An enhancement to sea ice motion and age products at the National Snow and Ice Data Center (NSIDC)

Abstract

Abstract. A new version of sea ice motion and age products includes several significant upgrades in processing, corrects known issues with the previous version, and updates the time series through 2018, with regular updates planned for the future. First, we provide a history of these NASA products distributed at the National Snow and Ice Data Center. Then we discuss the improvements to the algorithms, provide validation results for the new (Version 4) and older versions, and intercompare the two. While Version 4 algorithm changes were significant, the impact on the products is relatively minor, particularly for more recent years. The changes in Version 4 reduce motion biases by ∼ 0.01 to 0.02 cm s−1 and error standard deviations by ∼ 0.3 cm s−1. Overall, ice speed increased in Version 4 over Version 3 by 0.5 to 2.0 cm s−1 over most of the time series. Version 4 shows a higher positive trend for the Arctic of 0.21 cm s−1 per decade compared to 0.13 cm s−1 per decade for Version 3. The new version of ice age estimates indicates more older ice than Version 3, especially earlier in the record, but similar trends toward less multiyear ice. Changes in sea ice motion and age derived from the product show a significant shift in the Arctic ice cover, from a pack with a high concentration of older ice to a sea ice cover dominated by first-year ice, which is more susceptible to summer melt. We also observe an increase in the speed of the ice over the time series ≥ 30 years, which has been shown in other studies and is anticipated with the annual decrease in sea ice extent.

Reassessing Sea Ice Drift and Its Relationship to Long‐Term Arctic Sea Ice Loss in Coupled Climate Models

“…Several observational data sets are used to evaluate the CMIP5 models. For computing observed sea ice drift speed, we use daily drift velocity point measurements from the International Arctic Buoy Program (IABP) covering the period 1979–2015, as provided within the archive for the Polar Pathfinder data set (Tschudi et al, ). Since the IABP data are point measurements, care is required when comparing to gridded climate model output.…”

Towards a swath-to-swath sea-ice drift product for the Copernicus Imaging Microwave Radiometer mission

“…All block-based motion tracking algorithms need such a quality control step (e.g. Girard-Ardhuin and Haarpaintner, 2006;Tschudi et al 2020), but most authors remove the rogue vectors and the vector field has missing data cells. The quality control step of Lavergne et al (2010) both detects the questionable vectors and -most of the time-corrects them, reducing the occurrence of data gaps.…”

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

“…The CMST sea ice thickness and drift data can be download from https://doi.org/10.1594/PANGAEA.891475 (Mu et al, 2018b) and https://doi.org/10.1594/PANGAEA.906973 (Mu et al, 2019), respectively. The Polar Pathfinder Daily 25km EASE-Grid sea ice drift data are released by the National Snow and Ice Data Center (NSIDC, https://nsidc.org/data/nsidc-0116/versions/4, Tschudi et al, 2019;Tschudi et al, 2020). The PIOMAS sea ice thickness data are available at http://psc.apl.uw.edu/research/projects/arctic-sea-icevolume-anomaly/data/model_grid (Zhang and Rothrock, 2003).…”

“…The Polar Pathfinder Daily 25 km EASE-Grid sea ice drift data (V4) from NSIDC are used to calculate SIV fluxes because it contains year-round date for the time period investigated. The AVHRR, AMSR-E, SMMR, SSM/I, SSM/I, International Arctic Buoy Program (IABP) buoys observations and reanalysis wind data are integrated to derive the NSIDC sea ice motion (Tschudi et al, 2019;Tschudi et al, 2020). The NSIDC SID data are chosen as a reference to evaluate model ice drift and they are applied to calculate the sea ice flux, since they cover the time span from 2011 to 2016 including summer seasons.…”