Sea ice export through the Fram Strait derived from a combined model and satellite data set

Abstract

Abstract. Sea ice volume export through the Fram Strait plays an important role on the Arctic freshwater and energy redistribution. The combined model and satellite thickness (CMST) data set assimilates CryoSat-2 and Soil Moisture and Ocean Salinity (SMOS) thickness products together with satellite sea ice concentration. The CMST data set closes the gap of stand-alone satellite-derived sea ice thickness in summer and therefore allows us to estimate sea ice volume export during the melt season. In this study, we first validate the CMST data set using field observations, and then estimate the continuous seasonal and interannual variations of Arctic sea ice volume flux through the Fram Strait from September 2010 to December 2016. The results show that seasonal and interannual sea ice volume export vary from −244 (±43) to −973 (±59) km3 and −1974 (±291) to −2491 (±280) km3, respectively. The sea ice volume export reaches its maximum in spring and the mean amount of the melt season ice volume export accounts about one third of the yearly total amount. The minimum monthly sea ice export is −11 km3 in August 2015 and the maximum (−442 km3) appears in March 2011. Seasonal variations of sea ice thickness and drift frequency distributions infer that the thicker ice accompanied with slower ice motion is easier to appear when there is sea ice exporting through the Fram Strait outlet in summer.

Arctic Sea Ice Decline Preconditions Events of Anomalously Low Sea Ice Volume Export Through Fram Strait in the Early 21st Century

“…The FESOM control run well represents the declining trend and interannual variability of both Arctic sea ice volume and summer sea ice extent as depicted by the comparison with PIOMAS result and satellite observations in Figures 1a and 1b. The spatial patterns of sea ice thickness (with thicker sea ice north of Greenland and CAA and thinner sea ice toward the Eurasian coast) and sea ice drift (with anticyclonic circulation in the Canada Basin and the TDS toward Fram Strait) shown in Figure 1c are consistent with observations and reanalysis (Kwok, 2018; Min et al., 2019). The magnitudes of the drift speed are similar to those in CMST (Min et al., 2019).…”

“…The spatial patterns of sea ice thickness (with thicker sea ice north of Greenland and CAA and thinner sea ice toward the Eurasian coast) and sea ice drift (with anticyclonic circulation in the Canada Basin and the TDS toward Fram Strait) shown in Figure 1c are consistent with observations and reanalysis (Kwok, 2018; Min et al., 2019). The magnitudes of the drift speed are similar to those in CMST (Min et al., 2019). In particular, in Fram Strait, sea ice drift closely follows the satellite observation and the CMST result on the monthly time scale (Figure 2a).…”

“…The aforementioned observations revealed that sea ice volume export through Fram Strait has strong interannual variability, which can be mainly attributed to sea ice drift variability at the Fram Strait gateway (Min et al., 2019; Ricker et al., 2018). Different atmospheric modes have been used to explain the interannual variability of sea ice volume export through Fram Strait.…”

Reply on RC2

“…The CMST thickness data cover both the cold seasons and the melting seasons for the period of October 2010 to December 2016 on an 18-km grid. The CMST has been already quantitatively evaluated against observations by a previous study (Min et al, 2019;Mu et al, 2018), demonstrating an accurate performance in simulating the real sea ice drift and thickness. To reduce the noise in ice drift fields and hence divergence calculation, we follow Holland and Kimura (2016) and smooth ice drifts with a 400×400 km square-window filter.…”

Reply on RC1

“…Compared with the average from 2010 to 2016, an additional 233 km 3 of multiyear sea ice were exported through Fram Strait during the season of ice advance in 2011. Although the data used are different, previous studies have also shown an abnormal increase in sea ice fluxes through the Fram Strait in 2011 (Min et al, 2019;Ricker et al, 2018). Hence, multiyear sea ice loss for the season of sea ice advance has contributed to the negative summer sea ice thickness anomalies.…”