Synoptic/Mesoscale Circulation Impacts in the Siberian Arctic Marginal Ice Zone 2014

The 2014 Arctic Clouds in Summer Experiment (ACSE) field program is an atmospheric component of the SWERUS-C3 expedition, which consists of a cruise with the Swedish icebreaker R/V Oden near the marginal ice zone (MIZ) north of Russia in the Laptev, Siberian, and Chukchi Seas during July 5 - October 4, 2014. SWERUS investigated permafrost thawing, greenhouse gas venting, and ocean thermal structure on East Siberian Shelf and its adjacent slope and ridges. ACSE provided measurements of cloud macro- and microphysical characteristics; boundary-layer structure; and surface momentum, sensible heat, and latent heat fluxes during the summer ice-edge retreat and through the onset of the fall freeze-up in the emerging MIZ of the Laptev and East Siberian Seas. An impressive suite of instrumentation was deployed on the Oden for ACSE. On-board instrumentation included a stabilized W-band cloud radar, a 449 MHZ wind profiler, a radiometrics multi-channel microwave radiometer, a Regal laser wave-height recorder, a flux tower with sonic anemometer and Licor fast humidity and CO2 sensors, a motion-stabilized 14-channel HALO photonics scanning Doppler lidar, a motion-stabilized 14-channel HATPRO scanning radiometer, broadband radiometers, several ceilometers, 4X daily rawinsonde launches, a weather station for basic meteorological parameters, video webcams, a Datawell Waverider buoy, and remote and in-situ measurements of the surface temperature. In addition, synthetic aperture radar (SAR) images from Radarsat-2 and TerraSAR-X were available to provide details of the ice conditions, while fine-resolution (250 m) MODIS imagery was used to document the larger-scale cloud conditions and supplemented the SAR imagery by also providing intermittent documentation of the ice conditions. Upper ocean temperature profiles from CTD and BT casts are also being made by SWERUS, and will likely be available later during the analysis.

Processing and analysis of the ACSE data from this extensive suite of instruments is just now beginning. The purpose of this presentation is to summarize the data collected and the conditions encountered along the MIZ during this 3-month summer and autumn period, and present preliminary findings of interactions between atmospheric synoptic/mesoscale features and the ocean and the sea-ice surface in the MIZ. The satellite images reveal circulation systems of various physical scales, and the in-situ observations show a variety of intensities as the systems passed over the icebreaker. Some of these systems might be called “storms.” Conditions of both off-ice and on-ice flow were measured, impacting cloud and boundary-layer characteristics; influencing the magnitudes of turbulent heat, moisture, and momentum fluxes; possibly producing local mesoscale atmospheric and oceanic features; and advecting sea ice. Some preliminary analysis of the systems' structure will be presented using soundings and remote sensing data, and cases with clear impacts on the open water and sea ice in the MIZ will be discussed.