National Institute of Polar Research, Research Organization of Information and Systems, Kaga +-chome, Itabashi-ku, Tokyo +1-2/+/.

Transcript

1 165 Scientific Note + + +, -,. / Characteristics of sea ice thickness and snow depth distributions of the land-fast ice during summer in Lützow-Holmbukta, Antarctica, revealed from ship-based observations Shotaro Uto +, Haruhito Shimoda +, Koh Izumiyama +, Shuki Ushio,, Shigeru Aoki -, Gen Hashida,, Hiroyuki Wakabayashi. and Fumihiko Nishio /,**. / +* ;,**. 1 1 Abstract: Sea ice observations have been conducted onboard the Antarctic Research Vessel Shirase since The authors summarize these data to investigate spatial and inter-annual variability of sea ice thickness and snow depth of the summer land-fast ice in Lützow-Holmbukta. Probability density functions of annual total thickness (ice thickness snow depth) derived from video observations are categorized into two types, i.e. a thin-ice and a thick-ice type. The total thickness distributions observed by the electro-magnetic inductive method have a clear discontinuity, which reflects the past break-up of the land-fast ice. Thin first-year ice develops o#shore of this location, while multi-year ice mostly develops onshore. Ice thickness and snow depth gradually decrease toward the coast within about,* km o#shore, probably due to snow drift driven by the strong northeasterly wind. It is concluded that the past breakup of the land-fast ice as well as snow depth have dominant influence on the spatial distribution of ice thickness in Lützow-Holmbukta. The extent of break-up varies significantly year by year. The smaller extent enhances the development of thick multi-year ice, while the larger extent, coupled with the influence of snow drift, enhances reduction or extinction of thick multi-year ice. + National Maritime Research Institute, Shinkawa, Mitaka-shi, Tokyo +2+ ***.., National Institute of Polar Research, Research Organization of Information and Systems, Kaga +-chome, Itabashi-ku, Tokyo +1-2/+/. - Institute of Low Temperature Science, Hokkaido University, Kita-+3, Nishi-2, Kita-ku, Sapporo *0* *2+3.. Earth Observation Research and Application Center, Japan Aerospace Exploration Agency, + 2 +* Harumi, Chuo-ku, Tokyo +*. 0*,-. / Center for Environmental Remote Sensing, Chiba University, + -- Yayoi, Inage, Chiba,0-2/,,., Vol..2, No.-, +0/ +13,,**. Nankyoku Shiryô (Antarctic Record), Vol..2, No.-, +0/ +13,,**.,**. National Institute of Polar Research

2 166 :,* km NOAA AVHRR +. Comiso et al.,,**- JARE, ; +331.,,*** *+ EM Uto et al.,,**- EM Kovacs and Morey, +33+, Worby et al., +333 Kovacs and Holladay, +33* Haas, +332, Haas et al., +333 EM,.., +

3 167 EM EM +330 EM, EM EM--+ ICE, Geonics H p Fig Sea ice monitoring system onboard the Antarctic research vessel Shirase. Fig.,., EM Principle of the electro-magnetic inductive observation of total thickness of sea ice.

4 168 H s imaginary part s a: apparent conductivity H S s.*** a,pm * fs Im, H P + m * f s s a Z E,**- Z E b * b +ln s a b, b * +*.30/ b b,,./0+1, LD3*--+**HS, Riegl Z L, Z I Haas et al *., m Worby et al *.0 *.2 m +* -*.* + 1 m. / m , , + +, - 1.

5 !"ῌ#$%&'()+,-.:; ῌ + EM EM Photo +. Setup of EM Instruments. The EM and the laser distance sensor are contained in the wooden frame. +!"ῌ#$%&'() *)+,-. / Table +. Summary of the video observations of total thickness and snow depth of land-fast ice in Lu tzow-holmbukta. 169

6 * -, Fig. -. The outward-voyage tracks of Shirase in the land-fast ice in Lützow-Holmbukta. Seven tracks, for JARE-*, -,, -3,.+,.,,.- and.., are plotted.. Fig... Probability density functions of the total thickness of land-fast ice in Lützow-Holmbukta derived from video observations during the outward voyage.

