Seasonal Ice Zone Reconnaissance Surveys for Aircraft-Based Eulerian and Lagrangian Sampling of a Changing Arctic

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WHAT IS SIZRS?
Seasonal Ice Zone Reconnaissance Surveys (SIZRS) is a multi-investigator program of repeated ocean, ice, and atmospheric measurements to track and better understand sea ice change.These measurements make use of U.S. Coast Guard flights across the Seasonal Ice Zone (SIZ), the region between maximum winter ice extent and minimum summer ice extent in the Beaufort Sea.The project started in 2012, with current funding through 2023.
We fly once each month from June to October with US Coast Guard Air Station Kodiak C-130s along longitude 150°W (and when possible along 140ºW) from 72°N to 76°N or ~ 1 degree of latitude north of the ice edge, whichever is farther north.Scientific activities include: Aircraft eXpendable CTDs (AXCTDs) and Aircraft eXpendable Current Profilers (AXCPs) provide ocean temperature, salinity, and shear over the upper 1000 m and are dropped every 1 degree of latitude, typically while traveling northbound (PIs: Morison & Guthrie PIs: Morison & Guthrie).
Surface-drifting UpTempO buoys are also dropped that report time series of ocean temperature profiles over the upper 25 or 60 m (shallow sensor string buoys are deployed for drifting onto ths shelf); some also report salinity (PI: Steele PI: Steele).
Surface-drifting ice buoys are also dropped that provide surface meteorological variables and ice motion (PI: PI: Rigor Rigor).
On the return leg, we drop atmospheric dropsondes from 3000 meters altitude to measure atmospheric temperature, humidity, and winds (PIs: Science support is provided by PSC/APL/UW field engineers R. Andersen and J. Johnson.We fly in collaboration with other projects, e.g. Deployment of expendable ocean profilers via NOAA/PMEL's Arctic Heat project (PIs: K. Wood & S. PIs: K. Wood & S. Jayne Jayne).
Our typical sampling program in plan view: Our typical sampling program in cross section:

Ice:
Ice-based drifting buoys are deployed during SIZRS north of Alaska, complementing similar buoys deployed in the Arctic Seas.These generally measure sea level pressure, air or snow temperature, and ice motion.The data are sent in real time to the Global Telecommunications System for use in weather and climate forecasting.

Atmospheric profiles:
Low )Banzon et al. (2020)  found that the very popular global gridded Sea Surface Temperature (SST) data set OISST was providing overly warm values under the Arctic Ocean sea ice during summer.This was the result of a lack of in situ observations which SIZRS UpTempO buoys now provide.With these observations, new algorithms were developed and implemented in OISSTv2.1 that provide more realistic SSTs under the ice and in the Marginal Ice Zone (MIZ).Ocean buoys2:Fournier et al. (2019)Fournier et al. (2019)  found that satellite-derived sea surface salinity (SSS) bias and error relative to in situ observations (including SIZRS UpTempO buoys) increased at even very small sea ice concentrations (< 3%).However, Tang et al. (2021) Tang et al. (2021) have developed a new algorithm that holds promise for increasing the accuracy of satellite SSS closer to the ice edge.Ocean profiling1: Guthrie & Morison (2021) Guthrie & Morison (2021) found that vertical wavenumber spectra of horizontal kinetic energy were similar for SIZRS (2012-present) and AIWEX (1985) data, indicating that subsurface internal wave energy has not declined in recent years.They found that the main reason for low internal wave energy was NOT declining sea ice, but rather the thin surface mixed layer and the low value of planetary beta (the meridional gradient of the Coriolis parameter).Further, surface stratification is expected to increase in the future owing to an enhanced global hydrologic cycle, while beta is fixed.Thus, internal wave energy in the Arctic Ocean is expected to remain low in the future, even as the sea ice cover declines.Ocean profiling2: Hall et al. (2021) Hall et al. (2021) compared sea surface salinity from satellite, model, ocean reanalysis, and observed gridded hydrographic data sets with SIZRS AXCTD 5 m salinity.While some correlations were very good, more work is clearly needed to validate these data sets.
-level wind jets (LLJs) and strong surface winds are frequently observed near the sea ice edge in the presence of strong thermal contrast between open water and sea ice.Liu and Schweiger (2019)   Liu and Schweiger (2019) used SIZRS observations to find that sea ice strengthens the LLJ by extending it northward, increasing maximum wind speeds by up to 13% and as much as 29% further north at a lower altitude.However, the primary reason for enhanced winds is synoptic interactions between anticyclones and approaching cyclones.The effect of the surface thermal contrast on surface winds is controlled by a separate mechanism.The cold and stable boundary layer over sea ice prevents the momentum transport from the LLJ to the surface.This leads to weaker surface winds over sea ice and confines the strong surface winds close to the sea ice edge.This mechanism contributes to the frequent occurrence of surface "ice edge jets."References: Liu, Z., & Schweiger, A. (2019).Low-level and surface wind jets near sea ice edge in the Beaufort Sea in late autumn.Journal of Geophysical Research: Atmospheres, 124, 6873-6891.https://doi.org/10.1029/2018JD029770THE FUTURE SIZRS to the Makarov Basin: Plans for 2022 and beyond include a new annual flight to the Makarov Basin, a poorly sampled area that lies in a newly described center of action for dynamic ocean topography (Morison et al., 2021).More collaboration with the international ICEPPR aircraft surveys are also planned.Technology development: Next-generation UpTempO buoy development: integration with surface wave observations (new co-PI J. Thomson, APL/UW) Next-generation AXCTD/AXCP with frazil ice hardening for use in shoulder seasons (spring, fall).Remote sensing (lidar, IR, radar) Closer ties with modeling: Data to the GTS for forecasting Collaboration with NOAA and ONR daily/seasonal forecasters.Closer ties with satellite and UAV remote sensing: ICESat-2 underflights Oliktok Point overflights SIZRS is sponsored by the Office of Naval Rsearch, USA.Questions?Mike Steele: mas@apl.washington.., Kwok, R., Dickinson, S., Andersen, R., Peralta-Ferriz, C., Morison, D., Rigor, I., Dewey, S., & Guthrie, J. (2021).The Cyclonic Mode of Arctic Ocean Circulation, Journal of Physical Oceanography, 51(4), 1053-1075.Retrieved Dec 15, 2021, from https://journals.ametsoc.org/view/journals/phoc/51/4/JPO-D-20-0190.1.xml