Global warming is most pronounced in the Arctic, and the Arctic sea ice cover is a sensitive climate indicator. Multiyear ice is important because it differs from first-year in physical and biological respects. The total sea ice extent and area can be determined quite reliably from space, however until now observation of the area covered with multiyear ice poses much more difficulties. Especially the intra-annual development cannot be determined unambiguously: while according to scatterometer observations, the multiyear sea ice area decreases during the freezing season (from October to March), it increases if detected with passive microwave sensors which is physically not possible. The goal of this work is to establish a consistent and reliable time series of the Arctic multiyear sea ice with radiometers and scatterometers observatios, best from 1978 onwards.

Start of doctoral thesis: 01st October, 2011

Defence of doctoral thesis: 01st July, 2016 (view thesis)

Supervisor: Justus Notholt
Co-Supervisor: Georg Heygster
Further members: to be definded

Committee Meetings: 30.10.12, 17.10.13

• Ye, Y., Shokr, M., Heygster, G., Spreen, G., Improving multiyear ice concentration estimates with ice drift, MicroRad (Microwave Radiometry and Remote Sensing of the Environment) meeting 2016, Espoo, Finland, 11-14 April 2016 (Poster).

• Ye, Y., Heygster, G., Shokr, M., and Spreen, G., Improving multiyear ice concentration estimates with reanalysis air temperatures and ice drift, AGU (American Geophysical Union) Fall meeting 2015, San Francisco, USA, 14-18 December 2015 (Poster).

• Ye, Y., Heygster, G., and Shokr, M., Improving multiyear ice concentration retrieval with atmospheric data, IGARSS (International Geoscience and Remote Sensing Symposium) 2015, Milan, Italy, 26 - 31 July 2015 (Oral).

• Ye, Y., Heygster, G., and Shokr, M., Improving multiyear ice concentration retrieval with passive microwave and atmospheric model data, Open Seminar on Remote Sensing of Sea Ice and Climate Change Research, Beijing, China, 7 May 2015 (Oral).

• Ye, Y., Heygster, G., and Shokr, M., Improving multiyear ice concentration retrieval from passive microwave and atmospheric model data, International Sea Ice Concentration and Thickness Evaluation and Inter-comparison Workshop, Hamburg, Germany, 18 – 19 September 2014 (Poster).

• Ye, Y., Detection of multiyear sea ice from satellite observations, IUP-AWI block seminar: Ice-Ocean interaction, Bremerhaven, Germany, 29 July 2014 (Oral).

• Ye, Y., and Heygster, G., Arctic multiyear ice concentration retrieval with SSM/I data: A comparison of two techniques, AGU Fall Meeting 2012, San Francisco, USA, 3 - 7 December 2012 (Poster).

• Ye, Y. et al. (2012): Arctic multiyear ice concentration retrieval with SSM/I data: A comparison of two techniques. Helmholtz Research School on Earth System Science, Annual Retreat 2012, “Deutsches Auswandererhaus“, Bremerhaven, Germany, 30 November 2012 (Poster).

• Ye, Y., Cheng, X., Li, X., Liang, L., and Heygster, G., Monitoring Antarctic ice sheet melting periods with SSM/I 19H GHz data and time series analysis, IGARSS 2012 Symposium, Munich, Germany, 22 - 27 July 2012 (Poster).

 Used Software/Utilities/Programming languages: MATLAB, IDL, C, ArcGIS, ENVI

• Ye, Y., Shokr, M., Heygster, G., and Spreen, G. (2016). Improving multiyear sea ice concentration estimates with sea ice drift. Remote Sensing, 8(5), 397.

• Ye, Y., Heygster, G., and Shokr, M. (2016). Improving multiyear ice concentration estimates with air temperatures. IEEE Transactions on Geoscience and Remote Sensing, 54(5), 2602 - 2614.

• Ye, Y., and Heygster, G. (2015). Arctic multiyear ice concentration retrieval from SSM/I data using the NASA Team algorithm with dynamic tie points. In Towards an Interdisciplinary Approach in Earth System Science (pp. 99-108). Springer International Publishing.