7 171 / Fig. /. Distribution of total thickness and snow depth of the land-fast ice in Lützow-Holmbukta in (a) Leg-+, (b) Leg-, and (c) Leg-- derived from video observations during the outward voyage.,3 -* ,., *.2 +., m -,,.,,.. m., +.2,.* m.+...

8 172 / Fig. /. Distribution of total thickness and snow depth of the land-fast ice in Lützow-Holmbukta in (a) Leg-+, (b) Leg-, and (c) Leg-- derived from video observations during the outward voyage Continued. / - -3., , Leg-+ -,., Leg-,

9 173 0 Fig. 0. Scatter-plot between snow depth and total thickness of the land-fast ice in Lützow-Holmbukta derived from video observations during the outward voyage. Leg-- 03.* Snow depth *.,* Total Thickness, R, * Snow depth *.,* *.+/ Total Thickness. -.,. EM.,.-., *.+ 1 +* EM

10 174 1 EM Fig. 1. Distribution of total thickness of land-fast ice in Lützow-Holmbukta in (a) Leg-+, (b) Leg-, and (c) Leg-- derived from EM observations during the outward voyage. Those obtained by the video method are plotted for comparison. EM EM EM 2 EM EM 3* +330

11 175 2 EM a b Fig. 2. Comparison of total thicknesses between EM and drill-hole observations at (a) Ongul Strait and (b) o# Benten-jima. EM EM.. EM 1., 02.2, -2.2,.. 03.*0-3.,0 / -, ,**- NOAA AVHRR 3 a +33* 0 b,*** 0 c,**, 0 NOAA AVHRR 3a b -,., 0 0 / 1 3c..

12 $%&'() 176 ῌ 3 NOAA ῌ AVHRR ῌ a +33* 0 b,*** 0 c,**, 0!"# Fig. 3. NOAA/AVHRR images which show the break-up of land-fast ice in Lu tzow-holmbukta in (a) June, +33*, (b) June,,*** and (c) June,,**,.

13 177 snow ice superimposed ice Kawamura et al., +331 Kawamura et al * km /b 1b /a b., -3.,,* km,**- +* Fig. +*. Schematic view of distributions of ice thickness and snow depth of the summer land-fast ice along the track of Shirase in Lützow-Holmbukta.

14 178 +*., , m. *., *.+/ *.. *.- m,* km,* km 1,. m. *.. *.- m *.2 *.0 m /.,* km NOAA

15 / Comiso, J.C., Yang, J., Honjo, S. and Krishfield, R.A. (,**-): Detection of change in the Arctic using satellite and in situdata. J. Geophys. Res., +*2(C+,), --2., doi: +*.+*,3/,**,JC**+-.1. Haas, C. (+332): Evaluation of ship-based electromagnetic-inductive thickness measurements of summer sea-ice in the Bellingshausen and Amundsen Seas, Antarctica. Cold Regions Sci. Technol.,,1, Haas, C., Rupp, K.-H. and Uuskallio, A. (+333): Comparison of along track EM ice thickness profiles with ship performance data. Proc. the +/th Intl. Conf. Port and Ocean Eng. under Arctic Conditions, +, -.- -/ : / Kawamura, T., Ohshima, K.I., Takizawa, T. and Ushio, S. (+331): Physical, structural and isotopic characteristics and growth process of fast sea ice in Lützow-Holm Bay, Antarctica. J. Geophys. Res., +*, (C,), --./ --//. Kovacs A. and Holladay J.S. (+33*): Sea ice thickness measurement using a small airborne electromagnetic sounding system. Geophysics., //, +-, Kovacs A. and Morey R.M. (+33+): Evaluation of a portable electromagnetic induction instrument for measuring sea ice thickness. CRREL Rep., 3+ +,, : ++ +/0 +0* :.+ -// -0/.,**- : +32*,** Uto, S., Shimoda, H. and Izumiyama, K. (,**-): Sea ice thickness and snow depth distribution of the summer land-fast ice in Lützow-Holm Bay, East Antarctica. Proc. the +1th Intl. Conf. Port and Ocean Eng. under Arctic Conditions, +, +1/ +2-. Worby, A.P., Gri$n, P.W., Lytle, V.I. and Massom, R.A.(+333): On the use of electromagnetic induction sounding to determine winter and spring sea ice thickness in the Antarctic. Cold Regions Sci. Technol.,,3,.3 /2.