Introduction to Special Collection on Arctic Ocean Modeling and Observational Synthesis (FAMOS) 2: Beaufort Gyre Phenomenon

Abstract

One of the foci of the Forum for Artic Modeling and Observational Synthesis (FAMOS) project is improving Arctic regional ice‐ocean models and understanding of physical processes regulating variability of Arctic environmental conditions based on synthesis of observations and model results. The Beaufort Gyre, centered in the Canada Basin of the Arctic Ocean, is an ideal phenomenon and natural laboratory for application of FAMOS modeling capabilities to resolve numerous scientific questions related to the origin and variability of this climatologic freshwater reservoir and flywheel of the Arctic Ocean. The unprecedented volume of data collected in this region is nearly optimal to describe the state and changes in the Beaufort Gyre environmental system at synoptic, seasonal, and interannual time scales. The in situ and remote sensing data characterizing ocean hydrography, sea surface heights, ice drift, concentration and thickness, ocean circulation, and biogeochemistry have been used for model calibration and validation or assimilated for historic reconstructions and establishing initial conditions for numerical predictions. This special collection of studies contributes time series of the Beaufort Gyre data; new methodologies in observing, modeling, and analysis; interpretation of measurements and model output; and discussions and findings that shed light on the mechanisms regulating Beaufort Gyre dynamics as it transitions to a new state under different climate forcing.

Analysis of the Beaufort Gyre Freshwater Content in 2003–2018

“…The annual trend of freshwater content from the mooring data (534±152 km 3 /a) agrees within uncertainty bounds with the trend obtained from the annual hydrographic surveys (422±130 km 3 /a shown and discussed in Proshutinsky et al, ). The linear trend of freshwater content derived from ITP data (455±232 km 3 /a) also agrees within statistical uncertainty to the trends estimated from the mooring data and hydrographic surveys.…”

“…Based on the annual hydrographic surveys, the Beaufort Gyre region accumulated approximately 6,400 km 3 of fresh water (relative to 34.8 reference salinity) during 16 years between 2003 and 2018 (Proshutinsky et al, ; this special issue). This represents a 40% increase of fresh water volume in the region relative to the climatology of the 1970s.…”

“…The primary focus of this study is on quantifying variability and trends in liquid (water) and solid (sea ice) freshwater content in the Beaufort Gyre region, defined to be between 70 and 81°N, and 130–170°W where water depths exceed 300 m (Figure ). The Beaufort Gyre Exploration Program (BGEP) was initiated in 2003 to synthesize results of historical data analysis, design and conduct long‐term observations in the Beaufort Gyre region, and to provide information to guide numerical modeling activities (Proshutinsky, Krishfield, & Barber, ) under the umbrella of the FAMOS (Forum for Arctic Observing and Modeling Synthesis) project (Proshutinsky et al, , preface paper in this special issue). This regional focus and our analysis based on extensive measurements from the Beaufort Gyre Observational System (BGOS; Figure ; Krishfield et al, ; Proshutinsky, Krishfield, Timmermans, et al, ; Proshutinsky et al, , ) to some extent limits the major uncertainties associated with Arctic‐wide measurements.…”

“…The dashed black line shows the boundary of the Beaufort Gyre region. Colors and contours are freshwater content (relative to a reference salinity of 34.8), and white grid cells indicate no data, in (a) the 1970s (from gridded climatology of Timokhov and Tanis (, summer atlas) at depths 0, 5, 10, 15, 25, 50, 75, 100, 150, 200, 250, 300, 400, and 500m) and (b) from optimal interpolation of 2017 hydrographic data collected from July through October and averaged every 1‐ to 500‐m depth (see section ); see also Proshutinsky et al () where 2017 station locations and optimal interpolation errors are shown in supporting information S1. (c and d) Depth‐latitude sections of salinity along 140 and 150°W (thick dotted lines in panels a and b) in (c) the 1970s and (d) 2017.…”

“…The Beaufort Gyre Exploration Program (BGEP) was initiated in 2003 to synthesize results of historical data analysis, design and conduct long-term observations in the Beaufort Gyre region, and to provide information to guide numerical modeling activities (Proshutinsky, Krishfield, & Barber, 2009) under the umbrella of the FAMOS (Forum for Arctic Observing and Modeling Synthesis) project (Proshutinsky et al, 2019, preface paper in this special issue). This regional focus and our analysis based on extensive measurements from the Beaufort Gyre Observational System (BGOS; Figure 1; Krishfield et al, 2014;Proshutinsky, Krishfield, Timmermans, et al, 2009;Proshutinsky et al, 2015Proshutinsky et al, , 2019 to some extent limits the major uncertainties associated with Arcticwide measurements. However, uncertainties remain associated with limitations in measurement methods and data analysis, which are discussed below.…”