Polynyas, Ice Production and seasonal Evolution in the Ross Sea (PIPERS)
The one place with large sea ice increases is the western Ross Sea, which lies downstream of the largest coastal polynya where much of the Ross Sea ice production is thought to take place. The processes driving these sea ice increases have not been well established. While satellite observations show increases in Ross Sea ice extent, duration and concentration, it is unknown how sea ice thickness, and thus volume has changed. We also do not know if sea ice production (SIP) has similarly increased. If so, where (e.g., on versus off-shelf) and how (e.g., stronger winds or fresher ocean)? Increases in SIP in the polynyas would lead to increases in High Salinity Shelf Water (HSSW) and Antarctic Bottom Water (AABW) formation, thus affecting global thermohaline circulation, whereas increases in SIP off the shelf may only affect the upper ocean locally. If the former, a non-local source of freshening in the Ross Sea may mitigate against increases in HSSW/AABW, while also indicating the non-local source of freshening is even greater than reported. The uncertainties regarding SIP in the Ross Sea have global implications and are largely due to the lack of in situ observations of air-sea-ice interactions in the Ross Sea in autumn-winter. The challenge in addressing these system-level relationships is that all related processes must be measured nearly simultaneously to capture the full 3D evolution of air-sea-ice interactions controlling SIP and water mass transformation, requiring a project large in scope, interdisciplinary and well integrated.
To this end, we propose an interdisciplinary multiplatform field campaign to provide first time measurements of the local and large-scale controls on SIP through three complementary efforts: (i) measurements conducted during a 60-day cruise on the US icebreaker N. B. Palmer in April-May; (ii) data acquired from three autonomous buoy arrays providing space/time observations from May to October, and (iii) data acquired from two airborne surveys conducted by NSF LC-130 using the IcePod system in October. Using this approach, we propose the following: 1. Quantify the full 3-D suite of air-sea-ice interactions during rapid sea ice growth, including heat, salinity, momentum, and water mass modification due to SIP in polynyas and in ice-covered areas 2. Develop model parameterizations for air-ice-ocean fluxes for both polynyas and ice-covered areas 3. Measure new sea ice growth & export from polynyas; and new ice growth, deformation, and thickness evolution in pack ice; 4. Measure/validate remote monitoring of Ross Sea ice mass balance/volume export by combining autonomous buoy observations with satellite-based area ice export and NSF aircraft-based estimates of ice thickness.