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 in the Arctic freshwater and energy redistribution. The combined model and satellite sea ice 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 we estimate the continuous seasonal and interannual variations in 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 about -240(±40) to -970(±60) km3 and -1970(±290) to -2490(±280) km3, respectively. The sea ice volume export reaches its maximum in spring and about one-third of the yearly total volume export occurs in the melt season. The minimum monthly sea ice export is −11 km3 in August 2015, and the maximum (−442 km3) appears in March 2011. The seasonal relative frequencies of sea ice thickness and drift suggest that the Fram Strait outlet in summer is dominated by sea ice that is thicker than 2 m with relatively slow seasonal mean drift of about 3 km d−1.

Ensemble-based estimation of sea-ice volume variations in the Baffin Bay

“…We use monthly mean sea-ice thickness and drift to obtain the SIV fluxes following Ricker et al (2018). The formulas to derive the SIV inflows and outflows are the same as applied in Min et al (2019):…”

“…CMST provides daily sea-ice thickness (SIT), concentration (SIC) and drift (SID). CMST SIT was systematically validated within the Arctic basin by Mu et al (2018a) and its SID was further validated against the National Snow and Ice Data Center (NSIDC) and SAR data in the Fram Strait by Min et al (2019). Additionally, CMST is successfully applied to obtain a relatively accurate estimation of the year-round sea-ice volume export through the Fram Strait (Min et al, 2019).…”

Multi-model based estimation of sea ice volume variations in the Baffin Bay

“…In addition, the SIT simulations from NAOSIM and PIOMAS show a thicker estimation of sea ice than the CMST and TOPAZ4 data that assimilate satellite-observed SIT, while the SIT trends of CMST and TOPAZ4 are more consistent with SMOS. Furthermore, sea ice drift (SID) contributes much more to sea ice flux variation on its monthly scale (Min et al, 2019;Ricker et al, 2018). For this reason, an accurate simulation of SID is another vital factor to derive sea ice volume flux.…”

“…It should be noted that, because of the very limited in-situ SIT observations in the Baffin Bay, it is not possible to identify very accurate sea ice flux in this area. But a series of detailed validations of CMST, PIOMAS, TOPAZ4 and NAOSIM SIT are already performed in the Arctic basin and the Fram Strait (Min et al, 2019;Mu et al, 2018a;Wang et al, 2016;Xie et al, 2018, Sumata et al, 2019a and. The aim of this study is to give a state-of-the-art ensemble mean estimation of SIV flux based on a combination of model results and observations, and to conduct a first estimate of the thermodynamic growth of sea ice volume.…”

“…CMST provides daily sea ice thickness (SIT), concentration (SIC) and drift (SID). CMST SIT is systematically validated within the Arctic basin by Mu et al (2018a) and its SID were further validated against NSIDC and SAR data in the Fram Strait by Min et al (2019). Additionally, CMST is applied successfully in Fram Strait and obtained a relatively accurate estimate of the year-round sea ice volume export through Fram Strait (Min et al, 2019).…”