An advanced methodology for the detection and quantification of the ice-free period in the Arctic coastal zone is proposed. Ice-free period (IFP) dynamics is analyzed in the Kara Sea coastal zone near "Marresalya" and "Amderma" stations using long-term satellite data about sea ice concentrations. In a new method an advanced approach for defining the IFP characteristics (starting/ending dates and duration) was applied in addition to the conventional use of 15% sea ice concentration threshold. We provide estimates of the mean statistics and linear trends in the IFP characteristics using three long-term satellite-based sea ice concentration datasets: OSI SAF, NSIDC, JAXA and compare them to the estimates based upon direct observations on stations. Mean IFP durations and ending dates as well as linear trends derived from satellite data show a close comparability with observations with differences ranging within 2-7 days for IFP durations and within 0.01-0.05 days/year for IFP ending date trends. At the same time, strong deviations were found for both mean and long-term trends of the IFP starting dates, specifically showing negative trends in the satellite-derived starting dates which is not confirmed by observations. This results in a moderate agreement on trend estimates in IFP durations between satellite data and observations, while the mean characteristics are in a very good agreement and implies the necessity of more careful look onto representativeness of satellite data in the near-coastal zone during the onset season.
Ice-free period; open water season, sea ice concentration, arctic coastal zone, climate change
1. Barnhart, K., I. Overeem, R. Anderson (2014) , The effect of changing sea ice on the physical vulnerability of Arctic coasts, Cryosphere, 8, p. 1777-1799, https://doi.org/10.5194/tc-8-1777-2014
2. Cavalieri, D., P. Gloersen, W. Campbell (1984) , Determination of sea ice parameters with the NIMBUS 7 SMMR, J. Geophys. Res., 89, no. D4, p. 5355-5369, https://doi.org/10.1029/JD089iD04p05355
3. Comiso, J., H. Zwally (1984) , Concentration gradients and growth/decay characteristics of the seasonal sea ice cover, Journal of Geophysical Research: Oceans, 89, no. C5, p. 8081-8103, https://doi.org/10.1029/JC089iC05p08081
4. Comiso, J. (1986) , Characteristics of arctic winter sea ice from satellite multispectral microwave observations, Journal of Geophysical Research, 91, no. C1, p. 975-994, https://doi.org/10.1029/JC091iC01p00975
5. Dmitrenko, I., K. Tyshko, et al. (2005) , Impact of flaw polynyas on the hydrography of the Laptev Sea, Global Planet. Change, 48, p. 9-27, https://doi.org/10.1016/j.gloplacha.2004.12.016
6. Farquharson, L. M., D. H. Mann, et al. (2018) , Temporal and spatial variability in coastline response to declining sea-ice in northwest Alaska, Marine Geology, 404, p. 71-83, https://doi.org/10.1016/j.margeo.2018.07.007
7. Groisman, P., et al. (2017) , Northern Eurasia Future Initiative (NEFI): facing the challenges and pathways of global change in the twenty-first century, Progress in Earth and Planetary Science, 4, p. 41, https://doi.org/10.1186/s40645-017-0154-5
8. JASMES JAXA Satellite Monitoring for Environmental Studies. Polar Climate data (Sea Ice Concentration and Sea Ice Extent from 1978 to the present (2019)), JAXA. ftp://apollo.eorc.jaxa.jp/pub/JASMES/Polar _XXkm/ic0/climate/
9. Howell, S., C. Duguay, T. Markus (2009) , Sea ice conditions and melt season duration variability within the Canadian Arctic Archipelago: 1979-2008, Geophysical Research Letters, 36, p. 10, https://doi.org/10.1029/2009GL037681
10. Khon, V., I. Mokhov, et al. (2010) , Perspectives of Northern Sea Route and Northwest Passage in the twenty-first century, Climatic Change, 100, no. 3-4, p. 757-768, https://doi.org/10.1007/s10584-009-9683-2
11. Lavergne, T., A. M. Sorensen, et al. (2019) , Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records, Cryosphere, 13, p. 49-78, https://doi.org/10.5194/tc-13-49-2019
12. Meier, W., J. Stroeve (2008) , Comparison of sea-ice extent and ice-edge location estimates from passive microwave and enhanced-resolution scatterometer data, Annals of Glaciology, 48, p. 65-70, https://doi.org/10.3189/172756408784700743
13. Meier, W. N., F. Fetterer, M. Savoie, et al. (2017) , NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 3, NSIDC: National Snow and Ice Data Center, Boulder, Colorado USA, https://doi.org/10.7265/N59P2ZTG ([G02202], 04.03.2020)
14. Ogorodov, S., A. Baranskaya, et al. (2016) , Coastal dynamics of the pechora and kara seas under changing climatic conditions and human disturbances, Geography, Environment, Sustainability, 9, no. 3, p. 53-73, https://doi.org/10.15356/2071-9388_03v09_2016_04
15. OSI SAF, (2017) , Global Sea Ice Concentration Climate Data Record v2.0 - Multimission, EUMETSAT SAF on Ocean and Sea Ice, Norwegian and Danish Meteorological Institutes, https://doi.org/10.15770/EUM_SAF_OSI_0008 (Online)
16. Peng, G., W. N. Meier, et al. (2013) , A long-term and reproducible passive microwave sea ice concentration data record for climate studies and monitoring, Earth Syst. Sci. Data, 5, p. 311-318, https://doi.org/10.5194/essd-5-311-2013
17. Peng, G., M. Steele, A. Bliss, et al. (2018) , Temporal Means and Variability of Arctic Sea Ice Melt and Freeze Season Climate Indicators Using a Satellite climate data record, Remote Sens., 10, p. 1328, https://doi.org/10.3390/rs10091328
18. Reimnitz, E., D. Dethleff, D. Nürnberg (1994) , Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea, Marine Geology, 119, p. 215-225, https://doi.org/10.1016/0025-3227(94)90182-1
19. Shabanov, P. A., N. N. Shabanova (2019) , Open Water Season Changes Over the Kara Sea Coastal Zone: Marresalya Example, IEEE International Geoscience and Remote Sensing Symposium, p. 4218-4221, IGARSS, Yokohama, Japan, https://doi.org/10.1109/IGARSS.2019.8900056
20. Stroeve, J., T. Markus, et al. (2006) , Recent changes in the Arctic melt season, Annals of Glaciology, 44, p. 367-374, https://doi.org/10.3189/172756406781811583
