figure ).…”

Section: Summary and Discussionmentioning

confidence: 88%

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Effects of Mackenzie River discharge and bathymetry on sea ice in the Beaufort Sea

Nghiem

Hall

Rigor

et al. 2014

Geophysical Research Letters

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Mackenzie River discharge and bathymetry effects on sea ice in the Beaufort Sea are examined in 2012 when Arctic sea ice extent hit a record low. Satellite-derived sea surface temperature revealed warmer waters closer to river mouths. By 5 July 2012, Mackenzie warm waters occupied most of an open water area about 316,000 km 2 . Surface temperature in a common open water area increased by 6.5°C between 14 June and 5 July 2012, before and after the river waters broke through a recurrent landfast ice barrier formed over the shallow seafloor offshore the Mackenzie Delta. In 2012, melting by warm river waters was especially effective when the strong Beaufort Gyre fragmented sea ice into unconsolidated floes. The Mackenzie and other large rivers can transport an enormous amount of heat across immense continental watersheds into the Arctic Ocean, constituting a stark contrast to the Antarctic that has no such rivers to affect sea ice.

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Section: Summary and Discussionmentioning

confidence: 88%

“…Rawlins et al . [] reported a record discharge from the Mackenzie River in May 1998, and Perovich et al . [] showed significant underside ice melt resulting from solar heat input in 2008.…”

Section: Sea Ice In the Beaufort Sea Study Domain In 2012 Compared Tomentioning

confidence: 99%

Effects of Mackenzie River discharge and bathymetry on sea ice in the Beaufort Sea

Nghiem

Hall

Rigor

et al. 2014

Geophysical Research Letters

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“…The climate during this interval is well documented with instrumental data and displays the highest annual Mackenzie River discharge values on record (between 700 and 11 900 m 3 s −1 ), with a maximum reached in 1990. The Mackenzie Trough area is thus clearly affected by freshwater inputs from the Mackenzie River (Rawlins et al, 2009), which are probably controlled by regional and global oceanic and atmospheric (precipitations) circulation patterns, such as the PDO. The PDO is a major mode of North Pacific climate variability and is reflected in the evolution of North Pacific monthly surface temperatures (Mantua et al, 1997;Mantua and Hare, 2002;Minobe, 1997).…”

Section: Discussionmentioning

confidence: 99%

Quantitative reconstruction of sea-surface conditions over the last 150 yr in the Beaufort Sea based on dinoflagellate cyst assemblages: the role of large-scale atmospheric circulation patterns

et al. 2012

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Abstract. Dinoflagellate cyst (dinocyst) assemblages have been widely used over the Arctic Ocean to reconstruct seasurface parameters on a quantitative basis. Such reconstructions provide insights into the role of anthropogenic vs natural forcings in the actual climatic trend. Here, we present the palynological analysis of a dated 36 cm-long core collected from the Mackenzie Trough in the Canadian Beaufort Sea. Dinocyst assemblages were used to quantitatively reconstruct the evolution of sea-surface conditions (temperature, salinity, sea ice) and freshwater palynomorphs fluxes were used as local paleo-river discharge indicators over the last ∼ 150 yr. Dinocyst assemblages are dominated by autotrophic taxa (68 to 96 %). Cyst of Pentapharsodinium dalei is the dominant species throughout most of the core, except at the top where the assemblages are dominated by Operculodinium centrocarpum. Quantitative reconstructions of sea-surface parameters display a series of relatively warm, lower sea ice and saline episodes in surface waters, alternately with relatively cool and low salinity episodes. Variations of dinocyst fluxes and reconstructed sea-surface conditions may be closely linked to large scale atmospheric circulation patterns such as the Pacific Decadal Oscillation (PDO) and to a lesser degree, the Arctic Oscillation (AO). Positive phases of the PDO correspond to increases of dinocyst fluxes, warmer and saltier surface waters, which we associate with upwelling events of warm and relatively saline water from Pacific origin. Freshwater palynomorph fluxes increased in three phases from AD 1857 until reaching maximum values in AD 1991, suggesting that the Mackenzie River discharge followed the same trend when its discharge peaked between AD 1989 and AD 1992. The PDO mode seems to dominate the climatic variations at multi-annual to decadal timescales in the western Canadian Arctic and Beaufort Sea areas.

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“…In April, a transition period between streamflow dominated by baseflow and snowmelt runoff, groundwater contribution to streamflow has increased (Brabets and Walvoord, ). The changes in the ice/snow cover, permafrost, streamflow, soil moisture, vegetation, and other defining properties of ecosystems include important feedback processes transforming the ecology, surface energy balance, and hydrological cycle of northern Canada at local to global scales (Osterkamp et al ., ; Rawlins et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Hydrological sensitivity of a northern mountain basin to climate change

Rasouli

Pomeroy

Carey

et al. 2014

Hydrological Processes

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Abstract:The hydrological sensitivity of a northern Canadian mountain basin to change in temperature and precipitation was examined. A physically based hydrological model was created and included important snow and frozen soil infiltration processes. The model was discretized into hydrological response units in order to simulate snow accumulation and melt regimes and basin discharge. Model parameters were drawn from scientific studies in the basin except for calibration of routing and drainage. The model was able to simulate snow surveys and discharge measurements with very good accuracy. The forcing inputs of the hourly air temperatures and daily precipitation were scaled linearly to examine the model sensitivity to conditions included in a range of climate change scenarios: warming of up to 5°C and change in precipitation of +/À 20%. The results show that peak seasonal snow accumulation, snow season length, evapotranspiration, runoff, peak runoff, and the timing of peak runoff have a pronounced sensitivity to both warming and precipitation change, where the impact of warming is partly compensated for by increased precipitation and dramatically enhanced by decreased precipitation. The snow regime, including peak snow accumulation, snow-free period, intercepted snow sublimation, and blowing snow transport, was most sensitive to temperature, and the impact of a warming of 5°C could not be compensated for by a precipitation increase of 20%. However, basin discharge was more sensitive to precipitation, and the impact of warming could be compensated for by a slight increase in precipitation. The impacts of 5°C warming with a +/À20% change in precipitation resulted in snow accumulation, runoff, and peak streamflow decreasing by from one half to one fifth and the snow-free period lengthening by from 46 to 60 days; in both cases, the smaller change is associated with increased precipitation and the larger change with decreased precipitation. These results show that mountain hydrology in Northern Canada is extremely sensitive to warming, that snow regime is more sensitive to warming than streamflow and that changes in precipitation can partly modulate this response.

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Tracing freshwater anomalies through the air‐land‐ocean system: A case study from the Mackenzie river basin and the Beaufort Gyre

Abstract: Mackenzie River discharge was at a record low in water year (WY) 1995 (October 1994 to September 1995, was near average in WY 1996, and

Cited by 19 publications

References 31 publications

Effects of Mackenzie River discharge and bathymetry on sea ice in the Beaufort Sea

Effects of Mackenzie River discharge and bathymetry on sea ice in the Beaufort Sea

Quantitative reconstruction of sea-surface conditions over the last 150 yr in the Beaufort Sea based on dinoflagellate cyst assemblages: the role of large-scale atmospheric circulation patterns

Hydrological sensitivity of a northern mountain basin to climate change

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