Microwave Radiation Characteristics of Glacial Ice Observed by AMSR-E Hyangsun Han and Hoonyol Lee Kangwon National University, KOREA

Contents Introduction Study Area and Data Method Radiation Characteristics of Glacial Ice Conclusion

Introduction Glacial Ice Originated from fresh water (snow) Glaciers, Icebergs, Ice sheets, and Ice shelves Air bubbles are small enough to cause Rayleigh scattering Crystal size is very large because of slow recrystallization The GLACIAL ICE has different radiation characteristics from SEA ICE frozen from salty water Importance of glacial ice study Glacial ice changes coastal landform and environment of sea ice formation

Introduction Passive Microwave Sensor widely used to study the polar ice - sea ice concentration, snow depth, ice extent, … high temporal resolution, low spatial resolution AMSR-E is a typical passive microwave sensor Objective of study Evaluation of accuracy of glacial ice on AMSR-E sea ice concentration in George V Coast, Southern Antarctica Analysis of microwave radiation characteristics of glacial ice

Study Area Radarsat-1 mosaic image of the Antarctic George V Coast Southern Antarctica

ASAR Data and AMSR-E NT2 SIC Data SIC 100% 50% Ice sheet masked in AMSR-E NT2 SIC Two ENVISAT ASAR Images Wide Swath SLC/HH polarization 2006/04/20, 2006/04/26 AMSR-E L1 data products Brightness temperature, sea ice concentration 2006/04/20, 2006/04/26 ENVISAT ASAR image of the study area (2006/04/26, 100 km×100 km) AMSR-E sea ice concentration of the study area (2006/04/26, 100 km×100 km) Ice sheet

Identification of Ice Type in ASAR Most sea surface was covered with ice Several icebergs A ice tongue Distinction between sea ice and ice shelf is difficult by only ASAR data Ice sheet Icebergs Ice tongue Sea ice (new ice) ENVISAT ASAR image of the study area (2006/04/26, 100 km×100 km)

2006/04/ /02/192005/12/ /02/022004/03/082003/02/23 MODIS Imagery MODIS time-series images - A region of ice shelf is confirmed

Comparing ASAR SIC with AMSR-E SIC SIC 100% 50% Ice sheet masked in AMSR-E NT2 SIC Ice shelf Icebergs Sea ice Ice shelf Icebergs Sea ice Ice sheet

ASAR Ice Concentration Masking inland in ASAR images using land mask product of AMSR-E Classifying ice type into sea ice, icebergs, and ice shelf by supervised classification and digitizing Overall accuracy: 97.4% and 94.4% in each ASAR image Calculating ice concentration of sea ice, icebergs, and ice shelf Comparing with AMSR-E sea ice concentration

AMSR-E Sea Ice Algorithm AMSR-E 6.9, 10.7, 18.7, 23.8, 36.5, and 89.0 GHz dual polarized channels Daily sea ice concentration with 12.5 km spatial resolution by using NASA Team2 Algorithm NASA Team2 Algorithm Better spatial resolution and accuracy of sea ice concentration than NASA Team Algorithm Identifies Ice type A, B, C, and open water by data plotting in PR and GR domain (Cavalieri et al., 1997)

Comparing ASAR SIC with AMSR-E SIC Difference between ASAR and AMSR-E SIC Sea ice: very small difference (RMSE 1.4%) Icebergs: AMSR-E NT2 SIC was underestimated (RMSE 29.5%) Ice shelf: AMSR-E NT2 SIC was underestimated (RMSE 23.3%) → analysis of microwave radiation characteristics of the glacial ice in PR and GR domain is needed

PR(18)-GR(37V18V) Scattergram Sea iceIcebergsIce shelf PR(18) GR(37V18V)

GR(89H18H)-GR(89V18V) Scattergram Sea iceIcebergsIce shelf GR(89H18H) GR(89V18V) Ice type A-B line 100% Ice type A 100% Ice type B Open water 100% Ice type C

Conclusions We evaluated AMSR-E NASA Team2 sea ice concentration in Antarctic glacial ice region AMSR-E NT2 algorithm is very accurate in sea ice region We found that AMSR-E NASA Team2 algorithm underestimates ice concentration in icebergs and ice shelf Glacial ice has higher PR(18), GR(37V18V), GR(89V18V), and GR(89H18H) than those of sea ice Microwave radiation characteristics of glacial ice are quite different from that of sea ice and open water

Ongoing Study Analysis of radiation characteristics of microwave from glacial ice in various seasons and regions Improvement of the accuracy of AMSR-E NASA Team2 sea ice concentration by adding glacial ice concentration (GIC) GIC can be used for -Improvement of land mask product from AMSR-E NASA Team2 algorithm -Icebergs tracking -Monitoring of coastal landform change by movement of glacial ice