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Matthew Alkire

Senior Oceanographer





Department Affiliation

Polar Science Center


B.S. Marine Sciences, Richard Stockton College of New Jersey, 2003

M.S. Chemical Oceanography, Florida Institute of Technology, 2005

Ph.D. Oceanography, Oregon State University, 2010


2000-present and while at APL-UW

Combining physical and geochemical methods to investigate lower halocline water formation and modification along the Siberian continental slope

Alkire, M.B., I. Polyakov, R. Rember, A. Pnyushkov, V. Ivanov, and I. Ashik, "Combining physical and geochemical methods to investigate lower halocline water formation and modification along the Siberian continental slope," Ocean Sci., 13, 983-995, doi:10.5194/os-13-983-2017, 2017.

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24 Nov 2017

A series of cross-slope transects were occupied in 2013 and 2015 that extended eastward from St. Anna Trough to the Lomonosov Ridge. High-resolution physical and chemical observations collected along these transects revealed fronts in the potential temperature and the stable oxygen isotopic ratio that were observed north of Severnaya Zemlya (SZ). Using linear regressions, we describe mixing regimes on either side of the front that characterize a transition from a seasonal halocline to a permanent halocline. This transition describes the formation of lower halocline water (LHW) and the cold halocline layer via a mechanism that has been previously postulated by Rudels et al. (1996). Initial freshening of Atlantic Water (AW) by sea-ice meltwater occurs west of SZ, whereas higher influences of meteoric water and brine result in a transition to a separate mixing regime that alters LHW through mixing with overlying waters and shifts the characteristic temperature–salinity bend from higher (34.4  ≤  S  ≤  34.5) toward lower (34.2  ≤  S  ≤  34.3) salinities. These mixing regimes appear to have been robust since at least 2000.

On the geochemical heterogeneity of rivers draining into the straits and channels of the Canadian Arctic Archipelago

Alkire, M.B., A.D Jacobson, G.O. Lehn, R.W. Macdonald, and M.W. Rossi, "On the geochemical heterogeneity of rivers draining into the straits and channels of the Canadian Arctic Archipelago," J. Geophys. Res., 122, 2527-2547, doi:10.1002/2016JG003723, 2017.

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12 Oct 2017

Ten rivers across northern Canada and the Canadian Arctic Archipelago (CAA) were sampled during spring 2014 and summer 2015 to investigate their geochemical heterogeneity for comparison against larger North American (i.e., Mackenzie and Yukon Rivers) and Siberian rivers. In general, rivers draining the western and/or northern regions of the study area have higher solute concentrations and lower 87Sr/86Sr ratios compared to rivers draining the eastern and/or southern regions. The inorganic geochemical signatures largely reflect the bedrock geology, which is predominately carbonate in the western and/or northern regions and silicate in the eastern and/or southern regions. Riverine δ18O values primarily correlate with latitude, with only a few exceptions. Measurements of total alkalinity (TA) were combined with a regional analysis of bedrock geology and extrapolated to produce a range for the mean characteristic TA of rivers draining into the straits and channels of the CAA (628–819 μeq kg-1). Combining this estimate with contributions from the Mackenzie River yields a revised North American river runoff TA of 935–1182 μeq kg-1, which is much lower than that of the Mackenzie River (1540 μeq kg-1). This lower concentration suggests that TA may not be used to distinguish between North American and Siberian river contributions in regions such as Davis Strait.

A meteoric water budget for the Arctic Ocean

Alkire, M.B., J. Morison, A. Schweiger, J. Zhang, M. Steele, C. Peralta-Ferriz, and S. Dickinson, "A meteoric water budget for the Arctic Ocean," J. Geophys. Res., EOR, doi:10.1002/2017JC012807, 2017.

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6 Oct 2017

A budget of meteoric water (MW = river runoff, net precipitation minus evaporation, and glacial meltwater) over four regions of the Arctic Ocean is constructed using a simple box model, regional precipitation-evaporation estimates from reanalysis data sets, and estimates of import and export fluxes derived from the literature with a focus on the 2003–2008 period. The budget indicates an approximate/slightly positive balance between MW imports and exports (i.e., no change in storage); thus, the observed total freshwater increase observed during this time period likely resulted primarily from changes in non-MW freshwater components (i.e., increases in sea ice melt or Pacific water and/or a decrease in ice export). Further, our analysis indicates that the MW increase observed in the Canada Basin resulted from a spatial redistribution of MW over the Arctic Ocean. Mean residence times for MW were estimated for the Western Arctic (5–7 years), Eastern Arctic (3–4 years), and Lincoln Sea (1–2 years). The MW content over the Siberian shelves was estimated (~14,000 km3) based on a residence time of 3.5 years. The MW content over the entire Arctic Ocean was estimated to be ≥ 44,000 km3. The MW export through Fram Strait consisted mostly of water from the Eastern Arctic (3237 ± 1370 km3 yr-1) whereas the export through the Canadian Archipelago was nearly equally derived from both the Western Arctic (1182 ± 534 km3 yr-1) and Lincoln Sea (972 ± 391 km3 yr-1).

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Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center